WO2005114755A2 - Tellurides having novel property combinations - Google Patents

Tellurides having novel property combinations Download PDF

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WO2005114755A2
WO2005114755A2 PCT/EP2005/005345 EP2005005345W WO2005114755A2 WO 2005114755 A2 WO2005114755 A2 WO 2005114755A2 EP 2005005345 W EP2005005345 W EP 2005005345W WO 2005114755 A2 WO2005114755 A2 WO 2005114755A2
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telluride
thermoelectric
peltier
thermoelectric generator
tellurides
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PCT/EP2005/005345
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German (de)
French (fr)
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WO2005114755A3 (en
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Hans-Josef Sterzel
Klaus KÜHLING
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Basf Aktiengesellschaft
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B19/00—Selenium; Tellurium; Compounds thereof
    • C01B19/002—Compounds containing, besides selenium or tellurium, more than one other element, with -O- and -OH not being considered as anions
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B19/00—Selenium; Tellurium; Compounds thereof
    • C01B19/007—Tellurides or selenides of metals
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
    • H10N10/80—Constructional details
    • H10N10/85—Thermoelectric active materials
    • H10N10/851—Thermoelectric active materials comprising inorganic compositions
    • H10N10/852—Thermoelectric active materials comprising inorganic compositions comprising tellurium, selenium or sulfur
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
    • H10N10/80—Constructional details
    • H10N10/85—Thermoelectric active materials
    • H10N10/851—Thermoelectric active materials comprising inorganic compositions
    • H10N10/855—Thermoelectric active materials comprising inorganic compositions comprising compounds containing boron, carbon, oxygen or nitrogen
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/50—Solid solutions
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/40—Electric properties

Definitions

  • the present invention relates to tellurides as semiconductor material, thermoelectric generators and Peltier arrangements containing them, processes for producing these semiconductor materials, their use in thermoelectric generators or Peltier arrangements and a method for increasing the Seebeck coefficient and / or the electrical conductivity of thermoelectrically active ones tellurides.
  • thermoelectric generators and Peltier arrangements as such have long been known, p- and n-doped semiconductors, which are heated on one side and cooled on the other side, transport electrical charges through an external circuit. These thermoelectric generators can be used to perform electrical work on a consumer in the circuit. Peltier arrangements reverse the previously described thermoelectric process.
  • thermoelectric effects and materials are given e.g. Cronin B. Vining, "ITS Short Course on Thermoelectricity", November 8, 1993, Yokohama, Japan, “1997 Proceedings, Sixteenth International Conference on Thermoelectrics (ICT),” CRC Handbook of Thermoelectrics “, CRC-Press 1995 and” Materials Research Society Symposium Proceedings Volume 545: Thermoelectric Materials 1998 - The next generation materials for small-scale refrigeration and power generation applications ".
  • thermoelectric generators are used in space probes and satellites to generate direct currents, to protect pipelines against cathodic corrosion, to supply lighting and radio buoys for energy, to operate radios and televisions, and as a cooling unit in cool bags.
  • the advantages of thermoelectric generators and Peltier arrangements are their high reliability: They work independently of atmospheric conditions such as air humidity; there is no mass transport susceptible to malfunction, only a charge transport; the fuel is burned continuously - even catalytically without a free flame - which only releases small amounts of carbon monoxide, nitrogen oxides and unburned fuel; any operating materials can be used, from hydrogen to natural gas, petrol, kerosene, diesel fuel to biologically produced fuels such as rapeseed oil methyl ester.
  • the thermoelectric energy conversion adapts extremely flexibly to future needs such as hydrogen economy or energy generation from renewable energies.
  • thermoelectrically active materials are essentially assessed on the basis of their efficiency.
  • Z factor (figure of merit) is characteristic of thermoelectric materials:
  • Thermoelectric materials are preferred which have the lowest possible thermal conductivity, the highest possible electrical conductivity and the highest possible Seebeck coefficient, so that the figure of merit assumes the highest possible value.
  • the dimensionless product Z • T is often given for comparison purposes.
  • Previously known thermoelectric materials have maximum values of Z • T of approximately 1 at an optimal temperature. Beyond this optimal temperature, the values of Z • T are often lower than 1.
  • Materials such as Bi 2 Te 3 or PbTe currently embody the best available technology.
  • thermoelectric materials that have a suitable band gap.
  • thermoelectric materials that have only a small band gap are undesirable because they degenerate or become intrinsic under the selected conditions, with a simultaneous increase in the electrical and thermal conductivity of the material. This increase has a negative impact on the figure of merit.
  • the bandgaps of thermoelectric materials should not be too large, since otherwise the energy required to lift an electron into a conduction band is too large.
  • Bi 2 Te 3 is mainly used at low temperatures in Peltier coolers because it has the most favorable values for Z • T in this temperature range.
  • PbTe is a typical material for generators.
  • thermoelectric generators or pellet arrangements with a telluride as the thermoelectrically active semiconductor material is then characterized in that a substituted semiconductor material is used in which the positively polarized atoms of the crystal lattice of the telluride are partially substituted by silicon and / or germanium.
  • a typical composition of a material in this sense is e.g. B. PbTe ⁇ (Si 2 Te 3 ) o, o ⁇ .
  • “partial” means a degree of substitution with preferably 0.002 to 0.05, particularly preferably 0.003 to 0.02, in particular 0.008 to 0.013, per mole of formula unit telluride.
  • thermoelectric materials with improved thermoelectric properties.
  • the unsubstituted tellurides are generally tellurides known per se.
  • the metal Me carries formally positive charges (positively polarized), which means that the tellurium is negatively polarized.
  • an electron density is transferred from the metal to the tellurium, corresponding to the form ⁇ + ⁇ - Me a Te b .
  • thermoelectric materials with a high degree of efficiency (figure of merit) are obtained.
  • the thermoelectrically active semiconductor material contains lead and / or bismuth atoms as positively polarized atoms which are partially substituted by silicon and / or germanium.
  • This preferably gives the empirical formula Bi 2 Te 3 and / or PbTe for the telluride in unsubstituted form.
  • lead and / or bismuth as positively polarized atoms of the unsubstituted telluride, it is surprising that it is possible to introduce silicon or germanium into the telluride host lattice as positively polarized atoms, since known phase diagrams teach that no binary compounds are formed Bismuth or lead with silicon or germanium exist.
  • the compounds Si 2 Te 3 , GeTe or mixtures are formed as a result of the partial substitution of the positively polarized metal atoms within the crystal lattice of the telluride.
  • the stoichiometry of these compounds does not have to be maintained as such in the thermoelectrically active semiconductor material. However, it turned out to be preferred.
  • effects can also be found if other stoichiometries, for example SiTe or SiTe 2 , are generated in the resulting telluride.
  • a substituted telluride of the general formula (I) results for the semiconductor material of the thermoelectric generator or the Peltier arrangement
  • Me Bi and / or Pb
  • the preferred concentration of the “misfits” produced in the telluride crystal lattice is through
  • Misfit compounds dissolve at least partially in the telluride guest grille.
