Investigation of structural and luminescence properties of Ho3+ doped YAlO3 nanophosphors synthesized through solution combustion route

Abstract

YAlO3:Ho3+ (1–5mol%) nanophosphors have been prepared by solution combustion route using oxalyl dihydrazide (ODH) as a fuel. The final product was well characterized by powder X-ray diffraction (PXRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), UV–Vis, etc. PXRD patterns confirm the formation of highly crystalline orthorhombic phase structure. SEM and TEM studies show the particles are dumbbell shape, highly agglomerated and nano-size (∼30nm). The direct energy band gap (Eg) values estimated from Tauc’s relation were found to be in the range 5.76–5.99eV. Photoluminescence (PL) studies show green (540 and 548nm) and red (645 and 742nm) emissions upon excited at 452nm wavelength. The emission peaks at ∼742 and 645nm was associated with the transitions of 5F4→5I7 and 5F5→5I8 respectively. The higher energy bands located at 540 and 548nm were associated with 5F4, 5S2→5I8 transitions. Thermoluminescence (TL) studies of γ-irradiated YAlO3:Ho3+ (1–5mol%) show two glow peaks at 223 and 325°C recorded at a heating rate of 2.5°Cs−1. The 223°C glow peak follow linear behavior up to 1kGy and after that, it showed sub-linearity. Up to 1kGy, the phosphor is quite useful in radiation dosimetry. The kinetic parameters (E, b and s) were estimated from glow peak shape method. The CIE coordinate values lies within the green region. Therefore, the present phosphors may have potential application in WLEDs as green phosphor.