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XPS and SEM studies of Ca‐ and Ni‐substituted LaCrO 3 after quenching from reducing and oxidizing atmospheres at 800 °C
Author(s) -
Glenne Rita,
Horst Jens Anton,
Jørgensen Sissel,
Norby Truls,
Seiersten Marion
Publication year - 1994
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.740220160
Subject(s) - x ray photoelectron spectroscopy , oxidizing agent , annealing (glass) , sintering , materials science , analytical chemistry (journal) , recrystallization (geology) , metallurgy , mineralogy , nuclear chemistry , chemistry , chemical engineering , geology , environmental chemistry , paleontology , organic chemistry , engineering
Sintered and polished samples of La 1− x Ca x CrO 3 ( x = 0.0, 0.1, 0,3, 0.5) and La 1− x Ca x Cr 1− y Ni y O 3 ( x = 0.3, y = 0.05) were annealed and quenched under reducing or oxidizing conditions at 800 °C and analysed with XPS and SEM. After annealing in H 2 + H 2 O the surfaces of the samples with x = 0.3 and x = 0.5 were enriched in Ca in a 5 nm deep zone. Cr was not enriched and was present in the +3 state. Annealing in O 2 + H 2 O gave Ca enrichment and crystalline outgrowths, increasing with increasing Ca contents. The Cr in the surface was in the +3 and +6 states, and the amount of Cr 6+ increased with increasing Ca contents. These observations are assigned to precipitation of CaCrO 4 and possibly other phases. The Ni‐doped sample exhibited less grain growth during sintering and less surface recrystallization in oxidizing atmospheres than the corresponding sample without Ni.