Giant permittivity and humidity sensitivity of SrTiO3 based ceramics induced by K, Nb donor-acceptor co-doping

Abstract

This research utilizes a solid-state sintering process to fabricate a series of Sr1-xKxTi1-xNbxO3 (x =0.01, 0.02, 0.025, 0.03) ceramics. The sample with a doping concentration of x=0.025 achieved a dielectric constant of 10409 and a dielectric loss of 0.026 at 1 kHz. With increased dopant concentrations of K and Nb, the thermal stability of the ceramics is significantly enhanced, as evidenced by a dielectric constant variation of less than 15 % for x=0.025 sample over a temperature range from room temperature to 240 °C. Employing activation energy analysis, impedance spectroscopy, humidity response assessments, and X-ray photoelectron spectroscopy, it is indicated that the excellent electrical performance is attributed to the combined effects of the Internal Barrier Layer Capacitance and the formation of complex defect dipoles. Moreover, the insights into the moisture characteristics of SrTiO3 presented in this paper imply that the giant dielectric Sr1-xKxTi1-xNbxO3 ceramics have potential in the application of humidity sensing devices.