Effect of ligand field symmetry on upconversion luminescence in heat‐treated LaBGeO₅:Yb³⁺, Er³⁺ glass

Abstract

In this paper, we report upconversion (UC) luminescence enhancement in LaBGeO5:Yb3+, Er3+ glass‐ceramics (GCs), surface crystallized glass‐ceramics (SCGCs) and ceramics compared with the as‐melt glass fabricated by the conventional melt‐quenching technique. Based on structural investigations, we find that the nucleation and crystallization of trigonal stillwellite LaBGeO5:Yb3+, Er3+ nanocrystals occur first at the glass surface before the following volume crystallization. The local site symmetry around rare earth (RE) ions which was evaluated using the Eu3+ ions as a probe together with Judd‐Ofelt theory calculations exhibits a clear increase with the devitrification of the glass. Consequently, complete crystallization of the glass leads to largest enhancement in the UC emissions of the LaBGeO5:Yb3+, Er3+ ceramics. We ascribe the enhancement of UC luminescence in the LaBGeO5:Yb3+, Er3+ GCs, SCGCs, and ceramics to the structural ordering and the improvement of site symmetry surrounding RE ions that minimizes the rate of nonradiative relaxation process.

Surface crystallized Mn‐doped glass‐ceramics for tunable luminescence

“…Therefore, the two curves were fitted with a double exponential decay function:where, I ( t ), I 0 are the emission intensities at time t and 0, A 1 and A 2 are constants and 1 and 2 are the rapid and slow lifetimes for the exponents, respectively. The average lifetime (s) can be calculated as follows:…”

Color‐tunable and white emission of Tm3+ doped transparent zinc silicate glass‐ceramics embedding ZnO nanocrystals

“…Local symmetry of ligand field surrounding RE ions in glass and glass‐ceramics significantly influences their photoluminescence performance based on Judd‐Ofelt (JO) theory . PL spectra (Figure ) indicate that short‐time (5 minutes) heat treatment facilitates simultaneously producing strong blue emission originated from Tm 3+ ions and ZnO defect‐based yellow emission.…”

“…Local symmetry of ligand field surrounding RE ions in glass and glass-ceramics significantly influences their photoluminescence performance based on Judd-Ofelt (JO) theory. 22,23 PL spectra ( Figure 3) indicate that short-time (5 minutes) heat treatment facilitates simultaneously producing strong blue emission originated from Tm 3+ ions and ZnO defect-based yellow emission. The enhancement of blue luminescence intensity in glass-ceramic compared with that in precursor glass can be ascribed to the structural ordering and ligand field modification.…”