Physical, Structural and Optical properties of Iron doped Bismuth Silicate Glass Ceramics

摘要

Iron doped bismuth silicate glasses were synthesized by melt quenching technique. Based on the DSC data, the glass ceramics of these samples were prepared by annealing, the as prepared glasses at temperature ~50°C above the glass transition temperature (T_g) of material. The crystalline nature of the glass ceramic samples was ascertained by XRD patterns. The different peaks positions in XRD patterns were identified by JCPDS card Nos. 00-036-0287 and 01-089-7047 of ICDD (International centre for Diffraction Data) and were attributed to formation of Bi_2SiO_5 and Fe_2O_3 crystalline phase respectively. Analysis of XRD showed that mainly Bi_2SiO_5 crystalline phase existed in all the glass ceramics samples along with crystalline phase of Fe_2O_3 in glass ceramics samples with iron content. It was reported that Bi_2SiO_5 crystal had major properties like good dielectric, pyroelectric, thermoelectricity and nonlinear optics characteristics, its non-Centro symmetric structure may confer ferroelectric properties. Bi_2SiO_5 crystal was a dense, fast and radiation-hard scintillator for high energy physics experiments. The average crystallite size were calculated for diffracted peak of maximum intensity (311) peak (2θ=29.2~0) using Scherrer equation and observed to vary from 20.2 nm with x=0 to 24.98 nm with x=5 with increase in iron content. The values of density. molar volume and crystalline volume were measured and were found to decrease with increase in iron content. The FTIR spectra of the studied glass ceramic samples were taken at room temperature suggested that Fe_2O_3 modified the structure of bismuth silicate glass ceramics and it acted as both network modifier as well as network former. Bismuth also played the role of both network modifier (BiO_6 octahedra) as well as network former (BiO_3 pyramids) and SiO_2 existed in SiO_4 tetrahedral structural units with two nonbridging oxygens. The optical band gap energy (E_(op)) decreased with increase in Fe_2O_3 content