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β -Uranium Hydride: Heat Capacities from 1.4 to 23 °K and Some Derived Properties

1967; American Institute of Physics; Volume: 164; Issue: 2 Linguagem: Inglês

10.1103/physrev.164.755

1536-6065

Howard E. Flotow, Darrell W. Osborne,

Quantum, superfluid, helium dynamics

The heat capacity of the metallic, ferromagnetic compound $\ensuremath{\beta}\ensuremath{-}\mathrm{U}{\mathrm{H}}_{3}$ was determined from 1.4 to 23 \ifmmode^\circ\else\textdegree\fi{}K. An attempt was made to fit the data at the lowest temperatures by an equation of the form ${C}_{p}=\ensuremath{\gamma}T+A{T}^{3}+B{T}^{\frac{3}{2}}$, where $\ensuremath{\gamma}T$ is the contribution of the conduction electrons, $A{T}^{3}$ is the lattice contribution, and $B{T}^{\frac{3}{2}}$ is the magnetic contribution. The coefficient $\ensuremath{\gamma}$ is 29\ifmmode\pm\else\textpm\fi{}1 mJ \ifmmode^\circ\else\textdegree\fi{}${\mathrm{K}}^{\ensuremath{-}2}$ ${\mathrm{mole}}^{\ensuremath{-}1}$. Because of uncertainty in the magnetic contribution, no reliable estimate of $A$ or of the Debye $\ensuremath{\Theta}$ could be made. The thermodynamic functions ${S}^{\ensuremath{\circ}}$, $\frac{({H}^{\ensuremath{\circ}}\ensuremath{-}H_{0}^{}{}_{}{}^{\ensuremath{\circ}})}{T}$ and $\frac{({G}^{\ensuremath{\circ}}\ensuremath{-}H_{0}^{}{}_{}{}^{\ensuremath{\circ}})}{T}$ were reevaluated as 63.67\ifmmode\pm\else\textpm\fi{}0.13, 30.24\ifmmode\pm\else\textpm\fi{}0.06, and -33.43\ifmmode\pm\else\textpm\fi{}0.07 J ${(\mathrm{\ifmmode^\circ\else\textdegree\fi{}}\mathrm{K}\phantom{\rule{0ex}{0ex}}\mathrm{m}\mathrm{o}\mathrm{l}\mathrm{e})}^{\ensuremath{-}1}$, respectively, at 298.15 \ifmmode^\circ\else\textdegree\fi{}K.