MICROWAVE DIELECTRIC PROPERTIES AND DOPING MECHANISMS OF

The microwave dielectric properties of La doped Ba0.8Sr0.2TiO3(BST in abbreviation) and their doping mechanisms were studied. BST ceramics could be densified at a sintering temperature of 1300 oC via a sol-gel method. Different amounts of La(NO3)3 doped BST ceramics were prepared. When doped small amount of La(NO3)3, no second phase was detected, La act as a donor dopant. Meanwhile oxygen vacancy was compensated. When increasing amount of La(NO3)3 was added, a hexagonal La4Ba4Ti7O24 phase was detected, and the electronic donor-doping mechanism was replaced by an ionic compensation mechanism. For BST ceramic with 0.2mol % La(NO3)3 sintered at 1280 oC,the r, Q׃ value and f were 176,4148GHz and 63ppm / oC,respectively