Investigation of luminescence properties of Dy3+ doped YAlO3 phosphors synthesized through solid state method

Abstract

YAlO3:Dy3+ phosphor has been synthesized by the solid state reaction method with boric acid used as a flux. The resulting YAlO3:Dy3+ phosphor was characterized by XRD & FTIR and Scanning Electron microscope (HR-SEM/EDAX). The results of XRD patterns indicate that the prepared sample contain crystalline phases and has a orthorhombic structure with size in range of 52–65nm. The crystallites show dumbbell shape, agglomerated particles with different size. Thermoluminescence (TL) studies of YAlO3:Dy3+ have been carried out by irradiating with UV-radiation, at a heating rate of 6.7°Cs−1 showing three prominent peak at 83.7°C along with shoulder peak at around 148°C and 236°C. There are three prominent peaks at 90°C, 163 and 239°C have been observed to increase with UV exposures of YAlO3 doped with Dy3+. The prepared phosphor is less stable with UV exposure time but it shows opposite behaviour with gamma irradiation in case of gamma irradiation the high temperature peak at 193°C, 258°C and 361°C for 0.9Kgy and it shows continuous increase with gamma dose. Kinetic parameters also suggest that TL glow curve in YAlO3:Dy3+ phosphors is obeying first and general order kinetics. These methods indicated that the glow curve of this material is the superposition of a number of first- and general-order glow peaks, or at least due to the distribution of traps. The phosphors show sublinear response up to 0.9Kgy with γ dose and above it there was no saturation and TL glow curve of UV also shows sublinear response. PL studies of YAlO3:Dy3+ (3%) show blue (475,485nm) and yellow(570,575,580,585nm)emissions. The Photoluminescence excitation is around ∼254, 295, 326, 353, 390, 400 and 482nm. The broad band excitation spectrum associated with defects and vacancies of host material through two different crystalline phases present in host material. The PL emission spectra show that the intense peaks were observed in range of 365–620nm corresponds of YAlO3 host lattice by emission of Dy3+(4F9/2→6H15/2,6H13/2) accompanied by weak 4F7/2→6H13/2 transitions. The results of the XRD show that obtained YAlO3:Dy3+ phosphor has a orthorhombic structure with size in range of 61–65nm. The hypersensitive transitions of 4F9/2→6H13/2(Dy3+) are relatively lower than those of the insensitive transitions in YAlO3. This is conceivable that the YAlO3 structure provides low inversion symmetry sites for activator Dy3+ ions. The Kinetic parameters were estimated using Chen's glow peak method after deconvolution and results are discussed in details.