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Comments on the comparison of dynamic and static compression data
11
ABSTRACTS OF PAPERS TO APPEAR IN
disordering has been observed in each of. these materials by calorimetric investigations, the cationic transport properties are unlikely to be discontinuous at this temperature and the sudden disorderin~of the stnicture may not be easily identified by conductivity and diffusion measurements. Received 24 November 1969 Revised 9 February 1970
4.
EFFECT OF ORDERED VACANCIES ON ULTRASONIC WAVE PROPAGATION IN SOME MERCURY—INDIUM TELLURIDES G.A. Saunders and T. Seddon, Department of Applied Physics and Electronics, the University of Durham, England
The compounds HgTe, Hg5In 2Te8 and Hg3In 2Te ~ constitute a series in which the concentration of vacancies, sited regularly on the lattice array, increases progressively from zero. To assess the effect of vacancies on the mechanical properties the propagation of 10 MHz ultrasonic waves has been studied in these compounds. The elastic constants show a regular trend through the series, namely that the stiffness decreases as the vacancy concentration increases. In particular, the reduced bulk modulus is found to be directly proportional to the number of vacancies present. Bordoni-type relaxation peaks occur in all three compounds and are consistent with dislocation motion on the I liii and 11101 slip planes. The activation energies for kink formation and the Peierls stresses, calculated on the basis of the kink nucleation theory, show that dislocation motion becomes easier with increased vacancy concentration and takes place more readily on the 11111 slip planes.
J. PHYS. CHEM. SOLIDS
Vol. 8, No. 8
R. Grover, Lawrence Radiation Laboratory, University of California, Livermore, California A detailed discussion is presented of the relationship between dynamic shock wave data at high pressures, acoustic velocity data at low pressures and the static compression data at intermediate pressures reported by Vaidya and Kennedy in the previous paper. Received 12 January 1970 Revised 19 February 1970
6.
THERMODYNAMIC PROPERTIES OF SOLID Ar, Kr AND Xe BASED UPON A SHORT RANGE CENTRAL FORCE AND THE IMPROVED SELFCONSISTENT PHONON SCHEME M.L. Klein, Division of Chemistry, National Research Council of Canada, Ottawa, Ontario, Canada and V.V. Goldman and G.K. Horton, Department of Physics, Rutgers University, New Brunswick, N.J.
The thermodynamic properties of solid Ar, Kr and Xe are investigated within the framework of the self-consistent phonon method. We have used a central two-body potential of the Mie— Lennard—Jones type.. The lowest order selfconsistent scheme, the so-called self-consistent phonon harmonic approximation (sc), is shown to be inadequate. The effect of including, in the Helmholtz free energy, the leading terms omitted by the sc is examined in detail and a comparison is also made with our earlier work based on the Born—von K~rm~n approximation. We find substantial differences between the results based on different approximations to the free energy. Received 5 January 1970
5.
COMMENTS ON THE COMPARISON OF DYNAMIC AND STATIC COMPRESSION DATA
ABSTRACTS OF PAPERS TO APPEAR IN
disordering has been observed in each of. these materials by calorimetric investigations, the cationic transport properties are unlikely to be discontinuous at this temperature and the sudden disorderin~of the stnicture may not be easily identified by conductivity and diffusion measurements. Received 24 November 1969 Revised 9 February 1970
4.
EFFECT OF ORDERED VACANCIES ON ULTRASONIC WAVE PROPAGATION IN SOME MERCURY—INDIUM TELLURIDES G.A. Saunders and T. Seddon, Department of Applied Physics and Electronics, the University of Durham, England
The compounds HgTe, Hg5In 2Te8 and Hg3In 2Te ~ constitute a series in which the concentration of vacancies, sited regularly on the lattice array, increases progressively from zero. To assess the effect of vacancies on the mechanical properties the propagation of 10 MHz ultrasonic waves has been studied in these compounds. The elastic constants show a regular trend through the series, namely that the stiffness decreases as the vacancy concentration increases. In particular, the reduced bulk modulus is found to be directly proportional to the number of vacancies present. Bordoni-type relaxation peaks occur in all three compounds and are consistent with dislocation motion on the I liii and 11101 slip planes. The activation energies for kink formation and the Peierls stresses, calculated on the basis of the kink nucleation theory, show that dislocation motion becomes easier with increased vacancy concentration and takes place more readily on the 11111 slip planes.
J. PHYS. CHEM. SOLIDS
Vol. 8, No. 8
R. Grover, Lawrence Radiation Laboratory, University of California, Livermore, California A detailed discussion is presented of the relationship between dynamic shock wave data at high pressures, acoustic velocity data at low pressures and the static compression data at intermediate pressures reported by Vaidya and Kennedy in the previous paper. Received 12 January 1970 Revised 19 February 1970
6.
THERMODYNAMIC PROPERTIES OF SOLID Ar, Kr AND Xe BASED UPON A SHORT RANGE CENTRAL FORCE AND THE IMPROVED SELFCONSISTENT PHONON SCHEME M.L. Klein, Division of Chemistry, National Research Council of Canada, Ottawa, Ontario, Canada and V.V. Goldman and G.K. Horton, Department of Physics, Rutgers University, New Brunswick, N.J.
The thermodynamic properties of solid Ar, Kr and Xe are investigated within the framework of the self-consistent phonon method. We have used a central two-body potential of the Mie— Lennard—Jones type.. The lowest order selfconsistent scheme, the so-called self-consistent phonon harmonic approximation (sc), is shown to be inadequate. The effect of including, in the Helmholtz free energy, the leading terms omitted by the sc is examined in detail and a comparison is also made with our earlier work based on the Born—von K~rm~n approximation. We find substantial differences between the results based on different approximations to the free energy. Received 5 January 1970
5.
COMMENTS ON THE COMPARISON OF DYNAMIC AND STATIC COMPRESSION DATA