Internal Friction Tensor in Langasite (LA3Ga5SiO14)

Published

October 16, 2008

Author(s)

H M. Ledbetter, Sudook A. Kim

Abstract

Using acoustic spectroscopy, we measured the complete elastic-constant and internal-friction tensor C_y = C_y (1+Q^-1_y) of langasite, a trigonal-symmetry piezoelectric. To understand the internal friction, we need a mechanism that explains, or is consistent with, six observations: (1) Q^-1 (longinudinal) exceeds Q^-1 (longitudinal) exceeds Q^-1 (traqnsverse); (2) Q^-1 is much larger than expected for phonon-phonon interactions; (3)Q^-1 varies enormously from crystal to crystal; (4)Q^-1 varies with frequency as Q^-1 - ω, as predicted for vibrating dislocations or for phonon-phonon interactions; (5) Q^-1 does not depend on strain amplitude: (6) Q^-1increases with increasing temperature. Phonon scattering by static dislocations provides a possible mechanism, except that the predicted Q^-1 magnitude is too small. Phonon scattering by dynamic dislocations provides the best hypothesis.

Citation

Materials Science and Engineering

Pub Type

Journals

Keywords

dislocations, elastic constants, internal friction, langasite phonon-phonon interactions, piezoelectric

Citation

Ledbetter, H. and Kim, S. (2008), Internal Friction Tensor in Langasite (LA₃Ga₅SiO₁₄), Materials Science and Engineering (Accessed October 15, 2025)