Refinement of the structure of rankinite.

Saburi, Shinsuke; Kusachi, Isao; Henmi, Chiyoko; Kawahara, Akira; Henmi, Kitinosuke; Kawada, I.

doi:10.2465/minerj.8.240

Cited by 41 publications

(13 citation statements)

References 2 publications

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“…The distance between the Si and O atoms bridging the two Si atoms in a dimer is the longest SiÐO distance (mean value for all Si tetrahedra: 1.667 A Ê ) and the length between Si and the apical O atom is the shortest (mean value: 1.601 A Ê ). These values coincide well with the corresponding distances (1.668 and 1.605 A Ê ) of the dimer in rankinite (Ca 3 Si 2 O 7 ; Saburi et al, 1976). The mean CoÐO distances of the CoO 4 tetrahedra are in the range 1.945 (5)±1.958 (5) A Ê .…”

Section: Description Of the Structuresupporting

confidence: 82%

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Commensurate structure of Ca₂CoSi₂O₇, a new twinned orthorhombic structure

Hagiya

Kusaka

Ohmasa

et al. 2001

Acta Crystallogr Sect B

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The crystal structure of the commensurate phase of Ca(2)CoSi(2)O(7), dicalcium cobalt disilicate, has been derived from the modulated structure described in (3 + 2)-dimensional space. The structure is orthorhombic P2(1)2(1)2; a = 23.510 (4), b = 23.510 (4), c = 5.025 (1) A (at 170 K), Z = 18. Since the crystal is twinned and the apparent diffraction symmetry is 4/mmm, the parameters were refined by a newly developed least-squares program for the refinement of twinned crystals. The structure is essentially similar to the known structure of the melilite group, but with regular arrangement of the bundles along [001] formed with four arrays of the sixfold coordinated Ca polyhedra and an array of CoO(4) tetrahedra. The distribution of the bundles found in the present structure is different from that reported by Riester et al. [(2000), Z. Kristallogr. 215, 102-109].

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Section: Description Of the Structuresupporting

confidence: 82%

“…(2001). B57, 271±277 independent Ca atoms are described as sevenfold coordinated ones in rankinite (Saburi et al, 1976), but one of them (Ca1) can be regarded as a sixfold coordination if the length longer than 2.9 A Ê is excluded. The mean bond-valence sum of Co is 1.99 and that of Si is 3.94.…”

Section: Figurementioning

confidence: 99%

Commensurate structure of Ca₂CoSi₂O₇, a new twinned orthorhombic structure

Hagiya

Kusaka

Ohmasa

et al. 2001

Acta Crystallogr Sect B

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“…2). taining about 25% Si only), and no simple structural relationship could be established with other silicates of neighbouring compositions such as the rankinite and kilchoanite polymorphs of Ca^SiiOv (Saburi, Kusachi, Henmi, Kawahara, Henmi and Kawada, 1976;Taylor, 1971;Kimata, 1989). Two types of coordination are found for the Ca sites of the Ca5Ge30n structure: the Ca2, Ca21 and Ca3 atoms occupy distorted octahedral sites forming a three-dimensional framework via comer-sharing with the Ge04 tetrahedra (cf.…”

