{'fraction_non_alphanumeric': 0.03756476683937824, 'fraction_numerical': 0.034974093264248704, 'mean_word_length': 4.786516853932584, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Synthesis and Ab Initio Structure Determination from Powder Diffraction Data of K4Sn2Si6O18

Abstract. The crystal structure of a new potassium stannosilicateK 4 Sn 2 Si 6 O 18 (AV -11) has been determined ab initio from powder -Xray diffraction data. The unit cell is trigonal, space group R 3 (no. 146), Z=3 with cell dimensions a = 10.1587, c = 14.8039 A, γ= 120o, V = 1323 3A . The structure is made up of SnO 6 octahedra and SiO 4 tetrahedra by sharing corners. The SiO 4 tetrahedra form a helix chain, periodically repeating every six tetrahedra. These chains extend along the [001] direction and are linked by isolated Sn-O octahedron giving a mixed framework. Introduction The synthesis of inorganic microporous materials with mixed framework of interconnected octahedral- and tetrahedral-oxide is presently raising considerable interest [1]. Among these mixed framework materials, more than twenty stannosilicates are known and a few tannosilicate phasess have been crystallised from hydrothermal conditions ([2] and ref. therein). In the course of our work on the synthesis of stannosilicates, we found a patent by the Exxon Research and Engineering Company, 1992 [3] where the synthesis of six stannosilicates are reported, but with no structural information given. One of these materials, phase X, presents a -ray pattern similar to the material Xreported here. Thus, we wish to report the synthesis and the structural determination by powder XRD data of a new potassium stannosilicate, named AV-11 (Aveiro microporous solid no.11).