Structural, Optical, and Luminescent Studies of Vanadyl Doped Strontium Tin Phosphate by Solid-state Reaction Method

VO2+ doped SrSn(PO4)2 nanopowder was prepared by solid state reaction method. The obtained nanopowder was studied using XRD, SEM, HR-TEM, FT-IR, optical absorption, EPR and PL measurements. The X-ray diffraction analysis revealed a monoclinic structure of VO2+ doped SrSn(PO4)2 nanopowder and exhibited an average crystallite size of 26 nm. The size is in the nano scale and W-H plot approach was also in agreement with this value. SEM and HR-TEM images are showing the non-uniform stone-like particle morphology of the prepared sample and confirms information about the average particle size of nanopowder, while EDS analysis confirms elemental composition. The selected area electron diffraction pattern revealed the sample crystalline by means of rings corresponding to XRD planes. Vibration modes related to phosphate functional groups were observed in FT-IR studies. Optical absorption spectrum shows characteristic VO2+ peaks at 520, 668 and 824 nm, and the crystal field and tetragonal parameters were evaluated: Dq = 1497, Ds = -2331 and Dt = 1028 cm-1. From the EPR spectrum, Hamiltonian parameters and hyperfine coupling constant values were calculated. The associated CIE chromaticity coordinates and CCT parameters were computed from the PL spectrum, and they indicate possible applications in LEDs and lighting devices.