Effect of Li+ Doping On the Luminescence Intensity and Temperature Sensing Behaviour of Y2WO6:Yb3+/Er3+upconversion Nanomaterial

Abstract

The attraction of photon upconversion through the use of lanthanide-doped materials involves generation of photons at shorter wavelengths than the excitation wavelength after laser stimulation. Besides their extensive use in the field of bioimaging, drug delivery and sensors, temperature sensing based on the fluorescence intensity ratio (FIR) that suffers with low sensitivity still needs host crystal with strong upconversion luminescence (UCL) intensity. Here a series of Y2WO6:Er3+/Yb3+ crystals were synthesized via high temperature solid state method. For enhancing the UCL intensity, the crystal engineering route has been adopted by introducing a non-lanthanide ion (Li+ ) in different mol % inside the host lattice. The respective UCL intensities as well as the absolute sensitivity got enhanced. An in-depth structural analysis has been done by using the synchrotron X-ray diffraction (SXRD) experiments to trace the structural changes inside the crystal lattice after incorporation of Li+ , responsible for the above enhancement. As there are no major changes has been noticed in terms of structural and morphological analysis we headed for an atomic level study by calculating the lattice strain from the SXRD data using Williamson-Hall method. Interestingly, at highest value of strain, the local disorder is utmost with maximum UCL intensity and absolute sensitivity