Structure and electrical properties of Pr6O11-doped CaCu3Ti4O12 NTC ceramics

The x Pr 6 O 11 –(1 − x )CaCu 3 Ti 4 O 12 (CCTO) ceramics with perovskite structure were prepared by the solid-state reaction method. The effects of Pr 6 O 11 addition on the microstructure and electrical properties of the CCTO ceramics were studied. The addition of Pr 6 O 11 promoted the sintering of CCTO ceramics, and the mean grain sizes increased gradually from 2.13 to 5.08 μm with increasing Pr 6 O 11 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 B 25/75 decreased from 6883 to 5291 K as Pr 6 O 11 contents increased from 0.00 to 0.08. The analysis shows that the conductivity of Pr 6 O 11 –CCTO ceramics arises mainly from the electron hopping transport mechanism. The GB resistances are noticeably higher than grain resistances at the same Pr 6 O 11 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 Pr 6 O 11 concentration.