SUBSTITUTION SITE OF LANTHANUM IONS IN LA-DOPED SrBi_4Ti_4O_(15) AND Bi_4Ti_3O_(12)-SrBi_4O_(15)

摘要

Ferroelectric ceramics of lanthanum-modified SrBi_4Ti_4O_(15) and Bi_4Ti_3O_(12)-SrBi_4O_(15) have been synthesized, and Raman spectrum measurements have been carried out at room temperature. The investigation on the Raman spectra suggest that La~(3+) ions prefer to occupy the A site in the case of x < 0.10, and at higher content they tend to be incorporated into Bi_2O_2 layers in the La-doped SrBi_4Ti_4O_(15). As for La-doped Bi_4Ti_3O_(12)-SrBi_4Ti_4O_(15), the critical content of the doping ions is 0.50. An interesting phenomenon has been noticed that the remnant polarization maximized at about the critical doping content. Thus, it can be concluded that the Bi_2O_2 layers have a very important effect on the properties in the bismuth layer-structured ferroelectric materials.