A pseudo-merohedrally twinned rare-earth sulfate: K₆[Ce(HSO₄)₂(SO₄)₄]·H₂O, a novel structure type

This acidic ternary rare-earth sulfate is unique as it contains rare-earth monomers, [Ce(HSO₄)(SO₄)₄]^5-, and the structure is composed of these monomers, water mol­ecules, discrete hydrogensulfate ions and potassium ions held together by ionic inter­actions. There are two alternating layers in the structure, with the compositions [K₄Ce(HSO₄)(SO₄)₄]^- and [K₂(HSO₄)(H₂O)]⁺.