Optical and vibrational spectra of Bi1.8Fe1.2(1 – x)Ga1.2xSbO7 solid solutions with pyrochlore-type structure

Abstract

Optical and vibrational spectra of Bi_1.8Fe_{1.2(1 – x)}Ga_1.2xSbO₇ solid solutions with pyrochlore structure have been studied. It has been shown that the compounds have strongly disordered structure. It has been established that a decrease in iron content causes a marked shift of Bi_1.8Fe_{1.2(1 – x)}Ga_1.2xSbO₇ absorption edge. According to assessment of band gap width, Bi_1.8Ga_1.2SbO₇ is the most wide-band compound (2.90 eV), while Bi_1.8Fe_1.2SbO₇ is the most narrow-band compound (1.88 eV).