A Potassium Tantalum(V) Tetrasilicate KTaSi2O7

Lee, Jong Gyu; Höhn, Peter; Greenblatt, Martha

doi:10.1006/jssc.1996.0160

Cited by 7 publications

(4 citation statements)

References 5 publications

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“…Indeed, the SHG response of batisite is comparable to that of K (NbO) Si O ( Table 1), revealing that trans-connected chains of TiO octahedra oriented appropriately in a NCS structure constitute a crucial structural feature for the realization of second-order NLO material. Signi"cantly, the isotypic tantalum(V) analog of K (NbO) Si O adopts a centrosymmetric structure (space group P4/mbm) where the distortion of TaO octahedra is much less (21). As a rule, out-of-center distortion of MO octahedra decreases as we move from 3d to 4d to 5d cations in a group (8).…”

Section: Resultsmentioning

confidence: 97%

In Search of Inorganic Nonlinear Optical Materials for Second Harmonic Generation

Gopalakrishnan

Ramesha

Rangan

et al. 1999

Journal of Solid State Chemistry

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Section: Resultsmentioning

confidence: 97%

In Search of Inorganic Nonlinear Optical Materials for Second Harmonic Generation

Gopalakrishnan

Ramesha

Rangan

et al. 1999

Journal of Solid State Chemistry

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“…Mainly precipitation of perovskite ferroelectrics from multicomponent silicate glasses have been studied. 1-5 Ferroelectric grain-oriented glass-ceramics with distinct pyroelectric properties have also been obtained in PbOGeO 2 6,7 and La 2 O 3 -B 2 O 3 -GeO 2 8,9 systems based on Pb 5 Ge 3 O 11 and LaBGeO 5 ferroelectrics, respectively. For the system La 2 O 3 -B 2 O 3 -GeO 2 the range of stable glass formation is near the composition of the corresponding ferroelectric crystal.…”

Section: Introductionmentioning

confidence: 95%

“…They remain in a ferroelectric state up to congruent melting at 1180°C 10 and show valuable ionic conductivity along the c axis above 300°C as well as its structural analogue KTaSi 2 O 7 . 11 The acentric character of the structure of KNbSi 2 O 7 is mainly due to a sequence of short niobyl (0.176 nm) and long Nb-O (0.231 nm) bonds along the 4-fold axes. It is important to emphasize that the KNbSi 2 O 7 composition lies in the glassforming range of the ternary system K 2 O-Nb 2 O 5 -SiO 2 , and according to data from Ref.…”

Section: Introductionmentioning

confidence: 99%

Crystallization Behavior of Potassium Niobium Silicate Glasses

Pernice

Aronne

Сигаев

et al. 1999

Journal of the American Ceramic Society

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Crystallization behavior of potassium niobium silicate (KNS) glasses having compositions expressed by the general formula xK 2 OؒxNb 2 O 5 ؒ(1 − 2x)SiO 2 , with x = 0.167, 0.182, 0.200, 0.220, and 0.250, has been studied by DTA, X-ray diffraction, second harmonic optical generation (SHG), and electron microscopy. Bulk crystallization of potassium niobates in glasses with compositions near K 2 OؒNb 2 O 5 ؒ2SiO 2 , as well as surface crystallization of KNbSi 2 O 7 phase, has been established. Transparent glassceramics, based on potassium niobates with remarkable SHG signal values, can be obtained from glasses with the lowest silica content, by heat treatment at temperatures just above T g , while at higher temperatures from all of the glasses under investigation the main crystallizing phase is KNbSi 2 O 7 ferroelectric. Applying a dc electric field, grainoriented crystallization is produced in KNS glasses with development of significantly anisotropic arrangements of KNbSi 2 O 7 crystallites.