Section: Description Of the Casgeson Structurementioning

confidence: 98%

Crystal structures of Ca₅Ge₃O₁₁ and wollastonite-type GaGeO₃

Barbier¹,

Levy²

1997

Zeitschrift Für Kristallographie - Crystalline Materials

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The crystal structures of triclinic Ca^Ge^On and triclinic wollastonite-type CaGeO^h ave been determined by X-ray diffraction using single crystals grown from a K2M0O4 flux. Ca^Ge^On is closely related to monoclinic CasfGcSi^On and crystallizes in the CT space group with the cell parameters: a= 10.855 (2) A, b = 8.715(2) Ä, c = 10.998(2) Ä, a = 90.60(3)°, ß = 96.49(3)°, y = 90.17(3)°, Z = 4, wR(F2) = 0.080 for 4877 unique reflections. CajGeiOn is a mixed-anion germanate containing single and double tetrahedra, with a structural formula written as Ca.s[Ge04] [GeiOv]. CaGeO} is isostructural with CaSiOi, wollastonite-lT, and crystallizes in the PI space group with the cell parameters: a = 7.269(2) A, b = 7.526(2) Ä, c = 8.094(2) Ä, a = 103.44(3)°, ß = 94.42(3)°, y = 90.11(3)°, Z = 6, wR(F2) = 0.074 for 9279unique reflections. The CaGeO^structure contains tetrahedral dreier single chains corresponding to the structural formula Ca^luB,^) [Ge3Og]. The bonding in the two compounds is analyzed in terms of a comparison between observed bond valences and bond valences predicted from the bond topology.

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“…The solids selected for inclusion in this study were chosen by the following criteria: (1) the structure of the material had to be known through high‐quality diffraction studies; (2) the principal components of the chemical‐shift tensors had to have been measured to a high degree of accuracy; and (3) the NMR spectra of materials with more than one unique NMR‐active lattice site had to have been assigned unambiguously. For 29 Si calculations, the materials are SiO 2 , Li 2 Si 2 O 5 , Na 2 SiO 3 , Na 2 Si 2 O 5 , Mg 2 SiO 4 , MgSiO 3 , CaSiO 3 , Ca 3 Si 2 O 7 , and CaMgSiO 5 . For 31 P calculations, the materials are Mg 3 (PO 4 ) 2 , Mg 2 P 4 O 12 , Mg 2 P 2 O 7 , MgP 4 O 11 , Ca 4 P 2 O 9 , Li 6 O 6 P 18 ·3H 2 O, and SnHPO 4 .…”

Section: Computational Details and Theorymentioning

confidence: 99%

Analysis of the bond‐valence method for calculating ²⁹Si and ³¹P magnetic shielding in covalent network solids

et al. 2016

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(29) Si and (31) P magnetic-shielding tensors in covalent network solids have been evaluated using periodic and cluster-based calculations. The cluster-based computational methodology employs pseudoatoms to reduce the net charge (resulting from missing co-ordination on the terminal atoms) through valence modification of terminal atoms using bond-valence theory (VMTA/BV). The magnetic-shielding tensors computed with the VMTA/BV method are compared to magnetic-shielding tensors determined with the periodic GIPAW approach. The cluster-based all-electron calculations agree with experiment better than the GIPAW calculations, particularly for predicting absolute magnetic shielding and for predicting chemical shifts. The performance of the DFT functionals CA-PZ, PW91, PBE, rPBE, PBEsol, WC, and PBE0 are assessed for the prediction of (29) Si and (31) P magnetic-shielding constants. Calculations using the hybrid functional PBE0, in combination with the VMTA/BV approach, result in excellent agreement with experiment. © 2016 Wiley Periodicals, Inc.

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Refinement of the structure of rankinite.

Cited by 41 publications

References 2 publications

Commensurate structure of Ca₂CoSi₂O₇, a new twinned orthorhombic structure

Commensurate structure of Ca₂CoSi₂O₇, a new twinned orthorhombic structure

Crystal structures of Ca₅Ge₃O₁₁ and wollastonite-type GaGeO₃

Analysis of the bond‐valence method for calculating ²⁹Si and ³¹P magnetic shielding in covalent network solids

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Refinement of the structure of rankinite.

Cited by 41 publications

References 2 publications

Commensurate structure of Ca2CoSi2O7, a new twinned orthorhombic structure

Commensurate structure of Ca2CoSi2O7, a new twinned orthorhombic structure

Crystal structures of Ca5Ge3O11 and wollastonite-type GaGeO3

Analysis of the bond‐valence method for calculating 29Si and 31P magnetic shielding in covalent network solids

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Commensurate structure of Ca₂CoSi₂O₇, a new twinned orthorhombic structure

Commensurate structure of Ca₂CoSi₂O₇, a new twinned orthorhombic structure

Crystal structures of Ca₅Ge₃O₁₁ and wollastonite-type GaGeO₃

Analysis of the bond‐valence method for calculating ²⁹Si and ³¹P magnetic shielding in covalent network solids