Crystal Chemistry of the Microporous Zirconosilicate Na6Zr3[Si9O27], a Product of High-Temperature Transformation of Catapleiite, and Its Ag-Exchanged Form

Minerals

Anna A. Artamonova¹  Dmitry Yu. Pushcharovsky¹  Natalia V. Zubkova¹  Igor V. Pekov¹  Dmitry A. Ksenofontov¹  Natalia N. Koshlyakova¹  Andrey Yu. Bychkov¹  Nikita V. Chukanov² 

[1] Faculty of Geology, Moscow State University, Vorobievy Gory, 119991 Moscow, Russia;Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, 142432 Moscow, Russia;

关键词: catapleiite;    high-temperature transformation;    microporous zirconosilicate;    nine-membered si tetrahedral ring;    cyclosilicate;    ion exchange;    silver;    zeolitic properties;    crystal structure;   

DOI  :  10.3390/min10030243

来源: DOAJ

【 摘 要 】

The crystal structure of the Ag-exchanged form of the zirconosilicate with the simplified formula (Na_6-2xCa_xx)Zr₃[Si₉O₂₇] with x < 1 (the idealized formula Na₆Zr₃[Si₉O₂₇]), a product of thermal transformation of catapleiite, ideally Na₂Zr[Si₃O₉]·2H₂O, was studied using single crystal X-ray diffraction data. The crystal structure of Na₆Zr₃[Si₉O₂₇] is based on a heteropolyhedral framework built by nine-membered tetrahedral rings [Si₉O₂₇] and isolated [ZrO₆] octahedra. This zirconosilicate demonstrates high exchange capacity to Ag (experiment with 1 M AgNO₃ aqueous solution, 250 °C, 30 days). Its Ag-exchanged form with the simplified formula (Ag₅Ca_0.5)Zr₃[Si₉O₂₇] is characterized by a significant distortion of the heteropolyhedral framework and strongly disordered arrangement of extra-framework cations (Ag) which results in the doubling of a parameter of the hexagonal unit cell [a = 23.3462(3), c = 10.10640(10) Å, V = 4770.45(13) ų] and space group P6₃cm. Ag⁺ cations preferably occupy the sites that are close to the Na sites in Na₆Zr₃[Si₉O₂₇].

【 授权许可】

Unknown