CN101345284A

CN101345284A - P type europium cadmium stibium based pyroelectric material and preparation method thereof

Info

Publication number: CN101345284A
Application number: CNA2008100423231A
Authority: CN
Inventors: 张辉; 赵景泰; 汤美波; 满振勇; 杨昕昕
Original assignee: Shanghai Institute of Ceramics of CAS
Current assignee: Shanghai Institute of Ceramics of CAS
Priority date: 2008-08-29
Filing date: 2008-08-29
Publication date: 2009-01-14
Anticipated expiration: 2028-08-29
Also published as: CN101345284B

Abstract

The invention relates to a p-typed Eu-Cd-Sb based thermoelectric material and a preparation method thereof, belonging to the field of thermoelectric material technique. The invention provides the p-typed Eu-Cd-Sb based thermoelectric material which is characterized in that the composition of the p-typed Eu-Cd-Sb based electro-thermal material is AxByCz (wherein, x=0.9-1.1, y=1.8-2.2 and z=1.8-2.2); wherein, A is Eu or combination of Eu, Mg, Ca, Sr and Yb; B is Cd or the combination of Cd, Mg, Mn and Zn; C is Sb or the combination of Sb, As and Bi. The preparation method of the invention comprises three steps of: compounding, synchronizing and sintering. The p-typed Eu-Cd-Sb based thermoelectric material related to by the invention has high thermoelectric conversion efficiency at the temperature about 300 to 400 DEG C; for example, optimization coefficient of the p-typed Eu-Cd-Sb based thermoelectric material achieves 0.66 at the middle temperature near 377 DEG C and the optimized p-typed Eu-Cd-Sb based thermoelectric material can be used as a middle-temperature thermoelectric conversion device.

Description

A kind of p type europium cadmium stibium based pyroelectric material and preparation method thereof

Technical field

The present invention relates to a kind of p type europium cadmium stibium based pyroelectric material and preparation method thereof, belong to the technical field of thermoelectric material.

Background technology

Thermoelectric material is a kind of functional material with heat energy and the direct conversion of electric energy, and its principle is based on Seebeck effect and Pei Er Supreme Being's effect, is the key foundation material of high-tech new energy field.There is not mechanical driving part by its thermoelectric conversion element of making (as refrigerator, air-conditioning, military generator, power station etc.), it is simple in structure, in light weight, do not need harmful substances such as fluorine Lyons yet, have cleaning, efficient, pollution-free, do not have noise and series of advantages such as the life-span is long, firm, reliability height, can be widely used in utilization of national defence, space flight, automobile, microelectronics, high-technology field and vehicle exhaust, industry useless (gas) heat.

The key of thermoelectric heat generation system is a thermoelectric material, and its performance is used dimensionless performance index ZT (ZT=S usually ²σ T/ κ, wherein S is the seebeck coefficient; σ is a conductivity; κ is a thermal conductivity, and T is an absolute temperature) expression.The ZT value is high more, and the expression material property is good more, and thermopower generation efficiency is also just high more.At present, the ZT value of practical block thermoelectric material is generally near 1.0.Have the thermoelectric material of using value and application prospect to mainly contain at present (Bi, Sb) ₂(Te, Se) ₃, β-Zn ₄Sb ₃, Yb ₁₄MnSb ₁₁, fill drill with ferrule ore deposit, (PbTe) _0.85(AgSbTe) _0.15(TAGS), Pb ₁₈AgSbTe ₂₀, cage shape thing and SiGe etc.

Because the temperature range difference that the thermoelectric material of different systems is used, the preparation technology of existing thermoelectric material adopts methods such as vacuum melting-annealing-fragmentation-hot pressed sintering or long-time solid phase reaction-hot pressed sintering more in addition.The shortcoming of these methods is, solid phase reaction and hot pressed sintering time are long, very easily cause the component deviation, and the dephasign content height of prepared material causes thermoelectricity capability to reduce.The preparation method of p type europium cadmium stibium based pyroelectric material provided by the invention, be to adopt the high purity elemental raw material in glove box, to prepare burden, the assurance raw material is not oxidized, employing is coated with the carbon quartz ampoule as reaction vessel, for guaranteeing reaction evenly, adopts and slowly gives birth to temperature, long-time fusion, slowly the temperature schedule of hypothermic response adopts discharge plasma sintering (Spark Plasma sintering is called for short SPS) technology sintering block materials.SPS is novel special pressurization Fast Sintering technology, claims also on the document that has that SPS is a plasma activated sintering.The process advantage of SPS is: programming rate is fast, homogeneous heating, and sintering temperature is low, and temperature retention time is short, and production efficiency height, product are organized tiny even.

The thermoelectric material of the similar composition of bibliographical information such as Mg ₃Sb ₂, CaZn ₂Sb ₂, Ca _xYb _1-Zn ₂Sb ₂And BaZn ₂Sb ₂The ZT value between 0.21～0.52, a patent " a kind of cadmium-stibium-based p type thermal electrical material and preparation method thereof " gained sample YbCd is only arranged ₂Sb ₂The ZT value reaches 0.8 in the time of 430 ℃.The bibliographical information of data such as at present only synthetic about europium cadmium antimony, crystal structure and cryomagnetism does not have the research of thermoelectricity capability aspect.The high conversion efficiency of thermoelectric of p type europium cadmium stibium based pyroelectric material tool that the present invention relates to, during as 377 ℃, the figure of merit of europium cadmium antimony reaches 0.66.

