CN103579486A

CN103579486A - Bi85Sb15-xKx (Kalium mixed with bismuth-antimony) low-temperature thermoelectric material and preparing method thereof

Info

Publication number: CN103579486A
Application number: CN201310584413.4A
Authority: CN
Inventors: 宋春梅; 李来风
Original assignee: Zunyi Normal University
Current assignee: Zunyi Normal University
Priority date: 2013-11-20
Filing date: 2013-11-20
Publication date: 2014-02-12
Anticipated expiration: 2033-11-20
Also published as: CN103579486B

Abstract

The invention discloses a Bi85Sb15-xKx (kalium mixed with bismuth-antimony) low-temperature thermoelectric material and a preparing method thereof, wherein x in the formula represents any numerical value ranging from 1 to 4. The low-temperature thermoelectric material is prepared by chemically matching 5N parts of Bi, 5N parts of Sb and 5N parts of K and adopting a mechanical alloying and plasma spark sintering technology. The low-temperature thermoelectric material has good thermoelectric properties near the temperature of 200K, has the advantages of being high in mechanical strength, good in thermal electromotive force and electrical conductivity and has high quality when being placed at the low-temperature environment. The low-temperature thermoelectric material is stable in performance, simple in preparing technology, low in cost and easy to popularize and apply.

Description

It is Bi85Sb15-xKx low-temperature thermoelectric material and preparation method thereof that potassium mixes bismuth-antimony system

Invention field

The present invention relates to the field of thermoelectric material, relate in particular to a kind of Bi ₈₅sb _15-xk _xlow-temperature thermoelectric material and preparation method thereof, is applied to the semi-conducting material of thermoelectric refrigerating unit.

Background technology

Economic growth fast makes the energy and environmental problem become the tightest pretty challenge of new century facing mankind, and the friendly type clean energy technology of development environment is to keep national economy and social production can hold the important foundation of speed development.The major domain of semi-conductor thermoelectric material comprises: temperature difference electricity generation device, Peltier refrigerating plant and temperature sensor.The efficiency of thermoelectric cooling is described by figure of merit parameter Z conventionally, Z=α 2 σ/λ, α is Seebeck coefficient, the conductivity that σ is material, the thermal conductivity that λ is material.Be combined with temperature, become dimensionless factor ZT, ZT value is larger, and refrigerating capacity is stronger.The principal element that affects ZT value is the conductivity of material, Seebeck coefficient and thermal conductivity.

Since finding that ZT value approaches 1 Bi-Te and is p-type semi-conductor thermoelectric material the fifties, the efficiency that improves thermoelectric cooling does not have major progress, although the refrigeration device of preparing with these materials is applied at some special occasions, compare with mechanical refrigeration, only have the efficiency of mechanical refrigeration 30%.Want to be more widely used, this just need to bring up to the ZT value of thermoelectric material more than 3, could realize large-scale application.1996 Nian， U.S. Oak Ridge National Laboratory B.C. Sales etc. find RM4X12 (R:La, Ce, Nd etc.; M:Fe, Ru etc.; X:As, Sb etc.) the ZT value of type compound can reach 1.4, and this major progress, for the development of semiconductor thermoelectric refrigeration and new material injects vigour into.In recent years, the country such as the U.S., Japan, Australia was very active in the research of thermoelectric cooling Material Field, and high performance material continues to bring out.Current United States Naval Research Laboratory, several main National Laboratories and some companies actively get involved this direction.Research paper is published in Science again and again, Nature, the influential magazines such as Phys. Rev. Lett..These are broken through is mainly that to reduce material thermal conductivity be that ZT value is improved in breach.

Bi-Sb monocrystalline thermoelectric material is one of best thermoelectric material of current thermoelectricity capability at low temperatures.

In its figure of merit of 80 K, can reach 6.5 * 10 ^-3k ^-1.Bi be all semi-metallic with Sb, both have identical rhombohedron crystal structure and close lattice parameter, and the physical property of Bi-Sb alloy is relevant to the content of Sb. at 0<X<0.07Bi _1-xsb _xalloy shows as semimetal behavior, at 0.07<X<0.22, it is N-shaped semiconductor, at X>0.22, show as again semimetal behavior. still, the manufacturing cycle of monocrystalline is long, machining property is poor, cost is high, is unfavorable for large-scale industrial production.Visible, in prior art, lack a kind of high mechanical properties that both had, at low temperature warm area, there is again the thermoelectric material of better performance.Therefore the material that, exploration has high conversion efficiency of thermoelectric at lower temperature (below 200 K) is the focus that people study always. this invention applicant adopts mechanical alloy to add plasma spark sintering method, has prepared Bi ₈₅sb _15-xk _xsample bulk.

Summary of the invention

The object of the present invention is to provide a kind of Bi of doping ₈₅sb _15-xk _xthermoelectric material and preparation method thereof, is exactly to utilize mechanical alloying to add the method for superhigh pressure specifically, obtains the Bi with high thermoelectricity capability ₈₅sb _15-xk _xthe preparation method of thermoelectric material.

