Sol-Gel Synthesis and Spectral Characterizations of (35-x)B2O3-65Bi2O3-x Fe2O3 Glass System

摘要： Sol-gel technique was used to prepare glasses of the (35-x)B2O3-65Bi2O3-x Fe2O3 (0.1≤ x ≤ 0.4) system (A1-A4: x = 0.1, 0.2, 0.3, 0.4). The local structure and symmetry around trivalent iron were determined by studying X-band powder EPR spectra at room temperature. The EPR spectra of trivalent iron in glass samples are characterized by a more intense line at g = 4.2 and a less intense line at g = 2.0. The EPR line at g = 4.2 is attributed to trivalent iron in rhombic octahedral environment. The line at g = 2.0 is because of two or more trivalent iron coupling through dipole-dipole interactions in distorted octahedral symmetry. The intensity of EPR lines is dependent of Fe2O3 content in the glass samples. At higher concentration of Fe2O3, EPR line at g = 4.2 is less intense whereas the line at g = 2.0 is more intense which is ascribed to the formation of clusters of trivalent iron. The electronic spectra of glass samples show two broad bands corresponding to d-d transition in the range 410-450 nm and in the range 530-570 nm, respectively which are assigned to trivalent iron in distorted octahedral environment.