The system Cr2O3UO2O2

Felten, E.J.; Juenke, E.F.; Bartram, S. F.

doi:10.1016/0022-1902(62)80104-3

Cited by 14 publications

(7 citation statements)

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“…The form of the rule proposed by Jones (16) is While the modified uranyl stretching vibration is readily discernible in CuU04, it is less apparent in the cobalt type 1:1 compounds, and seems to be missing entirely in CrU04, FeU04, and «-NiU04. The spectrum of CrU04 appears to support the suggestion of Felten et al (8) that pentavalent uranium is present in CrU04. Their alternative sug gestion-the presence of equal amounts of U(IV) and U(VI)-is not compatible with the infrared data unless one assumes the existence of U(VI) without uranyl type bonding in this compound.…”

Section: Resultssupporting

confidence: 77%

Some Uranium-Transition Element Double Oxides

Hoekstra

Marshall

1967

Lanthanide/Actinide Chemistry

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The preparation and properties of some double oxides of uranium with the seven transition elements from chromium through zinc are described. Thirteen compounds with the composition MUO 4 or MU 3 O 10 were prepared by heating mixed oxides in air or in sealed silica tubes, by hydrothermal methods, and by high pressure techniques. Four of these compounds, (FeUO 4 , FeU 3 O 10 , NiUO 4 (20) and ZnUO 4 ) have not been previously reported. NiUO 4 has been pre pared in two crystal forms. The thermal stability, crystal structure, and infrared spectrum (from 1000-200 cm. -1 ) of each of the 13 compounds has been investigated. The struc ture of FeUO 4 and α-NiUO 4 is similar to CrUO 4 , while β-NiUΟ 4 and ZnUO 4 crystallize in the MgUO 4 structure. FeU 3 O 10 has the pseudo-hexagonal lattice characteristic of the transition element triuranates. TVecent investigations have shown that chromium, manganese, cobalt, nickel, copper, and zinc oxides react with uranium oxides at elevated temperatures to form double oxides with the formulas MU04 and MU3O10. Table I lists eight compounds for which some structural and thermal stability information has been reported.The double oxides are sometimes referred to as mono-and triuranates of the transition metals, even though the existence of U(VI) in some of the compounds is questionable. This is particularly true for CrU04 since divalent chromium is readily oxidized. When the double oxides are referred to as uranates in this paper, it should be borne in mind that 211 Downloaded by UCSF LIB CKM RSCS MGMT on December 3, 2014 |

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Section: Resultssupporting

confidence: 77%

Some Uranium-Transition Element Double Oxides

Hoekstra

Marshall

1967

Lanthanide/Actinide Chemistry

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“…Thus these U(V) containing monouranates, with their simple stoichiometries, allow in-depth structural and stability investigations. In spite of the increasing attention to these compounds, only some of their structural characteristics have been studied, 2,[8][9][10][11][12][13][14][15][16][17][18][19][20][21] and among those studies, few have used spectroscopic methods to probe local structures. 11,12,17,19,20 The oxidation state of U in MgUO 4 is generally regarded to be hexavalent, 11,21 yet those of U in CrUO 4 and FeUO 4 are less certain.…”

Section: Introductionmentioning

confidence: 99%

“…11,12,17,19,20 The oxidation state of U in MgUO 4 is generally regarded to be hexavalent, 11,21 yet those of U in CrUO 4 and FeUO 4 are less certain. 8,9 Moreover, there is limited thermodynamic data available for these simple monouranates, 2,10,[13][14][15][16]18 MgUO 4 was first synthesized by Haag et al 22 using solid state methods. It has an orthorhombic structure with the space group Imam; the lattice parameters are a = 6.52 Å, b = 6.59 Å, and c = 6.92 Å.…”

Section: Introductionmentioning

confidence: 99%

“…11 CrUO 4 belongs to the BiVO 4 structure type. It was discovered in 1959 by Borchardt 25 from reaction of Cr 2 O 3 and U 3 O 8 , and the pure phase was later synthesized by Felten et al 8 Like other BiVO 4 type uranates, CrUO 4 crystallizes in the orthorhombic structure with a symmetry of Pbcn 26,27 and has lattice parameters a = 4.86 Å, b = 11.78 Å, and c = 5.04 Å. 8,25 It is argued that the exclusive presence of U 6+ in this compound is unlikely due to the easy oxidation of Cr 2+ to Cr 3+ .…”

