Ultrasonic study of trapped hydrogen tunneling systems in Nb and Ta
The properties of trapped hydrogen tunneling systems in Nb and the analogous systems, H in Ta, and D in Nb were studied with ultrasonic techniques at low temperature. Attenuation due to H in Ta was measured between 0.5 K and 10 K for frequencies between 10 and 55 Mhz. The sound velocity change due to H in Nb was measured in both the normal and superconducting state at 10.8 MHz and 33 MHz at temperatures between 0.5K and 18 K. The attenuation and velocity change due to trapped D in Nb was measured in both the superconducting and normal states for two concentrations of oxygen trapping impurity. It is concluded that nearly all of the experimentally observed properties of this system can be understood in terms of a two-level model. All parameters of the model can be derived from the velocity data. Several features of the response predicted by the model were compared to the ultrasonic data on H and D tunneling systems. The observed relaxation rate of H in Ta was found to be consistent with an electronic mechanism for the relaxation. The most significant result found was that driving the Nb host into the normal state reduces the energy splitting of the tunneling systems as predicted for Nb-O-H.
- Research Organization:
- Illinois Univ., Urbana (USA)
- OSTI ID:
- 6546207
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360102 -- Metals & Alloys-- Structure & Phase Studies
360104* -- Metals & Alloys-- Physical Properties
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DEUTERIUM
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELEMENTS
HYDROGEN
HYDROGEN ISOTOPES
IMPURITIES
ISOTOPES
LIGHT NUCLEI
MATHEMATICAL MODELS
METALS
NIOBIUM
NONMETALS
NUCLEI
ODD-ODD NUCLEI
OXYGEN
PHYSICAL PROPERTIES
STABLE ISOTOPES
SUPERCONDUCTIVITY
TANTALUM
TRANSITION ELEMENTS
TRAPPING