Abstract
A brucite-type hydroxide of CazCo1−z(OH)2 with a high Ca content was synthesized and utilized as a single-source precursor for the fabrication of bulk ceramics of a semiconducting layered calcium cobaltite CayCoO2. Plate-like CazCo1−z(OH)2 particles with z up to 0.22 were reproducibly obtained by a reverse co-precipitation method using KOH as an alkaline source. Uniaxial pressing of the plate-like CazCo1−z(OH)2 particles (z = 0.22), which was calcined at 373 K beforehand, at a pressure as high as 500 MPa produced a highly dense green pellet where the plate-like particles were stacked along the pressing direction. The green pellet was then converted by a heat treatment at 923 K into an oxide ceramic of preferentially (010)-oriented CayCoO2 via a topotactic-like pyrolytic reaction maintaining edge-sharing CoO6 octahedra. Although the ceramic also contained a minor insulating Co3O4 phase (16.7 ± 0.7 mol% estimated from thermal analysis), the electrical measurements proved its p-type semiconducting behavior resulting from the CayCoO2 phase with enhanced Seebeck coefficient exceeding 160 μV/K at room temperature.
| Original language | English |
|---|---|
| Journal | Ceramics International |
| DOIs | |
| Publication status | Accepted/In press - 2018 Jan 1 |
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Keywords
- A. Powders: solid state reaction
- C. Electrical properties
- D. Transition metal oxides
- Thermoelectric properties
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Process Chemistry and Technology
- Surfaces, Coatings and Films
- Materials Chemistry
Cite this
Synthesis of Ca–Co hydroxides and their use in facile fabrication of textured CayCoO2 thermoelectric ceramics. / Shimonishi, Rina; Hagiwara, Manabu; Fujihara, Shinobu.
In: Ceramics International, 01.01.2018.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Synthesis of Ca–Co hydroxides and their use in facile fabrication of textured CayCoO2 thermoelectric ceramics
AU - Shimonishi, Rina
AU - Hagiwara, Manabu
AU - Fujihara, Shinobu
PY - 2018/1/1
Y1 - 2018/1/1
N2 - A brucite-type hydroxide of CazCo1−z(OH)2 with a high Ca content was synthesized and utilized as a single-source precursor for the fabrication of bulk ceramics of a semiconducting layered calcium cobaltite CayCoO2. Plate-like CazCo1−z(OH)2 particles with z up to 0.22 were reproducibly obtained by a reverse co-precipitation method using KOH as an alkaline source. Uniaxial pressing of the plate-like CazCo1−z(OH)2 particles (z = 0.22), which was calcined at 373 K beforehand, at a pressure as high as 500 MPa produced a highly dense green pellet where the plate-like particles were stacked along the pressing direction. The green pellet was then converted by a heat treatment at 923 K into an oxide ceramic of preferentially (010)-oriented CayCoO2 via a topotactic-like pyrolytic reaction maintaining edge-sharing CoO6 octahedra. Although the ceramic also contained a minor insulating Co3O4 phase (16.7 ± 0.7 mol% estimated from thermal analysis), the electrical measurements proved its p-type semiconducting behavior resulting from the CayCoO2 phase with enhanced Seebeck coefficient exceeding 160 μV/K at room temperature.
AB - A brucite-type hydroxide of CazCo1−z(OH)2 with a high Ca content was synthesized and utilized as a single-source precursor for the fabrication of bulk ceramics of a semiconducting layered calcium cobaltite CayCoO2. Plate-like CazCo1−z(OH)2 particles with z up to 0.22 were reproducibly obtained by a reverse co-precipitation method using KOH as an alkaline source. Uniaxial pressing of the plate-like CazCo1−z(OH)2 particles (z = 0.22), which was calcined at 373 K beforehand, at a pressure as high as 500 MPa produced a highly dense green pellet where the plate-like particles were stacked along the pressing direction. The green pellet was then converted by a heat treatment at 923 K into an oxide ceramic of preferentially (010)-oriented CayCoO2 via a topotactic-like pyrolytic reaction maintaining edge-sharing CoO6 octahedra. Although the ceramic also contained a minor insulating Co3O4 phase (16.7 ± 0.7 mol% estimated from thermal analysis), the electrical measurements proved its p-type semiconducting behavior resulting from the CayCoO2 phase with enhanced Seebeck coefficient exceeding 160 μV/K at room temperature.
KW - A. Powders: solid state reaction
KW - C. Electrical properties
KW - D. Transition metal oxides
KW - Thermoelectric properties
UR - http://www.scopus.com/inward/record.url?scp=85056298469&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85056298469&partnerID=8YFLogxK
U2 - 10.1016/j.ceramint.2018.11.020
DO - 10.1016/j.ceramint.2018.11.020
M3 - Article
JO - Ceramics International
JF - Ceramics International
SN - 0272-8842
ER -