Abstract

In this study, ZnxMn_3-xO₄ (x=0.95~1.20) specimens were prepared by using a conventional mixed oxide method. All specimens were sintered in air at 1,200℃ for 12 h and cooled at a rate of 2℃/min to 800℃, subsequently quenching to room temperature. We investigated the structural and electrical properties of Zn_xMn_3-xO₄ specimens with variation of ZnO amount for the application of NTC thermistors. As results of X-ray diffraction patterns, all specimens showed the formation of a complete solid solution with tetragonal spinel phase. And, the second phase was observed by the solubility limit of Zn ions in x≥1.10 composition. The average grain size was increased from 2.72 μm to 4.18 μm with increasing the compositional ratio of Zn ion from x=0.95 to 1.20, respectively. Zn_1.10 Mn_1.90 O₄ specimen showed the minimum electrical resistance of 57.5 kΩ at room temperature and activation energy of 0.392 eV.

• Keywords: Temperature sensors, Zn-Mn-O oxide, Structural properties, Electrical properties, Mixed-oxide method