1974 annual summary report Page: 50 of 126
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NT-03
in KXWO3, CsxWO3, and TI WO3. The values of x determined from the
.excess heat capacity agree reasonably well with the nominal composition
having x = 0. 33. The Einstein temperatures E for the metal ions vi-
brating in the channels formed by the six-membered rings of WO6 octa-
hedra were found to be 58 K for Rb, 70 K for Cs, and 38 K for Ti. Two
unexplained peaks in the heat capacity of KxWO3 near 20 K precluded an
accurate determination of E for this tungsten bronze, but O is estimated
to be between 60 and 90 K. The magnitudes of the Einstein temperatures
can be understood in terms of the masses and ionic radii of the metal
ions. All four hexagonal tungsten bronzes are superconductors. Measure-
ments of the heat capacity with a magnetic field showed RbXWO3 to be a
type-I superconductor, but K WO3 to be a type-II superconductor.
HEAT CAPACITY OF RUBIDIUM TUNGSTEN BRONZE
W. E. Kienzle, A. J. Bevolo, G. C. Danielson, P. W. Li, H. R. Shanks,
and P. H. Sidles
K. D. Timmerhaus, W. J. O'Sullivan and E. F. Hammel, eds., Low
Temperature Physics-LT 13, Vol. 3 (New York: Plenum Publishing Corp.,
1974) p. 408
Abstract--Heat capacity measurements were made from 1 to 16 K
on samples of hexagonal rubidium tungsten bronze (RbXWO3) which were
prepared by two different methods, electrolysis and solid state reaction.
All samples exhibited a superconducting transition near 2 K. A magnetic
field of a few hundred gauss was adequate to suppress the transition tem-
perature below 1 K. For all samples, C/T_ increased more rapidly than
T2 above 4 K. For Rb. 30WO3, prepared by solid state reaction, y was
2
2.35 mjoules/mole K and e was 311 K. For all samples prepared by
p
electrolysis a large additional non-linear contribution was observed which
precluded th'e direct determination of y and 98.39
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1974 annual summary report, report, July 1, 1975; [Ames,] Iowa. (https://digital.library.unt.edu/ark:/67531/metadc880613/m1/50/: accessed April 25, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.