Nonlinear I–V electrical behaviour of doped CaCu3Ti4O12 ceramics

In this work a comparative study of undoped CaCu3Ti4O12 (CCTO) and doped with Fe3+(CCTOF) and Nb5+(CCTON) ceramics, was aimed to modify the electronic transport. XRD patterns, FE-SEM microstructural analysis, impedance spectroscopy and I–V response curves were afforded to correlate the microstructure with the nonlinear I–V behaviour. The appearance of nonlinear behaviour in doped CCTO samples has been correlated with the ceramic microstructure that consists in n-type semiconductor grains, surrounded by a grain boundary phase based on CuO. The presence of this secondary grain boundary phase is the responsible of the assisted liquid phase sintering in CCTO ceramics. Doped samples showed cleaner grain boundaries than CCTO and nonlinearity in the I–V response.