Electronic Structures and Luminescence Properties of YNbO_4 and YNbO_4:Bi

摘要

The luminescence properties of fergusonite phosphors, YNbO_4 and YNbO4:Hi, were investigated with photoluminescence (PL) measurements and first-principles calculations. The various ab- sorption spectra of these phosphors have been interpreted using the calculated partial density of states in the framework of density functional theory. We were able to determine the charge- transfer gap of YNbO4, 4.3 eV, that agrees well with our experi- mental measurement. From our analysis of PL spectra and calculations, we have investigated the Hi effect in YNbO_4:Hi, which shows an excitation peak at a longer wavelength than YNbO_4, We have found that the charge transfer from oxygen to bismuth is the main reason for the peak position shift in the excitation spectra.