ScholarWorks@경상국립대학교

초록

(La1-xBixSr0.3)FeO3 ceramics exhibiting excellent magnetoresistance were synthesized via the conventional solid-state reaction method. The structural and electrical properties were investigated as a function of Bi3+ content to evaluate their potential application as temperature sensors. And the sintering temperature and time were 1,200°C and 4 h, respectively. The structural and electrical properties were investigated as a function of Bi content. With increasing Bi substitution, a slight enhancement in both average grain size and relative sintered density was observed. In particular, the specimen with x = 0.3 exhibited an average grain size of approximately 0.82 μm. All samples demonstrated negative temperature coefficient of resistance (NTCR) behavior, and the electrical resistivity decreased with increasing Bi content. The resistivity of the (La0.4Bi0.3Sr0.3)FeO₃ composition was 4.68 mΩ-cm at 25°C. Additionally, the temperature coefficient of resistance (TCR) and the B25/75-value, which quantify the sensitivity of resistivity to temperature variations, were found to increase with Bi content. (La0.4Bi0.3Sr0.3)FeO3 sample exhibited a TCR of 0.43%/°C and a B25/75-value of 1,096 K at room temperature. The electrical conduction mechanism of the (La1-xBixSr0.3)FeO3 system was well described by the small polaron hopping model, wherein thermally activated charge carriers hop between localized Fe–O–Fe sites via electron–phonon interactions.

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