Surface acoustic wave investigation of a Nb/sub 3/Ge film. [18 to 21. 5 degrees K]

Thesis/Dissertation · Mon Jan 01 04:00:00 EST 1979

OSTI ID:5669147

Salvo, Jr, H L

Measurements of the attenuation of a surface wave at 1190 MHz by a superconducting .5 mu thick film of Nb/sub 3/Ge have been made. The Nb/sub 3/Ge film was rf sputtered onto a piezo-electrically active AlN film, 3.2 mu thick, which had been chemically vapor deposited on an R-plane sapphire substrate. The Nb/sub 3/Ge film has a T/sub c/ = 21.5 K measured electrically, however, the ultrasound attenuation does not correspond to that expected for a superconductor with this transition temperature. In order to explain the attenuation results, it is proposed that the film has a homogeneous distribution of superconducting material with different transition temperatures. The distribution function is determined from both the ultrasonic data and the resistivity data with that distribution determined ultrasonically quite different from that determined electrically. Arguments are presented to explain the discrepancy between them and to show that the distribution function determined ultrasonically is a better characterization of the film. The ultrasonic data predicts that for the particular sample being measured the largest amount of Nb/sub 3/Ge is going superconducting at 18 K not 21.5 K. Also, theoretical calculations of the electron-phonon contribution to the attenuation of a surface wave on an isotropic elastic substrate covered by an isotropic metal film are presented.

• OSTI ID: 5669147
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
ACOUSTIC MEASUREMENTS
ALLOYS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
FILMS
GERMANIUM ALLOYS
INTERMETALLIC COMPOUNDS
MAGNETIC PROPERTIES
NIOBIUM ALLOYS
NIOBIUM BASE ALLOYS
PHYSICAL PROPERTIES
SUPERCONDUCTIVITY
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE