Synthesis and crystal structure of a triple chain silicate, Na2Mg4Si6O16(OH)2

✍ Scribed by Hiroshi Tateyama; Susumu Shimoda; Toshio Sudo

• Publisher: Springer
• Year: 1978
• Tongue: English
• Weight: 772 KB
• Volume: 66
• Category: Article
• ISSN: 0010-7999
• DOI: 10.1007/bf00372153

✦ Synopsis

In the system Na2CO3-MgO-SiO2-H20 a new sodium magnesium silicate was synthesized under hydrothermal conditions; 450 600 ~ C and 300-1000 Kg/cm 2. The structure of the specimen was determined by X-ray powder methods, and its properties were studied by chemical, infrared and TG analyses. The specimen has a triple chain structure (space group, C2/c) with the ideal chemical composition, 4 (NazMg4Si6016(OH)2) and lattice parameters, a= 10.152(2), b=27.137(4), c=5.276(1) A, and fi= 106.97(3) ~ .

The essential feature of the structure is shown by the presence of SiO~ tetrahedra linked to form chains which have three times the width of those in pyroxene. These triple chains have a periodicity, 5.27 A., along their lengths, and are bonded to each other laterally by the brucite layer made up by eight Mg cations and sandwiched between two inward pointing bands of tetrahedra. These units are linked back to back by cations (Mg or Na) in the Na(2) site and by a large cation (Na) at the Na(1) site.