COEXISTENCE OF CERIUM(III)/(IV) IN PHOSPHATE AND MOLYBDATE MELTS

  For the first time, the possibilities of controlled in fluence on the valence states of ceriumin phosphate and molybdate melts have been systematically analyzed. A series of molybdates with a scheelite structure, MICe(MoO4)2 (MI – Li, Na, K, Cs), were obtained by crystallization from melt...

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Дата:2025
Автори: Zozulia, Valeria, Slobodyanik, Mykola, Ushchapivska, Tetiana, Terebilenko, Kateryna
Формат: Стаття
Мова:English
Опубліковано: V.I.Vernadsky Institute of General and Inorganic Chemistry 2025
Онлайн доступ:https://ucj.org.ua/index.php/journal/article/view/702
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Назва журналу:Ukrainian Chemistry Journal

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Ukrainian Chemistry Journal
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spelling oai:ojs2.1444248.nisspano.web.hosting-test.net:article-7022025-04-08T13:55:05Z COEXISTENCE OF CERIUM(III)/(IV) IN PHOSPHATE AND MOLYBDATE MELTS Zozulia, Valeria Slobodyanik, Mykola Ushchapivska, Tetiana Terebilenko, Kateryna scheelite; cerium; molybdate; phosphate; saltmelt.   For the first time, the possibilities of controlled in fluence on the valence states of ceriumin phosphate and molybdate melts have been systematically analyzed. A series of molybdates with a scheelite structure, MICe(MoO4)2 (MI – Li, Na, K, Cs), were obtained by crystallization from melt solutions, and the crystallization regions of Na3Ce(PO4)2 were established. The role of the acidity of molybdate, phosphate-molybdate, and fluoride-phosphate melts in the stability of cerium compounds in different oxidation states was determined for the first time. The role of acidity in molybdate, phosphate-molybdate, and fluoride-phosphate melts on the stability of cerium compounds in various oxidation states has been established. In more acidic melts corresponding to the salts MI2Mo3O10 and MI2Mo2O7 (MI = Li, Na, K, Cs) with low M/Moratios (0.5–0.8), stabilization of the lower oxidation state of cerium (III) is observed. To optimize the conditions for obtaining monocrystalline doublephosphate Na3Ce(PO4)2 under milder conditions and at lower temperatures, we selected two systems: Na2O–P2O5–NaF and Na2O–P2O5–MoO3. The salts NaF and Na2MoO4 were chosen because their presence in phosphate melts is one of the factors that depolymerize phosphate tetrahedra and lower the melting temperature of the corresponding batch due to the formation of low-melting eutectics. Thus, with a sodium fluoride content ranging from 30 to 60 mol.%, the exclusive formation of Na3Ce(PO4)2 is observed. Thus, during spontaneous crystallization from fluoridemelts, the Na/P ratio plays a decisive role, while the influence of the fluoride component becomes structurally formative at NaF concentrations between 30 and 60%. Conversely, with an increase in the content of alkali elements in the molten salts, the formation of a phase with a high eroxidation state of cerium in the form of CeO2 occurs. The established pattern can be used to obtain a broader range of inorganic compounds based on cerium (III). V.I.Vernadsky Institute of General and Inorganic Chemistry 2025-01-31 Article Article Inorganic Chemistry Неорганическая химия Неорганічна хімія application/pdf https://ucj.org.ua/index.php/journal/article/view/702 10.33609/2708-129X.90.12.2024.57-66 Ukrainian Chemistry Journal; Vol. 90 No. 12 (2024): Ukrainian Chemistry Journal; 57-66 Украинский химический журнал; Том 90 № 12 (2024): Ukrainian Chemistry Journal; 57-66 Український хімічний журнал; Том 90 № 12 (2024): Ukrainian Chemistry Journal; 57-66 2708-129X 2708-1281 en https://ucj.org.ua/index.php/journal/article/view/702/353
institution Ukrainian Chemistry Journal
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datestamp_date 2025-04-08T13:55:05Z
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topic_facet scheelite
cerium
molybdate
phosphate
saltmelt.
format Article
author Zozulia, Valeria
Slobodyanik, Mykola
Ushchapivska, Tetiana
Terebilenko, Kateryna
spellingShingle Zozulia, Valeria
Slobodyanik, Mykola
Ushchapivska, Tetiana
Terebilenko, Kateryna
COEXISTENCE OF CERIUM(III)/(IV) IN PHOSPHATE AND MOLYBDATE MELTS
author_facet Zozulia, Valeria
Slobodyanik, Mykola
Ushchapivska, Tetiana
Terebilenko, Kateryna
author_sort Zozulia, Valeria
title COEXISTENCE OF CERIUM(III)/(IV) IN PHOSPHATE AND MOLYBDATE MELTS
title_short COEXISTENCE OF CERIUM(III)/(IV) IN PHOSPHATE AND MOLYBDATE MELTS
title_full COEXISTENCE OF CERIUM(III)/(IV) IN PHOSPHATE AND MOLYBDATE MELTS
title_fullStr COEXISTENCE OF CERIUM(III)/(IV) IN PHOSPHATE AND MOLYBDATE MELTS
title_full_unstemmed COEXISTENCE OF CERIUM(III)/(IV) IN PHOSPHATE AND MOLYBDATE MELTS
title_sort coexistence of cerium(iii)/(iv) in phosphate and molybdate melts
description   For the first time, the possibilities of controlled in fluence on the valence states of ceriumin phosphate and molybdate melts have been systematically analyzed. A series of molybdates with a scheelite structure, MICe(MoO4)2 (MI – Li, Na, K, Cs), were obtained by crystallization from melt solutions, and the crystallization regions of Na3Ce(PO4)2 were established. The role of the acidity of molybdate, phosphate-molybdate, and fluoride-phosphate melts in the stability of cerium compounds in different oxidation states was determined for the first time. The role of acidity in molybdate, phosphate-molybdate, and fluoride-phosphate melts on the stability of cerium compounds in various oxidation states has been established. In more acidic melts corresponding to the salts MI2Mo3O10 and MI2Mo2O7 (MI = Li, Na, K, Cs) with low M/Moratios (0.5–0.8), stabilization of the lower oxidation state of cerium (III) is observed. To optimize the conditions for obtaining monocrystalline doublephosphate Na3Ce(PO4)2 under milder conditions and at lower temperatures, we selected two systems: Na2O–P2O5–NaF and Na2O–P2O5–MoO3. The salts NaF and Na2MoO4 were chosen because their presence in phosphate melts is one of the factors that depolymerize phosphate tetrahedra and lower the melting temperature of the corresponding batch due to the formation of low-melting eutectics. Thus, with a sodium fluoride content ranging from 30 to 60 mol.%, the exclusive formation of Na3Ce(PO4)2 is observed. Thus, during spontaneous crystallization from fluoridemelts, the Na/P ratio plays a decisive role, while the influence of the fluoride component becomes structurally formative at NaF concentrations between 30 and 60%. Conversely, with an increase in the content of alkali elements in the molten salts, the formation of a phase with a high eroxidation state of cerium in the form of CeO2 occurs. The established pattern can be used to obtain a broader range of inorganic compounds based on cerium (III).
publisher V.I.Vernadsky Institute of General and Inorganic Chemistry
publishDate 2025
url https://ucj.org.ua/index.php/journal/article/view/702
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