Structure of Zeolitic K2TiSi3O9•H2O Determined ab initio from Powder Diffraction Data
نویسنده
چکیده
— The crystal structure of K2TiSi3O9•H2O has been solved ab initio from X-ray powder data. The unit cell is orthorhombic (space group P212121, Z = 4) with cell dimensions a = 7.1362(2) Å, b = 9.9084(3) Å, c = 12.9414(4) Å, V = 915.07 Å. The structural model was obtained from direct methods using 455 integrated intensities. The Rietveld refinement converged to final Bragg and profile indicators RB = 4.3 %, RP = 11.6 %. The structure is isostructural with that of mineral umbite K2ZrSi3O9•H2O and consists of SiO4 tetrahedra sharing corners, forming infinite [SiO3]n 2nchains extending along the a axis, connected by isolated TiO6 octahedra giving thus a mixed framework. Distorted octogonal channels running along the a axis are filled with exchangeable K cations and water molecules which can be reversibly disassociated.
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