Abstract
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.
| Original language | English |
|---|---|
| Pages (from-to) | 2973-2979 |
| Number of pages | 7 |
| Journal | Journal of Solid State Chemistry |
| Volume | 178 |
| Issue number | 10 |
| DOIs | |
| Publication status | Published - 2005 Oct 1 |
Keywords
- Ca-Co-Cu-O system
- Composite crystal
- Crystal structure
- Phase relations
- Rietveld analysis
- Solid solution
- Thermoelectric compounds
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry