Preparation and characterization of Fe~(3+)-doped Ni_(0.9)Co_(0.8)Mn_(1.3-x)Fe_xO_4(0≤x≤0.7)negative temperature coefficient ceramic materials

摘要

Based on spinel-type semiconducting electroceramics, negative temperature coefficient (NTC) thermistor materials, Ni_(0.9)Co_(0.8)Mn_(1.3-x)Fe_xO_4(0≤x≤0.7), with different compositions were synthesized by a co-precipitation method. The optimal pH value and the influence of Fe3* doping during the synthesis processing were discussed. As-prepared Ni_(0.9)Co_(0.8)Mn_(1.3-x)Fe_xO_4 materials were characterized by DT/TGA, XRD, FTIR, SEM, electrical measurement and impendance analysis. It was found that, as the Fe doping content in the Ni_(0.9)Co_(0.8)Mn_(1.3-x)Fe_xO_4 samples increased, both the grain size and the density decreased. The as-sintered Ni_(0.9)Co_(0.8)Mn_(1.3-x)Fe_xO_4 samples presented a single-phase cubic spinel structure. The impendance diagram indicated that the grain boundary resistance was dominant in the overall impendance of Ni_(0.9)Co_(0.8)Mn_(1.3-x)Fe_xO_4 NTC ceramic materials. The value of p2s. B25/50, slope and activation energy for the samples Ni_(0.9)Co_(0.8)Mn_(1.3-x)Fe_xO_4(0≤x≤0.7) sintered at 1200 °C were in the range of 453.1-2411 ncm, 3103-3355 K, 3.27325-3.43149 and 0.28207-0.29325 eV, respectively. This suggests that the electrical properties can be adjusted to desired values by controlling the Fe3* ion doping content.