A NOVEL POTASSIUM-RICH VARIANT OF TINSLEYITE, vertical bar K-1.5(H2O)(0.5)vertical bar [Al-2(OH){(OH)(0.5)(H2O)(0.5)}(PO4)(2)]

作者：Yakubovich Olga V^*; Massa Werner; Dimitrova Olga V

来源：The Canadian Mineralogist, 2012, 50(2): 559-569.

DOI：10.3749/canmin.50.2.559

• tinsleyite
• hydrothermal synthesis
• X-ray diffraction
• crystal structure
• hydrogen bonds
• leucophosphite group
• microporous compounds
• AlPO4-15
• structural relations

Crystals of a potassium-rich variant of the mineral tinsleyite were obtained by hydrothermal synthesis in the system K2O-Al2O3-P2O5-H2O. The new phase is monoclinic, space group P2(1)/n, a 9.4352(7), b 9.5254(10), c 9.4309(7) angstrom, beta 101.421(7)degrees, Z = 4. Its crystal structure was solved from single-crystal data collected at 193 K and refined to R = 0.0293, including positions of all hydrogen atoms. The crystal structure is built of units of four AlO6 octahedra sharing edges and vertices. The octahedron units are cross-linked by PO4 tetrahedra to form a three-dimensional framework with channels along the main crystallographic [010], [001] and [100] directions, where the large K+ ions and H2O molecules are distributed. The system of O - H center dot center dot center dot O asymmetric hydrogen bonds between H2O molecules, hydroxyl groups and framework oxygen atoms provides additional cross-linking in the structure. We show that a change in the alkalinity of the mineral-forming system correlates with the composition of the crystallizing phase and simultaneously influences the character of hydrogen bonding. The new K-rich variety of the tinsleyite is suggested as a possible mineral species. We evaluate the crystal chemistry of the leucophosphite group of minerals and the related synthetic compounds.

• 出版日期2012-4