Optical properties of selected 4d and 5d transition metal ion-doped glasses

Abstract

Selected 4d and 5d transition metal ion-doped lead borate (PbO–B₂O₃) and sodium borosilicate (SiO₂–Na₂O–B₂O₃) glasses have been prepared by the melting-quenching technique and their room temperature optical properties were investigated with a view to future co-doping with lanthanide ions. The oxidation states revealed from the diffuse reflectance spectra, absorption spectra, excitation and emission spectra of the glasses are Nb(V), Ta(V), Mo(V, VI), W(VI), Re(IV, VII), Ru(III, IV, VI), Rh(III), and Ir(III). The Ru, Rh, or Ir ion-doped glasses show distinctive strong absorption bands and a red-shifted absorption edge. Charge transfer emission bands are observed for Nb(V), Ta(V), and Mo(VI) at 474 nm, 420 nm and 553 nm, respectively, whereas no visible emission bands can be attributed to Ru, Rh or Ir species. The X-ray absorption spectra of Mo-doped glasses indicate the predominant tetrahedral Mo(VI) moiety. The presence of intense charge transfer absorption and emission bands for some of the transition metal ions provides us with the vision of energy transfer to co-doped lanthanide ions with the application of downshifted emission for a solar cell.