A low temperature calorimetric study of several high-T sub c superconductors

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:7071778

Reeves, M E

Sintered powders of La(1.85)Ba(0.15)CuO(4), La(1.8)Sr(0.2)CuO(4), YBa(2)Cu(3)O(7-x), and GdBa(2)Cu(3)O(7-x) were prepared by solid state reaction. The samples were carefully characterized for impurities by x ray diffraction and Raman spectroscopy. The resistivity and magnetic susceptibility of each sample was measured to characterize its superconducting transition. The specific heat of the samples was measured with an adiabatic, computer-controller calorimeter. The specific heat discontinuity for GdBa(2)Cu(3)O(7-x) was determined, and antiferromagnetic ordering and superconductivity were observed to coexist in this sample. For all the samples, a temperature dependent phonon density of states was inferred from the specific heat measured above 10 K. While the temperature range of the measurements extended from 2 to 180 K, particular attention was paid to the specific heat below 10 K. In this temperature range, the lattice and electronic contributions to the specific heat could be separated. In all the samples measured except for GdBa(2)Cu(3)O(7-x) an unexpected linear contribution to the specific heat was observed. By systematically eliminating the known impurities in a sample of YBa(2)Cu(3)O(7-x) and still observing the linear contribution, an argument is made against attributing this contribution to a parasitic phase. The magnetic field dependence of the specific heat of YBa(2)Cu(3)O(7-x) was determined for fields from O to 3T and in the temperature range 2 to 10 K. The field dependence was compared to a calculation based on Ginzburg-Landau theory. The theory did not predict the experimental results.

• Research Organization: Illinois Univ., Urbana, IL (USA)
• OSTI ID: 7071778
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
ALKALINE EARTH METAL COMPOUNDS
ANTIFERROMAGNETISM
BARIUM COMPOUNDS
BARIUM OXIDES
CALORIMETRY
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
FABRICATION
GADOLINIUM COMPOUNDS
GADOLINIUM OXIDES
HIGH-TC SUPERCONDUCTORS
IMPURITIES
LANTHANUM COMPOUNDS
LANTHANUM OXIDES
LASER SPECTROSCOPY
LOW TEMPERATURE
MAGNETIC PROPERTIES
MAGNETIC SUSCEPTIBILITY
MAGNETISM
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RAMAN SPECTROSCOPY
RARE EARTH COMPOUNDS
SINTERING
SPECIFIC HEAT
SPECTROSCOPY
STRONTIUM COMPOUNDS
STRONTIUM OXIDES
SUPERCONDUCTIVITY
SUPERCONDUCTORS
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
YTTRIUM OXIDES