CHARACTERIZATION OF THIN FILMS AND NOVEL MATERIALS USING RESONANT ULTRASOUND SPECTROSCOPY
Open Access
- Author:
- Gladden, III, Joseph Rhea
- Graduate Program:
- Physics
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- June 05, 2003
- Committee Members:
- Julian Decatur Maynard Jr., Committee Chair/Co-Chair
Peter C Eklund, Committee Member
Vincent Henry Crespi, Committee Member
Anthony A Atchley, Committee Member
Jayanth R Banavar, Committee Member - Keywords:
- alumina
dentin
nanotubes
phase transitions
thin films
elastic constants
acoustics
attenuation - Abstract:
- Crystalline thin films have become an important area of research in condensed matter and applied physics, electrical engineering, and materials science. There exists fundamental differences between 2 dimensional and bulk physics for many materials; and ever decreasing element sizes in mechanical and electronic devices requires a practical understanding of these differences. With an increased interest in thin films comes a need for new probes, able to gather information on structures with ever decreasing dimensions. This work describes a new extension of the acoustic method resonant ultrasound spectroscopy (RUS) to the measurement of the elastic tensor of a thin film deposited on a substrate. The thin film RUS technique has been successfully applied to various novel materials such as mats of carbon nanotubes, which exhibit novel attenuation effects on small mechanical resonators; and colossal magneto-resistance (CMR) films, for which a previously unreported phase transition has been detected. Typical film thicknesses studied were 100 - 1,000 nm for the CNT films, and 200 and 400 nm for the CMR films. In general, films occupying only 1/1,000 of the substrate can be reliably measured. In addition to thin films, traditional RUS was used to determine a correction to the sign of the C14 of alpha-alumina, previously measured over 40 years ago; and the first application of RUS to biological materials, specifically human dentin.