Temperature responsive behaviour of SrAl2O4(Eu, Dy):ZnGa2O4(Cr) phosphor-glass composite

Abstract

The current investigation reports on laser spectroscopy and temperature-sensitive optical response of composite consisting of phosphors (ZnGa₂O₄:Cr³⁺ and SrAl₂O₄:Eu²⁺, Dy³⁺) coated on a tellurite glass layer. Based on this composite, a temperature sensor, sensitve in the range of 298 K to 423 K, demonstrates a remarkable temperature sensitivity. Various analytical techniques, such as X-ray Diffraction, Scanning Electron Microscopy, High-Resolution Transmission Electron Microscopy, laser spectroscopy, etc., were employed to analyze the prepared composite. The investigation reveals the presence of ZGO and SrAl phosphors with crystalline sizes of approximately 36 nm and 25 nm, respectively, while the particle size ranges from 400 nm to 600 nm. A dip coating method was utilized to deposit tellurite-phosphor layers on the glass substrate to create a temperature sensor. SEM analysis indicates a layer thickness of around 93 µm. The existence of Eu²⁺ and Cr³⁺ ions was confirmed through photoexcitation and emission spectra on a 405 nm laser excitation. The temperature-dependent luminescence was studied using a ratiometric technique, showing a linear variation with temperature, resulting in an excellent temperature sensitivity of about 1.41 % K⁻¹ at 298 K. Our preliminary study of the phosphor-tellurite composite suggests significant potential for extensive use in the field of dual-mode highly sensitive optical thermometry.