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Thermogravimetric study of uranium phosphates

Part II: neutral uranyl phosphate and U(IV) phosphates

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Abstract

The thermal decomposition of (UO2)3(PO4)2 and U(HPO4)2 ·xH2O in the temperature range 25–1600‡, was investigated.

(UO2)3(PO4)2 decomposed first to 1/3[U3O8 + 3U2O3P2O7] and then to U3O5P2O7 before a loss of phosphorus was observed above 1350‡. Decomposition in air and in inert atmospheres was nearly identical.

Reduction with H2 or with carbon black in argon gave U3O5P2O7 and [UO2 + + (UO)2P2O7] before pure UO2 was formed.

U(HPO4)2 ·xH2O decomposed to UP2O7 in argon. It oxidized partly in air before the same product was obtained.

The high temperature stability of UP2O7 and U3(PO4)4 was also investigated.

Résumé

On a étudié la décomposition thermique de (UO2)3(PO4)2 et de U(HPO4)2 ·xH2O entre 25 et 1600‡.

(UO2)3(PO4)2 décompose d'abord en 1/3 (U3O8 + 3U2O3P2O7) puis en U3O5P2O7, avant que la perte en phosphore ne s'observe au-dessus de 1350‡. Le processus de la décomposition s'effectue à peu près de la mÊme faÇon dans l'air et en atmosphère inerte.

La réduction par H2 ou par le noir de carbone dans de l'argon donne U3O5P2O7 et [UO2 + + (UO)2P2O7] avant que UO2 ne se forme

Dans l'argon, U(HPO4)2 ·xH2O se décompose en UP2O7. Dans l'air, il subit une oxydation partielle avant la formation du mÊme produit.

On a également étudié la haute stabilité thermique de UP2O7 et de U3(PO4)4.

Zusammenfassung

Die thermische Zersetzung von (UO2)3(PO4)2 und U(HPO4)2 ·xH2O wurde im Temperaturbereich von 25 bis 1600‡00 untersucht.

(UO2)3(PO4)2 wurde zuerst zu 1/3 [U3O8 + 3U2O3P2O7] und darauf zu U3O5P2O7 zersetzt, ehe ein Phosphorverlust oberhalb von 1350‡ beobachtet wurde. Die Zersetzung verlief in Luft und inerter AtmosphÄre nahezu auf gleiche Weise.

Die Reduzierung mit H2 oder mit Kohlenstoff in Argon ergab U3O5P2O7 und [UO2 + + (UO)2P2O7] vor der Bildung von UO2. U(HPO4)2 ·xH2O wurde in Argon zu UP2O7 zersetzt. In Luft wurde es teilweise oxidiert, ehe dasselbe Produkt entstand. Die hohe TemperaturstabilitÄt von UP2O7 und U3(PO4)4 wurde ebenfalls geprüft.

РЕжУМЕ

ИсслЕДОВАН тЕРМОРАс пАД (UO2)3(PO4)2 И U(HPO4)2 ·хН2О В ОБлАстИ тЕМпЕР АтУРы 25–1600‡с. (UO2)3(PO4)2 РАспАДАЕтсь сНАЧАлА ДО 1/3[U3O8 + 3U2O3P2O7] И жАтЕМ ДО U3O5P2O7 ДО пОтЕРИ ФОсФОРА ВышЕ 1350‡с. РАспАД В ВОжД УхЕ И В ИНЕРтНОМ гАжЕ пРАкт ИЧЕскИ тОт жЕ сАМыИ.

пРИ ВОсстАНОВлЕНИИ с ВОДОРОДОМ ИлИ с УглЕР ОДОМ В АРгОНЕ ОБРАжОВАлИсь U3O5P2O7 И [UO2+(UO)2P2O2] ДО ОБРАжОВАНИь ЧИстОгО UO2. U(HPO4)2·хН2О РАспАДАЕтсь В UP2O7 В АРгОНЕ. ОНО ОкИсльЕт сь ЧАстИЧНО В ВОжДУхЕ ДО пОлУЧЕНИь тАкОгО жЕ п РОДУктА.

ИсслЕДОВАНА тАкжЕ Вы сОкАь. тЕРМОстАБИльН Ость UP2O7 И U3(РО4)4.

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Author notes

  1. J. M. Schaekers

    Present address: Department of Inorganic and Analytical Chemistry, University of Pretoria, Hillcrest, Pretoria, South Africa

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  1. Physical Metallurgy Division, Atomic Energy Board, Pretoria, South Africa

    J. M. Schaekers

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Additional information

Some of the results in this paper were taken from a thesis submitted in partial fulfilment of the requirements for an M. Sc. degree in Inorganic Chemistry.

I should like to thank Miss Cynthia Bennett for the assistance with the laboratory work, Mr. W. G. Greybe for the X-ray diffraction patterns and Mr. L. A. Goold for recording the many IR spectra.

I also wish to thank the Atomic Energy Board of South Africa for permission to publish this paper.

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Schaekers, J.M. Thermogravimetric study of uranium phosphates. Journal of Thermal Analysis 6, 543–554 (1974). https://doi.org/10.1007/BF01911559

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  • DOI: https://doi.org/10.1007/BF01911559

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