  • This solubility depends on the composition of the guest grid and cannot be determined in advance. However, it has turned out to be particularly preferred if this
  • the electrical conductivity of the substituted telluride is significantly increased. It is preferably at least 50%, particularly preferably at least 100%, in particular at least 130%, especially at least 150%, of the electrical conductivity of the correspondingly unsubstituted telluride.
  • the present tellurides can be used without further doping. Alternatively, they can also be doped. If the tellurides are doped, the proportion of doping elements is preferably up to 0.1 atom% (10 18-10 19 atoms per cubic centimeter of semiconductor material), particularly preferably up to 0.05 atom%, in particular up to 0.01 Atom-%. Higher carrier concentrations cause disadvantageous recombinations and thus a reduced mobility of the carriers. It is doped with elements that cause an excess or deficit of electrons in the crystal lattice. Suitable doping metals for p-semiconductors are, for example, the following elements: lithium, Sodium, potassium, magnesium, calcium, strontium, barium and aluminum. Suitable doping metals for n-semiconductors are the elements chlorine, bromine and iodine.
  • the conduction type can be converted into the opposite by doping.
  • the present invention also relates to the semiconductor materials (tellurides) described above and to processes for their production.
  • the tellurides according to the invention are generally produced by reacting the individual elements at temperatures above the melting temperature of the resulting tellurides. If all the individual components have melted below the reaction temperature and the reaction temperature is above the melting temperature of the tellurides produced, generally short reaction times of 0.1 to 5 hours, in particular 0.5 to 3, especially 1 to 2, are required. If the reaction temperature is below the melting temperature of the components with the highest melting point, this must be solved by the melt already present, which generally requires increased reaction times of 5 to 120 hours, in particular 10 to 100, especially 60 to 90.
  • the melting is generally carried out under an inert gas atmosphere, preferably an inert gas such as argon.
  • an inert gas such as argon.
  • Si 2 Te 3 is used as a constituent, a preferred embodiment results from the fact that the compound Si 2 Te 3 is prepared in a separate, upstream process step and the reactant in the telluride formation is not separated from silicon and tellurium, but as a finished compound Si 2 Te 3 , which melts at 885 ° C, begins. In this way it can be avoided that the dissolution of the small portions of the silicon melting at 1410 ° C. takes a long time.
  • This procedure is suitable for all tellurides according to the invention in which an individual element has a higher melting point than the other individual elements and / or as the resulting telluride.
  • Another embodiment of the method according to the invention thus results from the implementation of binary telluride precursor compounds of the individual elements, optionally in combination with the remaining individual element.
  • Furnaces are preferably used to melt the individual components
  • Crucible material is inert at the reaction temperatures used. Quartz is preferably used; Graphite is preferably used if none of the components forms carbides at the specified reaction temperatures. For example, graphite is wise in the presence of silicon at temperatures below 1400 ° C as a crucible material, because under these conditions no silicon carbide forms yet.
  • thermodynamically less preferred or metastable phases and element distributions can be obtained.
  • tellurides according to the invention are produced by a sintering process, it is preferred to use a hydrogen-containing atmosphere or pure hydrogen during the sintering in order to remove oxide layers which can be reduced with hydrogen during the process. If a hydrogen-containing atmosphere is used, the hydrogen content should preferably be at least 1% by volume.
  • the finished contours are also produced in the sintering process, preferably avoiding sawing of the melted material, which could lead to breakage or cracking.
  • the final contours are produced by pressing before sintering and the “cuboids” produced in this way are sintered separately. A separation after sintering is not necessary.
  • the assembly of the individual semiconductor cuboids to form usable modules is carried out according to the prior art, for example according to US 5,817,188 AI. Care must, however, be taken to ensure that components of the contact materials do not diffuse into the semiconductors and vice versa that semiconductor components do not diffuse into the contact materials.
  • Suitable contact materials are inert contact materials such as nickel, chromium, titanium, titanium diboride or copper, which is coated with nickel, chromium, titanium or titanium diboride, or nickel-phosphorus alloys such as nickel-phosphide.
  • the present invention relates to a method for increasing the Seebeck coefficient and / or the electrical conductivity of thermoelectrically active tellurides of the formula PbTe and / or Bi 2 Te 3 by partial substitution of the lead or bismuth atoms by silicon and / or germanium.
  • the semiconductor materials described above are formed here.
  • Another object of the present invention is the use of the semiconductor material described above in thermoelectric generators and or Peltier arrangements.
  • the semiconductor material according to the invention is suitable for use in thermoelectric generators or Peltier arrangements in clothes dryers.
  • Another object of the present invention is accordingly a tumble dryer with at least one thermoelectric module, containing a thermoelectric generator according to the invention and / or a Peltier arrangement according to the invention, via which a laundry material to be dried is heated directly or indirectly and the water vapor produced during drying is directly cooled become.
  • a tube furnace was used to temper the samples, which was moved up and down around the transverse axis with a period of approx. 2 min for better mixing of the components or the melt.
  • the heating rate was 300 ° C / h to the final temperature.
  • the samples were left at 1,000 ° C for 4 hours and then allowed to cool uncontrollably at an initial cooling rate of 400 ° C / h.
  • n-conducting PbTe was taken from a commercially available high-performance module of a thermoelectric generator for comparison measurement.
  • the Seebeck coefficient S was determined as the average Seebeck coefficient in the temperature range from 30 ° C to 130 ° C.
  • the electrical conductivity was determined more realistically than in the literature, namely also in the Seebeck experiment, while the cold side was kept at 30 ° C and the hot side at 130 ° C.
  • the measure of the electrical conductivity results from the quotient of short-circuit current and open circuit voltage, the short-circuit current being measured with very low resistance using a measuring instrument with an internal resistance of 0.035 ⁇ .
  • the error in the measurement of the open circuit voltage was ⁇ 2%, that in the measurement of the short-circuit current was ⁇ 20%.

Abstract

The invention relates to thermoelectric generators or Peltier arrays which comprise a telluride as the thermoelectrically active semiconducting element. The inventive generators or Peltier arrays are characterized in that the positively polarized atoms of the crystal lattice of the telluride are partially replaced by silicon and/or germanium.

Description

Telluride mit neuen Eigenschaftskombinationen Telluride with new property combinations
Die vorliegende Erfindung betrifft Telluride als Halbleitermaterial, diese enthaltende thermoelektrische Generatoren und Peltier-Anordnungen, Verfahren zur Herstellung dieser Halbleitermaterialien, deren Verwendung in thermoelektrischen Generatoren oder Peltier- Anordnungen sowie ein Verfahren zur Erhöhung des Seebeck-Koeffizienten und/oder der elektrischen Leitfähigkeit von thermoelektrisch aktiven Telluriden.The present invention relates to tellurides as semiconductor material, thermoelectric generators and Peltier arrangements containing them, processes for producing these semiconductor materials, their use in thermoelectric generators or Peltier arrangements and a method for increasing the Seebeck coefficient and / or the electrical conductivity of thermoelectrically active ones tellurides.
