| Abstract: | A density functional plane-wave pseudopotential method is used to study the doping mechanisms of impurity defects(Bi_(Ba),Y_(Ti)) in BaTi O_3-BiYO_3. Single Bi_(Ba) and Y_(Ti) impurities have little structure distortion. Bi forms ionic bond with nearby O atom in single Bi impurity, Y formed YO_6] octahedral in single Y impurity. However, in the co-doped Bi_(Ba) and Y_(Ti) structure, Bi formed three valence bonds with nearby O atom, which causes the large structure distortion. The doped ion makes the mobile of Ti~(4+) difficult and loss local ferroelectricity, which will broaden the dielectric constant temperature curve and increase the temperature stability of BaTiO_3 ceramic matrix. |
