Photoluminescence of CaGa2O4 Activated with Rare Earth Ions Yb3+ and Er3+

Calcium gallate is a promising material for the synthesis of phosphors based on it. Most of the known calcium gallate photoluminophores emit in the visible region of the spectrum. At the same time, luminophores emitting in the infrared range, which are used to create latent images and markers, are of scientific interest as photoconverters of radiation. Infrared phosphors based on calcium gallate have been little studied The results of a study of the luminescent properties of calcium gallate activated by trivalent rare-earth ions Yb3+ and Er3+ are presented. The IR luminescence spectra of samples with one activator Ca1–xYbxGa2O4 and Ca1–xErxGa2O4 when excited by radiation sources with a wavelength of 940 and 790 nm, respectively, are studied. The dependence of the luminescence intensity of the samples on the concentration of rare-earth ions is obtained. Upon excitation of the two-activator composition Ca1–x–yYbxEryGa2O4 by a semiconductor laser diode with a wavelength of 940 nm, IR luminescence is recorded in the regions of 980 to 1100 and 1450 to 1670 nm. The emission in these bands corresponds to electronic transitions in Yb3+ and Er3+ ions, respectively. For the luminescence band with a maximum at a wavelength of 1540 nm, the excitation spectra are measured and the maximum intensity falls on the wavelengths: 930, 941, 970, and 980 nm. The dependence of the intensity of the IR luminescence of the solid Ca1–x–yYbxEryGa2O4 solution on the concentration of Er3+ ions. With an increase in the concentration of Er3+ ions in the luminescence spectra, a redistribution in the intensities of the bands belonging to Yb3+ and Er3+ ions is observed, which indicates the presence of energy transfer processes between these ions. The kinetics of decay of IR luminescence for series with one and two activators is investigated: Ca1–xYbxGa2O4, Ca1–xErxGa2O4, and Ca1–x–yYbxEryGa2O4. It is found that the decay of luminescence occurs predominantly according to an exponential law, which indicates the predominance of the intracenter luminescence mechanism in the studied structures. Based on the analysis of the excitation and luminescence spectra of the experimental samples, conclusions were drawn about the interaction of the ions of Yb3+ and Er3+ activators in the crystal lattice of calcium gallate.