Thermoelektrische Generatoren und Peltier-Anordnungen als solche sind seit langem bekannt, p- und n-dotierte Halbleiter, die auf einer Seite erhitzt und auf der anderen Seite gekühlt werden, transportieren elektrische Ladungen durch einen äußeren Stromkreis. Durch diese thermoelektrischen Generatoren kann an einem Verbraucher im Stromkreis elektrische Arbeit verrichtet werden. Peltier-Anordnungen kehren den zuvor beschriebenen thermoelektrischen Prozess um.Thermoelectric generators and Peltier arrangements as such have long been known, p- and n-doped semiconductors, which are heated on one side and cooled on the other side, transport electrical charges through an external circuit. These thermoelectric generators can be used to perform electrical work on a consumer in the circuit. Peltier arrangements reverse the previously described thermoelectric process.
Einen guten Überblick über thermoelektrische Effekte und Materialien gibt z.B. Cronin B. Vining, „ITS Short Course on Thermoelectricity", 8. November 1993, Yokohama, Japan, „1997 Proceedings, Sixteenth International Conference on Thermoelectrics (ICT), „CRC Handbook of Thermoelectrics", CRC-Press 1995 und „Materials Research Society Symposium Proceedings Volume 545: Thermoelectric Materials 1998 - The next generation mate- rials for small-scale refrigeration and power generation applications".A good overview of thermoelectric effects and materials is given e.g. Cronin B. Vining, "ITS Short Course on Thermoelectricity", November 8, 1993, Yokohama, Japan, "1997 Proceedings, Sixteenth International Conference on Thermoelectrics (ICT)," CRC Handbook of Thermoelectrics ", CRC-Press 1995 and" Materials Research Society Symposium Proceedings Volume 545: Thermoelectric Materials 1998 - The next generation materials for small-scale refrigeration and power generation applications ".
Gegenwärtig werden thermoelektrische Generatoren in Raumsonden und Satelliten zur Erzeugung von Gleichströmen, zum kathodischen Korrosionsschutz von Pipelines, zur Energieversorgung von Leucht- und Funkbojen, zum Betrieb von Radios und Fernsehapparaten sowie als Kühlaggregat in Kühltaschen eingesetzt. Die Vorteile von thermoelektrischen Generatoren und Peltier-Anordnungen liegen dabei in ihrer hohen Zuverlässigkeit: So arbeiten sie unabhängig von atmosphärischen Bedingungen wie Luftfeuchte; es erfolgt kein störungsanfälliger Stofftransport, sondern nur ein Ladungstransport; der Betriebsstoff wird kontinuierlich - auch katalytisch ohne freie Flamme - verbrannt, wodurch nur geringe Mengen an Kohlenmonoxid, Stickoxiden und unverbranntem Betriebsstoff frei werden; es sind beliebige Betriebsstoffe einsetzbar, von Wasserstoff über Erdgas, Benzin, Kerosin, Dieselkraftstoff bis zu biologisch erzeugten Kraftstoffen wie Rapsölmethylester. Damit passt sich die thermoelektrische Energiewandlung äußerst flexibel in künftige Bedürfnisse wie Wasserstoffwirtschaft oder Energieerzeugung aus regenerativen Energien ein.Currently, thermoelectric generators are used in space probes and satellites to generate direct currents, to protect pipelines against cathodic corrosion, to supply lighting and radio buoys for energy, to operate radios and televisions, and as a cooling unit in cool bags. The advantages of thermoelectric generators and Peltier arrangements are their high reliability: They work independently of atmospheric conditions such as air humidity; there is no mass transport susceptible to malfunction, only a charge transport; the fuel is burned continuously - even catalytically without a free flame - which only releases small amounts of carbon monoxide, nitrogen oxides and unburned fuel; any operating materials can be used, from hydrogen to natural gas, petrol, kerosene, diesel fuel to biologically produced fuels such as rapeseed oil methyl ester. Thereby, the thermoelectric energy conversion adapts extremely flexibly to future needs such as hydrogen economy or energy generation from renewable energies.
Thermoelektrisch aktive Materialien werden im Wesentlichen anhand ihres Wirkungsgrades bewertet. Kennzeichnend für thermoelektrische Materialien ist diesbezüglich der so genannte Z-Faktor (figure of merit):Thermoelectrically active materials are essentially assessed on the basis of their efficiency. In this regard, the so-called Z factor (figure of merit) is characteristic of thermoelectric materials:
Z = KZ = K
mit dem Seebeck-Koeffizienten S (μV/Grad), der elektrischen Leitfähigkeit σ (Ω"1 • cm"1) und der Wärmeleitfähigkeit K (mW/cm • Grad). Bevorzugt werden thermoelektrische Materialien, die eine möglichst geringe Wärmeleitfähigkeit, eine möglichst große elektrische Leitfähigkeit und einen möglichst großen Seebeck-Koeffizienten aufweisen, sodass der fi- gure of merit einen möglichst hohen Wert annimmt.with the Seebeck coefficient S (μV / degree), the electrical conductivity σ (Ω "1 • cm " 1 ) and the thermal conductivity K (mW / cm • degree). Thermoelectric materials are preferred which have the lowest possible thermal conductivity, the highest possible electrical conductivity and the highest possible Seebeck coefficient, so that the figure of merit assumes the highest possible value.
Zu Vergleichszwecken wird darüber hinaus oftmals das dimensionslose Produkt Z • T angegeben. Bisher bekannte thermoelektrische Materialien weisen maximale Werte von Z • T von ungefähr 1 bei einer optimalen Temperatur auf. Jenseits dieser optimalen Temperatur sind die Werte von Z • T oft niedriger als 1. Den optimalen Stand der Technik verkörpern zurzeit Materialien wie Bi2Te3 oder PbTe.In addition, the dimensionless product Z • T is often given for comparison purposes. Previously known thermoelectric materials have maximum values of Z • T of approximately 1 at an optimal temperature. Beyond this optimal temperature, the values of Z • T are often lower than 1. Materials such as Bi 2 Te 3 or PbTe currently embody the best available technology.
Dass sich diese Telluride sich als thermoelektrische Materialien eignen, liegt ferner daran, dass sie eine geeignete Bandlücke aufweisen. So sind thermoelektrische Materialien, die nur eine geringe Bandlücke aufweisen, unerwünscht, da sie unter den gewählten Bedingungen leicht degenerieren bzw. intrinsisch werden, wobei es zu einem gleichzeitigen Anstieg der elektrischen und thermischen Leitfähigkeit des Materials kommt. Dieser Anstieg wirkt sich negativ auf den figure of merit aus. Gleichzeitig sollten die Bandlücken von thermoelektrischen Materialien auch nicht zu groß sein, da andernfalls die Energie, die erforderlich ist, um ein Elektron in ein Leitungsband zu heben, zu groß ist.The fact that these tellurides are suitable as thermoelectric materials is also due to the fact that they have a suitable band gap. For example, thermoelectric materials that have only a small band gap are undesirable because they degenerate or become intrinsic under the selected conditions, with a simultaneous increase in the electrical and thermal conductivity of the material. This increase has a negative impact on the figure of merit. At the same time, the bandgaps of thermoelectric materials should not be too large, since otherwise the energy required to lift an electron into a conduction band is too large.
