Diversity of Local Environments of RE Ions in Aluminoborosilicate Glasses
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rsity of Local Environments of RE Ions in Aluminoborosilicate Glasses E. V. Malchukovaa, *, B. Boizotb, and E. I. Terukova, c aIoffe
Institute, Russian Academy of Sciences, St. Petersburg, 194021 Russia of Irradiated Solids, École Polytechnique, Palaiseau Cedex, 91128 France c St. Petersburg Electrotechnical University (LETI), St. Petersburg, 197376 Russia *e-mail: [email protected]
bLaboratory
Received February 14, 2020; revised March 16, 2020; accepted March 27, 2020
Abstract—Luminescence and excitation spectra are analyzed along with the kinetics of luminescence decay for aluminoborosilicate glasses containing rare earth (Sm, Eu and Ce) oxides. It is found that the measured spectra depend on the moment of experimental registration, the wavelength of excitation, and the concentration of rare earth activators. Variations in spectra are associated with differences in the local environment of the rare earth activator. DOI: 10.3103/S1062873820070187
INTRODUCTION The study of oxide glasses doped with rare earth (RE) ions is of great practical interest in many fields of science and technology (e.g., fiber optics and telecommunications (materials for fiberglass and optical amplifiers) [1], optical electronics (remote chemical sensors and white light emitting diodes (W-LEDs)) [2, 3], and medicine (active media of solid-state lasers and ionizing radiation detectors) [4–6]), and in nuclear energy (model matrices for immobilization of nuclear fuel waste) [7]. RE ions characterized by partly filled d and f orbitals are mainly embedded in the structure of the glass in a trivalent state. However, some RE ions can exist inside a glass matrix in the divalent state. It is known that spectroscopic characteristics of RE ions are determined by their local environment and distribution in the matrix. The connection between the structure of a base matrix and the properties of RE activator ions must be understood in developing and synthesizing materials for different optical applications [8]. There are two main reasons why RE ions are frequently used as activators. First, their narrow energy levels can act as structural probes for determining the immediate environment of RE activator ions. Second, the modification of the structure of energy levels of RE ions caused by the glass environment can result in interesting technical applications. The existence of more than one position of RE activator ions, confirmed via fluorescence line narrowing (FLN) and time-resolved photoluminescence, was discussed in the literature more than 15 years ago [9–11]. It should be noted that optical excitation is the easiest way of
detecting the nonequivalence of activator centers, since light reacts with ions of the activator virtually without affecting the matrix, making it easier to select centers according to a particular ion parameter [12]. The aim of this work was to analyze spectra of luminescence, luminescence excitation, and the kinetics of luminescence decay, depending on the wavelength of the exciting light, the experimental conditions,
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