Electron paramagnetic resonance of Fe³⁺ions in borate glass: computer simulations

Abstract

Computer simulations of Fe3+ electron paramagnetic resonance specmaat X (9.5 GHz) and Q (34 GHz) bands in the alkali borate glass LizO-ZB203 doped with Fez03 have been carried out using nn approach b m d on the eigenfield method applied to the 'rhombic' spin Hamiltonian. which contains only the Zeeman and quadrupole fine-structure term. In order to account for the structurd disorder in the glass, two different distribution densities of finestructm parameters D md E have been tried: a two-dimensional Gaussian function of D and ). = IE/DI. and the 'Czjzek function', analogous to the one used in Mdssbauercffect studies.In simulating the experimental spectra, care has been taken to fit not only to the most prominent features arising at &t = 4.3 (at X and Q bands) and 64 2.0 (at Q band), but also to an obvious platenu of the derivative of the absorption, which extends down to the magnetic field corresponding to fisf 1 9.7 (at both bands). As a result, the Qjjzek function can be ruled out. The agreement bemeen the experimental and computer-simulated spectra found with the Gaussian distribution density suggests the existence, besides orthorhombic symmetry sites (with A 2 113). of a considerable number of Fe3+ sites with axial or feebly rhombic distortions 0 . < 0.08). The relatively high mean value of the mid finestructure parameter D is consistent with a highly distorted environment of Fe)+ ions in the glass.

EPR Spectroscopy of the Mn2+and Cu2+Centres in Lithium and Potassium-Lithium Tetraborate Glasses

“…By computer simulation in [19] it was shown that the weak EPR line with g ≈ 2.00 in borate glasses belongs to isolated Fe 3+ ions, localised in sites with nearly cubic symmetry. One can notice that the presence of dominated Fe 3+ signal with g ≈ 4.29 clearly demonstrating the classical glass structure of investigated samples.…”

Properties and structural features of iron doped BABAL glasses

“…More recently, L. Cugunov et al 20 , E.M. Yahiaoui 11 , and R. Berger et al 9,21 carried out studies with computer simulations of the Fe 3+ resonance in borate glass. The experimental EPR spectra were well described by assuming that the environment of Fe 3+ ions are highly distorted and in addition to the orthorhombic distortion related to the g = 4.3 feature, an important part of Fe 3+ arises from axial or slightly rhombic distortions.…”

“…At low iron concentrations (< 1 mol%), only a sharp g ef ≈ 4.3 resonance is commonly observed 9 . As the concentration is increased, a broad line begins to grow at about g ef ≈ 2 11 . In many oxide glasses the intensity of the line with g = 2 increases much faster than that of g = 4.3 with increasing Fe 3+ ions concentration above 5 mol%.…”

EPR study of the impurity paramagnetic centres in (CaO−Ga2O3−GeO2) glasses

“…It was shown by theoretical analysis and computer simulation of Fe 3+ EPR spectra in a disordered environment (with distributed crystal field parameters) [29][30][31] that the g~tr = 2.00 line appears for the small axial field range (D << gflH). It is known that in all activated and non-activated Ca3GazGe3012 and Ca3Ga2Ge4014 crystals the Fe ~+ impurity is present.…”