Influence of local structural disorders on spectroscopic properties of multi-component CaF2–Bi2O3–P2O5–B2O3 glass ceramics with Cr2O3 as nucleating agent

• CaF2–Bi2O3–P2O5–B2O3 glasses doped with Cr2O3 were crystallized by heat treatment.
• Glass ceramic samples were characterized by XRD, SEM, EDS and DTA data.
• Optical absorption, FTIR, Raman and EPR studies were carried out on these glass ceramics.
• XRD, DTA and SEM studies indicated that the samples contain different crystalline phases.
• Studies indicated that part of Cr3 + ions is converted into Cr6 + ions that occupy the Td positions in ceramic matrix.

Multi-component CaF2–Bi2O3–P2O5–B2O3 glasses doped with different concentrations of Cr2O3 were crystallized through heat treatment. The prepared glass ceramic samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and differential thermal analysis (DTA). Spectroscopic studies viz., optical absorption, Fourier transform infrared (FTIR), Raman and electron paramagnetic resonance (EPR) were carried out. The XRD, SEM and DTA studies indicated that the samples contain different crystalline phases. Results of optical absorption and EPR studies pointed out the gradual conversion of chromium ions from Cr3 + state to Cr6 + state with an increase of Cr2O3 content from 0.1 to 0.5 mol%. The results of FTIR, Raman and EPR studies revealed that Cr6 + ions participate in the glass network in tetrahedral positions and seemed to increase the polymerization of the glass ceramics. The quantitative analysis of results of the spectroscopic studies further indicated that the glasses crystallized with low concentration of Cr2O3 are favourable for solid state laser devices.

Optical absorption spectra of the titled glass ceramics have exhibited two prominent absorption bands at about 457 and 636 nm due to 4A2g → 4T1g(F) and 4A2g → 4T2g(F) respectively and two shoulders at 663 (4A2g → 2T1g), and 690 nm (4A2g → 2Eg). These bands indicate the presence of chromium ions in Cr3 + (d3) state in octahedral environment in the glass matrix.Figure optionsDownload as PowerPoint slide