Improved non-ohmic and dielectric properties of Cr3+ doped CaCu3Ti4O12 ceramics prepared by a polymer pyrolysis solution route

CaCu3-xCrxTi4O12 (x = 0.00-0.20) ceramics were prepared via a polymer pyrolysis solution route. Their dielectric properties were improved by Cr3+ doping resulting in an optimal dielectric constant value of 7156 and a low tans value of 0.092 in a sample with x = 0.08. This might have resulted from a decrease in oxygen vacancies at grain boundaries. XANES spectra confirmed the presence of Cu+ ions in all ceramic samples with a decreasing Cu+/Cu2+ ratio due to an increased content of Cr3+ ions. All CaCu3 center dot xCrxTi4O12 ceramics showed nonlinear characteristic with improvement in both the breakdown field (E-b) and its nonlinear coefficient (alpha). Interestingly, the highest values of alpha, similar to 114.4, and that of E-b, similar to 8455.0 +/- 123.6 V cm(-1), were obtained in a CaCu3-xCrxTi4O12 sample with x = 0.08. The improvement of dielectric and nonlinear properties suggests that they originate from a reduction of oxygen vacancies at grain boundaries.