Pr3+ doped BaNb2O6 reddish orange emitting phosphor for solid state lighting and optical thermometry applications

A novel reddish-orange emitting BaNb2O6: Pr3+ phosphor was synthesized by conventional solid-state reaction method and its structural, morphological, optical properties and temperature dependent photoluminescence properties were investigated. The Le Bail profile matching of XRD patterns confirmed the orthorhombic phase presence and the corresponding cell parameters were calculated.Through a profound investigation of UV-visible diffuse reflectance spectra, a decrease in optical-band gap energy and an increase in Urbach tail width were noticed in doped sample as compared to undoped sample. Under the blue light excitation, the emission spectra exhibit peaks in reddish-orange region due to intra f-f transitions of Pr3+ ions. Strong covalence between Pr3+ and O2- was estimated by calculating nephelauxetic ratio, bonding parameter and covalency using the excitation spectra. The involvement of intervalence charge transfer (IVCT) state results in nonradiative relaxation increase, for which the emission peak intensities decreased with increase in temperature. The configurational coordinate model was used to demonstrate this phenomenon. The fluorescence intensity ratio technique was utilized for temperature sensing applications. The suitable CIE coordinates and significant temperature dependent PL makes the BaNb2O6: Pr3+ material to be a potential candidate for contributing red component in WLED and temperature sensing applications. (C) 2019 Elsevier B.V. All rights reserved.