Graphical abstract showing the photoluminescence studies (emission spectra) of Er³⁺ doped SYW phosphors. The emission spectra recorded under the 380 nm excitation wavelength in the range 500–700 nm

Abstract

A series of Er³⁺ ions doped Sr₉Y₂W₄O₂₄ (SYW) phosphors have been synthesised using solid-state reaction technique. For optical thermometry and solid state lighting applications, the crystal structure, morphological, and luminescence features of the SYW : Er³⁺ phosphors were explored. X-ray diffraction (XRD) reveal that synthesized phosphors having single phase with a tetragonal crystal structure and I4₁/a space group. Scanning electron microscopy (SEM) was used to examine the morphological behaviour and presence of composition elements. The optical bandgap of the phosphor was evaluated using UV-Vis diffuse reflection spectra (DRS). The photoluminescence (PL) emission spectra were captured under 380 nm excitation, and the peak with the maximum intensity was identified at 563 nm ascribed to transition ⁴S_3/2→⁴I_15/2, that emits green color in visible region. The temperature dependent PL (TD-PL) spectra show that SYW phosphor is substantially more thermally stable, having thermal activation energy of about 0.247 eV. Additionally, the fluorescence intensity ratio (FIR) was used to study the optical sensing characteristics of the thermal quenching transitions (²H_11/2, ⁴S_3/2) with maximum relative sensitivity (S_R) and an absolute sensitivity (S_A) being 1.33 % K⁻¹and 0.307 % K⁻¹, respectively. All of the aforementioned findings demonstrate that SYW : Er³⁺ ions doped phosphors have potential for optical thermometry and other photonic devices.