High-temperature, high-pressure hydrothermal synthesis, characterization, and structural relationships of layered uranyl arsenates.

Five new uranyl arsenates, Na14[(UO2)5(AsO4)8]·2H2O (1), K6[(UO2)5O5(AsO4)2] (2a), K4[(UO2)3O2(AsO4)2] (2b), Rb4[(UO2)3O2(AsO4)2] (3), and Cs6[(UO2)5O2(AsO4)4] (4), were synthesized by high-temperature, high-pressure hydrothermal reactions at about 560 °C and 1440 bar and were characterized by single-crystal X-ray diffraction, thermogravimetric analysis, and photoluminescence spectroscopy. Crystal data for compound 1: triclinic, P1, a = 7.0005(3) A, b = 12.1324(4) A, c = 13.7428(5) A, α = 64.175(2)°, β = 89.092(2)°, γ = 85.548(2)°, V = 1047.26(7) A3, Z = 1, R1 = 0.0185; compound 2a: monoclinic, P21/c, a = 6.8615(3) A, b = 24.702(1) A, c = 7.1269(3) A, β = 98.749(2)°, V = 1193.89(9) A3, Z = 2, R1 = 0.0225; compound 2b: monoclinic, P21/c, a = 6.7852(3) A, b = 17.3640(8) A, c = 7.1151(3) A, β = 98.801(3)°, V = 828.42(6) A3, Z = 2, R1 = 0.0269; compound 3: monoclinic, P21/m, a = 6.9783(3) A, b = 17.4513(8) A, c = 7.0867(3) A, β = 90.808(3)°, V = 862.94(7) A3, Z = 2, R1 = 0.0269; compound 4: triclinic, P1, a...