Zur Kenntnis zweier Formen des Zinkorthoarsenates: α-Zn₃(AsO₄)₂ und β-Zn₃(AsO₄)₂/On Two Forms of Zinc Orthoarsenate: α -Zn₃(AsO₄)₂ and β-Zn₃(AsO₄)₂

Abstract

Abstract Single crystals of two forms of zinc orthoarsenate (α-Zn 3 (AsO 4 ) 2 (I) and β-Zn 3 (AsO 4 ) 2 (II)) have been prepared by flux techniques. Both compounds crystallize monoclinically, space groups (I): C 2h 5 -P2 1 /c, (II): C 2h 5 -P2 1 /n, with the lattice parameters (I): a = 6.306(2), b = 8.652(2), c =1.321(4) Å, β = 92.25(5) °, Z = 4 and (II): a = 5.281(1), b = 8.494(2), c = 7.726(3) Å, β = 96.39(3)°, Z = 2. α-Zn 3 (AsO 4 ) 2 is isotypic to I-Cu 3 (AsO 4 ) 2 and β-Zn 3 (AsO 4 ) 2 to γ-Zn 3 (PO 4 ) 2 . Similarities and differences of the crystal structures are discussed.