A study of Li₂TiOSiO₄ and Li₂TiOGeO₄ by X-ray powder and electron single-crystal diffraction, ¹⁷O MAS NMR and O K-edge and Ti L _2,3-edge EELS

Abstract

X-ray powder and electron single-crystal diffraction of crystals of Li 2 TiOSiO 4 and Li 2 TiOGeO 4 showed them to be tetragonal, space group P4/nmm unit-cell parameters a 6X4379 2, c 4X40032 2 A Ê for Li 2 TiOSiO 4 and a 6X6110 8, c 4X4372 6 A Ê for Li 2 TiGeO 4 . The compounds are isostructural with their sodium analogues but are considerably compressed along the c axis owing to the smaller size of lithium compared with sodium atoms. Square-pyramidal TiO 5 groups are joined in these compounds by tetrahedral SiO 4 and GeO 4 groups, respectively. 17 O nuclear magnetic resonance spectra of the two compounds, isotopically enriched with 17 O, showed peaks due to the apical titanyl, TiÐO, and basal, bridging, TiÐOÐSi or TiÐOÐGe, oxygen atoms of the title compounds. By comparison with reference spectra, oxygen K edges and titanium L 2,3 edges of electron energy-loss spectra were tentatively assigned.

Solid State NMR Interaction Parameters of Oxygens Linking Titanium and Silicon in Crystalline Cyclic Titanodiphenylsiloxanes

“…To date the only 17 O information reported from Ti-O-Si linkages in well-defined crystalline compounds has been from fresnoite [20] and Li 2 TiOSiO 4 [28]. In fresnoite a resonance at 190 ppm was observed from the Ti-O-Si unit but no other parameters could be deduced.…”

Solution based synthesis of mixed-phase materials in the Li2TiO3–Li4SiO4 system

“…The 1:1:1 ternary compound LTS (Li 2 TiSiO 5 ), was observed significantly in materials of compositions containing both Si and Ti fabricated using lithium chloride (compositions 2-10). This tetragonal ternary phase was first reported by Kim and Hummel in 1959 and has since been the subject of a small number of further studies [32,[53][54][55]. The presence of this phase is apparent in the presence of diffraction peaks at 20.2°, 24.5°, 27.7° and 34.5° 2θ corresponding to (001), (101), (200) and (201) planes [53].…”

“…This tetragonal ternary phase was first reported by Kim and Hummel in 1959 and has since been the subject of a small number of further studies [32,[53][54][55]. The presence of this phase is apparent in the presence of diffraction peaks at 20.2°, 24.5°, 27.7° and 34.5° 2θ corresponding to (001), (101), (200) and (201) planes [53]. At high Ti content, the existence of the LTS phase alongside some titanate spinel may indicate the existence of an as yet unreported compatibility tie-line between these two phases.…”

Synthesis and characterization of Li2TiSiO5 obtained by melting and solid-state reaction

“…Some attempts to synthesize this compound are found in the literature, such as by co-hydrolysis [6], polymeric precursors method [5,7] and mixed oxides [8,9]. However, in this work two different routes were applied to synthesize the Li 2 TiSiO 5 compound from a stoichiometric mixture of Li 2 CO 3 , SiO 2 …”