Section: Introductionmentioning

confidence: 99%

“…Presence of U 5+ or equal quantities of U 4+ and U 6+ may be more probable. 8 Structural analyses using techniques sensitive to local structure such as X-ray absorption near edge structure (XANES) and XPS can help potentially resolve this issue. FeUO 4 , first studied in 1967 by Bacmann et al 28 also possesses the BiVO 4 structure with lattice parameters a = 4.88 Å, b = 11.93 Å and c = 5.11 Å.…”

Section: Introductionmentioning

confidence: 99%

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U(v) in metal uranates: a combined experimental and theoretical study of MgUO₄, CrUO₄, and FeUO₄

Guo

Tiferet

et al. 2016

Dalton Trans.

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Although pentavalent uranium can exist in aqueous solution, its presence in the solid state is uncommon. Metal monouranates, MgUO4, CrUO4 and FeUO4 were synthesized for detailed structural and energetic investigations. Structural characteristics of these uranates used powder X-ray diffraction, synchrotron X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, and (57)Fe-Mössbauer spectroscopy. Enthalpies of formation were measured by high temperature oxide melt solution calorimetry. Density functional theory (DFT) calculations provided both structural and energetic information. The measured structural and thermodynamic properties show good consistency with those predicted from DFT. The presence of U(5+) has been solidly confirmed in CrUO4 and FeUO4, which are thermodynamically stable compounds, and the origin and stability of U(5+) in the system was elaborated by DFT. The structural and thermodynamic behaviour of U(5+) elucidated in this work is relevant to fundamental actinide redox chemistry and to applications in the nuclear industry and radioactive waste disposal.

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Ternäre Oxide. VIII. Ternäre Uran(V)‐oxide mit 3‐wertigen Kationen

Rüdorff

Erfurth

Kemmler‐Sack

1967

Zeitschrift anorg allge chemie

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Im System La2O3  U2O5 treten in Bereich zwischen 16–60 Mol‐% LaO1,5 folgende Phasen auf: U3O8 neben einer (La, U(V), U(IV)‐Fluoritphase (16 – 33 Mol‐%, LaO1,5) eine (La, U(V))‐Fluoritphase (33 – 47 Mol‐% LaO1,5), eine Fluoritphase und eine rhomboedrische Phase (50 – 60 Mol‐% LaO1,5). Es werden die folgenden im Fluorigitter kristallisierenden U(V)‐Verbindungen dargestellt: ScUO4, YUO4, NdUO4, SmUO4, EuUO4, GdUO4 und YbUO4. BiUO4 (a = 5,481 Å) besitzt eine nur sehr geringe Phasenbreite. Auf der uranreichen Seite des Systems Bi2O3  U2O5 existiert eine (Bi, U(V), U(IV))‐Fluoritphase neben U3O8. Bei einem Bi: U‐Verhältnis > 1 entstehen neben einer Fluoritphase Wismutmetall und Wismuturan(VI)‐oxid. Durch UO2 wird BiUO4 reduziert, mit UO2,25 bildet es eine (Bi, U(V), U(IV))‐Fluoritphase. FeUO4 kristallisiert wie CrUO4 rhombisch. Es werden die Reflexionsspektren der beiden Verbindungen mitgeteilt.

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The system Cr2O3UO2O2

Cited by 14 publications

References 4 publications

Some Uranium-Transition Element Double Oxides

Some Uranium-Transition Element Double Oxides

U(v) in metal uranates: a combined experimental and theoretical study of MgUO₄, CrUO₄, and FeUO₄

Ternäre Oxide. VIII. Ternäre Uran(V)‐oxide mit 3‐wertigen Kationen

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The system Cr2O3UO2O2

Cited by 14 publications

References 4 publications

Some Uranium-Transition Element Double Oxides

Some Uranium-Transition Element Double Oxides

U(v) in metal uranates: a combined experimental and theoretical study of MgUO4, CrUO4, and FeUO4

Ternäre Oxide. VIII. Ternäre Uran(V)‐oxide mit 3‐wertigen Kationen

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U(v) in metal uranates: a combined experimental and theoretical study of MgUO₄, CrUO₄, and FeUO₄