Electronic Theses and Dissertations

Date of Award

2011

Document Type

Dissertation

Degree Name

Ph.D. in Physics

Department

Physics and Astronomy

First Advisor

Joseph R. Gladden

Second Advisor

Gregory Tschumper

Third Advisor

Joel Mobley

Relational Format

dissertation/thesis

Abstract

The goal of this dissertation is to characterize the elastic properties of palladium hydride near the tri-critical point as a classic example of metal hydride systems using the resonant ultrasound spectroscopy. A high temperature and high pressure resonant ultrasound spectroscopy system which include the RUS cell and the direct contact transducer set-up was designed and constructed. The temperature and pressure dependent of elastic moduli of palladium hydride and palladium crystals were obtained at five isotherms near the critical temperature, 293 °C and for pressure range of 250–500 psi. A strong softening of the shear modulus was observed at temperature and pressure points around the critical points, 293 °C and 290 psi respectively. On the other hand, anomalous softening of the bulk modulus and the C' was observed in the same temperature and pressure region. The investigations includes study of the equilibrium dynamics of hydrogen absorption/desorption in metal hydrides. A color map of the equilibrium dynamics pattern was developed and correlation between the color map and the palladium hydride phases was established.

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