Sound Attenuation at High Temperatures in Pt

R.K. Singh and K.K. Pandey H.C.P.G. College, Varanasi-221001, U.P., India

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Received: 04 10 2005;

Ultrasonic attenuation due to phonon-phonon interaction and thermoelastic loss was evaluated in VIII group transition metal Pt in a wide temperature range (100 K to 1500 K) for longitudinal and shear waves along〈100〉, 〈110〉 and〈111〉 directions and for shear waves polarised along different directions. Electrostatic and Born-Mayer potentials were used to obtain second and third order elastic constants, taking nearest-neighbour distance and hardness parameter as input data. Second and third order elastic constants data obtained at different temperatures were used to obtain Gruneisen parameters and non-linearity or anisotropy parameters which in turn were used to evaluate (α/f2)l and (α/f2)s in Akhiezer regime. The results were discussed and it was found that at lower temperatures (α/f2) increases rapidly with temperature and then rate of increase becomes very small. Contribution to the total attenuation due to thermoelastic loss is negligible so that due to phonon-phonon interaction establishing that major part of energy from sound wave is removed due to interaction with thermal phonons (lattice vibrations).

DOI: 10.12693/APhysPolA.109.219 PACS numbers: 62.20.Dc, 62.65.+k