Structure of Na2CaSi2O6

Ohsato, Hitoshi; Maki, Iwao; Takéuchi, Yoshio

doi:10.1107/s0108270185008617

Cited by 36 publications

(39 citation statements)

References 2 publications

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“…We solved the structures of both compounds (Fischer, 1983;Fischer & Tillmanns, 1983) and refined them in space group R3m (high-temperature form) and P32 (10w-temperature form), respectively. The structural features including the cation distribution (Fischer, 1983) are nearly identical to what has been found and described by Ohsato et al (1985Ohsato et al ( , 1986 for the synthetic analogues, except for the fact that we were not able to refine the low-temperature form in one of the proposed enantiomorphous space groups P3121 or P3221. Ohsato et aL (1986) relate this to the fact that we (presumably) did not carry out site-occupancy refinements, which in fact, we did (Fischer, 1983).…”

Section: Introduction and Resultssupporting

confidence: 70%

“…Table 2 contains the results of the refinements for the high-temperature form of combeite. The reinvestigation of the two structures included a constrained refinement of the site occupancies and the results are compared with those given by Fischer (1983) and Ohsato et al (1985Ohsato et al ( , 1986. (Table 1) given by Ohsato et aL (1986), but a site-occupancy refinement of sodium on this position gave only approximately 0.3Na/unit cell, and therefore it has not been included in the final refinements.…”

Section: Introduction and Resultsmentioning

confidence: 99%

“…shift/a -~ 0.005, mean shift/a < 0.001; highest peak in difference Fourier map close to M4 with approximately 1.3 e A -3. A second peak with approximately 1.1 eA -3 at 0.16, 0, 0.5 is about 1 A away from O 1 and not comparable with the split position (Table 2) given by Ohsato et al (1985). Si-O distances range from 1.584 (4) to 1.625 (4) tl, with a mean value of 1.605 (4) A.…”

Section: Experimental and Crystal Datamentioning

confidence: 99%

“…t Offset (A) from twofold symmetry for the atoms given by Fischer (1983) in P32. Ohsato et aL (1985) Site symmetry Atoms/unit cell Total, this work 15.8 9.0 Total, Ohsato et al (1985) 17.49 9.26 * Statistically occupied by 18 oxygen atoms. t In our refinements constrained to give M 1 (Ca) + M3 (Ca) = 6, assuming full occupation of M 1, M3 and M4.…”

Section: Experimental and Crystal Datamentioning

confidence: 99%

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Revised data for combeite, Na2Ca2Si3O9

Fischer¹,

Тиллманнс²

1987

Acta Crystallogr C

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Refinements of the crystal structures of the high-and low-temperature modifications of combeite, previously described by Fischer & Tillmanns [Neues Jahrb. Mineral Monatsh. (1983), pp. 49-59] are revised and compared with synthetic analogues. Both forms of the mineral with approximate composition Na2Ca2Si30 9 (Z = 6) consist of six-rings of SiO 4 tetrahedra which are circular in the high-temperature form

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Section: Introduction and Resultssupporting

confidence: 70%

Section: Introduction and Resultsmentioning

confidence: 99%

Section: Experimental and Crystal Datamentioning

confidence: 99%

Section: Experimental and Crystal Datamentioning

confidence: 99%

See 2 more Smart Citations

Revised data for combeite, Na2Ca2Si3O9

Fischer¹,

Тиллманнс²

1987

Acta Crystallogr C

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“…structure analysis played the role of a convenient analytical probe. In the meantime crystal structure investigations have been performed for the following compounds: Na 2 CaSiO 4 (Dollase and Ross 1991), Na 2 Ca 3 Si 3 O 10 (Treushnikov et al 1971), Na 4 CaSi 3 O 9 (Fischer and Tillmanns 1984), α-Na 2 Ca 2 Si 3 O 9 (Ohsato et al 1990), β-Na 2 Ca 2 Si 3 O 9 (Fischer and Tillmanns 1987), Na 2 CaSi 2 O 6 (Ohsato et al 1985), Na 2 Ca 3 Si 6 O 16 (Ihara et al 1984;Kahlenberg et al 2010), Na 2 Ca 2 Si 2 O 7 (Kahlenberg and Hösch 2002) and Na 2 Ca 6 Si 4 O 1 5 (Armbruster and Röthlisberger 1990). …”

