The electrical properties of (Ba,Ca, Ce,Ti, Zr)O3 thermistor for wide-temperature sensor architecture

A series of new negative temperature coefficient (NTC) thermal materials based on (Ba_0.85Ca_0.15)_1-xCe_x/2(Zr_0.1Ti_0.9)O₃ (0.00 ≤ x ≤ 0.20) ceramics were synthesized by a solid-state method. X-ray diffraction, scanning electron microscope and X-ray photoelectron spectroscopy were used to demonstrate the crystal structure, morphology, and composition of the (Ba_0.85Ca_0.15)_1-xCe_x/2(Zr_0.1Ti_0.9)O₃ ceramics, which were composed of solid solution based on the BaTiO₃ phase. The average grain size of doped ceramic samples experienced the process of first decreasing and then increasing. The doping of Ce has reduced the sintering temperature. The temperature-dependent resistance analysis revealed that with the change of doping amount x, the thermal constant B_300/1200 (1.21 × 10⁴–1.13 × 10⁴ K) and the activation energy E_a300/1200 (0.9777–1.0471eV) was initially increased to maximum values at x = 0.05, followed by the decreasing when x > 0.05. It has been established that the concentration of oxygen vacancies is affected by the transition between Ce⁴⁺ and Ce³⁺ provided by high levels of Ce doping. (Ba_0.85Ca_0.15)_1-xCe_x/2(Zr_0.1Ti_0.9)O₃ ceramics exhibited excellent negative temperature characteristics in the range of 300–1200 °C. Moreover, the temperature resistance linearity was improved after samples were aged. Hence, the (Ba_0.85Ca_0.15)_1-xCe_x/2(Zr_0.1Ti_0.9)O₃ ceramics were regarded as a promising material for high-temperature NTC thermistors in a wide temperature range.