Task of the present invention is to provide the Bi of a kind of K of doping ₈₅sb _15-xk _xthe preparation method of (wherein x represents any number between 1-4) thermoelectric material.The object of the invention is to realize by following steps:

A) 99.999%Bi powder is mixed according to the ratio in each comfortable described molecular formula with the K of Sb powder and 99.5%, mixture is put into quartz ampoule and vacuumize also tube sealing, then put into stove, at 600 degree temperature, sintering is 10 hours.

B) by the Bi after sintering ₈₅sb _15-xk _xblock materials is pulverized with mechanical means, and puts into ball mill and carry out ball milling 50 hours.

C) powder after ball milling being put into the carbon die that diameter is 12mm, is 523K through plasma spark sintering (SPS) sintering temperature, and pressure is 50 MPa, and sintering time is within 20 minutes, to obtain bulk thermoelectric material.

In said method, prepare described Bi ₈₅sb _15-xk _x, wherein x represents any number between 1-4.The method of producing powder is: by Bi ₈₅sb _15-xk _xbulk is pulverized with mechanical means, puts into agate tank, after vacuumizing, passes into high-purity argon gas, carries out ball-milling reaction, Ball-milling Time 50 hours.

The present invention passes through at Bi ₈₅sb ₁₅in mix K element, obtaining molecular formula is Bi ₈₅sb _15-xk _xthermoelectric material, compare Bi provided by the present invention with other thermoelectric material under low temperature ₈₅sb _15-xk _xthere is following advantage in thermoelectric material:

1) this thermoelectric material is that low temperature warm area below 115K has larger Seebeck coefficient in temperature, and its Seebeck coefficient can reach approximately-155.98 μ V/K.

2) this thermoelectric material is that low temperature warm area below 200K has larger Seebeck coefficient absolute value in temperature.

3) thermoelectric potential of this thermoelectric material can be by regulating the content of the K element in material to realize.

4) this thermoelectric material mechanical strength is high, and conductivity and thermoelectric potential are better.

5) this thermoelectric material manufacturing process is easier, is easy to apply.

Advantage of the present invention: adopt mechanical alloying to add superhigh pressure method, at Bi ₈₅sb ₁₅basis on, mix K unit usually part substitute Bi ₈₅sb ₁₅in Sb element, obtain a kind of novel thermoelectric material in the following temperature of 200k with higher merit figue.The present invention can provide a kind of economy, the Bi that simple, near practical low temperature warm area 200K has good thermoelectricity capability ₈₅sb _15-xk _xthermoelectric material and preparation method, wherein x represents the Any Digit between 1-4.

Embodiment

Embodiments of the present invention realize by lower technical scheme:

Bi provided by the invention ₈₅sb _15-xk _xthermoelectric material, wherein x represents the Any Digit of 1-4, adopts mechanical alloying to add plasma agglomeration method and makes.Its chemical first raw material is pure bismuth, antimony, potassium simple substance element and high-purity argon gas.

Its preparation method comprises the steps:

1) putting into quartz ampoule after bismuth metal, antimony, potassium are weighed by the mass ratio in chemical formula and vacuumize rear tube sealing, is sintering 10 hours under 600 degree in temperature, then the bulk of sintering is carried out to mechanical crushing, puts into mechanical ball grinding jar, in vacuum degree, is 2 * 10 ^-3during Pa, fill pure argon and enter, ball milling 50 hours;

2) powder after mechanical ball milling being put into the carbon die that diameter is 12mm, through plasma spark sintering, is 523K in temperature, and pressure is 5 MPa, and sintering time is within 20 minutes, to be pressed into the bulk thermoelectric material of 12mm.

Claims

1. to mix bismuth-antimony system be Bi for a potassium ₈₅sb _15-xk _xthermoelectric material, is characterized in that: the chemical analysis of this thermoelectric material is bismuth, antimony and potassium element, and chemical formula is: Bi ₈₅sb _15-xk _x, wherein quantity x represents the numerical value between 1-4, with potassium element, is that K mixes the alternative Bi of part ₈₅sb ₁₅in Sb element, with mechanical alloying, add plasma spark sintering technique and make thermoelectric material.

2. to mix bismuth-antimony system be Bi for a potassium ₈₅sb _15-xk _xthe processing method of thermoelectric material material, is characterized in that: adopt mechanical alloy to add superhigh pressure method, its preparation method comprises the steps:

1) put into quartz ampoule after the potassium of 99.999% metal bismuth meal, antimony powder and 99.5% is weighed by stoicheiometry and vacuumize rear tube sealing, in temperature, it is sintering 10 hours under 600 degree, then the bulk of sintering being carried out to mechanical crushing, put into mechanical ball grinding jar, is 2 * 10 in vacuum degree ^-3during Pa, fill pure argon and enter, ball milling 50 hours;

2) powder after mechanical ball milling being put into carbon die, through plasma spark sintering, is 523K in temperature, and pressure is 5 MPa, and sintering time is within 20 minutes, to obtain bulk thermoelectric material.