Investigation of X-ray excited optical luminescence properties of Er, Nd-doped YVO4 phosphors using a hard X-ray beam

Scintillators based on YVO₄:Er³⁺ and YVO₄:Er³⁺, Nd³⁺, synthesized through glucose-assisted sol-gel method and calcined under different temperatures were studied via X-ray excited optical luminescence (XEOL). The samples' crystalline structure was studied via X-ray powder diffraction and the crystallite size estimated by Scherrer's method. The results indicated the crystal purity phase in all samples, indexed as YVO₄, and crystallite size in nanometric order, which is in accordance with Transmission Electron Microscopy results that indicate the formation of nanoparticles with spherical shape tendency. The spectroscopic studies taken by XEOL demonstrated typical Er³⁺ and Nd³⁺ transitions were dominant on the emission spectra. An unusual host emission was also identified c.a. 340 and 600 nm and ascribed as an intrinsic host vanadate emission related with the material optical band gap (c.a. 3.5 eV) and/or associated with VO₄³⁻ to rare earth ions energy transfer. The scintillators kept the emission stability even exposed to ∼10¹⁰ photon/sec, which demonstrated their radiation hardness, which is an important feature to the application of YVO₄ based-materials as scintillators. Independently of the calcination temperature, glucose-assisted sol-gel method was reliable to produce YVO₄-based scintillators nanopowders with stable optical properties with potential to be applied in biological imaging and/or in theranostics.