Studies in the System MgUO₃—MgUO₄

Abstract

Magnesium uranate was prepared by standard solid-state synthetic techniques. Decomposition pressures were measured between 1000° and 137OOC. At oxygen contents less than MgU03.5 a solid solution of fluorite structure was found.Above MgU03.7s the orthorhombic magnesium uranate phase was observed. The two phases were in equilibrium in air at 126OOC. The heat of solution of O2 in the fluorite phase was 45 kcal mole-1 and the heat of the reaction MgU03.6 + 0.1202 -+ MgU03.75 was 83.3 kcal mole-' ( 0 2 ) .

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

“…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.…”