najoNanosystems: Physics, Chemistry, MathematicsНаносистемы: физика, химия, математика2220-80542305-7971Университет ИТМО10.17586/2220-8054-2024-15-6-781-792najo-163Research ArticleCHEMISTRY AND MATERIALS SCIENCEХИМИЯ И НАУКА О МАТЕРИАЛАХPhase formation and thermal analysis in the LaPO4–GdPO4–H2O systemФазообразование и термический анализ в системе LaPO4-GdPO4-H2Ohttps://orcid.org/0000-0002-9633-4421ЕникееваМ. О.EnikeevaM. O.

Maria O. Enikeeva

194021 St. Petersburg

199034, St. Petersburg

i@odin2tri.ruhttps://orcid.org/0009-0007-6447-7341ЖидомороваК. А.ZhidomorovaK. A.

Kseniya A. Zhidomorova

199034, St. Petersburg

190013, St. Petersburg

zhidomorovak@gmail.comhttps://orcid.org/0000-0001-7110-557XДаниловичД. П.DanilovichD. P.

Dmitriy P. Danilovich

190013, St. Petersburg

dmitrydanilovich@gmail.comhttps://orcid.org/0000-0002-7661-9155НеведомскийВ. Н.NevedomskiyV. N.

Vladimir N. Nevedomskiy

194021 St. Petersburg

nevedom@mail.ioffe.ruhttps://orcid.org/0000-0002-2807-375XПроскуринаО. В.ProskurinaO. V.

Olga V. Proskurina

194021 St. Petersburg

190013, St. Petersburg

proskurinaov@mail.ruhttps://orcid.org/0000-0003-4375-6388ГусаровВ. В.GusarovV. V.

Victor V. Gusarov

194021 St. Petersburg

gusarov@mail.ioffe.ruIoffe Institute; Branch of Petersburg Nuclear Physics Institute named after B. ˙P. Konstantinov of National Research Centre “Kurchatov Institute” – Institute of Silicate ChemistryRussian FederationBranch of Petersburg Nuclear Physics Institute named after B. ˙P. Konstantinov of National Research Centre “Kurchatov Institute” – Institute of Silicate Chemistry; St. Petersburg State Institute of TechnologyRussian FederationSt. Petersburg State Institute of TechnologyRussian FederationIoffe InstituteRussian FederationIoffe Institute; St. Petersburg State Institute of TechnologyRussian Federation202405062025156781792Copyright © Enikeeva M.O., Zhidomorova K.A., Danilovich D.P., Nevedomskiy V.N., Proskurina O.V., Gusarov V.V., 20252025Еникеева М.О., Жидоморова К.А., Данилович Д.П., Неведомский В.Н., Проскурина О.В., Гусаров В.В.Enikeeva M.O., Zhidomorova K.A., Danilovich D.P., Nevedomskiy V.N., Proskurina O.V., Gusarov V.V.Данная работа распространяется под лицензией Creative Commons Attribution 4.0.This work is licensed under a Creative Commons Attribution 4.0 License.https://nanojournal.ifmo.ru/jour/article/view/163

Structural transformations of nanocrystals in the LaPO4–GdPO4–(H2O) system under hydrothermal conditions at 230 ◦C were studied depending on the duration of isothermal holding (2 hours, 3 days, and 5 days). It has been shown that a phase with the rhabdophane-like structure, La1−xGdxPO4*nH2O (0.00≤ x ≤1.00), exhibits a weighted average crystallite size of 4–7 nm and crystallizes in the system prior to hydrothermal treatment. As a result of hydrothermal treatment, samples in the LaPO4–GdPO4–(H2O) system are completely transformed into a phase with a monazite structure within five days, with the slowest transfor- mation observed for gadolinium orthophosphate. It was found that nanoparticles with a rhabdophane structure, GdPO4*nH2O, possess a single-crystal structure. The thermal analysis data indicated that the samples obtained via the precipitation method contain an X-ray amorphous phase and impurity compounds. The onset temperature of the structural transformation from rhabdophane to monazite, as well as the number of water molecules in the rhabdophane-like structure, depends on the chemical composition of the compound, particularly with regard to the isomorphic substitution of lanthanum cations with gadolinium cations.

Исследованы структурные трансформации нанокристаллов в оксидной системе LaPO4-GdPO4-(H2O) в гидротермальных условиях при 230°C в зависимости от продолжительности изотермической выдержки (2 часа, 3 суток и 5 суток). Показано, что в системе до гидротермальной обработки кристаллизуется фаза со структурой рабдофанаLa1-xGdxPO4·nH2O (0.00≤x≤1.00) со средневзвешенным значением размеров кристаллитов4-7 нм. В результате гидротермальной обработки образцы в системе LaPO4-GdPO4-(H2O) полностью трансформируются в фазу со структурой монацита за пять суток, медленнее всего процесс трансформации наблюдается для ортофосфата гадолиния. Определено, что наночастицы со структурой рабдофана GdPO4·nH2O имею монокристаллическое строение. Методом синхронного термического анализа показано, что образцы, полученные методом осаждения, содержат рентгеноаморфную фазу и примесные соединения, температура структурного превращения рабдофан→монацит и количество молекул воды в структуре рабдофана зависит от химического состава соединения при изоморфном замещении катиона лантана на катион гадолиния.

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The authors declare that there are no conflicts of interest present.