Sol-gel synthesis of Gd2O3:Nd3+ nanopowders and the study of their luminescent properties

The paper presents the results of the sol-gel synthesis of Gd2O3:Nd3+ nanopowders by the citrate method, as well as the study of their structure and luminescent properties. A technique for using two different organic stabilizers with different thermal stability in sol-gel synthesis has been proposed and tested. The luminescent properties of the obtained Gd2O3:Nd3+ powders have been studied in the ultraviolet and near infrared spectral regions. The citrate sol-gel method was used to synthesize the materials. Aqueous solutions of metal nitrates were used as the main initial components. Citric acid and polyvinylpyrrolidone were used as organic modifying components, playing a double role in the synthesis process, i.e. acting as stabilizers of forming nanoparticles in colloidal solutions and serving as a fuel additive in the process of heat treatment of materials. Infrared spectroscopy and differential thermal and thermogravimetric analyses were used to study the evolution of the structure of materials during synthesis. Crystalline Gd2O3:Nd3+ nanopowders were obtained by a low-temperature sol-gel method using citric acid and polyvinylpyrrolidone as stabilizers. The data of infrared spectroscopy and differential thermal and thermogravimetric analyses show that the formation of Gd2O3:Nd3+ nanoparticles begins at the stage of the crude gel and the evolution process develops during the drying and heat treatment of materials. It is shown that the use of two different organic stabilizers with different thermal stability provides stabilization of the forming Gd2O3:Nd3+ nanoparticles at different stages of synthesis in a wide temperature range. The luminescence spectra are observed in the UV spectral region under excitation of the synthesized nanopowders by radiation with a wavelength of 238 nm. They are determined by electronic transitions in the Gd2O3 crystalline matrix. The synthesized Gd2O3:Nd3+ nanopowders exhibit intense photoluminescence in the UV and near-IR spectral regions. The results can be used in the development of a technology for the synthesis of various composite phosphors, as well as in the creation of luminescent nanopowders for nanothermometry in medicine.