Mixed alkali effect in Mn2+ doped 20ZnO+xLi2O + (30-x)K2O+50B2O3(5 ≤ x ≤ 25) glasses

Divalent Mn2+ ions containing 20ZnO + xLi(2)O + (30 - x)K2O + 50B(2)O(3)(5 <= x <= 25) mol% glasses are prepared by using melt quench technique and are characterized by several spectroscopic techniques. Various physical parameters are evaluated from the measured values of density and refractive index for the observation of mixed alkali effect. Structural changes of Mn2+ doped ZLKB glasses are investigated by Powder XRD, UV-VIS absorption, Electron Paramagnetic Resonance and FT-IR spectroscopic studies. The XRD pattern indicates the amorphous nature of prepared glasses. FT-IR measurements of all glasses revealed that the network structure of glass system are mainly based on BO3 and BO4 units placed in different structural groups in which the BO3 units being dominant. The EPR spectra of Mn2+ ions doped glasses exhibited a characteristic hyperfine sextet around g = 2.0. The spectroscopic analyses of the obtained results confirmed near octahedral site symmetry for the Mn2+ impurity ions. Crystal field and Racah parameters are evaluated from optical absorption spectra. The optical band gap and Urbach energies are determined which exhibited the mixed alkali effect. (C) 2012 Elsevier B.V. All rights reserved.