Summary of the invention

The purpose of this invention is to provide a kind of p type europium cadmium stibium based pyroelectric material and preparation method thereof.

The europium cadmium stibium based high efficiency thermoelectric transition material of the p type that the present invention relates to is characterized in that composition formula is A _xB _yC _z(z=1.8-2.2): A is the combination of Eu or Eu and Mg, Ca, Sr, Yb for x=0.9-1.1, y=1.8-2.2; B is the combination of Cd or Cd and Mg, Mn, Zn; C is the combination of Sb or Sb and P, As, Bi.

Preparation method of the present invention comprises batching, synthetic and three steps of sintering:

(1) be raw material with high pure metal simple substance, according to A _xB _yC _z(z=1.8-2.2): A is the combination of Eu or Eu and Mg, Ca, Sr, Yb for x=0.9-1.1, y=1.8-2.2; B is the combination of Cd or Cd and Mg, Mn, Zn; C is the combination of Sb or Sb and P, As, Bi.

(2) the compound inclosure with step (1) preparation is coated with in the quartz ampoule of carbon, and atmosphere is vacuum or charges into small amounts of inert gas.Quartz ampoule slowly is heated to 700～900 ℃ of insulations 7～14 days, makes raw metal carry out abundant chemical reaction, slowly cool to room temperature, fully grind, promptly get the powder of p type europium cadmium stibium based pyroelectric material.

(3) with the fine and close block of the powder sintered one-tenth of the discharging plasma sintering equipment p type europium cadmium stibium based pyroelectric material that step (2) is synthetic, sintering condition is pressure 30～100MPa, 300～500 ℃ of temperature, and temperature retention time 5～30min, atmosphere is vacuum.

Description of drawings

Fig. 1 is p type EuCd provided by the invention ₂Sb ₂The X ray diffracting spectrum of thermoelectric material illustrates that its principal phase is an europium cadmium antimony.The cell parameter that records is And

Fig. 2 is p type EuCd provided by the invention ₂Sb ₂The structure of thermoelectric material illustrates EuCd ₂Sb ₂Be stratiform CaAl ₂Si ₂Type trigonal crystal structure (P-3m), Eu is positioned at [Cd ₂Sb ₂] between the double-layer network.

Fig. 3 is p type EuCd provided by the invention ₂Sb ₂The conductivity of thermoelectric material and Seebeck coefficient, illustrate europium cadmium antimony have high conductivity (75～113S/cm), high Seebeck coefficient (227～306 μ V/K).

Fig. 4 is p type EuCd provided by the invention ₂Sb ₂The thermal conductivity of thermoelectric material illustrates EuCd ₂Sb ₂Has low lattice thermal conductivity (1.42～0.74W/mK).

Fig. 5 is p type EuCd provided by the invention ₂Sb ₂The power factor of thermoelectric material and figure of merit illustrate p type EuZn ₂Sb ₂Have high power factor (7.5 μ W/cmK ²) and high figure of merit (0.66).

Embodiment

Further specify the present invention below by embodiment, but be not limited only to embodiment.

In following examples, with conductivity (S/cm), the conductivity of expression material, this numerical value is high more, illustrates that conductivity is good more; With the thermoelectric force of Seebeck coefficient (μ V/K) expression material, this numerical value is high more, illustrates that the electrical potential difference of temperature difference generation is high more; Power (μ W/cmK with the conversion of the thermoelectricity of power factor representation material ²), this numerical value is high more, illustrates that the power of thermoelectric conversion is high more; With the thermal conductivity of thermal conductivity (W/mK) expression material, this numerical value is low more, illustrates that thermal loss is more little; Represent the conversion efficiency of thermoelectric of material with figure of merit, this numerical value is high more, illustrates that the efficient of thermoelectric conversion is high more.

Table 1 has been listed structure and the performance of embodiment 1, and table 2 has been listed composition and the preparation technology of embodiment 1-8.

Embodiment 1

Adopting high-purity (＞99.9%) metal simple-substance to press the component batching of table 2 appointment respectively, raw material is put in the graphite crucible, enclose quartz ampoule, is vacuum in the quartz ampoule.Above-mentioned quartz ampoule is put into high temperature furnace, slowly give birth to temperature, be incubated 14 days, slowly cool to room temperature, fully grind, promptly get the thermoelectric material powder to 800 ℃.Above-mentioned powder is prepared into bulk material with the discharging plasma sintering equipment direct sintering, and sintering condition is pressure 60MPa, 400 ℃ of temperature, and temperature retention time 15min, atmosphere is vacuum.Then, test X ray diffracting data, thermal conductivity, Seebeck coefficient and conductivity.Fig. 1-Fig. 5 has provided the characteristic X-ray diffracting spectrum of embodiment 1, structure and The performance test results figure.

