Thermodynamic behavior of Ca.sub.3./sub.Co.sub.3.93+x./sub.O.sub.9+δ./sub. ceramics

0385911 - FZÚ 2013 RIV CZ eng J - Journal Article
Jankovský, O. - Sedmidubský, D. - Šofer, Z. - Šimek, P. - Hejtmánek, Jiří
Thermodynamic behavior of Ca₃Co_3.93+xO_9+δ ceramics.
Ceramics - Silikáty. Roč. 56, č. 2 (2012), s. 139-144. ISSN 0862-5468. E-ISSN 1804-5847
Institutional research plan: CEZ:AV0Z10100521
Keywords : misfit cobaltites * thermoelectric materials * heat capacity * Debye-Einstein model * phase equlibria
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 0.418, year: 2012

Based on the results of differential thermal analysis, differential scanning calorimetry, thermogavimetric analysis, low temperature calorimetry and X-Ray powder diffraction of equilibrated samples as well as on the assessed thermodynamic data phase a section of the Ca-Co-O diagram for p(O2) = 0.21 was calculated using the FactSage software. Among the involved phases the misfit cobaltite Ca3Co3.93+xO9+delta is well known for its distinctive thermoelectric properties. As shown by our experiments and reproduced by the proposed thermodynamic model the Ca3Co3.93+xO9+δ phase actually exhibits a narrow homogeneity range with respect to cation composition. The primary focus was put on the heat capacity of Ca3Co3.93+xO9+δ collected in a broad temperature range and analyzed in terms of a combined Debye - Einstein model.
Permanent Link: http://hdl.handle.net/11104/0215068