Dielectric properties and structural features of barium-iron phosphate glasses

The dielectric constant of barium-iron phosphate glasses with the general composition (40− x)BaO · xFe 2O 3 · (60− x)P 2O 5 has been investigated at two fixed frequencies (100 kHz and 9.0 GHz). The dielectric constant measured using microwave technique, and the ratio O/P of these glasses increase with increasing Fe 2O 3 content. The structure and valence states of the iron ions in these glasses were investigated using Mössbauer spectroscopy, infrared spectroscopy and differential thermal analysis. Both Fe(II) and Fe(III) ions present in these glasses in octahedral coordination act as permanent dipoles, and the increase of the iron concentration increase these permanent dipoles, contributing to the dielectric constant.