Optical properties of 3dᴺ transition metal ion-doped lead borate glasses

Glasses from the lead borate system of the composition 50%PbO-50%B₂O₃ together with samples containing different concentrations of 3d-transition metal (TM) species from V to Zn were prepared by the melting-quenching technique and their optical properties were investigated. The X-ray absorption near edge spectra of V, Cr, and Mn-doped glasses indicates that the oxidation states of V(IV/V), Cr(III, VI) and Mn(II, III/IV) exist in the studied glasses. The oxidation states revealed from the diffuse reflectance spectra, absorption spectra, excitation and emission spectra of the glasses are V(IV), Cr(III, VI), Mn(II, III), Fe(II), Co(II), Ni(II), and Cu(II). The undoped lead borate glass exhibits strong UV absorption which corresponds to interconfigurational transitions of Pb²⁺ and the host absorption, and intrinsic broad host emission at 470 nm using excitation at 350 nm. The 3d-TM ions from V to Cu doped at high concentration (0.5 or 2 mol%) show additional distinctive strong absorption bands and a red-shifted absorption edge. The Mn²⁺ emission at 625 nm due to the ⁴T₁ɡ(⁴G) → ⁶A₁ɡ (⁶S) spin-forbidden transition of octahedrally-coordinated Mn²⁺ was observed under excitation at 412 nm or 369 nm. Copyright © 2016 Elsevier Ltd.