In diesen Halbleitermaterialien werden Bismut häufig mit einem geringen Anteil von Antimon und Blei mit einem geringen Anteil von Zinn legiert. Ferner hat es sich als vorteilhaft herausgestellt, wenn das verwendete Tellur mit geringen Anteilen an Selen legiert ist. Mit diesen, sehr sorgfältig optimierten Legierungen kann die Wärmeleitfähigkeit der Halblei- termaterialien weiter erniedrigt werden als die elektrische Leitfähigkeit, sodass ein höheres Z • T erhalten wird.In these semiconductor materials, bismuth is often alloyed with a small amount of antimony and lead with a small amount of tin. It has also proven to be advantageous if the tellurium used is alloyed with small amounts of selenium. With these very carefully optimized alloys, the thermal conductivity of the semi- term materials are further reduced than the electrical conductivity, so that a higher Z • T is obtained.
Bi2Te3 wird hauptsächlich bei niedrigen Temperaturen in Peltier-Kühlern eingesetzt, weil es in diesem Temperaturbereich die günstigsten Werte für Z • T aufweist. PbTe ist dagegen ein typisches Material für Generatoren.Bi 2 Te 3 is mainly used at low temperatures in Peltier coolers because it has the most favorable values for Z • T in this temperature range. PbTe, on the other hand, is a typical material for generators.
Trotz intensiver Forschung haben jedoch bis jetzt kaum neue Materialien Eingang in die praktische Anwendung gefunden; dort werden bisher im Wesentlichen die bekannten Tellu- ride eingesetzt.Despite intensive research, hardly any new materials have found their way into practical use; So far, the well-known Telluride have been used there.
Gelänge es nunmehr, jeweils im Anwendungstemperaturbereich ein Z • T von 2 oder größer zu erhalten, so stünden weitere Einsatzgebiete offen. So könnte beispielsweise Solarenergie über Spiegelkonzentratoren mit Wirkungsgraden größer 20 % ohne bewegte Teile direkt zu elektrischem Strom umgesetzt werden. Andererseits könnte man wirtschaftlicher als gegenwärtig Fahrzeuge und Wohnungen wartungsfrei bzw. -arm im Sommer kühlen und mit der gleichen Vorrichtung im Winter heizen.If it were now possible to obtain a Z • T of 2 or greater in the application temperature range, further areas of application would be open. For example, solar energy could be converted directly to electrical current via mirror concentrators with efficiencies greater than 20% without moving parts. On the other hand, it would be more economical to cool vehicles and apartments maintenance-free or low-maintenance in summer and to heat them in winter with the same device.
Daher bestand für die vorliegende Erfindung die Aufgabe, Halbleitermaterialien zu finden, die bei einem engen Bandabstand zwischen Valenz- und Leitungsband möglichst hohe Seebeck-Koeffizienten bei gleichzeitg hoher elektrischer Leitfähigkeit und niedriger Wärmeleitfähigkeit aufweisen.It was therefore an object of the present invention to find semiconductor materials which, with a narrow band gap between the valence band and the conduction band, have the highest possible Seebeck coefficients with high electrical conductivity and low thermal conductivity.
Erfindungsgemäß wird diese Aufgabe gelöst durch thermoelektrische Generatoren oder Pel- tier-Anordnungen mit einem Tellurid als thermoelektrisch aktives Halbleitermaterial. Der thermoelektrische Generator oder die Peltier-Anordnung ist dann dadurch gekennzeichnet, dass ein substituiertes Halbleitermaterial eingesetzt wird, in dem die positiv polarisierten Atome des Kristallgitters des Tellurids partiell durch Silizium und/oder Germanium substituiert sind. Eine typische Zusammensetzung eines Materials in diesem Sinne ist z. B. PbTe ■ (Si2Te3)o,oι. Unter „partiell" wird im Sinne der vorliegenden Erfindung ein Substitutionsgrad mit vorzugsweise 0,002 bis 0,05, besonders bevorzugt 0,003 bis 0,02, insbesondere 0,008 bis 0,013, pro Mol Formeleinheit Tellurid verstanden.According to the invention, this object is achieved by thermoelectric generators or pellet arrangements with a telluride as the thermoelectrically active semiconductor material. The thermoelectric generator or the Peltier arrangement is then characterized in that a substituted semiconductor material is used in which the positively polarized atoms of the crystal lattice of the telluride are partially substituted by silicon and / or germanium. A typical composition of a material in this sense is e.g. B. PbTe ■ (Si 2 Te 3 ) o, oι. For the purposes of the present invention, “partial” means a degree of substitution with preferably 0.002 to 0.05, particularly preferably 0.003 to 0.02, in particular 0.008 to 0.013, per mole of formula unit telluride.
Erfindungsgemäß ist somit vorgesehen, dass man die positiv polarisierten Atome des Kristallgitters von Telluriden, die vorzugsweise bereits ausgeprägte thermoelektrische Eigen- scharten aufweisen, partiell durch Silizium und/oder Germanium ersetzt. Hierdurch ergeben sich thermoelektrische Materialien mit verbesserten thermoelektrischen Eigenschaften. Bei den nicht-substituierten Telluriden handelt es sich im Allgemeinen um an sich bekannte Telluride.It is therefore provided according to the invention that the positively polarized atoms of the crystal lattice of tellurides, which preferably already have pronounced thermoelectric characteristics, are partially replaced by silicon and / or germanium. This results in thermoelectric materials with improved thermoelectric properties. The unsubstituted tellurides are generally tellurides known per se.
Durch die partielle Substitution der positiv polarisierten Atome in dem Kristallgitter des Tellurids durch Silizium und/oder Germanium bildet sich, ohne an eine Theorie gebunden zu sein, ein elektronischer „Misfϊt" in dem Kristallgitter des thermoelektrischen Halbleitermaterials. In den Telluriden der FormDue to the partial substitution of the positively polarized atoms in the crystal lattice of the telluride by silicon and / or germanium, an electronic “defect” is formed in the crystal lattice of the thermoelectric semiconductor material, without being bound to any theory. In the tellurides of the form
MeaTeb Me a Te b
trägt das Metall Me formal positive Ladungen (positiv polarisiert), wodurch das Tellur negativ polarisiert ist. Hierdurch wird eine Elektronendichte vom Metall auf das Tellur übertragen, entsprechend der Form δ+ δ- Mea Teb.the metal Me carries formally positive charges (positively polarized), which means that the tellurium is negatively polarized. As a result, an electron density is transferred from the metal to the tellurium, corresponding to the form δ + δ- Me a Te b .
Dadurch, dass man nunmehr durch die erfindungsgemäße partielle Substitution der positiv polarisierten Metallatome Me durch Silizium und oder Germanium „Misfits" in das Tellu- ridkristallgitter einführt, werden thermoelektrische Materialien mit einem hohen Wirkungs- grad (figure of merit) erhalten.By now introducing “misfits” into the telluride crystal lattice through the partial substitution of the positively polarized metal atoms Me by silicon and or germanium according to the invention, thermoelectric materials with a high degree of efficiency (figure of merit) are obtained.
