The Effect Of Nb⁵⁺/Ta⁵⁺dopant On The Structure And The Dielectric Properties Of BaTiO₃ Ceramics

Barium titanate(BaTiO3) with perovskite(ABO3) structure is the very essential material for electronic devices, such as multilayer ceramic capacitor etc. With the development of electronic industry, the requirements for electronic material are also more demanding. The ceramics doped with BaTiO3 can achieve the purpose of modification. In this thesis, the BaTiO3 ceramics were doped by Nb5+ and Ta5+, and discussed the influence on the properties of ceramics.1. B-site of BaTiO3 was substituted by Nb5+. The results show that when the Nb5+ doping content is less than 0.05, grain size decreases and the Nb5+ doping content is more than 0.05, the grain size gradually increases with the increase of doping amount. There's no second phase appeared as the doped amount increase from 0.5% to 10%. With the increase of Nb5+ content, the dielectric constant decreases first and then increases, the Curie temperature shifts to lower temperature, the Curie peak broadening. When the doping content is greater than 0.05, the ceramic samples exhibit relaxation ferroelectric phenomenon. With the increase of Nb5+ content,Pr and Ec decreases.2. B-site of BaTiO3 was substituted by Ta5+. The results show that: when the Ta5+ doping content is less than 0.05, the grain size changed little and the Ta5+ doping content is more than 0.05, the grain size gradually increases with the increase of doping amount. There's no second phase appeared as the doped amount increase from 0.5% to 10%. With the increase of Ta5+ content, the dielectric constant decreases first and then increases, the Curie temperature shifts to lower temperature, the Curie peak broadening. When the doping content is greater than 0.05, the ceramic samples exhibit relaxation ferroelectric phenomenon. With the increase of Ta5+ content,Pr and Ec decreases.3. The difference between the valence of the doped ions and Ti4+, impurities or defects would result in the random electrical field or random stress field, leading to random orientation nanodomain or microdomain, which result in relaxor behavior in ferroelectrics. The defect configuration was stimulated using molecular dynamic and dielectric relaxation response were discussed using random field model.