najoNanosystems: Physics, Chemistry, MathematicsНаносистемы: физика, химия, математика2220-80542305-7971Университет ИТМО10.17586/2220-8054-2023-14-6-660-671najo-157Research ArticleCHEMISTRY AND MATERIALS SCIENCEХИМИЯ И НАУКА О МАТЕРИАЛАХSynthesis under hydrothermal conditions and structural transformations of nanocrystals in the LaPO4–YPO4–(H2O) systemВлияние условий спекания нанокристаллов со структурой монацита La0.9Y0.1PO4 на термические и механические свойства материалаhttps://orcid.org/0000-0002-9633-4421ЕникееваМ. О.EnikeevaM. O.

Maria O. Enikeeva

194021 St. Petersburg

190013 St. Petersburg

odin2tri45678@gmail.comhttps://orcid.org/0000-0002-2807-375XПроскуринаО. В.ProskurinaO. V.

Olga V. Proskurina

194021 St. Petersburg

190013 St. Petersburg

proskurinaov@mail.ruhttps://orcid.org/0000-0002-3230-3335ГерасимовЕ. Ю.GerasimovE. Yu.

Evgeny Yu. Gerasimov

Novosibirsk 630090

gerasimov@catalysis.ruhttps://orcid.org/0000-0002-7661-9155НеведомскийВ. Н.NevedomskiyV. N.

Vladimir N. Nevedomskiy

194021 St. Petersburg

nevedom@mail.ioffe.ruhttps://orcid.org/0000-0002-7661-9155ГусаровВ. В.GusarovV. V.

Victor V. Gusarov

194021 St. Petersburg

nevedom@mail.ioffe.ruIoffe Institute; St. Petersburg State Institute of TechnologyRussian FederationFederal Research Center, Boreskov Institute of Catalysis SB RASRussian FederationIoffe InstituteRussian Federation202302062025146660671Copyright © Enikeeva M.O., Proskurina O.V., Gerasimov E.Y., Nevedomskiy V.N., Gusarov V.V., 20252025Еникеева М.О., Проскурина О.В., Герасимов Е.Ю., Неведомский В.Н., Гусаров В.В.Enikeeva M.O., Proskurina O.V., Gerasimov E.Y., Nevedomskiy V.N., 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/157

Structural transformations of nanocrystals in the LaPO4–YPO4–(H2O) oxide system were investigated under hydrothermal conditions at 230C, depending on isothermal holding times (2 hours, 7 days and 28 days). It was shown that before hydrothermal processing, phases crystallize in the system with rhabdophane structures La1-xYxPO4  nH2O (0 x 0:80) and xenotime YPO4. It has been determined that increasing the duration of isothermal treatment under hydrothermal conditions leads to the transformation of the rhabdophane phase into phases with monazite and equilibrium xenotime structures, with an intermediate crystallization of the metastable monazite phase. It is noted that only after 28 days of hydrothermal treatment at 230C, the system approaches the equilibrium composition of the phases with monazite structures La0:97Y0:03PO4 (with crystal sizes of 18–50 nm) and xenotime YPO4 (with crystal sizes of 45–90 nm). In a single-phase sample with a monazite structure La0:75Y0:25PO4, the average crystal size remains unchanged at around 20 nm after 2 hours, 7 days and 28 days of hydrothermal treatment at 230C.

Исследованы структурные трансформации нанокристаллов в оксидной системе LaPO4-YPO4-(H2O) в гидротермальных условиях при 230°C в зависимости от продолжительности изотермической выдержки (2 часа, 7 суток и 28 суток). Показано, что до гидротермальной обработки в системе кристаллизуются фазы со структурами рабдофана La1-xYxPO4·nH2O (0≤x≤0.80) и ксенотима YPO4. Определено, что увеличение продолжительности изотермической выдержки в гидротермальных условиях приводит к трансформации фазы со структурой рабдофана в фазы со структурами монацита и ксенотима равновесного состава с промежуточной кристаллизацией метастабильной фазы монацита. Отмечено, что только после 28 суток гидротермальной обработки при 230°C система приближается к равновесному составу фаз со структурами монацита La0.97Y0.03PO4 (с размерами кристаллитов 18-50 нм и ксенотима YPO4 (с размерами кристаллитов от 45-90 нм). В однофазном образце со структурой монацита La0.75Y0.25PO4 после 2 часов, 7 суток и 28 суток ГТО при 230 °С средний размер кристаллитов не изменяется и составляет около 20 нм. 

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