ORCID Profile
0000-0002-2588-7088
Current Organisation
Joanneum Research Forschungsgesellschaft mbH
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Publisher: International Union of Crystallography (IUCr)
Date: 10-07-2008
DOI: 10.1107/S0108768108016029
Abstract: A high-temperature X-ray diffraction study revealed that brownmillerite-type Ca 2 Al 2 O 5 transforms to an incommensurately modulated structure at elevated temperatures. Single crystals of Ca 2 Al 2 O 5 were synthesized in an end-loaded piston cylinder press at 2.5 GPa and 1273 K. The diffraction pattern observed at 1090 (10) K by in situ single-crystal diffraction experiments can be indexed by an I -centred orthorhombic cell and a modulation wavevector of q = 0.595 (1) c * . A (3 + 1)-dimensional model in superspace group Imma (00γ) s 00 was used to refine the modulated structure. The structure is assembled from two building units: (i) layers of corner-sharing [AlO 6 ] octahedra, stacked along b alternate with (ii) layers of zweier single chains of [AlO 4 ] tetrahedra running along a . The modulated structure arises from an aperiodic sequence of two different configurations of the chains within the tetrahedral layers. The modulated high-temperature phase of Ca 2 Al 2 O 5 is isotypic to the modulated high-temperature modification of Ca 2 Fe 2 O 5 . A large hysteresis was found in the phase-transition temperature. On heating, the transition occurs at ca 1075 (10) K on cooling, satellite reflections can be observed down to 975 (10) K. The characterization of Ca 2 Al 2 O 5 is completed by Raman spectroscopy, including a partial interpretation of the spectra.
Publisher: American Chemical Society (ACS)
Date: 02-2013
DOI: 10.1021/CM3038476
Publisher: Elsevier BV
Date: 11-2005
Publisher: Elsevier BV
Date: 03-2007
Publisher: Mineralogical Society
Date: 12-2014
DOI: 10.1180/MINMAG.2014.078.7.06
Abstract: A description of the new mineral innsbruckite, Mn 33 (Si 2 O 5 ) 14 (OH) 38 , a hydrous manganese phyllosilicate found in Tyrol, Austria is given. The crystal structure was determined by singlecrystal synchrotron radiation diffraction experiments at the X06DA beamline at the Swiss Light Source (Paul Scherrer Institute, Villigen, Switzerland). The space group is Cm and lattice parameters are a = 17.2760(19), b = 35.957(5), c = 7.2560(8) Å , β = 91.359(7)º, V = 4506.1(10) Å 3 , Z = 2. Innsbruckite belongs to the group of modulated 1:1 layer silicates and is chemically and structurally quite closely related to bementite, Mn 7 (Si 2 O 5 ) 3 (OH) 8 . The chemical analysis revealed a close to ideal composition with only minor amounts of Al, Fe and Mg. Using Liebau’s nomenclature for silicate classification the silicate anion can be described as an unbranched siebener single layer. Innsbruckite shows a complex topology of the silicate sheet, exhibiting 4-, 5-, 6- and 8-membered rings. The silicate sheet is fully characterized using vertex symbols, and its topology is compared to those in other complex sheet silicates. Furthermore, the structural investigation is complemented with Raman spectroscopic studies.
No related grants have been discovered for Reinhard Kaindl.