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Influence of Ca content and oxygen partial pressure on microstructural evolution of (Co,Ca)O at elevated temperatures
Author(s) -
KUSINSKI J.,
CIENIEK L.,
PETOTERVAS G.,
PETOT C.,
BALDINOZZI G.
Publication year - 2006
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1111/j.1365-2818.2006.01650.x
Subject(s) - spinel , partial pressure , cobalt , transmission electron microscopy , microstructure , precipitation , oxygen , cobalt oxide , materials science , analytical chemistry (journal) , electrical resistivity and conductivity , doping , oxide , conductivity , mineralogy , crystallography , chemistry , metallurgy , nanotechnology , physics , optoelectronics , organic chemistry , engineering , chromatography , meteorology , electrical engineering
Summary Ca‐doped (1, 1.7, 5 and 10 mol% CaO) cobalt oxide single‐crystal samples, with an [001] orientation, were annealed at elevated temperatures of 1000–1200 °C for different times and at different oxygen partial pressures. The microstructure was examined by means of transmission light and electron microscopy. High‐temperature X‐ray diffractometry was used, with the aim of determining the temperature of the CoO ⇔ Co 3 O 4 transition in these materials. Extensive precipitation of Ca‐free Co 3 O 4 spinel crystals was observed with increasing Ca content and oxygen activity. It is suggested that the electrical conductivity changes in this material may be related to this precipitation, because it changes the electronic state of cobalt cations.