Electrical properties and temperature sensitivity of Li/Mg modified Ni0.7Zn0.3O based ceramics

Abstract

Li/Mg modified Ni0.7Zn0.3O powders with nominal compositions of [(Ni0.7Zn0.3)1-xMgx]1-yLiyO (x ≤ 0.5, y ≤ 0.06) were prepared through a wet chemical synthesis method. The powders were compacted and sintered by the conventional ceramic processing to obtain the related ceramics. The X-ray diffraction analysis indicates that all the ceramics have single phase with cubic structure and exhibit typical effect of negative temperature coefficient (NTC) of resistivity. The adjustable room-temperature resistivity (ranging from 22 Ω cm to 13.621 kΩ cm) and thermal-sensitivity constant (changing from 2444 K to 5613 K) of ceramics were achieved by altering the cationic concentrations of Li+ and Mg2+. The complex impedance analysis reveals that both grain effect and grain boundary effect contribute collectively to the electrical conduction and NTC feature of the ceramics. The possible conduction models including polaron hopping conduction and band conduction were proposed accordingly.