Design, synthesis, and fabrication of lead-free (Ba_0.4Sr_0.4Bi_0.2)(Ti_0.75Fe_0.2Ce_0.05)O₃ perovskite materials for industrial temperature sensing applications

This paper reports a multivalent (Ba_0.4Sr_0.4Bi_0.2)(Ti_0.75Fe_0.2Ce_0.05)O₃ (BSBTFCO) ceramic-oxide-based temperature sensor using an unusual solid-state sintering method. The X-ray diffraction study confirms that the synthesized material has a polycrystalline structure. The scanning electron microscope (SEM) analysis shows that the morphology of BSBTFCO has a porous structure with many grains with well-defined grain boundaries and even distributions of grains. Complex impedance spectroscopy and normalized imaginary impedance analysis ascertain the semiconducting properties and thermally activated relaxation phenomena at various temperatures and frequencies. There was a noticeable trend of decreasing grain boundary resistance with a rise in temperature, showing that the developed sensor has a negative temperature coefficient of resistance (NTCR) characteristic. Compared with previously reported sensors with similar features, the BSBTFCO sensor showed an improved level of function, including high levels of impedance variation, significant sensitivity (~ − 0.209% °C⁻¹), good linearity (R² = 0.9858), a low level of hysteresis (< 1.85%), and quick response and recovery times of 14 s and 17 s, respectively. Its operational stability can last up to 120 days with negligible fluctuations during testing. On the basis of the results, this sensor has the potential for use in advanced temperature-sensing applications.