X-ray study of the binary oxides of niobium and tantalum

Reactivity of T-Nb2O5 or H-Nb2O5 towards V2O5. Synthesis in the solid state and properties of V4Nb18O55

“…Crystallizing in a tetragonal system, VNb 9 O 25 melts congruently at 1290ºC [4,6,10]. Most probably it has homogeneity range reaching composition V 3 Nb 17 O 50 [12]. VNbO 5 crystallizes in an orthorhombic system and decomposes at 758ºC into VNb 9 O 25 and V 2 O 5 [3,5,[7][8][9].…”

Two new lithium uranyl tungstates Li2(UO2)(WO4)2 and Li2(UO2)4(WO4)4O with framework based on the uranophane sheet anion topology

“…For example, anhydrous uranyl oxides of the family UO 2 XO 4 with X ¼ S; Cr, Se, Mo and W are well known [18][19][20][21] and adopt the same crystal structure which results from the association of (UO 2 )O 5 pentagonal bipyramids sharing four equatorial oxygen atoms with different XO 4 tetrahedra, the last equatorial oxygen atom being shared with an apical oxygen atom of a neighboring (UO 2 )O 5 bipyramid. During the study of the UO 2 -WO 3 system, four phases U(WO 4 ) 2 , UW 3 O 11 , UW 4 O 14 and UW 5 O 17 have been identified by X-ray powder diffraction and high resolution electron microscopy [22].…”

Properties of thermally contracting tantalum tungstates. [Ta/sub 22/W/sub 4/O/sub 67/, Ta/sub 2/WO/sub 8/, Ta/sub 16/W/sub 18/O/sub 94/]

“…X-ray diffraction patterns and crystallographic data for these three compounds have been reported. (2)(3)(4)(5)(6)(7)(8) The purpose of this study, performed at the Oak Ridge Y-12 Plant(a), was to investigate the properties of Ta22W4057, Ta2WOg, and Ta15W1s094 in order to better understand the mechanism of their thermal-contraction behavior as related to structure.…”