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Calcium cobaltate-based oxide thermoelectric material and its prepn.

A technology of thermoelectric materials and oxides, applied in cobalt compounds, chemical instruments and methods, circuits, etc., can solve the problems of high reaction temperature, high energy consumption, long reaction time, etc., and achieve good chemical uniformity, low reaction temperature, The effect of short reaction times

Inactive Publication Date: 2003-01-08
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The improved method also has the problem of time-consuming, and the ball milling process is easy to introduce impurities, and the quality of the product is difficult to control
[0004] To sum up, solid-phase synthesis has high reaction temperature, relatively long reaction time, poor chemical uniformity, high energy consumption, and it is difficult to obtain nanoscale thermoelectric compounds.

Method used

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  • Calcium cobaltate-based oxide thermoelectric material and its prepn.
  • Calcium cobaltate-based oxide thermoelectric material and its prepn.
  • Calcium cobaltate-based oxide thermoelectric material and its prepn.

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] Example 1. Ca 3 co 4 o 9

[0037] Ca(NO 3 ) 2 4H 2 O(30mmol), Co(NO 3 ) 2 ·6H 2 O (40mmol), C 6 h 8 o 7 ·H 2O (105 mmol) was added into the beaker, and then the mixture was dissolved with deionized water and stirred until a transparent solution; the temperature was raised to 60° C. until the solution became a sol. It was then dried at 100°C for 12 hours. After the dry gel is ground, it is pre-fired at 400°C to remove citric acid and nitrate. The resulting powder is sintered at 800°C to obtain a bulk thermoelectric material. For compound characterization see figure 1 with 2 . At 700°C, conductivity σ=10S / cm, Seebeck coefficient S=120μV / K, power factor PF=0.14×10 -4 W / mK 2 , ZT=0.13.

Embodiment 2

[0038] Example 2. Ca 3 co 4 o 9

[0039] Ca(NO 3 ) 2 4H 2 O(30mmol), Co(NO 3 ) 2 ·6H 2 O (40mmol), C 6 h 8 o 7 ·H 2 O (91 mmol) was added to the beaker, then the mixture was dissolved with deionized water and stirred until a clear solution. Raise the temperature to 100°C until the solution becomes a sol. It was then dried at 130°C for 10 hours. After the dry gel is ground, it is pre-fired at 600°C to remove citric acid and nitrate. The resulting powder is sintered at 950°C to obtain a bulk thermoelectric material. At 700°C, conductivity σ=10S / cm, Seebeck coefficient S=120μV / K, power factor PF=0.14×10 -4 W / mK 2 , ZT=0.13.

Embodiment 3

[0040] Example 3. Ca 3 co 4 o 9

[0041] Ca(NO 3 ) 2 4H 2 O(30mmol), Co(NO 3 ) 2 ·6H 2 O (40mmol), C 6 h 8 o 7 ·H 2 O (140 mmol) was added into the beaker, then the mixture was dissolved with deionized water and stirred until a clear solution. Raise the temperature to 80°C until the solution becomes a sol. It was then dried at 110°C for 12 hours. After the dry gel is ground, it is pre-fired at 500°C to remove citric acid and nitrate. The obtained powder is sintered at 850°C to obtain a bulk thermoelectric material. At 700°C, conductivity σ=10S / cm, Seebeck coefficient S=120μV / K, power factor PF=0.14×10 -4 W / mK 2 , ZT=0.13.

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Abstract

The present invention relates to a calcium cobaltate base oxide thermoelectric material and its preparation method. Said invention utilizes sel-gel process, uses inorganic nitrate as raw material, uses citric acid as complexing agent to form sol at 60 deg.C-100 deg.C and form gel at 100 deg.C-130 deg.c, then utilizes presintering process to obtain precursor nano powder, finally utilzies sintering process to obtain block body material. The non-dimensional thermoelectric optimum value ZT of said prepared Ca3Co4O9 base oxide thermoelectric material is about 0.2 (in 1000 K). Said invented product can be used in the field of waste-head utilization and high-temp. power generation.

Description

technical field [0001] The invention relates to a new method for synthesizing calcium cobaltate-based oxide (Ca-Co-O) thermoelectric materials. The invention belongs to the technical field of oxide thermoelectric material and its preparation in functional materials. Background technique [0002] Rowe gave a detailed introduction to thermoelectric materials in his book "CRC Handbook of Thermoelectrics" (published by CRC Press in 1995). Among all current thermoelectric materials (that is, materials with thermoelectric power generation and thermoelectric cooling functions), lead telluride (PbTe)-based semiconductor materials are currently recognized as the best thermoelectric materials in the medium temperature region. It has the highest medium temperature thermoelectric quality factor ZT(=TσS 2 / λ, T=temperature, σ=electrical conductivity, λ=thermal conductivity, S=Seebeck coefficient). [0003] Compared with traditional lead telluride alloy thermoelectric materials, Ca-Co-...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01G51/00C04B35/32C04B35/622H01L21/02
Inventor 南策文南军邬俊波邓元
Owner TSINGHUA UNIV
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