Specific Heat of Single-Crystal Undoped and V-DopedTi2O3

Abstract

The specific heat ($C_p$) of single crystals of ${\left({\mathrm{Ti}}_{1-x}{\mathrm{V}}_x\right)}_2{\mathrm{O}}_3$ with $0\le x\le 0.04$ has been measured between - 125 and 440°C. An anomaly in $C_p$ and a change in enthalpy $\Delta H$ were observed in ${\mathrm{Ti}}_2$ ${\mathrm{O}}_3$ in the vicinity of the electrical transition (380-550 K), which are larger than those reported previously. Both the $C_p$ anomaly and $\Delta H$ were found to be smaller the larger the V content, and both vanished for $x=0.04\mathrm{}$. The $C_p$ anomaly in ${\mathrm{Ti}}_2$ ${\mathrm{O}}_3$ is accounted for by calculating the specific heat of electrons in two $\mathrm{T}\mathrm{i}-3d$ subbands which approach and ultimately overlap as the temperature is increased. The influence of V on the heat capacity is discussed briefly in terms of electronic bands like those used for ${\mathrm{Ti}}_2$ ${\mathrm{O}}_3$.