In einer bevorzugten Ausführungsform der vorliegenden Erfindung enthält das thermoelektrisch aktive Halbleitermaterial als positiv polarisierte Atome, die durch Silizium und/oder Germanium partiell substituiert sind, Blei und/oder Bismutatome. Damit ergibt sich für das Tellurid in nicht-substituierter Form vorzugsweise die Summenformel Bi2Te3 und/oder PbTe. Insbesondere bei der Verwendung von Blei und/oder Bismut als positiv polarisierte Atome des nicht substituierten Tellurides ist es überraschend, dass es gelingt, Silizium oder Germanium als positiv polarisierte Atome in das Tellurid- Wirtsgitter einzubringen, da bekannte Phasendiagramme lehren, dass keine binären Verbindungen aus Bismut oder Blei mit Silizium oder Germanium existieren.In a preferred embodiment of the present invention, the thermoelectrically active semiconductor material contains lead and / or bismuth atoms as positively polarized atoms which are partially substituted by silicon and / or germanium. This preferably gives the empirical formula Bi 2 Te 3 and / or PbTe for the telluride in unsubstituted form. Particularly when using lead and / or bismuth as positively polarized atoms of the unsubstituted telluride, it is surprising that it is possible to introduce silicon or germanium into the telluride host lattice as positively polarized atoms, since known phase diagrams teach that no binary compounds are formed Bismuth or lead with silicon or germanium exist.
In einer bevorzugten Ausführungsform der vorliegenden Erfindung bilden sich durch die partielle Substitution der positiv polarisierten Metallatome innerhalb des Kristallgitters der Tellurids die Verbindungen Si2Te3, GeTe oder Mischungen. Die Stöchiometrie dieser Ver- bindungen muss nicht als solche in dem thermoelektrisch aktiven Halbleitermaterial eingehalten werden. Sie hat sich jedoch als bevorzugt herausgestellt. Die erfindungsgemäßen Effekte sind jedoch auch dann zu finden, wenn andere Stöchiometrien, beispielsweise SiTe oder SiTe2 in dem resultierenden Tellurid erzeugt werden.In a preferred embodiment of the present invention, the compounds Si 2 Te 3 , GeTe or mixtures are formed as a result of the partial substitution of the positively polarized metal atoms within the crystal lattice of the telluride. The stoichiometry of these compounds does not have to be maintained as such in the thermoelectrically active semiconductor material. However, it turned out to be preferred. The invention However, effects can also be found if other stoichiometries, for example SiTe or SiTe 2 , are generated in the resulting telluride.
In einer besonders bevorzugten Ausführungsform der vorliegenden Erfindung ergibt sich somit für das Halbleitermaterial des thermoelektrischen Generators oder der Peltier- Anordnung ein substituiertes Tellurid der allgemeinen Formel (I)In a particularly preferred embodiment of the present invention, a substituted telluride of the general formula (I) results for the semiconductor material of the thermoelectric generator or the Peltier arrangement
(MeaTeb)1-x (Si2Te3, GeTe, SiTe, SiTe2)x (I)(Me a Te b ) 1-x (Si 2 Te 3 , GeTe, SiTe, SiTe 2 ) x (I)
mitWith
Me = Bi und/oder Pb, x = 0,002 bis 0,05, vorzugsweise 0,003 bis 0,02, besonders bevorzugt 0,008 bis 0,013, und a, b = 1 bis 3.Me = Bi and / or Pb, x = 0.002 to 0.05, preferably 0.003 to 0.02, particularly preferably 0.008 to 0.013, and a, b = 1 to 3.
Die bevorzugte Konzentration der im Telluridkristallgitter erzeugten „Misfits" ist durchThe preferred concentration of the “misfits” produced in the telluride crystal lattice is through
Versuche zu ermitteln. Entscheidend für die Konzentration von Misfit- Verbindungen ist, dass sich die Misfit- Verbindungen zumindest teilweise im Gastgitter des Tellurids lösen.Attempts to determine. It is crucial for the concentration of Misfit compounds that the Misfit compounds dissolve at least partially in the telluride guest grille.
Diese Löslichkeit hängt von der Zusammensetzung des Gastgitters ab und lässt sich nicht im Voraus bestimmen. Es hat sich jedoch als besonders bevorzugt herausgestellt, wenn dieseThis solubility depends on the composition of the guest grid and cannot be determined in advance. However, it has turned out to be particularly preferred if this
Konzentration ungefähr 1 % beträgt.Concentration is approximately 1%.
Die elektrische Leitfähigkeit des substituierten Tellurids ist deutlich erhöht. Sie beträgt vorzugsweise mindestens 50 %, besonders bevorzugt mindestens 100 %, insbesondere mindes- tens 130 %, speziell mindestens 150 %, der elektrischen Leitfähigkeit des entsprechend nicht substituierten Tellurids.The electrical conductivity of the substituted telluride is significantly increased. It is preferably at least 50%, particularly preferably at least 100%, in particular at least 130%, especially at least 150%, of the electrical conductivity of the correspondingly unsubstituted telluride.
Die vorliegenden Telluride können ohne weitere Dotierung eingesetzt werden. Alternativ können sie aber auch zusätzlich dotiert sein. Wenn die Telluride dotiert sind, so beträgt der Anteil an Dotierungselementen vorzugsweise bis zu 0,1 Atom-% (1018 - 1019 Atome pro Kubikzentimeter Halbleitermaterial), besonders bevorzugt bis zu 0,05 Atom-%, insbesondere bis zu 0,01 Atom-%. Höhere Ladungsträgerkonzentrationen bewirken nachteilige Rekombinationen und damit eine reduzierte Ladungsträgerbeweglichkeit. Dotiert wird mit Elementen, die einen Elektronenüber- oder -unterschuss im Kristallgitter bewirken. Geeig- nete Dotiermetalle für p-Halbleiter sind beispielsweise die folgenden Elemente: Lithium, Natrium, Kalium, Magnesium, Kalzium, Strontium, Barium und Aluminium. Geeignete Dotiermetalle für n-Halbleiter sind die Elemente Chlor, Brom und Jod.The present tellurides can be used without further doping. Alternatively, they can also be doped. If the tellurides are doped, the proportion of doping elements is preferably up to 0.1 atom% (10 18-10 19 atoms per cubic centimeter of semiconductor material), particularly preferably up to 0.05 atom%, in particular up to 0.01 Atom-%. Higher carrier concentrations cause disadvantageous recombinations and thus a reduced mobility of the carriers. It is doped with elements that cause an excess or deficit of electrons in the crystal lattice. Suitable doping metals for p-semiconductors are, for example, the following elements: lithium, Sodium, potassium, magnesium, calcium, strontium, barium and aluminum. Suitable doping metals for n-semiconductors are the elements chlorine, bromine and iodine.
Durch Dotieren lässt sich der Leitungstyp in das Gegenteil überführen.The conduction type can be converted into the opposite by doping.
Die vorliegende Erfindung betrifft darüber hinaus die zuvor beschriebenen Halbleitermaterialien (Telluride) sowie Verfahren zu ihrer Herstellung.The present invention also relates to the semiconductor materials (tellurides) described above and to processes for their production.
