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

20ZnF2–(20 − x)Bi2O3–60P2O5:xCr2O3 (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 CrO6(od) and CrO42−(Td) 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 4A2g(F) ⟶ 4T1g(F), 4A2g(F) ⟶ 4T2g(F), 4A2g(F) ⟶ 2T1g(G) and 4A2g(F) ⟶ 2Eg(G) transitions of Cr3+ ions. The highest concentration of Cr3+ ions (in octahedral sites, with network modifying positions) is found in the sample with 2.0 mol% of Cr2O3. The analysis of dielectric properties indicates a gradual increase in semiconducting character with increase in the concentration of Cr2O3 from 0.2 to 2.0 mol%. The studies on dielectric breakdown strength identify the highest insulating strength for lowest mol% of Cr2O3 in the present samples.