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Contributions to anelasticity in langasite and langatate

Published

Author(s)

Ward L. Johnson, Sudook A. Kim, Christine F. Rivenbark, Satoshi Uda

Abstract

Maximization of the quality factors Q of langasite (LGS) and langatate (LGT) is necessary for optimal performance of acoustic resonators of these materials in frequency-control and high-temperature sensing applications. In this report, measurements and least-squares analysis of 1/Q as a function of ultrasonic frequency and temperature (up to 750~K) of undoped LGS and LGT reveal a superposition of physical effects, including point defect relaxations and intrinsic phonon-phonon loss. In LGS, these effects are superimposed on a large temperature-dependent background with weak frequency dependence that is understood to arise from a relaxation process with a distribution of activation energies. This distributed relaxation is suggested to be consistent with anelastic kink migration. No evidence for a significant background of this form is found in the more recently fabricated LGT crystal. The analysis of the frequency- and temperature-dependence of 1/Q of LGT indicates that, at near-ambient temperatures, the damping in this specimen is close to the intrinsic limit determined by phonon-phonon interactions. Piezoelectric/carrier relaxation, which must occur at sufficiently elevated temperatures, is not found to be a significant contribution to $1/Q, relative to defect-related contributions, in either LGS or LGT in the measured range of temperatures.
Citation
Physical Review B
Volume
110
Issue
12

Keywords

acoustic resonance, anelasticity, dislocation damping, high-temperature sensors, kink migration, langasite, langatate, phonon-phonon damping, point defect relaxation, quality factor, ultrasonic attenuation

Citation

Johnson, W. , Kim, S. , Rivenbark, C. and Uda, S. (2011), Contributions to anelasticity in langasite and langatate, Physical Review B, [online], https://doi.org/10.1063/1.3672443 (Accessed April 16, 2024)
Created December 30, 2011, Updated November 10, 2018