Dy3+ - Activated NaY9Si6O26 luminescent ceramic powder: Optical and thermometric properties

Abstract

Here, we elaborated the structural, morphological, optical and thermometric properties of Dy3+- activated NaY9Si6O26 oxyapatite phosphor synthesized hydrothermally and annealed at high temperature. X-ray diffraction patterns of NaY9Si6O26: xDy3+(x =0.5; 1; 2; 4; 6; 8 mol% Dy3+) samples confirmed a single-phase hexagonal structure with P63/m space group. Transmission electron microscopy images showed dense agglomerates composed of round-shaped nanoparticles with a size of ~50 nm. Room temperature photoluminescent emission spectra show distinct emission bands in the visible spectral region corresponding to 4I15/2 → 6H15/2 (~454 nm, blue), 4F9/2 → 6H15/2 (~488 nm, blue), and 4F9/2 → 6H13/2 (~573 nm, yellow) f-f transitions. Lifetime measurements reveal the double exponenational nature of emission decay showing decrase in lifetime values with the increase of Dy3+concentration (from 1.32 ms for the lowest to 0.16 ms for the highest Dy3+concentration). Temperature dependent emission spectra were measured for the sample with the highest emission intensity resulting in a luminescence intensity ratio (LIR) study employing the ratio of 4I15/2 → 6H15/2 and 4F9/2 → 6H15/2 transitions for thermometry. Absolute (Sa) and relative sensitivity (Sr) of 2.960 K-1 @ 725 K, and 1.67 %K 1 @ 300 K, respectively, were calculated.