Spectroscopic and dielectric response of zinc bismuth phosphate glasses as a function of chromium content

Abstract 20ZnF 2 –(20 − x )Bi 2 O 3 –60P 2 O 5 : x Cr 2 O 3 (0 ≤ x ≤2 mol%) glasses are prepared by melt quenching technique. Amorphous nature of these samples is confirmed by X-ray diffraction (XRD) analysis. FTIR study reveals bands due to CrO 6 (o d ) and CrO 4 2− (T d ) units along with conventional phosphate groups. The optical absorption and ESR studies of present glasses are analyzed as a function of chromium content. The absorption bands are assigned to 4 A 2g (F) ⟶ 4 T 1g (F), 4 A 2g (F) ⟶ 4 T 2g (F), 4 A 2g (F) ⟶ 2 T 1g (G) and 4 A 2g (F) ⟶ 2 E g (G) transitions of Cr 3+ ions. The highest concentration of Cr 3+ ions (in octahedral sites, with network modifying positions) is found in the sample with 2.0 mol% of Cr 2 O 3 . The analysis of dielectric properties indicates a gradual increase in semiconducting character with increase in the concentration of Cr 2 O 3 from 0.2 to 2.0 mol%. The studies on dielectric breakdown strength identify the highest insulating strength for lowest mol% of Cr 2 O 3 in the present samples.