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 tanδ 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-xCrxTi4O12 ceramics showed nonlinear characteristic with improvement in both the breakdown field (Eb) and its nonlinear coefficient (α). Interestingly, the highest values of α, ∼ 114.4, and that of Eb, ∼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.