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“…The study of ferroelectric-dielectric properties has shown that K 2 Nb 2 (Si 4 O 12 )O 2 is a ferroelectric material with low dielectric permittivity range {4,14]. The isostructural compound K 2 Ta 2 (Si 4 O 12 )O 2 , which may has nonlinear properties, was also synthesized [16].…”

Section: Introductionmentioning

confidence: 99%

Rippite, K2(Nb,Ti)2(Si4O12)O(O,F), a New K-Nb-Cyclosilicate from Chuktukon Carbonatite Massif, Chadobets Upland, Krasnoyarsk Territory, Russia

et al. 2020

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Rippite K2(Nb,Ti)2(Si4O12)(O,F)2, a new K-Nb-cyclosilicate, has been discovered in calciocarbonatites from the Chuktukon massif (Chadobets upland, SW Siberian Platform, Krasnoyarsk Territory, Russia). It was found in a primary mineral assemblage, which also includes calcite, fluorcalciopyrochlore, tainiolite, fluorapatite, fluorite, Nb-rich rutile, olekminskite, K-feldspar, Fe-Mn–dolomite and quartz. Goethite, francolite (Sr-rich carbonate–fluorapatite) and psilomelane (romanèchite ± hollandite) aggregates as well as barite, monazite-(Ce), parisite-(Ce), synchysite-(Ce) and Sr-Ba-Pb-rich keno-/hydropyrochlore are related to a stage of metasomatic (hydrothermal) alteration of carbonatites. The calcite–dolomite coexistence assumes crystallization temperature near 837 °C for the primary carbonatite paragenesis. Rippite is tetragonal: P4bm, a = 8.73885(16), c = 8.1277(2) Å, V = 620.69(2) Å3, Z = 2. It is closely identical in the structure and cell parameters to synthetic K2Nb2(Si4O12)O2 (or KNbSi2O7). Similar to synthetic phase, the mineral has nonlinear properties. Some optical and physical properties for rippite are: colorless; Mohs’ hardness—4–5; cleavage—(001) very perfect, (100) perfect to distinct; density (meas.)—3.17(2) g/cm3; density (calc.)—3.198 g/cm3; optically uniaxial (+); ω = 1.737-1.739; ε = 1.747 (589 nm). The empirical formula of the holotype rippite (mean of 120 analyses) is K2(Nb1.90Ti0.09Zr0.01)[Si4O12](O1.78OH0.12F0.10). Majority of rippite prismatic crystals are weakly zoned and show Ti-poor composition K2(Nb1.93Ti0.05Zr0.02)[Si4O12](O1.93F0.07). Raman and IR spectroscopy, and SIMS data indicate very low H2O content (0.09–0.23 wt %). Some grains may contain an outermost zone, which is enriched in Ti (+Zr) and F, up to K2(Nb1.67Ti0.32Zr0.01)[Si4O12](O1.67F0.33). It strongly suggests the incorporation of (Ti,Zr) and F in the structure of rippite via the isomorphism Nb5+ + O2− → (Ti,Zr)4+ + F1−. The content of a hypothetical end-member K2Ti2[Si4O12]F2 may be up to 17 mol. %. Rippite represents a new structural type among [Si4O12]-cyclosilicates because of specific type of connection of the octahedral chains and [Si4O12]8− rings. In structural and chemical aspects it seems to be in close with the labuntsovite-supergroup minerals, namely with vuoriyarvite-(K), K2(Nb,Ti)2(Si4O12)(O,OH)2∙4H2O.

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A Potassium Tantalum(V) Tetrasilicate KTaSi2O7

Cited by 7 publications

References 5 publications

In Search of Inorganic Nonlinear Optical Materials for Second Harmonic Generation

In Search of Inorganic Nonlinear Optical Materials for Second Harmonic Generation

Crystallization Behavior of Potassium Niobium Silicate Glasses

Rippite, K2(Nb,Ti)2(Si4O12)O(O,F), a New K-Nb-Cyclosilicate from Chuktukon Carbonatite Massif, Chadobets Upland, Krasnoyarsk Territory, Russia

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