2013 年 38 巻 2 号 p. 249-252
LaNbO4: Eu3+, Dy3+ phosphors prepared by a solid-state reaction were characterized by X-ray diffraction (XRD) and photoluminescence spectra. The XRD patterns of LaNbO4 doped with Eu3+ and Dy3+ essentially agreed with those of LaNbO4, indicating that the doping of Eu3+ and Dy3+ ions does not change the host crystal structure. From the strong emission peak at 615 nm corresponding to 5D0→7F2, Eu3+ was thought to occupy the sites with lower symmetry. In addition to the usual emission transitions from 5D0, the emission transitions from the higher 5D1 and 5D2 levels were observed. The transitions from the higher levels were explained by the reduced multi-phonon relaxation from the 5D1 and 5D2 to the lowest excited level 5D0 due to the lower vibrational energy of NbO43-. The relative emission intensity of the 5D0→7F2 transition decreased with an increase in the amount of Dy3+. This was attributed to energy transfer to the Dy3+ ions.