Accession Number : AD0282943

Title :   THE PROPAGATION OF ULTRASONIC WAVES IN ALKALI HALIDE SINGLE CRYSTALS

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE LAB FOR INSULATION RESEARCH

Personal Author(s) : PAPADAKIS,EMMANUEL P.

Report Date : JUN 1962

Pagination or Media Count : 1

Abstract : Ultrasonic diffraction, internal conical refraction, and attenuation in NaCl and other materials were studied by the pulse-echo method. In the same manner the elastic constants of NaCl were also determined, while their rates of change with temperature were found by pulse-echo interferometry. Ultrasonic diffraction of compression waves was observed along the pure-mode axes in NaCl as well as along the (100) direction in KClAND IN ONE DIRECTION IN ISOTROPIC STEEL. Diffraction of the Fresnel type occurred and was strongly dependent upon the anisotropy of the material and the shape of the input wave front. Internal conical refraction of shear waves was observed by selective absorption in the (111) direction in NaCl and in the (100) direction in trigonal CaCO3. The attenuation of 5 to 200 Mc waves was measured for all the pure modes in NaCl and was found to vary as f squared times omega (f = frequency, omega = orientation factor) in accordance with dislocation-damping theory. The attenuation decreased under X-ray irradiation for modes with omega not equal to zero, but held constant for omega equal to zero. Theoretical approaches for deriving the diffraction effect and the rates of change of the elastic moduli with temperature are suggested. (Author)

Descriptors :   *ALKALI METALS, *CHLORIDES, *PROPAGATION, *SINGLE CRYSTALS, *ULTRASONIC RADIATION, ATTENUATION, DIFFRACTION, POTASSIUM COMPOUNDS, SODIUM COMPOUNDS

Distribution Statement : APPROVED FOR PUBLIC RELEASE