Low-energy excitations in yttria-stabilized zirconia
Walker, Frederick Joseph
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https://hdl.handle.net/2142/25360
Description
Title
Low-energy excitations in yttria-stabilized zirconia
Author(s)
Walker, Frederick Joseph
Issue Date
1983
Doctoral Committee Chair(s)
Anderson, A.C.
Department of Study
Physics
Discipline
Physics
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
low-energy excitations
yttria-stabilized zirconia
thermal conductivity
specific heat
dielectric constant
thermal expansion
Language
en
Abstract
Thermal conductivity, specific heat, dielectric constant and thermal expansion measurements below 2 K on single crystal samples of Zr02 :Y203 with 10.5, 16 and 18 mole % Y2O3 contents exhibit properties typical of glasses. The presence of glass-like excitations having a broad spectrum of energies is indicated by the quadratic temperature dependence of the thermal conductivity and the linear temperature dependence of the specific heat. Excitations with relaxation times on the order of 0.5 sec were observed through the specific heat experiments, which implies the existence of a broad range of relaxation times, as predicted by the tunneling model developed for glasses. This material also possesses a Gruneisen parameter larger than expected for a pure crystalline material with a magnitude similar to that observed in other crystals displaying glass-like low-temperature properties. Changing the Y203 content from 10.5 to 16 mole , increases the number of excitations contributing to the specific heat while the phonon scattering does not change appreciably.
Although Zr02:Y203 has a crystal structure, there is disorder arising from defects introduced by the Y203. Two models of these defects in a disordered environment were examined as possible tunneling
states. The predictions of these models have been compared with
tunneling model parameters derived from the data. Neither model compared favorably with the experimental data.
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