Structural and magnetic investigations of Fe2O3–TeO2 glasses

A series of tellurite glasses containing Fe2O3 with the nominal composition x(Fe2O3)–(1−x)(TeO2), where x = 0.05, 0.10, 0.15, and 0.20, have been synthesized and investigated using X-ray photoelectron spectroscopy (XPS) and magnetization techniques. The Te 3d core level spectra for all glass samples show symmetrical peaks at essentially the same binding energies as measured for TeO2 indicating that the chemical environment of the Te atoms in these glasses does not vary significantly with the addition of Fe2O3. Furthermore, the full-width at half-maximum (FWHM) of each peak does not vary with increasing Fe2O3 content which suggests that the Te ions exist in a single configuration, namely TeO4 trigonal bipyramid (tbp). The O 1s spectra are narrow and symmetric for all compositions such that oxygen atoms in the Te–O–Te, Fe–O–Fe and Te–O–Fe configurations must have similar binding energies. The analysis of the Fe 3p spectra indicates the presence of Fe3+ ions only, which is consistent with the valence state of the Fe ions determined from magnetic susceptibility measurements.