Low-temperature specific heat anomalies in the group V transition metals
Anomalies previously reported in the specific heat curve of normal-state niobium at 3 and 9.5 K prompted new measurements on single crystals of niobium, tantalum, and vanadium from their superconducting T/sub c/'s up to 20 K. The upper anomaly was confirmed in Nb and found to occur at 10.3 K. At this temperature the C/T vs. T/sup 2/ curve changed abruptly from a line with constants ..gamma../sub 2/=7.67 mJ/K/sup 2/ mole and theta/sub 2/=241 K to one with ..gamma../sub 3/=9.16 mJ/K/sup 2/ mole and theta/sub 3/=250 K. The Nb T/sub c/ was 9.275 K. Anomalies similar to that occurring at 3 K in the niobium curve were discovered to exist in tantalum and vanadium as well, but at the higher temperatures of 7.19 and 7.47 K, respectively. The tantalum data yielded line constants of ..gamma../sub 1/=5.42 mJ/K/sup 2/ mole, theta/sub 1/=238 K, ..gamma../sub 2/=4.36 mJ/K/sup 2/ mole, and theta/sub 2/=228 K and a T/sub c/ of 4.475 K. For vanadium theta/sub 1/=397 K is higher than previous specific heat values of theta/sub 1/=382 K, and in agreement with that obtained from elastic constant measurements (399 K). The discontinuities in the slopes of the specific heat curves are analyzed in terms of anomalies in the electron and phonon spectra of the materials investigated.
- Research Organization:
- U. S. Army Electronics Technology and Devices Laboratory (ECOM), Fort Monmouth, New Jersey
- OSTI ID:
- 7208796
- Journal Information:
- J. Low Temp. Phys.; (United States), Journal Name: J. Low Temp. Phys.; (United States) Vol. 28:3; ISSN JLTPA
- Country of Publication:
- United States
- Language:
- English
Similar Records
SUPERCONDUCTING AND NORMAL SPECIFIC HEATS OF NIOBIUM
Specific heat of A 15 Nb/sub 3/Sn in fields to 18 tesla
Related Subjects
360104* -- Metals & Alloys-- Physical Properties
656102 -- Solid State Physics-- Superconductivity-- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena-- (-1987)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELEMENTS
METALS
NIOBIUM
PHYSICAL PROPERTIES
REFRACTORY METALS
SPECIFIC HEAT
SUPERCONDUCTIVITY
TANTALUM
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENTS
ULTRALOW TEMPERATURE
VANADIUM
VERY LOW TEMPERATURE