Research on Rare-Earth Metals and Compounds and Development of Applications Based on Their Magnetic Properties
Semiannual technical rept. 2 Nov 1970-1 May 1971
RICE UNIV HOUSTON TX MATERIALS SCIENCE LAB
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The report describes the technical accomplishments of the first six- month phase of a research program on the magnetic and magnetoelastic properties of the rare-earth elements and alloys and compounds rich in the rare earths. A primary goal of the program was the development of high efficient high-frequency ultrasonic transducers utilizing the extremely high magnetostriction found in most rare-earth materials. Ultrasonic transducers in the form of thin polycrystalline films deposited on nonmagnetic substrates have been constructed using pure rare earths. In order to better understand the magnetoelastic coupling which is responsible for the large magnetostriction of the rare earths, studies have been made on the attenuation and velocity of 20 MHz ultrasonic waves at various temperatures in single-crystal rare-earth material as a function of applied magnetic field. The results show an extremely strong magnetoelastic interaction in the case of terbium crystals. The results also indicate the possibility of the development of efficient ultrasonic switches and modulators for high-frequency operation. Finally, an effort has been made to construct apparatus for the preparation of single-crystal specimens of rare- earth materials for use in this program.
- Electricity and Magnetism