“…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].…”