TY - JOUR
T1 - Compounds and subsolidus phase relations in the CaO - Co3O 4-CuO system
AU - Miyazaki, Yuzuru
AU - Huang, Xiangyang
AU - Kajitani, Tsuyoshi
N1 - Funding Information:
This study was partly supported by the Core Research for Evolution Science and Technology (CREST) Project of Japan Science and Technology Agency (JST), and also by a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
PY - 2005/10
Y1 - 2005/10
N2 - We have investigated the subsolidus phase relations in the system CaO-Co3O4-CuO at 920°C under 1 atm of oxygen by means of powder X-ray diffraction method. Apart from the three known phases of Ca2CuO3, Ca3Co2O6 and (Co1-xCux)3O4 spinel (0≤x≤0.06), two misfit-layered cobaltates have been identified. The first misfit is a solid solution, having a chemical formula [Ca2(Co1-xCux)O3]pCoO2 with 0≤x≤0.12, while the other misfit has a pinpoint composition of [Ca2(Co0.65Cu0.35)2O4]pCoO2. Both the phases have an incommensurate b-axes ratio, p∼0.62, due to the size difference between the two subsystems. Another phase is found in the Cu-rich quasi-one-dimensional composite crystal Cap(Cu1-xCox)O2(p∼0.83,0.08≤x≤0.34), but the terminal compound Ca0.83CuO2 is not synthesized. The octahedral Co site in the Ca3Co2O6 phase can be partially substituted with Cu, up to 6%, to form the Ca3(Co1-xCux)2O6(0≤x≤0.06) solid solution.
AB - We have investigated the subsolidus phase relations in the system CaO-Co3O4-CuO at 920°C under 1 atm of oxygen by means of powder X-ray diffraction method. Apart from the three known phases of Ca2CuO3, Ca3Co2O6 and (Co1-xCux)3O4 spinel (0≤x≤0.06), two misfit-layered cobaltates have been identified. The first misfit is a solid solution, having a chemical formula [Ca2(Co1-xCux)O3]pCoO2 with 0≤x≤0.12, while the other misfit has a pinpoint composition of [Ca2(Co0.65Cu0.35)2O4]pCoO2. Both the phases have an incommensurate b-axes ratio, p∼0.62, due to the size difference between the two subsystems. Another phase is found in the Cu-rich quasi-one-dimensional composite crystal Cap(Cu1-xCox)O2(p∼0.83,0.08≤x≤0.34), but the terminal compound Ca0.83CuO2 is not synthesized. The octahedral Co site in the Ca3Co2O6 phase can be partially substituted with Cu, up to 6%, to form the Ca3(Co1-xCux)2O6(0≤x≤0.06) solid solution.
KW - Ca-Co-Cu-O system
KW - Composite crystal
KW - Crystal structure
KW - Phase relations
KW - Rietveld analysis
KW - Solid solution
KW - Thermoelectric compounds
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U2 - 10.1016/j.jssc.2005.06.042
DO - 10.1016/j.jssc.2005.06.042
M3 - Article
AN - SCOPUS:25644439925
SN - 0022-4596
VL - 178
SP - 2973
EP - 2979
JO - Journal of Solid State Chemistry
JF - Journal of Solid State Chemistry
IS - 10
ER -