Chemical thermodynamic considerations in sintering of LaCrO sub 3 -based perovskites

Journal Article · Mon Apr 01 04:00:00 EST 1991 · Journal of the Electrochemical Society; (United States)

DOI:https://doi.org/10.1149/1.2085708· OSTI ID:5097019

Yokokawa, H; Sakai, N; Kawada, T; Kokiya, M ^[1]

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1. National Chemical Lab. for Industry, Tsukuba Research Center, Tsukuba, Ibaraki 305 (JP)

This paper reports on the thermodynamic properties of LaCrO{sub 3} and related compounds estimated and utilized to correlate sinterability with phase relations in the La-M-Cr-O (M = Mg, Ca, Sr) systems. Chemical equilibria calculations reveal that calculated vapor pressures of gaseous chromium oxides (especially CrO{sub 3}) can be well correlated with our previous experimental results on sinterability. The poor sinterability can be ascribed to the formation of a thin layer of Cr{sub 2}O{sub 3}(s) which is formed from incongruently vaporized CrO{sub 3}(g) at the interparticle neck during the initial stage of sintering in air. Improvement of sinterability of Cr{sub 2}O{sub 3}-based oxides can be achieved by removing this Cr{sub 2}O{sub 3} layer or by decreasing CrO{sub 3}(g) vapor pressure to prevent the formation of Cr{sub 2}O{sub 3} layer. These suggest that (La{sub 1{minus}x}Ca{sub x})CrO{sub 3} perovskites are the most suitable materials for high sinterability, since these materials have the low CrO{sub 3} vapor pressure without precipitation of La{sub 2}O{sub 3}.

• OSTI ID: 5097019
• Journal Information: Journal of the Electrochemical Society; (United States), Journal Name: Journal of the Electrochemical Society; (United States) Vol. 138:4; ISSN JESOA; ISSN 0013-4651
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201 -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
ALKALINE EARTH METAL COMPOUNDS
CALCIUM COMPOUNDS
CALCIUM OXIDES
CHALCOGENIDES
CHROMIUM COMPOUNDS
CHROMIUM OXIDES
FABRICATION
LANTHANUM COMPOUNDS
LANTHANUM OXIDES
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
OXIDES
OXYGEN COMPOUNDS
PEROVSKITES
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
SINTERING
STRONTIUM COMPOUNDS
STRONTIUM OXIDES
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS