Synthesis of Nanosized Luminophores Gd2O3:Nd3+ by Polymer-Salt Method and Study of Their Main Characteristics

Abstract

The problems of manufacturing nanoscale Gd₂O₃:Nd³⁺ phosphors using the liquid polymer-salt method have been considered. Within the framework of this method, the dual role of polyvinylpyrrolidone (PVP) as an organic solvent in the synthesis process has been determined. On the one hand, it stabilizes the formation of Gd₂O₃ crystals, preventing their uncontrolled growth and agglomeration, and on the other, it serves as a fuel during decomposition (combustion), contributing to an increase in the reaction temperature and thereby influencing the structural and emission properties of phosphors. It has been shown that successive drying of the initial homogeneous solution containing gadolinium and neodymium salts, as well as PVP, at room temperature for 24 h and heat treatment at 1000°C for 2 h make it possible to obtain high-luminescent near-infrared phosphors Gd₂O₃:Nd³⁺, whose crystals are characterized mainly by a cubic structure and an average size of about 40 nm. It has been experimentally confirmed that the developed method is suitable for modifying hollow-core antiresonant optical fibers made of silica glass with thin-film coatings based on the synthesized material and does not cause structural and phase transformation of the formed Gd₂O₃ crystals. It has been found out that the emission spectra of the nanoscale Gd₂O₃:Nd³⁺ phosphors obtained by the polymer-salt method at temperatures of 550 and 1000°C are identical, namely: (1) the shape of the luminescence peaks is the same for both specified heat treatment regimes regardless of intensity, (2) the main lum-inescence peak is located near 1064 nm wavelength and corresponds to the electron transition ⁴F_3/2–⁴I_11/2, and (3) additional luminescence peaks are located near 900 and 1340 nm wavelengths and correspond to the ⁴F_3/2–⁴I_9/2 and ⁴F_3/2–⁴I_13/2 electron transitions, respectively.