Research On The Dielectric Properties Of BaTiO₃ Ceramics

The research on improving the dielectric performance of BaTiO₃-based ceramics is necessary for two reasons as following. BaTiO₃-based ceramics have been regarded as one of the main dielectric materials since the doped-BaTiO₃-based ceramics are industrialized for the excellent dielectric properties of doped-BaTiO₃-based ceramics. The development of electronic industry demands new dielectric materials with better dielectric performance. The researches on doped-BaTlO₃-based ceramics have always been reported all around world but the perfect theory on doped-BaTiO₃-based ceramics does not set up.The study on the influence of donors and acceptors co-doped-BaTiO₃-based ceramics on dielectric properties is made for few of research on the influence of donors and acceptors co-doped-BaTiO₃-based ceramics on dielectric properties. The Mn²⁺,Co³⁺ are used as acceptors respectively and La³⁺,Bi³⁺,Nb⁵⁺ are used as donors. In addition Cu²⁺ is used to replaced Mn²⁺,Co³⁺. The dielectric properties (dielectric constant-temperature, dielectric constant-frequency and dielectric loss-frequency) are measured by using Agilent4284A impedance analyzer. In order to analyze the influence of donors and acceptors co-doped-BaTiO₃-based ceramics on dielectric properties the polarization field hysteretic loop is measured by using ZT—I ferroelectric testing system at room temperature. Meanwhile piezoelectric constant is measured by using ZJ-4AN at room temperature.The results show that the properties of donors and acceptors co-doped-BaTiO₃-based ceramics are influenced by the ratio of donors and acceptors. (1)The dielectric constant-temperature shows ferroelectric relaxor characteristics with the big ratio of donors and acceptors and dielectric constant-temperature indicates general ferroelectric behavior with the small ratio of donors and acceptors. (2)The slope of polarization field hysteretic loop is bigger as the ratio of donors and acceptors become smaller at room temperature. (3)At the same time piezoelectric constants become bigger with increase of remnant polarization field. (4)The conductivity of BaTiO₃-based ceramics decreases with the increasing of Mn²⁺or Co³⁺. Moreover the conductivity is relative small and the dielectric, loss increase with increasing of frequency with the big ratio of donors and acceptors; the conductivity is relative big and the dielectric loss-frequency indicates conductive loss characteristic with the small ratio of donors and acceptors. (5) The dielectric loss of BaTiO₃-based ceramics decreases at lower temperature(-30～50℃) and the conductivity increases with adding of CuO .