Effect of Bi₂O₃ and Y₂O₃ doping methods on electrical properties and PTCR behavior of Ba_0.95Ca_0.05TiO₃ ceramics

摘要

Lead-free PTCR ceramics based on Bi₂O₃ and Y₂O₃ doped Ba_0.95Ca_0.05TiO₃ were fabricated by the conventional mixed oxide method, while Bi₂O₃ and Y₂O₃ were doped directly or after pre-calcining, in the molar ratio of Bi₂O₃:Y₂O₃ = 1:1. There were two synthesizing route, i.e. the materials were pre-calcined at 900 °C to obtain BiYO₃ firstly and then doped into the basic materials, and the materials were directly doped into the starting materials, both of which could obtain samples with different electrical properties and PTCR behavior. The samples were characterized by using X-ray diffraction, scanning electron microscope, dielectric constant-temperature and resistivity-temperature measurement instrument. It was revealed that the perovskite lattice, the microstructure and the PTCR behavior of Ba_0.95Ca_0.05TiO₃ varied with different doping contents and methods. A further research was conducted so as to study the electrical properties of ceramics by impedance spectroscopy.