Dielectric properties of V2O3 and (V0.989Cr0.011)2O3 from temperature-dependent ac impedance measurements

The dielectric properties of the various insulating phases in pure ${\mathrm{V}}_{2}{\mathrm{O}}_{3}$ and ${({\mathrm{V}}_{0.989}{\mathrm{Cr}}_{0.011})}_{2}{\mathrm{O}}_{3}$ crystals have been investigated. Large dielectric constants on the scale of ${10}^{3}$ were obtained, which were attributed to the backflow effect of normal carriers and also the periodic charge configuration relevant to V-V dimers in an antiferromagnetic insulating state or the bond contraction of V-Cr-V in a paramagnetic insulating phase. We propose that if Cr dopants are arranged nearly uniformly, the charge density of ${({\mathrm{V}}_{0.989}{\mathrm{Cr}}_{0.011})}_{2}{\mathrm{O}}_{3}$ in the paramagnetic insulating phase will exhibit a doping-induced wavelike distribution in real space, and thus the polarization of the system will be enhanced.