Green-emitting Er3+-doped La3GaO6 phosphors: gel-combustion synthesis, rietveld refinement and photoluminescence properties for solid-state lighting applications

Abstract

Er3+-doped La3GaO6 (LGO) nanophosphors were prepared via a gel-combustion route and their structural as well as optical properties were studied in detail. Rietveld-refined XRD analysis confirmed the orthorhombic crystal structure of the prepared nanophosphor with a Cmc21 space group. The synthesized phosphors were characterized by Field Emission Scanning Electron Microscopy (FE-SEM) and Energy Dispersive X-ray Spectroscopy (EDX) to evaluate their morphology and elemental composition. A prominent excitation peak centered at 379 nm was observed in the photoluminescence (PL) excitation spectrum accredited to 4I15/2 → 4G11/2 transition. On excitation at this wavelength, the phosphor exhibited a strong green emission peak at 549 nm arising from radiative transition (4S3/2 → 4I15/2) of Er3+ ions. The emission intensity reached a maximum value at 4 mol% Er3+ concentration, beyond which it progressively decreases due to concentration quenching (CQ). The critical distance of 18.2451 Å and interaction parameter (Q ≈ 8) suggested that dipole–quadrupole interactions are responsible for non-radiative energy transfer process. The CIE chromaticity coordinates (0.3186, 0.6418), color purity (85.07%) and correlated color temperature (5718.44 K) show that the 4 mol% of Er3+ doped LGO phosphor has good optical performance for future applications in solid state lighting systems.