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Computer Simulation of Point Defects at Finite Temperatures
Author(s) -
Monti A. M.
Publication year - 1994
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221840104
Subject(s) - vacancy defect , crystallographic defect , thermal , lattice (music) , atmospheric temperature range , range (aeronautics) , materials science , thermal expansion , condensed matter physics , molecular physics , physics , thermodynamics , acoustics , composite material
A self‐consistent calculation method based on conjugate gradients is applied to obtain the atomic structure and thermodynamic properties of microstructural defects in solids at finite temperatures. The lattice free energy, described in the local harmonic approximation, consists of two contributions: static and vibrational. The former depends on the atomic coordinates, which change with thermal expansion. The latter explicitly depends on temperature and frequencies of the normal modes. Frequencies, obtained in an Einstein‐type approximation, are implicit functions of atomic coordinates, therefore they may also change with thermal expansion. The formation free energy for self‐interstitials and vacancy‐type defects is calculated for Cu over the broad temperature range 0 to 1200 K. A remarkable decrease of the formation free energy with temperature increase is observed. Such decrease is near 20% for vacancy‐type defects and 35% for self‐interstitials, over the whole temperature range.