Формування структури нанопорошків складних оксидних фаз LaLuO3:Yb3+ типу перовськіту, отриманих комплексоутворюючим цитратним методом Печіні

• Datum: 2025
• Hauptverfasser: Lobunets, T.F., Shyrokov, О.V., Korniienko, O.A., Yurchenko, Yu.V., Tomila, T.V., Ragulya, A.V.
• Format: Artikel
• Sprache: Englisch
• Veröffentlicht: Chuiko Institute of Surface Chemistry National Academy of Sciences of Ukraine 2025
• Schlagworte: прекурсори; метод Печіні (цитратний); питома поверхня; нанопорошки; перовськіт LaLuO3; ізотерми сорбції
• Online Zugang: https://www.cpts.com.ua/index.php/cpts/article/view/806
• Назва журналу: Chemistry, Physics and Technology of Surface

The synthesis of nanopowders is of significant importance in the development of new materials. The sol-gel method is one of the simplest methods for the synthesis of unstable precursors, the thermal decomposition of which allows for the production of nanodispersed powders. The objective of this study was to examine the thermal decomposition of a precursor synthesized by the citrate method of polymer complexes, with the aim of obtaining nanopowders of perovskite-type complex oxide phases in the La2O3?Lu2O3?Yb2O3 system as one of the important stages in the creation of materials with specified characteristics. The study of the thermal decomposition of the precursor revealed that the destruction of the polymer matrix in the temperature range of 180–750 °C is accompanied by the formation of an         X-ray amorphous intermediate. Upon further heating to 800–820 °C, this intermediate crystallizes with negligible decomposition (according to XRD) into perovskite of orthorhombic syngony with lattice parameters a = 0.6016 nm, b = 0.8390 nm, c = 0.5821 nm and density ?xrd = 8.18 g/cm3, and capillary-slit pore structure, with a specific surface area of 12–17 m2/g, which corresponds to a particle size of 40–60 nm. The thermal decomposition of the precursor occurs through the storage and formation of a non-rigid component of the pore structure of intermediate metastable amorphous products before the formation of the perovskite phase in the La2O3?Lu2O3?Yb2O3 system at the temperature of 750 °C. The dependence of the general porosity characteristics of the studied samples on temperature during the non-isothermal decomposition of the precursor synthesized by the citrate method is not monotonic, with inflection points at 750 and 800 °C. At the temperature of 750 °C, the system undergoes a collapse, accompanied by a sharp decrease in the volume and specific surface area of mesopores. This is concomitant with the disappearance of the non-rigid component of the pore structure of intermediate amorphous products, as evidenced by a ledge on their nitrogen sorption isotherms. This signifies the completion of the thermal decomposition of polymeric complexes and the subsequent formation of perovskite-type complex oxide phases in the La2O3?Lu2O3?Yb2O3 system by nucleation, self-assembly, self-organization, and crystallization. An increase in the percentage of ytterbium dopant from 1 to 4 % does not affect significantly the general characteristics of the porous structure of perovskite samples; however, it does result in changes to their morphology. At the concentration of 4 % Yb3+, the perovskite structure consists of particles of uniform morphology.