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Submicroscopic twinning and chemical inhomogeneity of ilvaite, a mixed-valence iron sorosilicate HCaFe22 + Fe3 + Si2O9

Published/Copyright: July 28, 2010
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Zeitschrift für Kristallographie - Crystalline Materials
From the journal Zeitschrift für Kristallographie - Crystalline Materials Volume 209 Issue 11

Abstract

Series of structural studies of systematically selected local portions of the same crystal of ilvaite CaFe22 + Fe3 + OOHSi2O7 with moderate size have revealed a trend that the monoclinic and apparently orthorhombic structures co-exist in the crystal regardless of their mode of occurrence. The diffraction-intensity profiles of high angle reflections such as 24,0,0 and 008 were then studied by means of step-scanning on a four-circle diffractometer, using graphite monochromatized MoKα radiation: the former was scanned along c* and the latter along a*. The result has brought out that either reflection from the crystals of high monoclinicity (β ≈ 90.2° ∼ 90.3°) splits into a double peak, suggesting that those crystals are most likely made up of two kinds of domains, each having a monoclinic structure with β = 90.45°, one twinned on (001) and the other twinned on (100). In the case of crystals of low monoclinicity (β ≈ 90.0°), those reflections tend to exhibit single broad profiles with fine structure. A profile-fitting procedure has shown that they are in general composite of three peaks, suggesting that they consist of complex composites of fine monoclinic components twinned on (001) and those twinned on (100). The distribution of Mn in the crystals studied tends to increase towards their marginal portions. Crystal portions containing more than roughly 0.25 Mn per formula unit assume orthorhombic symmetry without exception. The coexistence of the different symmetries in the same crystal of ilvaite is thus originated in the variation in scale or mode of twinnings incorporated mainly with inhomogeneous distribution of Mn in the crystal. The occurrence of orthorhombic ilvaite is unlikely.

Published Online: 2010-7-28
Published in Print: 1994-11-1

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Articles in the same Issue

  1. Thermal dependence of the Pb5Al3F19 lattice parameters in phases I–IV
  2. Crystal growth and crystal structure of arsenicv ditelluroidide semihydrate, AsTe2I · 0.5 H2O
  3. Submicroscopic twinning and chemical inhomogeneity of ilvaite, a mixed-valence iron sorosilicate HCaFe22 + Fe3 + Si2O9
  4. Substitutional disorder in the system Mg1 − xCu2 + xO3: Cu2+ in a compressed octahedral environment
  5. A crystal structure determination of HgC2O4 from synchrotron X-ray and neutron powder diffraction data
  6. Crystal and molecular structure of 5-(3-methylbut-2-enyloxy)-7-methoxy-8-(3-methylbut-2-enyl)-2 H-[1]-benzopyran-2-one (Sesibiricin)
  7. Structural studies on oxalatotriorganostannates. Crystal structure of trimethylsulfonium catena-O,O′-oxalatotriphenylstannate
  8. Crystal and molecular structures of P,P-dicyclohexyl-N-methyl-phosphinylthioformamide, P,P-dicyclohexyl-N-phenyl-phosphinylthioformamide, P,P-dicyclohexyl-N-methyl-thiophosphinylthioformamide, and P,P-dicyclohexyl-N-phenyl-thiophosphinylthioformamide
  9. Two organically-templated vanadium arsenate phases: V4As6O30H6 · 2 N2C6H14 · 4 H2O and V4As6O30H8 · 2 N(CH3)4 · 5.33 H2O
  10. Crystal structure of manganese ultraphosphate, MnP4O11
  11. Crystal structure of c-6-[N,N-bis(trimethylsilyl)amino]-5,6-dihydro-r-4-[(1′-hydroxy-1′-methyl)ethyl]-t-5-methyl-3-phenyl-4H-1,2-oxazine, ONC(CH)(CH)(CH)(C6H5)C(OH)(CH3)2(CH3)NSi(CH3)3Si(CH3)3
  12. Crystal structure of 2-methyl-6-phenyl-pyridin-3-al, (C6H5)C(CH)2CCNCHO(CH3)
  13. Crystal structure of 3-O-(5,6-dihydro-5-methyl-3-phenyl-4H-1,2-oxazin-6-yl)-1,2:5,6-di-O-isopropyliden-α-D-glucofuranose, O(CH)4OCO(CH3)2CHCH2OCO(CH3)2OCHCHCH2CNO(CH3)(C6H5)
  14. Crystal structure of 1,3-bis(3-trifluoromethylphenyl)-2,2,4,4-tetramethyl-1,3-diaza-2,4-disila-cyclobutane, (F3C(C6H4)NSi(CH3)2)2
  15. Crystal structure of 5-ethyl-2′-deoxyuridine, C11H16N2O5
  16. Crystal structure of 3,6-dimethyl-5-methylthio-thieno[3,2-b]-thiophen-2-carbaldehyde, C10H10OS3
  17. Crystal structure of anti-5,13-di-tert-butyl-8,16-difluoro-[2.2]metacyclophane, C24H30F2
  18. Crystal structure of 1-(3,5-difluoro-2,6-di(trans-stilbenyl)phenyl)-2-phenyl-diazene, (C6H5)NN(C6F2H(C(C6H5)CH(C6H5))2)
  19. Crystal structure of di(bis(1,1-dimethylethyl)phosphinic amide) hydrobromide,((C4H9)2(NH2)PO)2(HBr)
  20. Crystal structure of bis(lignocainium) dioxotrichloronitratouranate(IV), (C14H22ON2)2(UO2(NO3)Cl3)
  21. Crystal structure of bis(lignocainium) tetrathiocyanatocobaltate(II) hydrate, (C14H22ON2)2 Co(NCS)4 (H2O)
  22. Crystal structure of bis(lignocainium) tetrabromocuprate(II), (C14H22ON2)2CuBr4
  23. Crystal structure of terbium chromium aluminium, Tb6Cr4+xAl43−x (x = 1.6), erbium chromium aluminium, Er6Cr4+xAl43−x (x = 1.96), holmium chromium aluminium, Ho6Cr4+xAl43−x (x = 1.6), and lutetium chromium aluminium, Lu6Cr4+xAl43−X (x = 2.76)
https://doi.org/10.1524/zkri.1994.209.11.861

