Dipotassium selenate tellurate

This work is a correction of our earlier structural study where the structure of K₂SeO₄Te(OH)₆ (KSeTe) was published in the non-centrosymmetric space group Cc [Dammak et al. (1999). J. Solid State Chem. 145, 612-618]. The present X-ray structure determination, using remeasured intensities, shows that KSeTe is monoclinic in space group C2/c. In this structure, the Te atom lies on a centre of symmetry and the Se atom on a twofold axis.

Cs₂(SO₄)_0.57(SeO₄)_0.43·Te(OH)₆, an adduct between dicaesium sulfate selenate and telluric acid

The title compound, dicaesium sulfate selenate-telluric acid adduct, Cs₂(SO₄)_0.57(SeO₄)_0.43·Te(OH)₆, is a solid solution in the series Cs₂(SO₄)·Te(OH)₆/Cs₂(SeO₄)·Te(OH)₆. It crystallizes in the same structure as the end member Cs₂(SeO₄)·Te(OH)₆ in space group P2₁/c, whereas the corresponding sulfate adopts another structure type and crystallizes in space group R3. The structure contains planes of statistically distributed SO₄/SeO₄ tetra­hedra alternating with planes of Te(OH)₆ octa­hedra, and with Cs⁺ cations situated between the planes. Both Te atoms lie on centres of symmetry.