Structure and electrical properties of Pr6O11-doped CaCu3Ti4O12 NTC ceramics

The xPr6O11–(1 − x)CaCu3Ti4O12 (CCTO) ceramics with perovskite structure were prepared by the solid-state reaction method. The effects of Pr6O11 addition on the microstructure and electrical properties of the CCTO ceramics were studied. The addition of Pr6O11 promoted the sintering of CCTO ceramics, and the mean grain sizes increased gradually from 2.13 to 5.08 μm with increasing Pr6O11 content. All the samples had noticeable negative temperature coefficient (NTC) effect, and both the grain and grain boundary effects contributed to their NTC characteristics. The thermistor characteristic parameter B25/75 decreased from 6883 to 5291 K as Pr6O11 contents increased from 0.00 to 0.08. The analysis shows that the conductivity of Pr6O11–CCTO ceramics arises mainly from the electron hopping transport mechanism. The GB resistances are noticeably higher than grain resistances at the same Pr6O11 content. All the samples showed electrical relaxation behavior. The above observations indicate that the structures and electrical properties of CCTO ceramics can be attuned precisely by adjusting the Pr6O11 concentration.