Die erfindungsgemäßen Telluride werden im Allgemeinen durch Reaktion der Einzelele- mente bei Temperaturen oberhalb der Schmelztemperatur der resultierenden Telluride hergestellt. Sind dabei alle Einzelkomponenten unterhalb der Reaktionstemperatur aufgeschmolzen und liegt die Reaktionstemperatur oberhalb der Schmelztemperatur der erzeugten Telluride, so sind im Allgemeinen kurze Reaktionszeiten von 0,1 bis 5 Stunden, insbesondere 0,5 bis 3, speziell 1 bis 2, erforderlich. Liegt die Reaktionstemperatur unterhalb der Schmelztemperatur der am höchsten schmelzenden Komponenten, so muss diese durch die bereits vorhandene Schmelze gelöst werden, was im Allgemeinen erhöhte Reaktionszeiten von 5 bis 120 Stunden, insbesondere 10 bis 100, speziell 60 bis 90, erfordert.The tellurides according to the invention are generally produced by reacting the individual elements at temperatures above the melting temperature of the resulting tellurides. If all the individual components have melted below the reaction temperature and the reaction temperature is above the melting temperature of the tellurides produced, generally short reaction times of 0.1 to 5 hours, in particular 0.5 to 3, especially 1 to 2, are required. If the reaction temperature is below the melting temperature of the components with the highest melting point, this must be solved by the melt already present, which generally requires increased reaction times of 5 to 120 hours, in particular 10 to 100, especially 60 to 90.
Das Aufschmelzen wird im Allgemeinen unter einer inerten Gasatmosphäre, vorzugsweise eines Edelgases wie Argon, durchgeführt. Wird Si2Te3 als Bestandteil eingesetzt, so ergibt sich eine bevorzugte Ausführungsform dadurch, dass man die Verbindung Si2Te3 in einem gesonderten, vorgelagerten Verfahrensschritt herstellt und als Reaktand bei der Telluridbil- dung nicht Silizium und Tellur getrennt, sondern als fertige Verbindung Si2Te3, das bereits bei 885 °C schmilzt, einsetzt. Hierdurch kann vermieden werden, dass das Auflösen der geringen Anteile des bei 1410 °C schmelzenden Siliziums geraume Zeit beansprucht. Diese Verfahrensweise bietet sich bei allen erfindungsgemäßen Telluriden an, bei denen ein Einzelelement einen höheren Schmelzpunkt als die anderen Einzelelemente und/oder als das resultierende Tellurid aufweist. Damit ergibt sich eine weitere Ausführungsform des erfindungsgemäßen Verfahrens dadurch, dass eine Umsetzung von binären Telluridvorläuferver- bindungen der Einzelelemente, gegebenenfalls in Kombination mit dem verbleibenden Einzelelement, durchgeführt wird.The melting is generally carried out under an inert gas atmosphere, preferably an inert gas such as argon. If Si 2 Te 3 is used as a constituent, a preferred embodiment results from the fact that the compound Si 2 Te 3 is prepared in a separate, upstream process step and the reactant in the telluride formation is not separated from silicon and tellurium, but as a finished compound Si 2 Te 3 , which melts at 885 ° C, begins. In this way it can be avoided that the dissolution of the small portions of the silicon melting at 1410 ° C. takes a long time. This procedure is suitable for all tellurides according to the invention in which an individual element has a higher melting point than the other individual elements and / or as the resulting telluride. Another embodiment of the method according to the invention thus results from the implementation of binary telluride precursor compounds of the individual elements, optionally in combination with the remaining individual element.
Zum Aufschmelzen der Einzelkomponenten werden vorzugsweise Öfen verwendet, derenFurnaces are preferably used to melt the individual components
Tiegelmaterial bei den verwendeten Reaktionstemperaturen inert ist. Vorzugsweise wird Quarz eingesetzt; Grafit wird vorzugsweise verwendet, wenn keine der Komponenten bei den angegebenen Reaktionstemperaturen Carbide bildet. So eignet sich Graphit beispiels- weise in Gegenwart von Silizium bei Temperaturen unterhalb von 1400 °C als Tiegelmaterial, weil sich unter diesen Bedingungen noch kein Siliziumcarbid bildet.Crucible material is inert at the reaction temperatures used. Quartz is preferably used; Graphite is preferably used if none of the components forms carbides at the specified reaction temperatures. For example, graphite is wise in the presence of silicon at temperatures below 1400 ° C as a crucible material, because under these conditions no silicon carbide forms yet.
Je nach Material kann es vorteilhaft sein, die Schmelze mit bestimmten Abkühlgeschwin- digkeiten abzukühlen, um thermische Spannungen in den meist spröden Materialien zu minimieren oder um für die Anwendung optimale Korngrößen in den Materialien zu erzielen. Dazu kann es vorteilhaft sein, besonders definiert und langsam einzelne Temperaturstufen zu durchlaufen. Bei anderen Materialien kann ein Abschrecken z. B. in Eiswasser, gefolgt von einer Temperaturbehandlung unterhalb des Schmelzpunkts (sog. Tempern) vorteilhaft sein. Dadurch können thermodynamisch wenig bevorzugte oder metastabile Phasen und Elementverteilungen erhalten werden.Depending on the material, it can be advantageous to cool the melt at certain cooling speeds in order to minimize thermal stresses in the mostly brittle materials or to achieve optimum grain sizes in the materials for the application. For this purpose, it can be advantageous to run through individual temperature levels in a particularly defined and slow manner. For other materials, quenching e.g. B. in ice water, followed by a temperature treatment below the melting point (so-called. Annealing) may be advantageous. Thereby, thermodynamically less preferred or metastable phases and element distributions can be obtained.
Es ist auch möglich, das Material nach dem Abkühlen zu einem Pulver zu zerkleinern und das erhaltene Pulver in Formen unter Druck zu kompaktieren und die Kompaktate unterhalb ihrer Schmelztemperatur entweder unter Druck oder drucklos zu Formkörpern genügender Festigkeit zu sintern.It is also possible to comminute the material into a powder after cooling and to compact the powder obtained in molds under pressure and to sinter the compacts below their melting temperature either under pressure or without pressure to give moldings of sufficient strength.
In einem ebenfalls anwendbaren Verfahren ist es möglich, die Einzelelemente in Form von Pulvern mit Korngrößen vorzugsweise unterhalb 50 μm, besonders bevorzugt unter 25 μm, homogen zu mischen, unter Druck zu kompaktieren und die Kompaktate unterhalb der Schmelztemperatur der Zielverbindung zu sintern. Dieses Verfahren setzt jedoch voraus, dass die eingesetzten Pulver möglichst frei von störenden Oxidschichten sind, was beispielsweise durch Handhabung unter Schutzgas sowie Reduktionsschritte unter Wasserstoff erreicht wird.In a method which can also be used, it is possible to homogeneously mix the individual elements in the form of powders with particle sizes preferably below 50 μm, particularly preferably below 25 μm, to compact them under pressure and to sinter the compactates below the melting temperature of the target compound. However, this method assumes that the powders used are as free as possible from disruptive oxide layers, which is achieved, for example, by handling under protective gas and reducing steps under hydrogen.
