Synthesis and Characterization of K₂Ba₃(P₂O₇)₂:VO²⁺ Nanopowder: Reddish-Orange Emission for LED Applications

Solid-state reaction method is employed to prepare K₂Ba₃(P₂O₇)₂:VO²⁺ nanopowder and studied by using powder x-ray diffraction (XRD), scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, optical absorption spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, and photoluminescence (PL) spectroscopy. XRD studies revealed VO²⁺ ion doped K₂Ba₃(P₂O₇)₂ nanopowder have 21 nm crystallite size, orthorhombic phase, and Pmn2₁ space group. From Williamson-Hall analysis, crystallite size is found as 24 nm. SEM morphology recorded the presence of irregular-sized and round-shaped agglomerates. FT-IR and Raman spectra reveal characteristic bands of phosphate groups. Three characteristic peaks are observed at 848, 695, and 452 nm in optical absorption spectrum. Also, crystal and tetragonal field parameters are calculated as Dq = 1439, Ds = -2789, and Dt = 3422 cm^-1. In addition, bandgap energy is found as 3.97 eV. Optical and EPR analyses led to understand the incorporation of vanadyl ions into host lattice. Spin Hamiltonian parameters are evaluated. Basing PL spectrum, Commission Internationale de l'Éclairage's (CIE) chromaticity coordinates are calculated, which are present in reddish-orange region with good color correlated temperature (CCT) and color rendering index (CRI) values facilitating the use in lighting applications and LEDs.