Photoluminescence Properties of Ho³⁺-doped Fluoroborate Optical Glasses

A trivalent rare earth ion Holmium doped zinc magnesium lithium fluoroborate (ZMLB) glasses with the composition of 10ZnO-10MgO-20LiF-(60-x)B2O3-xHo(2)O(3) (where x = 0, 0.1, 0.3, 0.5 and 1 mol%) were prepared by a well-known melt quenching procedure. The produced glass samples structural, optical, emission and decay curve characteristics have been investigated. From the X-ray diffraction investigation, it is confirmed all the produced glasses possess amorphous nature. The borate-oxygen and vibration bonds were noticed by using Fourier transform infrared analysis. From the ultraviolet-visible absorption studies, the produced glasses absorption peaks were noticed and optical energy band gap values also identified by using Tauc's relation. Under excitation with 456 nm, the Ho3+ activated ZMLB glasses luminescence spectra consist of three luminescence bands positioned at 550, 677 and 764 nm were corresponding electronic transitions are S-5(2) + F-5(4) -> I-5(8), F-5(5)-> I-5(8) and F-5(4)-> I-5(7), respectively. From all these emission bands the prominent emission band observed at 550 nm (green). For the Ho3+ activated ZMLB glasses, the lifetimes were decreased with the enhance of Ho3+ doping content owing to energy transfer in resonance form in between Ho3+ ions. From emission spectra, the CCT and CIE coordinates were estimated, and the CIE values are pointed greenish-yellow area in CIE image. Therefore, all these findings convey that the current zinc magnesium lithium fluoroborate glasses conceivably significant candidate for green display and lighting applications.