Wenn man die erfindungsgemäßen Telluride über einen Sinterprozess herstellt, so ist es bevorzugt, dass man während des Sinterns eine wasserstoffhaltige Atmosphäre oder reinen Wasserstoff einsetzt, um während des Prozesses mit Wasserstoff reduzierbare Oxid- schichten zu entfernen. Falls man eine wasserstoffhaltige Atmosphäre verwendet, so sollte der Wasserstoffgehalt vorzugsweise mindestens bei 1 Vol.-% liegen. In dem Sinterverfahren werden auch die fertigen Endkonturen hergestellt, wobei man ein Sägen des erschmolzenen Materials, das zu Brüchen oder Rissbildung führen könnte, vorzugsweise vermeidet.If the tellurides according to the invention are produced by a sintering process, it is preferred to use a hydrogen-containing atmosphere or pure hydrogen during the sintering in order to remove oxide layers which can be reduced with hydrogen during the process. If a hydrogen-containing atmosphere is used, the hydrogen content should preferably be at least 1% by volume. The finished contours are also produced in the sintering process, preferably avoiding sawing of the melted material, which could lead to breakage or cracking.
In einer weiteren bevorzugten Ausführungsform werden die Endkonturen vor dem Sintern durch Pressen hergestellt und die so hergestellten „Quaderchen" getrennt gesintert. Ein Trennen nach dem Sintern ist dabei nicht erforderlich. Das Assemblieren der einzelnen Halbleiterquader zu einsetzbaren Modulen erfolgt nach dem Stand der Technik, beispielsweise gemäß US 5,817,188 AI. Es muss dabei jedoch Sorge getragen werden, dass es nicht zu einer Diffusion von Bestandteilen der Kontaktmaterialien in die Halbleiter und umgekehrt zu einer Diffusion von Halbleiterbestandteilen in die Kontaktmaterialien kommt. Geeignete Kontaktmaterialien sind inerte Kontaktmaterialien wie Nickel, Chrom, Titan, Titandiborid oder Kupfer, welches mit Nickel, Chrom, Titan oder Titandiborid beschichtet ist, oder Nickel-Phosphor-Legierungen wie Nickel-Phosphid.In a further preferred embodiment, the final contours are produced by pressing before sintering and the “cuboids” produced in this way are sintered separately. A separation after sintering is not necessary. The assembly of the individual semiconductor cuboids to form usable modules is carried out according to the prior art, for example according to US 5,817,188 AI. Care must, however, be taken to ensure that components of the contact materials do not diffuse into the semiconductors and vice versa that semiconductor components do not diffuse into the contact materials. Suitable contact materials are inert contact materials such as nickel, chromium, titanium, titanium diboride or copper, which is coated with nickel, chromium, titanium or titanium diboride, or nickel-phosphorus alloys such as nickel-phosphide.
Darüber hinaus betrifft die vorliegende Erfindung ein Verfahren zur Erhöhung des Seebeck- Koeffizienten und/oder der elektrischen Leitfähigkeit von thermoelektrisch aktiven Telluriden der Formel PbTe und/oder Bi2Te3 durch partielle Substitution der Blei- oder Bismutatome durch Silizium und/oder Germanium. Hierbei bilden sich die zuvor beschriebenen Halbleitermaterialien.In addition, the present invention relates to a method for increasing the Seebeck coefficient and / or the electrical conductivity of thermoelectrically active tellurides of the formula PbTe and / or Bi 2 Te 3 by partial substitution of the lead or bismuth atoms by silicon and / or germanium. The semiconductor materials described above are formed here.
Weiterer Gegenstand der vorliegenden Erfindung ist die Verwendung des oben beschriebenen Halbleitermaterials in thermoelektrischen Generatoren und oder Peltier-Anordungen.Another object of the present invention is the use of the semiconductor material described above in thermoelectric generators and or Peltier arrangements.
Insbesondere eignet sich das erfindungsgemäße Halbleitermaterial zur Verwendung in thermoelektrischen Generatoren oder Peltier-Anordungen in Wäschetrocknern.In particular, the semiconductor material according to the invention is suitable for use in thermoelectric generators or Peltier arrangements in clothes dryers.
Weiterer Gegenstand der vorliegenden Erfindung ist demnach ein Wäschetrockner mit mindestens einem thermoelektrischen Modul, enthaltend einen erfindungsgemäßen thermoelektrischen Generator und/oder eine erfindungsgemäße Peltier-Anordnung, über den ein zu trocknendes Wäschematerial direkt oder indirekt aufgeheizt und der bei der Trocknung an- fallende Wasserdampf direkt abgekühlt werden.Another object of the present invention is accordingly a tumble dryer with at least one thermoelectric module, containing a thermoelectric generator according to the invention and / or a Peltier arrangement according to the invention, via which a laundry material to be dried is heated directly or indirectly and the water vapor produced during drying is directly cooled become.
Die vorliegende Erfindung wird anhand der nachfolgend geschilderten Beispiele näher erläutert.The present invention is explained in more detail with reference to the examples described below.
BeispieleExamples
Sämtliche Synthesen wurden in evakuierten Quarzröhrchen von 10 mm Durchmesser und 1 mm Wandstärke durchgeführt.All syntheses were carried out in evacuated quartz tubes with a diameter of 10 mm and a wall thickness of 1 mm.
Zur Temperierung der Proben wurde ein Rohrofen benutzt, der zur besseren Durchmischung der Komponenten bzw. der Schmelze mit einer Periode von ca. 2 min um die Querachse auf und ab bewegt wurde. Die Aufheizrate betrug 300 °C/h bis zur Endtemperatur. Die Proben wurden 4 h bei 1.000 °C belassen und danach unkontrolliert mit einer anfänglichen Kühlrate um 400 °C/h abkühlen gelassen.A tube furnace was used to temper the samples, which was moved up and down around the transverse axis with a period of approx. 2 min for better mixing of the components or the melt. The heating rate was 300 ° C / h to the final temperature. The samples were left at 1,000 ° C for 4 hours and then allowed to cool uncontrollably at an initial cooling rate of 400 ° C / h.
Die Vermessung der Eigenschaften des hergestellten Materials erfolgte relativ zum Stand der Technik. Dazu wurde aus einem kommerziell erhältlichen Hochleistungsmodul eines thermoelektrischen Generators ein n-leitendes PbTe zur Vergleichsmessung entnommen.The properties of the material produced were measured relative to the prior art. For this purpose, an n-conducting PbTe was taken from a commercially available high-performance module of a thermoelectric generator for comparison measurement.