Articles in the same Issue

  1. Thermal dependence of the Pb5Al3F19 lattice parameters in phases I–IV
  2. Crystal growth and crystal structure of arsenicv ditelluroidide semihydrate, AsTe2I · 0.5 H2O
  3. Submicroscopic twinning and chemical inhomogeneity of ilvaite, a mixed-valence iron sorosilicate HCaFe22 + Fe3 + Si2O9
  4. Substitutional disorder in the system Mg1 − xCu2 + xO3: Cu2+ in a compressed octahedral environment
  5. A crystal structure determination of HgC2O4 from synchrotron X-ray and neutron powder diffraction data
  6. Crystal and molecular structure of 5-(3-methylbut-2-enyloxy)-7-methoxy-8-(3-methylbut-2-enyl)-2 H-[1]-benzopyran-2-one (Sesibiricin)
  7. Structural studies on oxalatotriorganostannates. Crystal structure of trimethylsulfonium catena-O,O′-oxalatotriphenylstannate
  8. Crystal and molecular structures of P,P-dicyclohexyl-N-methyl-phosphinylthioformamide, P,P-dicyclohexyl-N-phenyl-phosphinylthioformamide, P,P-dicyclohexyl-N-methyl-thiophosphinylthioformamide, and P,P-dicyclohexyl-N-phenyl-thiophosphinylthioformamide
  9. Two organically-templated vanadium arsenate phases: V4As6O30H6 · 2 N2C6H14 · 4 H2O and V4As6O30H8 · 2 N(CH3)4 · 5.33 H2O
  10. Crystal structure of manganese ultraphosphate, MnP4O11
  11. Crystal structure of c-6-[N,N-bis(trimethylsilyl)amino]-5,6-dihydro-r-4-[(1′-hydroxy-1′-methyl)ethyl]-t-5-methyl-3-phenyl-4H-1,2-oxazine, ONC(CH)(CH)(CH)(C6H5)C(OH)(CH3)2(CH3)NSi(CH3)3Si(CH3)3
  12. Crystal structure of 2-methyl-6-phenyl-pyridin-3-al, (C6H5)C(CH)2CCNCHO(CH3)
  13. Crystal structure of 3-O-(5,6-dihydro-5-methyl-3-phenyl-4H-1,2-oxazin-6-yl)-1,2:5,6-di-O-isopropyliden-α-D-glucofuranose, O(CH)4OCO(CH3)2CHCH2OCO(CH3)2OCHCHCH2CNO(CH3)(C6H5)
  14. Crystal structure of 1,3-bis(3-trifluoromethylphenyl)-2,2,4,4-tetramethyl-1,3-diaza-2,4-disila-cyclobutane, (F3C(C6H4)NSi(CH3)2)2
  15. Crystal structure of 5-ethyl-2′-deoxyuridine, C11H16N2O5
  16. Crystal structure of 3,6-dimethyl-5-methylthio-thieno[3,2-b]-thiophen-2-carbaldehyde, C10H10OS3
  17. Crystal structure of anti-5,13-di-tert-butyl-8,16-difluoro-[2.2]metacyclophane, C24H30F2
  18. Crystal structure of 1-(3,5-difluoro-2,6-di(trans-stilbenyl)phenyl)-2-phenyl-diazene, (C6H5)NN(C6F2H(C(C6H5)CH(C6H5))2)
  19. Crystal structure of di(bis(1,1-dimethylethyl)phosphinic amide) hydrobromide,((C4H9)2(NH2)PO)2(HBr)
  20. Crystal structure of bis(lignocainium) dioxotrichloronitratouranate(IV), (C14H22ON2)2(UO2(NO3)Cl3)
  21. Crystal structure of bis(lignocainium) tetrathiocyanatocobaltate(II) hydrate, (C14H22ON2)2 Co(NCS)4 (H2O)
  22. Crystal structure of bis(lignocainium) tetrabromocuprate(II), (C14H22ON2)2CuBr4
  23. Crystal structure of terbium chromium aluminium, Tb6Cr4+xAl43−x (x = 1.6), erbium chromium aluminium, Er6Cr4+xAl43−x (x = 1.96), holmium chromium aluminium, Ho6Cr4+xAl43−x (x = 1.6), and lutetium chromium aluminium, Lu6Cr4+xAl43−X (x = 2.76)
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