The structure of table 1 embodiment 1 and performance

Embodiment 2-8

The preparation process reference example 1 of embodiment 2-8, composition and the preparation technology of embodiment 2-8 see Table 2.

Composition and the preparation technology of table 2 embodiment 2-8

Embodiment	Form	Synthesis temperature time atmosphere	The sintering temperature pressure time
Embodiment	Form	Synthesis temperature time atmosphere	The sintering temperature pressure time	Embodiment 1	EuCd ₂Sb ₂	800 ℃ of 14 days vacuum	400 ℃ of 60MPa 15 minutes
Embodiment 2	Eu _0.9Cd _2.2Sb _1.8	800 ℃ of 14 days vacuum	400 ℃ of 60MPa 15 minutes	Embodiment 1	EuCd ₂Sb ₂	800 ℃ of 14 days vacuum	400 ℃ of 60MPa 15 minutes
Embodiment 2	Eu _0.9Cd _2.2Sb _1.8	800 ℃ of 14 days vacuum	400 ℃ of 60MPa 15 minutes	Embodiment 3	(Eu _0.5Yb _0.5)Cd ₂Sb ₂	900 ℃ of 14 days vacuum	500 ℃ of 80MPa 15 minutes
Embodiment 4	(Eu _0.5Yb _0.2Ca _0.2Sr _0.1)Cd ₂Sb ₂	900 ℃ of 14 days vacuum	450 ℃ of 100MPa 15 minutes	Embodiment 3	(Eu _0.5Yb _0.5)Cd ₂Sb ₂	900 ℃ of 14 days vacuum	500 ℃ of 80MPa 15 minutes
Embodiment 4	(Eu _0.5Yb _0.2Ca _0.2Sr _0.1)Cd ₂Sb ₂	900 ℃ of 14 days vacuum	450 ℃ of 100MPa 15 minutes	Embodiment 5	Eu(CdZn)Sb ₂	800 ℃ of 14 days vacuum	440 ℃ of 40MPa 10 minutes
Embodiment 6	Eu(CdZn _0.5Mg _0.3Mn _0.2)Sb ₂	900 ℃ of 14 days vacuum	500 ℃ of 100MPa 30 minutes	Embodiment 5	Eu(CdZn)Sb ₂	800 ℃ of 14 days vacuum	440 ℃ of 40MPa 10 minutes
Embodiment 6	Eu(CdZn _0.5Mg _0.3Mn _0.2)Sb ₂	900 ℃ of 14 days vacuum	500 ℃ of 100MPa 30 minutes	Embodiment 7	EuCd ₂(SbBi)	700 ℃ of 7 days Ar gas	400 ℃ of 30MPa 5 minutes
Embodiment 8	EuCd ₂(SbBi _0.5P _0.3As _0.2)	700 ℃ of 7 days Ar gas	400 ℃ of 30MPa 5 minutes	Embodiment 7	EuCd ₂(SbBi)	700 ℃ of 7 days Ar gas	400 ℃ of 30MPa 5 minutes

Claims

1, a kind of p type europium cadmium stibium based pyroelectric material is characterized in that composition formula is A _xB _yC _z,

Wherein A is the combination of Eu or Eu and Mg, Ca, Sr, Yb;

B is the combination of Cd or Cd and Mg, Mn, Zn;

C is the combination of Sb or Sb and P, As, Bi;

X=0.9-1.1 wherein; Y=1.8-2.2; Z=1.8-2.2.

2, by the described a kind of p type europium cadmium stibium based pyroelectric material of claim 1, it is characterized in that A is Eu, B is Cd, and C is Sb.

3, by the described a kind of p type europium cadmium stibium based pyroelectric material of claim 1, it is characterized in that composition formula is EuCd ₂Sb ₂Or Eu _0.9Cd _2.2Sb _1.8Or (Eu _0.5Yb _0.5) Cd ₂Sb ₂Or (Eu _0.5Yb _0.2Ca _0.2Sr _0.1) Cd ₂Sb ₂Or Eu (CdZn) Sb ₂Or Eu (CdZn _0.5Mg _0.3Mn _0.2) Sb ₂Or EuCd ₂(SbBi) or EuCd ₂(SbBi _0.5P _0.3As _0.2).

4, a kind of preparation method by claim 1 or 2 or 3 described p type europium cadmium stibium based pyroelectric materials is characterized in that comprising the steps:

(1) is raw material with the metal simple-substance, presses composition formula proportioning raw material;

(2) compound that step (1) is prepared grinds after 700～900 ℃ of insulations and obtains powder under vacuum or inert atmosphere;

(3) adopt discharge plasma sintering step (2) to obtain the fine and close block of powder sintered one-tenth.

5, a kind of preparation method by the described p type of claim 4 europium cadmium stibium based pyroelectric material is characterized in that described temperature retention time is 7～14 days.

6, a kind of preparation method by the described p type of claim 4 europium cadmium stibium based pyroelectric material is characterized in that described sintering condition is pressure 30～100MPa, 300～500 ℃ of temperature.

7, a kind of preparation method by the described p type of claim 4 europium cadmium stibium based pyroelectric material, the atmosphere that it is characterized in that described sintering process is vacuum.