Mechanochemical synthesis of YNbO4:Eu nanocrystalline powder and its structural,microstructural and photoluminescence properties

In this research we prepared nanocrystalline YNbO₄:Eu³⁺ phosphor, i.e. nanophosphor, powder using an efficient mechanochemical method followed by annealing. X-ray diffraction analysis revealed that YNbO₄:Eu³⁺ crystallizes in monoclinic structure C2/c where, from the point of view of A and B in ABO₄ compounds, cation coordination can be noted as [6+2, 4+2]. Crystallite size of about 40 nm, was estimated using Debye Scherrer's equation. Raman spectroscopy with 785 and 532 nm excitation wavelengths is performed to record a majority of materials phonon modes and to provide more in depth understanding of the YNbO₄ structure. Scanning electron microscopy observations indicate that the mechanical treatment during synthesis is causing non-uniformity of the powder microstructure. High resolution photoluminescent measurements upon UV excitation showed intense emission coming from f–f transitions of the europium ion with the lifetime of 0.68 ms, suggesting that the obtained YNbO₄:Eu³⁺ is a good potential phosphor. A comparison of emissive properties with microcrystalline YNbO₄:Eu³⁺ was made and it showed higher values of emission intensity and lifetime of the nanocrystalline sample.