Heat Capacity of RuO2 and IrO2 between 0.54° and 10°K

Abstract

The heat capacities of the metallic transition‐metal oxides IrO₂ and RuO₂ have been measured between 0.54° and 10°K. Both compounds exhibited heat capacities characteristic of metals, with contributions due to nuclear quadrupole interactions apparent in the ³He region. The heat capacity of IrO₂ was found to be ${\text{C\hspace{0.17em}=\hspace{0.17em}0.308T}}^{\text{−2}}{\text{\hspace{0.17em}+\hspace{0.17em}0.0565T}}^3\text{\hspace{0.17em}+\hspace{0.17em}5.51T}$ (mJ/mole·°K). The heat capacity of RuO₂ was found to be ${\text{C\hspace{0.17em}=\hspace{0.17em}0.059T}}^{\text{−2}}{\text{\hspace{0.17em}+\hspace{0.17em}0.0225T}}^3\text{\hspace{0.17em}+\hspace{0.17em}5.77T}$ (mJ/mole·°K). The results are discussed in relation to electrical resistivity, paramagnetic susceptibility, and Mössbauer effect studies on these materials.