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Thermodynamic Regularities in Perovskite and K 2 NiF 4 Compounds
Author(s) -
Yokokawa Harumi,
Kawada Tatsuya,
Dokiya Masayuki
Publication year - 1989
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1989.tb05971.x
Subject(s) - enthalpy , perovskite (structure) , ion , crystallography , chemistry , standard enthalpy change of formation , coordination number , standard enthalpy of formation , thermodynamics , physics , organic chemistry
It has been found that the enthalpy of formation of perovskite compounds, Δ f H° (ABO 3 , B = transition metais), from binary oxides can be well characterized in terms the tolerance factor, t≡(r A + r o )√2 (r B + r o ), where r A and r B are the radii of A‐site ions with 12‐coordination and B‐site ions with 6‐coordination, respectively, and Δ f H°=−168 + 270(1 − t) kJ·mol −1 for A I B V O 3 , Δ f H°=−125 + 1000(1 − t) kJ·mol −1 for A II B IV O 3 , and Δ f H°=− 90 + 720(1 − t) kJ·mol −1 for A III B III O 3 . Although the thermodynamic data of K 2 NiF 4 compounds are not extensive, a similar regularity can be found when use is made of the radii of A‐site ions with 9‐coordination for the K 2 NiF 4 compounds. These correlations will be quite useful in predicting.