Da von vornherein ein Gastgitter mit niedriger Wärmeleitfähigkeit eingesetzt wurde, wurde auf deren aufwendige und oft fehlerhafte Messung verzichtet und zum Leistungsvergleich der so genannte „Power-factor" P herangezogen, der sich aus P = S2 • σ ergibt. Dabei wird nicht der absolute Wert von p angegeben, sondern der relativ zum Standard aus S prob8 * O" Probe
Figure imgf000010_0001
S Standard ' ö StandardSince a guest lattice with low thermal conductivity was used from the outset, its elaborate and often incorrect measurement was dispensed with and the so-called "power factor" P, which results from P = S 2 • σ, was used to compare the performance Value of p given, but the relative to the standard from S p ro b8 * O " sample
Figure imgf000010_0001
S standard 'ö standard
Dazu wurde der Seebeck-Koeffizient S als mittlerer Seebeck-Koeffizient im Temperaturbereich von 30 °C bis 130°C bestimmt. Die elektrische Leitfähigkeit wurde realitätsnaher als in der Literatur bestimmt, nämlich ebenfalls im Seebeck-Experiment, während die kalte Seite auf 30 °C und die heiße Seite auf 130 °C gehalten wurde. Das Maß für die elektrische Leitfähigkeit ergibt sich aus dem Quotienten aus Kurzschlussstrom und Leerlaufspannung, wobei der Kurzschlussstrom sehr niederohmig mit einem Messinstrument mit 0,035 Ω Innenwiderstand gemessen wurde. Der Fehler bei der Messung der Leerlaufspannung betrug ± 2 %, der bei der Messung des Kurzschlussstroms betrug ± 20 %. For this purpose, the Seebeck coefficient S was determined as the average Seebeck coefficient in the temperature range from 30 ° C to 130 ° C. The electrical conductivity was determined more realistically than in the literature, namely also in the Seebeck experiment, while the cold side was kept at 30 ° C and the hot side at 130 ° C. The measure of the electrical conductivity results from the quotient of short-circuit current and open circuit voltage, the short-circuit current being measured with very low resistance using a measuring instrument with an internal resistance of 0.035 Ω. The error in the measurement of the open circuit voltage was ± 2%, that in the measurement of the short-circuit current was ± 20%.
Figure imgf000011_0001
Figure imgf000011_0001

Claims

Patentansprüche claims
1. Thermoelektrischer Generator oder Peltier- Anordnung mit einem Tellurid als thermoelektrisch aktivem Halbleitermaterial, dadurch gekennzeichnet, dass ein substituiertes Halbleitermaterial eingesetzt wird, in dem die positiv polarisierten Atome des Kristallgitters des Tellurids partiell durch Silizium und oder Germanium substituiert sind.1. Thermoelectric generator or Peltier arrangement with a telluride as thermoelectrically active semiconductor material, characterized in that a substituted semiconductor material is used in which the positively polarized atoms of the crystal lattice of the telluride are partially substituted by silicon and or germanium.
2. Thermoelektrischer Generator oder Peltier- Anordnung nach Anspruch 1, dadurch gekennzeichnet, dass die positiv polarisierten Atome des Tellurids Blei und oder Bismu- tatome sind.2. Thermoelectric generator or Peltier arrangement according to claim 1, characterized in that the positively polarized atoms of the telluride are lead and or bismuth atoms.
3. Thermoelektrischer Generator oder Peltier- Anordnung nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass das substituierte Tellurid Si2Te3, GeTe, SiTe, SiTe2 oder Mischungen davon enthält.3. Thermoelectric generator or Peltier arrangement according to claim 1 or 2, characterized in that the substituted telluride contains Si 2 Te 3 , GeTe, SiTe, SiTe 2 or mixtures thereof.
4. Thermoelektrischer Generator oder Peltier-Anordnung nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass das substituierte Tellurid der allgemeinen Formel (I) entspricht: (MeaTeb)1-x (Si2Te3, GeTe, SiTe,SiTe2)x (I) mit4. Thermoelectric generator or Peltier arrangement according to one of claims 1 to 3, characterized in that the substituted telluride corresponds to the general formula (I): (Me a Te b ) 1 - x (Si 2 Te 3 , GeTe, SiTe, SiTe 2 ) x (I) with
Me = Bi und oder Pb, x = 0,002 bis 0,05, a, b = 1 bis 3.Me = Bi and or Pb, x = 0.002 to 0.05, a, b = 1 to 3.
5. Thermoelektrischer Generator oder Peltier-Anordnung nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, dass die elektrische Leitfähigkeit des substituierten Tellurids mindestens 50 % größer ist als die elektrische Leitfähigkeit des nicht substituierten Tellurids.5. Thermoelectric generator or Peltier arrangement according to one of claims 1 to 4, characterized in that the electrical conductivity of the substituted telluride is at least 50% greater than the electrical conductivity of the unsubstituted telluride.
6. Halbleitermaterial, wie in einem der Ansprüche 1 bis 5 definiert.6. Semiconductor material as defined in one of claims 1 to 5.
7. Verfahren zur Herstellung von Halbleitermaterialien gemäß Anspruch 6 durch Reaktion der Einzelelemente oder von binären Telluridvorläuferverbindungen der Einzel- elemente, gegebenenfalls in Kombination mit dem verbleibenden Einzelelement, bei Temperaturen oberhalb der Schmelztemperatur der resultierenden Telluride.7. The method for producing semiconductor materials according to claim 6 by reaction of the individual elements or of binary telluride precursor compounds of the individual elements, possibly in combination with the remaining individual element, at temperatures above the melting temperature of the resulting tellurides.
8. Verfahren zur Erhöhung des Seebeck-Koeffizienten und/oder der elektrischen Leitfä- higkeit von thermoelektrisch aktiven Telluriden der Formel PbTe und/oder Bi2Te3 durch partielle Substitution der Blei- oder Bismutatome durch Silizium und/oder Germanium.8. Process for increasing the Seebeck coefficient and / or the electrical conductivity of thermoelectrically active tellurides of the formula PbTe and / or Bi 2 Te 3 by partial substitution of the lead or bismuth atoms by silicon and / or germanium.
9. Verwendung eines Halbleitermaterials nach Anspuch 6 in thermoelektrischen Genera- toren und/oder Peltier-Anordnungen, insbesondere in Wäschetrockner.9. Use of a semiconductor material according to claim 6 in thermoelectric generators and / or Peltier arrangements, in particular in a tumble dryer.
10. Wäschetrockner mit mindestens einem thermoelektrischen Modul, enthaltend einen thermoelektrischen Generator und/oder eine Peltier-Anordnung gemäß einem der Ansprüche 1 bis 5, über den ein zu trocknendes Wäschematerial direkt oder indirekt auf- geheizt und der bei der Trocknung anfallende Wasserdampf direkt oder indirekt abgekühlt werden. 10. Tumble dryer with at least one thermoelectric module, containing a thermoelectric generator and / or a Peltier arrangement according to one of claims 1 to 5, via which a laundry material to be dried is heated directly or indirectly and the water vapor produced during drying is directly or indirectly be cooled.
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WO2006089938A1 (en) * 2005-02-24 2006-08-31 Basf Aktiengesellschaft Semiconducting bismuth sulphides having new combinations of properties and use thereof in thermoelectrics and photovoltaics
WO2007104603A2 (en) * 2006-03-16 2007-09-20 Basf Se Lead-germanium-tellurides for thermoelectrical applications
WO2007104601A3 (en) * 2006-03-16 2007-11-22 Basf Ag Doped lead tellurides for thermoelectric applications
WO2007104603A3 (en) * 2006-03-16 2007-12-13 Basf Ag Lead-germanium-tellurides for thermoelectrical applications
US8716589B2 (en) 2006-03-16 2014-05-06 Basf Aktiengesellschaft Doped lead tellurides for thermoelectric applications
CN115368136A (en) * 2022-08-26 2022-11-22 武汉理工大学 Polycrystalline Bi suitable for batch preparation 2 Te 3 Method for producing a bulk thermoelectric material
CN115368136B (en) * 2022-08-26 2023-07-14 武汉理工大学 Be applicable to batch preparation polycrystal Bi 2 Te 3 Method for preparing thermoelectric material of base body

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