Section: Editorial Handling: M Atm Broekmansmentioning

confidence: 99%

On the existence of a high-temperature polymorph of Na2Ca6Si4O15—implications for the phase equilibria in the system Na2O-CaO-SiO2

Kahlenberg

Maier

2016

Miner Petrol

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Singe crystals of a new high-temperature polymorph of Na 2 Ca 6 Si 4 O 15 have been obtained from solid state reactions performed at 1300°C. The basic crystallographic data of this so-called β-phase at ambient conditions are as follows: space group P1c1, a = 9.0112(5) Å, b = 7.3171(5) Å, c = 10.9723(6) Å, β = 107.720(14)°, V = 689.14(7) Å 3 , Z = 2. The crystals showed twinning by reticular merohedry (mimicking an orthorhombic C-centred unit cell) which was accounted for during data processing and structure solution. Structure determination was accomplished by direct methods. Least-squares refinements resulted in a residual of R(|F|) = 0.043 for 5811 observed reflections with I > 2σ(I). From a structural point of view β-Na 2 Ca 6 Si 4 O 15 can be attributed to the group of mixed-anion silicates containing [Si 2 O 7 ]-dimers as well as isolated [SiO 4 ]-tetrahedra in the ratio 1:2, i.e. more precisely the formula can be written as Na 2 Ca 6 [SiO 4 ] 2 [Si 2 O 7 ]. The tetrahedral groups are arranged in layers parallel to (100). Sodium and calcium cations are located between the silicate anions for charge compensation and are coordinated by six to eight nearest oxygen ligands. Alternatively, the structure can be described as a mixed tetrahedral-octahedral framework based on kröhnkite-type [Ca(SiO 4 ) 2 O 2 ]-chains in which the CaO 6 -octahedra are corner-linked to bridging SiO 4 -tetrahedra. The infinite chains are running parallel to [001] and are concentrated in layers parallel to (010). Adjacent layers are shifted relative to each other by an amount of +δ or −δ along a*. Consequently, a … ABABAB… stacking sequence is created. A detailed comparison with related structures such as α-Na 2 Ca 6 Si 4 O 15 and other A 2 B 6 Si 4 O 15 representatives including topological as well as group theoretical aspects is presented. There are strong indications that monoclinic Na 2 Ca 3 Si 2 O 8 mentioned in earlier studies is actually misinterpreted β-Na 2 Ca 6 Si 4 O 15 . In addition to the detailed crystallographic analysis of the previously unknown compound our results will also help to improve the interpretation of the phase relationships between the compounds in the ternary system Na 2 O-CaO-SiO 2 which are of interest for several applications related to the field of applied mineralogy and materials science.

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Silicate und Perowskite: zwei Themen mit Variationen

Liebau

1999

Angewandte Chemie

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Eine Zwischenstellung zwischen Oxosilicaten und Nitridosilicaten einerseits und Silicaten und Siliciumoxosalzen andererseits nimmt Ce16Si15O6N32 ein. Diese Verbindung ist ein Perowskit‐Derivat, in dem die oktaedrisch koordinierten Kationen weitgehend durch tetraedrisch koordinierte ersetzt sind, was sich durch die Formel Ce16(Si[6]Si[4]14□)(O6N32□10) beschreiben läßt ([n] = Koordinationszahl, □ = Leerstelle). Das Vorhandensein von Leerstellen sowohl in der Kationen‐ als auch in der Anionen‐Teilstruktur läßt eine Ionenleitfähigkeit erwarten.

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Structure of Na2CaSi2O6

Cited by 36 publications

References 2 publications

Revised data for combeite, Na2Ca2Si3O9

Revised data for combeite, Na2Ca2Si3O9

On the existence of a high-temperature polymorph of Na2Ca6Si4O15—implications for the phase equilibria in the system Na2O-CaO-SiO2

Silicate und Perowskite: zwei Themen mit Variationen

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