The semiconductors based on simple oxide have unique features with controllable electrical property by element doping. Y3+ doped NiO (Ni1−xYxO, x ≤ 0.01) and Mg2+ substituted Ni0.995Y0.005O (Ni0.995−yY0.005MgyO, y ≤ 0.5) powders were synthesized by a wet chemical method. The related ceramics were obtained by conventional ceramic processing. Phase component, microstructure, electrical property and temperature sensitivity of the prepared ceramics were investigated. All ceramics have a rock‐salt type crystalline structure. The room‐temperature resistivity of the ceramics can be widely adjusted from 254 to 12 322 Ω·cm by changing the concentrations of Y3+ and Mg2+ ions. The samples show typical characteristics of negative temperature coefficient of resistivity and have high temperature sensitivity with material constants higher than 4745 K. The analysis of impedance spectra indicates that the electrical properties resulted from both grain effect and grain boundary effect. Both band conduction and small polaron hopping were proposed as possible conduction mechanisms in the studied ceramics.

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Nb/Al-modified CuO ceramics (yNb/0.02Al-CuO, 0 ≤ y ≤ 0.07, denoted as NACO) were synthesized using sol-gel method for applications in negative temperature coefficient (NTC) thermistors. The phase structure, microstructure and electrical properties of the ceramics were investigated. XRD investigation reveals that the NACO ceramics has the main phase with monoclinic crystalline structure. The analysis of X-ray photoelectron spectroscopy proved the existence of Cu 2+ /Cu + and Nb 5+ /Nb 4+ ions. Temperature dependence of the resistivity indicated that the NACO ceramics present typical NTC characteristic. The NTC materials' constant, B value, can be adjusted from 2430 K to 3805 K by changing the Nb-concentration in the Al-doped CuO ceramics. Among four applied calibration equations the Hoge-3 equation is the most effective one for the resistancetemperature calibration of the prepared NTC thermistors. The complex impedance analysis was performed and revealed that both grain effect and grain boundary effect similarly contribute to the electrical conductive behaviour and NTC feature of the NACO ceramics. The band conduction and polaron hopping conduction are proposed as the conduction mechanisms in the NACO thermistors.