ASA 124th Meeting New Orleans 1992 October

1pPAa5. Application of resonant ultrasound spectroscopy to the study of small single crystal wafers.

P. S. Spoor

M. J. McKenna

J. D. Maynard

Penn State Univ., University Park, PA 16802

The study of acoustic waves in a solid can reveal many of its fundamental properties, such as the Debye temperature, the second derivatives of the free energy, and the strength of the electron--phonon coupling---but only if a specimen can be considered a single crystal with a minimum of defects and impurities. Such specimens tend to be extremely small and fragile, especially for newly discovered materials. Often, as the case with the high-temperature copper oxide superconductors, the samples can only be grown as wafers, typically 200x200x40 (mu)m in size. These extremely small sizes and the ``plate'' proportions complicate the resonant ultrasound technique because stress on the sample from the transducers is more of a concern; second, only the ``plate'' modes, which have no dependence on the thin dimension, can be excited, and the overtones are widely spaced in frequency, so frequency-dependent mechanisms have to be considered; for example, measurements of the attenuation are of particular interest in high T[sub c] materials. Applications to high T[sub c] and TiB[sub 2] crystals will be discussed. [Work supported by NSF Grant No. DMR-9000549 and by the Office of Naval Research.]