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Thermodynamic Equilibria in Two‐Phase, Elastically Stressed Ionic Crystals
Author(s) -
Johnson William C.
Publication year - 1994
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.1151-2916.1994.tb09760.x
Subject(s) - ionic bonding , thermodynamics , ternary operation , phase (matter) , crystal (programming language) , thermodynamic equilibrium , thermodynamic potential , stress (linguistics) , materials science , chemistry , physics , ion , linguistics , philosophy , organic chemistry , computer science , programming language
The conditions for thermodynamic equilibrium in two‐phase, multicomponent, elastically stressed ionic crystals are derived within the realm of phenomenological thermodynamics using a Gibbsian variational approach. Equilibria between a stressed ionic crystal and a fluid and between two elastically stressed crystals possessing a coherent interface are examined, and an expression for the dependence of the electrochemical potential on stress is derived. The equilibrium conditions are used to calculate composition changes in a ternary (Mg, Ni)O film and the corresponding change in the thermodynamic stability of the film owing to substrate‐induced stress. In this example, a substrateinduced strain of 1% yields an absolute shift in composition of 1.1 at.% at 1000 K. Significantly smaller or larger shifts are possible depending upon material parameters.