Ba0.57Sr0.39Ca0.03Ti1.01NbxO3基正温度系数陶瓷材料制备及电学性能OA

Low Curie temperature Barium titanate-based positive temperature coefficient(PTC)ceramics,which exhibit significant resistivity changes with temperature in low temperature environments,fulfill the demand for precise temperature sensor components and hold broad application potential in deep space exploration.However,achieving both low low-temperature resistivity and high PTC intensity remains challenging in low Curie temperature barium titanate-based PTC materials.This study focuses on optimizing the performance of low-Curie-temperature barium titanate-based PTC ceramics through element doping,addressing the critical contradiction between elevated low-temperature resistivity and insufficient PTC intensity.A low Curie temperature barium titanate-based PTC thermistor ceramic material Ba0.57Sr0.39Ca0.03Ti1.01NbxO3(x=0.0020,0.0025,0.0030,0.0035,0.0040,0.0045,0.0050)was prepared via solid-state synthesis.X-ray diffraction(XRD),scanning electron microscope(SEM)and electric tests were implemented to clarify the mechanism of structures and properties.Electrical property tests on samples sintered at different temperatures confirmed 1375℃as the optimal sintering temperature.XRD analysis verified single crystalline phase composition.SEM images confirmed niobium's role in grain refinement.Resistivity-temperature tests on samples with varying Nb doping content showed that at x=0.0025 and 0.0030,the low-temperature resistivity dropped to 103 Ω·cm with a PTC intensity greater than 6,demonstrating excellent PTC characteristics.Dielectric constant-temperature spectra further confirmed the Curie temperature at 0℃and the dielectric constant showed an oscillatory increase with the rise of Nb doping content.Alternating current complex impedance spectra revealed that the PTC effect originates from grain boundary effects.Strontium doping reduced the Curie temperature to 0℃,while niobium as a donor dopant decreased the low-temperature resistivity.Manganese was introduced to enhance the PTC intensity.This study pioneered the fabrication of barium titanate-based PTC ceramics exhibiting low Curie temperatures,exceptionally small low-temperature resistivity,and high PTC intensity,establishing a paradigm shift for developing cryogenic temperature sensors critical to aerospace thermal management systems.