TY - JOUR
T1 - First-principles theory of the coherency strain, defect energetics, and solvus boundaries in the PbTe-AgSbTe2 system
AU - Barabash, S. V.
AU - Ozolins, V.
AU - Wolverton, C.
PY - 2008/12/1
Y1 - 2008/12/1
N2 - Using first-principles data for the elastic properties of PbTe, AgSbTe2, and related compounds, we extend our previous theoretical study of the thermodynamics of PbTe-AgSbTe2 and present an in-depth analysis of the effects of elastic strain on the thermodynamics of ordering and coherent solvus boundaries. We find that the substitutional site preference for Pb in ordered AgSbTe2 and the large asymmetry of the PbTe-AgSbTe2 miscibility gap share a common physical origin in the peculiar defect energetics of AgSbTe2. In particular, we find that Pb substitution on Ag sites has approximately the same energy cost as a complex defect consisting of Pb substitution on an Sb site combined with an SbAg antisite defect. Configurational entropy contributions strongly favor the latter, explaining why Pb substitutes almost exclusively on the Sb sites in AgSbTe2. Coherency strain is shown to increase the solubility limits by a factor of ∼2 relative to the bulk values both for Ag,Sb in PbTe and for Pb in AgSbTe2.
AB - Using first-principles data for the elastic properties of PbTe, AgSbTe2, and related compounds, we extend our previous theoretical study of the thermodynamics of PbTe-AgSbTe2 and present an in-depth analysis of the effects of elastic strain on the thermodynamics of ordering and coherent solvus boundaries. We find that the substitutional site preference for Pb in ordered AgSbTe2 and the large asymmetry of the PbTe-AgSbTe2 miscibility gap share a common physical origin in the peculiar defect energetics of AgSbTe2. In particular, we find that Pb substitution on Ag sites has approximately the same energy cost as a complex defect consisting of Pb substitution on an Sb site combined with an SbAg antisite defect. Configurational entropy contributions strongly favor the latter, explaining why Pb substitutes almost exclusively on the Sb sites in AgSbTe2. Coherency strain is shown to increase the solubility limits by a factor of ∼2 relative to the bulk values both for Ag,Sb in PbTe and for Pb in AgSbTe2.
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U2 - 10.1103/PhysRevB.78.214109
DO - 10.1103/PhysRevB.78.214109
M3 - Article
AN - SCOPUS:58149473316
SN - 1098-0121
VL - 78
JO - Physical Review B - Condensed Matter and Materials Physics
JF - Physical Review B - Condensed Matter and Materials Physics
IS - 21
M1 - 214109
ER -