CN101508560B - Process for producing codoped In2O3 based pyroelectric material - Google Patents

Abstract

A method for preparing double-doped In2O3 based thermoelectric materials relates to oxide ceramics and the preparation thereof. The method comprises the steps as follows: powders of ZnO, GeO2 and In2O3 are weighed according to the stoichiometric ratio of In(2-2x)ZnxGexO3 (0<x<=0.20), and then the powders are mixed and calcined at the temperature of 250-700 DEG C, the phase-forming stage is completed; the calcined powder is put into a graphite mould and compacted, and then is sintered into a bulk material by the discharge plasma at the temperatureof 850-1000 DEG C, thus obtaining the double-doped In2O3 oxide thermoelectric materials of Zn and Ge. Compared with the common solid phase sintering, the invention has short reaction time and low sintering temperature and can effectively overcome the disadvantages that the reaction temperature in the prior art is high, the reaction time is long, the energy consumption is high and the compound deviates from the stoichiometric ratio, etc. Besides, the property of the sintered samples is greatly enhanced and the ZT value thereof can achieve 0.6 at the temperature of 700 DEG C.

Description

A kind of codope In＜sub〉2＜/sub〉O＜sub〉3＜/sub〉preparation method of base thermoelectricity material

Technical field

The invention belongs to material science, particularly oxide ceramic material and preparation method thereof is mainly concerned with a kind of codope In ₂O ₃The preparation method of oxide pyroelectric material.

Background technology

Thermoelectric material be a kind of can be under solid state, the material that needs movable part just heat energy and electric energy can be changed mutually hardly.For the needs of environmental protection, the research of novel thermoelectric material is subjected to people and more and more pays close attention in recent years.Thermoelectric (Thermoelectric) but material can be used as heat energy and the electric energy carrier of inverse conversion mutually, with the thermoelectric material is the thermoelectric device of nucleus module, have that structure is light, volume is little, long service life, free from environmental pollution, advantage such as can under the condition of environmental condition very severe, use, and the invertibity of thermoelectric effect has also determined thermoelectric device to have amphicheirality-can make refrigerator also can do pyrotoxin.At present, with the competition of the refrigeration modes of routine and conventional power source in, key is to improve the operating efficiency of thermoelectric cooling module or electric organ, and main path is how to improve the performance of thermoelectric material.

Thermoelectricity capability can generally use thermoelectric figure of merit (being translated into thermoelectric factor of merit or thermoelectric figure of merit again) Z to describe by the thermoelectricity capability of material:

Compare with alloy thermoelectric material commonly used, oxide pyroelectric material have resistance to oxidation, high temperature resistant, do not contain poisonous volatile unit

$Z=\frac{{\mathrm{\&alpha;}}^2\mathrm{\&sigma;}}{\mathrm{\&kappa;}}$

Plain characteristics are applicable to aspects such as industrial waste heat generating, automobile exhaust gas generating.The main inferior position of oxide pyroelectric material is that operating efficiency is lower at present.And In ₂O ₃Base oxide pyroelectric material can obtain higher elevated temperature heat electrical property by doping vario-property, therefore will be expected to become the research focus in thermoelectric field.

In ₂O ₃Base oxide pyroelectric material mainly is to adopt solid phase reaction synthetic, and raw material is mixed by stoichiometric proportion, and grind the calcining back, then 1300 ℃-1450 ℃ high temperature sintering 10-15 hour.

Sum up solid phase reaction synthetic method reaction temperature height, the reaction time is long, and energy consumption is big, and the In volatilization is serious under the high temperature, causes compound to depart from the chemistry ratio.

Summary of the invention

The objective of the invention is at the synthetic In of available technology adopting solid reaction process ₂O ₃The problems that base oxide pyroelectric material exists provide a kind of discharge plasma sintering (SPS) method low temperature that utilizes to prepare In fast ₂O ₃The new technology of base oxide pyroelectric material.

Technical scheme of the present invention is as follows:

A kind of codope In ₂O ₃The preparation method of base thermoelectricity material is characterized in that this method carries out as follows:

1) presses In _2-2xZn _xGe _xO ₃Stoichiometric proportion, take by weighing ZnO, GeO ₂And In ₂O ₃Powder, 0＜x≤0.20 wherein;

2) with ZnO, GeO ₂And In ₂O ₃After the powder, under 250 ℃～700 ℃ conditions, calcine, finish the one-tenth phase stage of thing phase;

3) powder after the calcining is put into graphite jig, compacting sinters block materials into discharge plasma, and sintering temperature is 850～1000 ℃, promptly obtains Zn, Ge codope In ₂O ₃Oxide pyroelectric material.

In the technique scheme, described step 2) calcination time in is preferably 1～6 hour; The heating rate of step 3) sintering is 100～200 ℃/min, temperature retention time 2～10 minutes.

The present invention has the following advantages and the high-lighting effect: compare with common solid-phase sintering, have the reaction time weak point, sintering temperature is low, can effectively overcome prior art reaction temperature height, and the reaction time is long, and energy consumption is big, and compound departs from shortcomings such as chemistry compares.And the properties of sample of sintering improves a lot, and its ZT value can reach 0.6 under 700 ℃.

