The new cadmium and manganese-based phosphate CdMn₄(HPO₄)₂(PO₄)₂.4H₂O, was synthesized by a hydrothermal method and its structure investigated by single crystal X-ray diffraction. The accuracy of the resulting structural model was verified using the Bond-Valence-Sum (BVS) and Charge-Distribution (CD) methods. This phase is a new member of the Hureaulite family and crystallizes within the monoclinic system (space group C2/c, a = 17.6932(5) Å, b = 9.1862(3) Å, c = 9.5417(3) Å, β = 96.562(1)°, and Z = 4). In this crystal structure the metal cations are statically distributed over three independent sites. The first two are located at the general position 8f and are entirely filled by Cd(1)²⁺/Mn(1)²⁺ and Cd(3)²⁺/Mn(3)²⁺ while the remaining site is situated at the special position 4e(2) and fully occupied by Cd(2)²⁺/Mn(2). The main structural groups of the asymmetric unit consist of three distorted [(Cd(1)/Mn(1))O₅(OH₂)], [(Cd(2)/Mn(2))O₆], and [(Cd(3)/Mn(3))O₄(OH₂)₂] octahedra with two regular PO₄ and HPO₄ tetrahedra. The 3D-structure is made up of five sequential octahedral (Cd/Mn)₅ O₁₆(OH₂)₆ units of edge-sharing running along the [001] direction. The connecting PO₄ and HPO₄ groups bind the interconnected units to one another by corners-sharing to create a 3D-framework defining a sizable void along the [001] direction hosting some H₂O molecules.

PDF (Download Full text)

| Download Citation (XML)