Spectral, surface and thermometric investigations of upconverting Er3+/Yb3+ co-doped Na3Y(PO4)2 phosphor

Abstract

Upconverting Er3+–Yb3+ co-doped Na3Y(PO4)2 phosphors were synthesized by employing the solution combustion method for optical thermometry application. The fundamental physicochemical properties of the prepared phosphors were examined. X-ray powder diffraction analysis and field emission scanning electron microscopy had been used to characterize the crystal structure and surface morphology of the nanophosphors, respectively. The prepared phosphors retained the monoclinic crystal structure even after the addition of the Er3+/Yb3+ dopant ions. Up-conversion (UC) luminescence studies showed that the emission bands of the prepared phosphors appear in the green and red region under 980 nm laser excitation. The green and red bands arising from the transition 2H11/2 and 4S3/2, 4F9/2 levels to the ground level (4I15/2) in the Er3+ ions had been accomplished via analyzing the temperature dependence intensity variations. The UC mechanism had been interpreted on the grounds of laser power-induced UC properties. Temperature sensing behavior of the Na3Y(PO4)2:Yb3+/Er3+ phosphors using the fluorescence intensity ratio of thermally and non-thermally coupled emission bands had been explored. The results exhibit that the maximum sensitivity of the thermally coupled green band was 0.0027 K−1 and of the red band was 0.0034 K−1 at 670 K and 330 K, respectively. Whereas the maximum sensitivity of the non-thermally coupled bands was 0.16 K−1. The temperature sensing results reveal the capability of the prepared phosphor Na3Y(PO4):Er3+/Yb3+ in temperature sensing devices using a dual-color scheme.