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Na5InSi4O12 has been synthesized by a high-temperature, high-pressure hydrothermal method and characterized by single-crystal X-ray diffraction and solid-state NMR spectroscopy. It is isotypic to Na5ScSi4O12. The structure consists of 12-membered single rings of corner-sharing SiO4 tetrahedra linked together via corner sharing by single InO6 octahedra to form a 3-D framework that delimits two types of channels along the c-axis. There are six independent sodium sites. The Na atoms within the 12-ring channels are immobile and the Na atoms within 7-ring channels are highly mobile. The 29Si MAS NMR exhibits one Q3 and one Q4 resonance, each of which is split into two peaks because of inequivalent chemical environments caused by partially occupied Na sites in the 7-ring channels. Na ion conductivity measurements on a pressed pellet of the title compound were performed. The Arrhenius plot of dc conductivity shows a change in slope near 220 °C. We attribute this to the activation of the Na site that is situated ...

A new vanadium(IV) silicate, Rb(2)(VO)(Si(4)O(10)).xH(2)O (x approximately 0.1), has been synthesized by a high-temperature, high-pressure hydrothermal method. It crystallizes in the tetragonal space group I4(1)md (No. 109) with a = 12.2225(7) A, c = 7.7948(6) A, and Z = 4. The structure consists of spiral chains of corner-sharing SiO(4) tetrahedra linked to neighboring chains via corner sharing to form a 3-D silicate framework which delimits channels to accommodate the VO(2+) groups. The Rb(+) ions are located in the cavities within the silicate framework. Magnetic susceptibility confirms the valence of vanadium. A partially occupied lattice water site is confirmed by IR and solid state (1)H NMR spectroscopy. The structure of the title compound is considerably different from those of the synthetic silicate K(2)(VO)(Si(4)O(10)).H(2)O and the two polymorphs of the natural mineral Ca(VO)(Si(4)O(10)).4H(2)O, although they have identical framework stoichiometry.

A new vanadium(IV) silicate, Rb2(VO)(Si4O10)·xH2O (x ≈ 0.1), has been synthesized by a high-temperature, high-pressure hydrothermal method. It crystallizes in the tetragonal space group I41md (No. 109) with a = 12.2225(7) A, c = 7.7948(6) A, and Z = 4. The structure consists of spiral chains of corner-sharing SiO4 tetrahedra linked to neighboring chains via corner sharing to form a 3-D silicate framework which delimits channels to accommodate the VO2+ groups. The Rb+ ions are located in the cavities within the silicate framework. Magnetic susceptibility confirms the valence of vanadium. A partially occupied lattice water site is confirmed by IR and solid state 1H NMR spectroscopy. The structure of the title compound is considerably different from those of the synthetic silicate K2(VO)(Si4O10)·H2O and the two polymorphs of the natural mineral Ca(VO)(Si4O10)·4H2O, although they have identical framework stoichiometry.

Na5InSi4O12 has been synthesized by a high-temperature, high-pressure hydrothermal method and characterized by single-crystal X-ray diffraction and solid-state NMR spectroscopy. It is isotypic to Na5ScSi4O12. The structure consists of 12-membered single rings of corner-sharing SiO4 tetrahedra linked together via corner sharing by single InO6 octahedra to form a 3-D framework that delimits two types of channels along the c-axis. There are six independent sodium sites. The Na atoms within the 12-ring channels are immobile and the Na atoms within 7-ring channels are highly mobile. The 29Si MAS NMR exhibits one Q3 and one Q4 resonance, each of which is split into two peaks because of inequivalent chemical environments caused by partially occupied Na sites in the 7-ring channels. Na ion conductivity measurements on a pressed pellet of the title compound were performed. The Arrhenius plot of dc conductivity shows a change in slope near 220 °C. We attribute this to the activation of the Na site that is situated ...