Ultrasonic properties at the nanoscale in some metals

The ultrasonic attenuation, velocity and their related parameters are evaluated in nanocrystalline Pt and Pd metals as a function of their size at 300 K along <100>, <110> and <111> orientations. Second- and third-order elastic constants (SOEC and TOEC, respectively) of the metals at nanoscale at 300 K are also calculated starting with only two basic parameters. Dislocation drag coefficients for the evaluation of thermal losses due to motion of linear imperfections are calculated for the metals at different size along <100> orientation. Significant contribution of thermal conductivity to the size dependency of the total attenuation in the metals has been found.