| Abstract: | Thermal deformations of Na6(UO2)2O(MoO4)4 were studied by high-temperature powder X-ray diffraction. The compound crystallizes in the triclinic system, space group Р(bar 1), a = 7.636(7), b = 8.163(6), c = 8.746(4) Å, α = 72.32(9)°, β = 79.36(4)°, γ = 65.79(5)°, V = 472.74(4) Å3. It is stable in the temperature interval 20–700°С. The thermal expansion coefficients (TECs) are α11 = 25.5 × 10–6, α22 = 7.8 × 10–6, and α33 = 1.1 × 10–6 (°C)–1. The orientation of the TEC pattern relative to the crystallographic axes is a33^Z = 45°, a33^X = 122°, a22^Z = 59°, and a22^X = 66°. The anisotropy of the thermal expansion is due to specific features of the crystal structure of the compound. |
