Crystal structure of K2U7O22

Thermal and X-ray studies on mixed alkali uranates of Na–K–U–O system

“…In the Na-K-U-O system, solubility of K in Na 2 U 2 O 7 forming (Na, K) 2 U 2 O 7 is reported up to 2.6 mol% of K [7]. M 2 U 2 O 7 (M = Na, K and Rb) are reported to have rhombohedral, orthorhombic and monoclinic structure [8,9]. In the present studies, the mixed diuranates were prepared by heating the respective mixtures of Na 2 U 2 O 7 and K 2 U 2 O 7 for a period of 100 h at 1273 K. The XRD data of the heated products showed additional weak lines and which were indexable on a lower symmetry monoclinic cell and the lattice parameters are given in Table 1.…”

“…% thermal expansion = δa/a 298 × 100 (8) and α T = (δ a /δ T ) × 1/a 298 (9) where δ a is change in lattice parameter corresponding to a change in temperature δ T and a 298 is the lattice parameter at 298 K. Fig. 6 shows the plot of % thermal expansion against temperature plot for (K x Na 1−x )UO 3 for x = 1, 0.8 and 0.5.…”

Synthesis, crystal structure, infrared and electrical conductivity of the layered rubidium uranate Rb4U5O17

“…Rb 2 UO 4 , Rb 2 U 4 O 13 , Rb 2 U 7 O 22 [10,11], and the recently reported Rb 2 U 2 O 7 and Rb 8 U 9 O 13 [12]. Different studies of alkaline uranates family confirmed the high-temperature stability of these compounds, generally beyond 1300 • C, and their highmelting points or decomposition temperatures, explaining the difficulty to obtain single crystals of these phases [7][8][9]11,[13][14][15][16][17].…”

Phase study in the Na–Sr–U–O system: Characterization of new phase

“…2. was drawn on the basis of the phase analysis of the fifteen samples listed in Table 1 and using the XRD data of above mentioned compounds in the Na 2 O-UO 3 and SrO-UO 3 systems and a new quaternary compound Na 8 Sr 2 U 6 O 24 [19][20][21][22][23].…”