Description of drawings

The XRD figure of product spectrum among Fig. 1: the embodiment 1.

The fracture SEM pattern of product among Fig. 2: the embodiment 1.

The XRD figure of product spectrum among Fig. 3: the embodiment 2.

The fracture SEM pattern of product among Fig. 4: the embodiment 2.

The XRD figure of product spectrum among Fig. 5: the embodiment 3.

The fracture SEM pattern of product among Fig. 6: the embodiment 3.

The XRD figure of product spectrum among Fig. 7: the embodiment 4.

The fracture SEM pattern of product among Fig. 8: the embodiment 4.

Embodiment

The preparation method of a kind of codope In2O3 base thermoelectricity material provided by the invention, its processing step is as follows:

1) at first presses In _2-2xZn _xGe _xO ₃Stoichiometric proportion, take by weighing ZnO, GeO ₂And In ₂O ₃Powder, 0＜x≤0.20 wherein;

2) with ZnO, GeO ₂And In ₂O ₃After the powder, under 250 ℃～700 ℃ conditions, calcine, finish the one-tenth phase stage of thing phase; Calcination time is preferably 1～6 hour.

3) powder after the calcining is put into graphite jig, compacting sinters block materials into discharge plasma, and sintering temperature is 850～1000 ℃, and the heating rate of sintering is generally 100～200 ℃/min, temperature retention time 2～10 minutes.Promptly obtain Zn, Ge codope In ₂O ₃Oxide pyroelectric material.

Below by several specific embodiments so that the present invention will be further described.

Embodiment 1:

According to In _1.98Zn _0.01Ge _0.01O ₃Proportioning, take by weighing ZnO, GeO ₂And In ₂O ₃, after the mixing, by burning till technology in advance, sintering is 1 hour in 250 ℃ of air, finishes the one-tenth phase stage of material thing phase.Mixing, granulation then, and under 850 ℃ of conditions, utilize SPS discharge plasma sintering furnace sintering, 100 ℃/min of heating rate is incubated 2 minutes and can obtains In _1.98Zn _0.01Ge _0.01O ₃Pottery.Its feature is seen Fig. 1, and 2 show.Its ZT value can reach 0.4 under 700 ℃.

Embodiment 2:

According to In _1.90Zn _0.05Ge _0.05O ₃Proportioning, take by weighing ZnO, GeO ₂And In ₂O ₃, after the mixing, by burning till technology in advance, sintering is 3 hours in 400 ℃ of air, finishes the one-tenth phase stage of material thing phase.Mixing, granulation then, and under 900 ℃ of conditions, utilize SPS discharge plasma sintering furnace sintering, 130 ℃/min of heating rate is incubated 4 minutes and can obtains In _1.94Zn _0.03Ge _0.03O ₃Pottery.Its feature is seen Fig. 3, and 4 show.Its ZT value can reach 0.6 under 700 ℃.

Embodiment 3:

According to In _1.70Zn _0.15Ge _0.15O ₃Proportioning, take by weighing ZnO, GeO ₂And In ₂O ₃, after the mixing, by burning till technology in advance, sintering is 5 hours in 600 ℃ of air, finishes the one-tenth phase stage of material thing phase.Mixing, granulation then, and under 950 ℃ of conditions, utilize SPS discharge plasma sintering furnace sintering, 160 ℃/min of heating rate is incubated 7 minutes and can obtains In _1.70Zn _0.15Ge _0.15O ₃Pottery.Its feature is seen Fig. 5, Fig. 6.Its ZT value can reach 0.4 under 700 ℃.

Embodiment 4:

According to In _1.60Zn _0.2Ge _0.2O ₃Proportioning, take by weighing ZnO, GeO ₂And In ₂O ₃, after the mixing, by burning till technology in advance, sintering is 6 hours in 700 ℃ of air, finishes the one-tenth phase stage of material thing phase.Mixing, granulation then, and under 1000 ℃ of conditions, utilize SPS discharge plasma sintering furnace sintering, 200 ℃/min of heating rate is incubated 10 minutes and can obtains In _1.60Zn _0.2Ge _0.2O ₃Pottery.Its feature is seen Fig. 7, Fig. 8.Its ZT value can reach 0.2 under 700 ℃.

Claims (1)

1. codope In ₂O ₃The preparation method of base thermoelectricity material is characterized in that this method carries out as follows:

1) presses In _2-2xZn _xGe _xO ₃Stoichiometric proportion, take by weighing ZnO, GeO ₂And In ₂O ₃Powder, 0＜x≤0.20 wherein;

2) with ZnO, GeO ₂And In ₂O ₃After the powder, calcine under 250 ℃～700 ℃ conditions, calcination time is 1～6 hour, finishes the one-tenth phase stage of thing phase;

3) powder after the calcining is put into graphite jig, compacting sinters block materials into discharge plasma, and sintering temperature is 850～1000 ℃, and the heating rate of sintering is 100～200 ℃/min, and temperature retention time 2～10 minutes promptly obtains Zn and Ge codope In ₂O ₃Oxide pyroelectric material.

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