Elucidation of physical, structural, optical and luminescence properties of Cr2O3-doped B2O3-TeO2-Li2O-SrO glasses for deep red-light and NIR luminescence applications
摘要
The standard melt quenching technique was used to prepare samples with nominal composition (50-x)B2O3-15TeO2-20Li2O-15SrO-xCr2O3, where 0 < x < 0.5. XRD validates the non-crystalline nature of BTLSC glass. Density and molar volume exhibited an inverse trend, and other physical parameters were calculated. SEM and EDS determined the morphological and elemental composition of the BTLSC samples. The FTIR and Raman spectra explain reduced pentaborate units and caused the production of ortho and pyroborate units, including tetrahedral [CrO4] and octahedral [CrO6] units in the glasses with Cr2O3 incorporation. The UV-Vis absorption band showed redshift from 351 nm to 461 nm, with three major bands at 626 nm, 663 nm, and 701 nm of Cr3+ (octahedral sites) in the BTLSC glasses. The direct bandgap and indirect bandgap were reduced from 3.44 eV to 2.58 eV and from 3.01 eV to 2.08 eV, respectively. The observed Urbach energy increases from 0.216 eV to 0.266 eV, confirming the distortion in the BTLSC glasses. Furthermore, optical properties were calculated from refractive index and bandgap values. The photoluminescence spectra showed a small narrow band emission at ~ 690 nm and a broad band ~ 750 nm with two excitation wavelengths, ~ 420 nm and ~ 580 nm. The CIE coordinates and CCT values indicate that BTLSC-3 glass is ideal for deep red-light solid-state lighting and NIR luminescence material applications.