This paper reports the spectroscopic properties of phosphates KLuP2O7, Sr9Sc(PO4)7, K3Lu(PO4)2, doped with Pr3+ ions. Photoluminescence (PL) spectra under selective excitation with UV photons, PL excitation spectra, and decay kinetics of pulsed cathodoluminescence are studied. Recordings of luminescence spectra were done with non-irradiated samples and after their irradiation with fast electrons (E = 10 MeV) or fast reactor neutrons. Three typical channels of electronic excitations radiative relaxation have been identified: interconfigurational d−f transitions, intraconfigurational f−f transitions in Pr3+ ions and luminescence associated with defects. After irradiation, significant changes in the luminescence characteristics were observed: a redistribution of the intensity of the intraconfigurational d−f transitions, an increase in the luminescence yield of defects and the manifestation of new emission centers. The formation of radiation-induced defects presumably occurs due to the formation of complexes consisting of phosphorus and oxygen atoms.

The conversion of the energy absorbed by cubic Gd_2O_3 nanocrystals doped with Er^3+ and codoped with Yb^3+ and Zn^2+ ions in a temperature range of 95–425 K is studied at various concentrations of dopants. The photoluminescence spectra confirm the ability of excitation energy transfer from the Gd^3+ ions or the matrix towards the Er^3+ ions. The population of upper excited states in the Er^3+ ions depends on the way of excitation, which cause the alterations in the probability of multiphonon relaxation from the excited states to the radiative levels. The kinetics of photoluminescence decay exhibit the possible energy transfer from anionic defects created by extra doping with Zn^2+ ions. The temperature dependences of the upconversion luminescence yield for emission lines of 560 and 660 nm are found to be different.

In this work luminescence properties of crystalline powders of Sr9Lu(PO4)7 doped with Pr3+ ions were studied upon excitation in UV range in temperature range 5-320 K. Photoluminescence spectra show intensive emission corresponding to radiative interconfigurational 5d→4f electronic transitions, weak narrow lines of intraconfigurational 4f→4f transitions as well as emission of two types of crystal lattice defects. Upon pulsed excitation, timing characteristics of emission related to the impurity center and defects were studied, as well as temperature dependence of emission yield. The processes of energy transfer between impurity center and defects are discussed.