Method for preparing layered cobalt base oxide thermoelectric material

A thermoelectric material and oxide technology, which is applied in the manufacture/processing of thermoelectric devices, thermoelectric device node lead-out materials, cobalt compounds, etc., can solve the problems of high reaction temperature, long process cycle, long reaction time, etc., and achieve chemical High stability, low reaction temperature and short reaction time

Inactive Publication Date: 2005-06-29
BEIJING UNIV OF TECH
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  • Abstract
  • Description
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Problems solved by technology

In order to obtain a uniform single-phase product, it is generally necessary to repeat grinding and roasting, resulting in long process cycle, impure product, and difficult control of grain size.
K.Takahata et al. improved on this basis, using high-energy mechanical ball mills for a long time to repeatedly ball mill, and the calcined mixture was sintered to prepare cobalt-based thermoelectric materials (Physical Review B, Vol.61, No.19 (2000 )pp.R12551-12554), but the improved method still has time-consuming problems, and the ball milling process is easy to introduce impurities, and it is difficult to accurately control the quality of the product
In short, the traditional solid-phase synthesis method has a series of problems such as high reaction temperature, relatively long reaction time, poor chemical uniformity, high energy consumption, and difficulty in obtaining thermoelectric compounds with fine grain size.

Method used

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  • Method for preparing layered cobalt base oxide thermoelectric material
  • Method for preparing layered cobalt base oxide thermoelectric material
  • Method for preparing layered cobalt base oxide thermoelectric material

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] [Example 1] Ca 2 Co 2 O 5 Preparation

[0031] The reactant Co(NO 3 ) 3 ·6H 2 O and Ca (NO 3 ) 2 ·4H 2 O is configured into Ca at a molar ratio of 1:1 2+ The mixed solution with a concentration of 0.1 mol / L is then added dropwise with NaOH solution under constant stirring to make the pH value of the solution reach 12.50. The resulting precipitate is filtered and washed until the filtrate is neutral to remove the residual NaOH in the product. After drying the washed precipitate, put it in a muffle furnace and heat it to 750°C and heat it for 2 hours. Finally, put the calcined powder product into the mold and put it in the SPS sintering furnace to quickly heat it to 850°C and keep it warm. The bulk thermoelectric material is obtained in 5 minutes. The phase and fracture morphology of the bulk compound can be seen figure 1 with 2 , The product appears as single-phase Ca 2 Co 2 O 5 The phase structure is arranged in sheets. At 700°C, the ZT value of the compound reached 0.21. ...

Embodiment 2

[0032] [Example 2] Ca 2 Co 2 O 5 Preparation

[0033] The reactant Co(NO 3 ) 3 ·6H 2 O and Ca (NO 3 ) 2 ·4H 2 O is configured into Ca at a molar ratio of 1:1 2+ A mixed solution with a concentration of 0.5mol / l, and then Na is added dropwise to it under constant stirring 2 CO 3 Solution, make the pH of the solution reach 13.20. Filter and wash the formed precipitate until the filtrate is neutral to remove residual Na in the product 2 CO 3 . After drying the washed precipitate, put it in a muffle furnace and heat it to 600°C and heat it for 5 hours. Finally, put the calcined powder product into the mold and put it in the SPS sintering furnace to quickly heat it to 900°C and keep it warm. The bulk thermoelectric material is obtained in 3 minutes. The phase and fracture morphology of the product image 3 with 4 , Manifested as single-phase Ca 2 Co 2 O 5 The phase structure is arranged in sheets. At 700°C, the ZT value of the compound reached 0.21.

Embodiment 3

[0034] [Example 3] Ca 2 Co 2 O 5 Preparation

[0035] The reactant Co(NO 3 ) 3 ·6H 2 O and Ca (NO 3 ) 2 ·4H 2 O is configured into Ca at a molar ratio of 1:1 2+ The mixed solution with a concentration of 0.2mol / l, and then add dropwise (NH 4 ) 2 C 2 O 4 Solution, make the pH of the solution reach 13.60. The formed precipitate is filtered and washed until the filtrate is neutral. After drying the washed precipitate, put it in a muffle furnace and heat it to 700°C and heat it for 3 hours. Finally, put the calcined powder product into the mold and put it in the SPS sintering furnace to quickly heat it to 700°C and keep it warm. The bulk thermoelectric material is obtained in 10 minutes. The phase and fracture morphology of the compound can be seen Figure 5 with 6 , Manifested as single-phase Ca 2 Co 2 O 5 The phase structure is arranged in sheets. At 700°C, the ZT value of the compound reached 0.20.

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Abstract

It is a layer cobalt oxidation thermoelectricity material process method, which comprises the following steps: to process the solution with concentration of 0.1 to 0.5mol/l by adding Ca#-[2]Co#-[2]O#-[5]íóCa#-[3]Co#-[4]O#-[9]íó M#-[x]Ca#-[2-x]Co#-[2]O#-[5]íóM#-[x]Ca#-[3-x]Co#-[4]O#-[9] as their positive ion countered; to mix the solution and drop with co-deposit agent of sodium hydroxide, sodium carbonate, oxalic acid ammonium or their mixture; to control the pH value between 12.5 to 13.6 to process drive powder after depositing, filtering and washing and drying; to burn it under 600 to 800 degrees for two to six hours and put it into the mode.

Description

Technical field [0001] The invention relates to a layered cobalt-based oxide Ca 2 Co 2 O 5 And Ca 3 Co 4 O 9 The method for synthesizing the doped oxide thermoelectric material belongs to the technical field of oxide thermoelectric material in functional materials and its preparation. Background technique [0002] Thermoelectric material is a kind of material that uses the Seebeck effect and Peltier effect to convert heat and electric energy. The thermoelectric conversion device made of it has no mechanical transmission part, and is clean, efficient, and noise-free. Pollution and hazardous material emissions, long life, robustness, high reliability, stability, and a series of advantages, and meet the requirements of environmental protection, can be widely used in military generators, automobile exhaust gas generators, industrial waste (gas) thermal power generation and other fields (Including waste incinerator temperature difference power generation module, internal combustion en...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F11/00C01G1/02C01G51/00H01L35/12H01L35/34
Inventor 路清梅张久兴张艳峰刘燕琴周美玲
Owner BEIJING UNIV OF TECH
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