Enhanced Sensitivity in Capacitive Temperature Sensors Through Synergistic Relaxor/Antiferroelectric Composites

In the pursuit of highly effective capacitive temperature sensors, a pivotal requirement lies in discovering materials that exhibit a high temperature-dependent variation in capacitance, i.e., high dC/dT value, while retaining the essential linearity within their temperature-dependent capacitive response. Relaxor ferroelectric (RFE) materials have been known for their nearly linear behavior, while antiferroelectric (AFE) materials showcase high dC/dT values. Bridging these two different classes could hold the key to unlocking high-temperature sensing capabilities. In this study, we synthesized composite materials of ( ${1}- {x}$ )Bi2MnCoO6–( ${x}$ ) NaNbO3 (with ${x}$ = 0, 0.02, 0.04, and 0.06) via the solid-state reaction method where the synergy of these materials can fulfill both requirements of linearity and sensitivity simultaneously. The dielectric response of all the synthesized composites showed almost linear behavior with high dC/dT values. The temperature-dependent capacitive response reveals that the sensitivity of Bi2MnCoO6 (RFE) is 0.42 pF $\cdot ^{\circ }\text {C}^{\text {-1}}$ within the temperature range of 35 °C–110 °C. However, the sensitivity improves significantly with the addition of NaNbO3 (AFE). The composite material with an ${x}$ value of 0.06 demonstrates the highest average sensitivity of 115 pF $\cdot ^{\circ }\text{C}^{\text {-1}}$ out of all the materials, specifically within a temperature range of 35 °C–240 °C. This study shows that the synergistic approach of utilizing RFE and AFE composites can pave the way to design a promising temperature sensor with enhanced sensitivity.