Effect of Cr addition on the structure and electrical properties of CaCu3Ti4O12 NTC thermistor

In the present work, CaCu3Ti4O12 (CCCTO, 0 <= x <= 1) ceramics were prepared by a solid-state reaction. The influence of Cr on the structure and electrical properties of the CCCTO ceramics was investigated in detail. X-ray diffractometry (XRD) revealed that all samples' main phases were CaCu3Ti4O12 (CCTO), but CuO and CaTiO3 phases were also found. Cr doping suppressed the abnormal growth of grains, thus the grain size distribution became more uniform with the increase of Cr doping content. The resistance-temperature analysis revealed that all CCCTO ceramics had a noticeable Negative Temperature Coefficient (NTC) effect. The resistivity rho(30) of the CCCTO ceramics decreased from 1.15 x 10(6) to 8.73 x 10(4) Omega cm with an increase in the value of x, along with a decrease in the thermal constant B from 6596 to 3267 K. It was also observed that both the grain and grain-boundary effects contributed to their NTC characteristics. The analysis revealed that the conductivity of the ceramics arose mainly from the electron hopping mechanism. All the samples showed an electrical relaxation behavior. The observations indicated that the structures and electrical properties of CCCTO ceramics could be attuned precisely by adjusting the concentration of the Cr2O3 doping agent. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study investigates the influence of Cr on the structure and electrical properties of CCCTO ceramics. It was found that Cr doping suppressed abnormal grain growth, resulting in a more uniform grain size distribution, and all samples exhibited a noticeable Negative Temperature Coefficient (NTC) effect.