Die Kristallstruktur des Koenenits, eine Doppelschichtstruktur mit zwei inkommensurablen Teilgittern
Abstract
Koenenite 4NaCl · 4(Mg,Ca)Cl2 · 5Mg(OH)2 · 4Al(OH)3 is built up of two trigonal substructures: [Na4(Ca,Mg)2 Cl12]4− and [Mg7Al4 (OH)22]4+ (space group R[unk]m and P[unk]m1 respectively). In direction of the common c axis (c = 3 · 10.88 Å or c = 10.88 Å respectively) NaCl-like chlorine double layers (acl = 4.072 Å) alternate with brucite-like OH double layers (aOH = 3.052 Å). All possible octahedral sites are randomly occupied by the metal ions. The Cl double layers have the following rhombohedral sequence: –BC–AB–CA–BC–. Evidence of a common supercell could not be found. The [100] directions of both subcells form an angle of 28.3 ± .1°. The distances Me–Cl and Me–OH are 2.79 Å and 2.02 Å respectively, the distances between the layers are Cl–Cl = 3.02 Å, OH–OH = 1.99 Å and Cl–OH = 2.94 Å. The double layers of both lattices are held together by their opposite charge and by hydrogen bonds. The reliability index for 215 independent structure factors is R = 0.056.
Articles in the same Issue
- A special case of two-dimensionally disordered crystals
- Die Kristallstruktur des Koenenits, eine Doppelschichtstruktur mit zwei inkommensurablen Teilgittern
- Zur Indizierung von Pulverdiagrammen tetragonaler und hexagonaler Substanzen
- Etch patterns on apophyllite basal cleavages
- Die Kristallstruktur von Li2(Si0,25Ge0,75)2O5
- The crystal structure of LiAlSi2O6-II (“β spodumene”)
- Phase solution of para-chlorophenol
- Crystal structure of an eighteen-layered polytype of cadmium iodide
- X-ray diffraction effects by non-ideal crystals of biotite, muscovite, montmorillonite, mixed-layer clays, graphite, and periclase*
- The crystal structure of alamosite, PbSiO31
- Sauerstoff als Koordinationszentrum in Kristallstrukturen
- Low-iron polymorphs in the pyrrhotite group
- Revised crystal structure of dehydrated Na-Type A zeolite
- Verfeinerung der Tl2O3-Struktur mittels Neutronenbeugung
- The location of hydrogen atoms in crystalline ionic hydrates
- Disorder phenomenon in cadmium iodide crystals
- Crystal structure of single-layer lizardite
- Proof that the pgg packing of ellipses has never the maximum density
- Weighting function in crystal-structure analysis*
- Tetrahedral metal groups in Fe2B and Mn4B structures
- Antisymmetrische OD-Strukturen
- Studies on etching of neutron-irradiated calcium fluoride single crystals
- Matrix methods in Fourier summations
- Electron-optical studies of etch patterns on calcium fluoride
- Structure of etch pattern at helical dislocations in NaCl single crystals
- Crystal structure of l(+)-cysteine hydrochloride monohydrate*
- Eighth International Congress of Crystallography
- Intercongress Meeting, 1968
Articles in the same Issue
- A special case of two-dimensionally disordered crystals
- Die Kristallstruktur des Koenenits, eine Doppelschichtstruktur mit zwei inkommensurablen Teilgittern
- Zur Indizierung von Pulverdiagrammen tetragonaler und hexagonaler Substanzen
- Etch patterns on apophyllite basal cleavages
- Die Kristallstruktur von Li2(Si0,25Ge0,75)2O5
- The crystal structure of LiAlSi2O6-II (“β spodumene”)
- Phase solution of para-chlorophenol
- Crystal structure of an eighteen-layered polytype of cadmium iodide
- X-ray diffraction effects by non-ideal crystals of biotite, muscovite, montmorillonite, mixed-layer clays, graphite, and periclase*
- The crystal structure of alamosite, PbSiO31
- Sauerstoff als Koordinationszentrum in Kristallstrukturen
- Low-iron polymorphs in the pyrrhotite group
- Revised crystal structure of dehydrated Na-Type A zeolite
- Verfeinerung der Tl2O3-Struktur mittels Neutronenbeugung
- The location of hydrogen atoms in crystalline ionic hydrates
- Disorder phenomenon in cadmium iodide crystals
- Crystal structure of single-layer lizardite
- Proof that the pgg packing of ellipses has never the maximum density
- Weighting function in crystal-structure analysis*
- Tetrahedral metal groups in Fe2B and Mn4B structures
- Antisymmetrische OD-Strukturen
- Studies on etching of neutron-irradiated calcium fluoride single crystals
- Matrix methods in Fourier summations
- Electron-optical studies of etch patterns on calcium fluoride
- Structure of etch pattern at helical dislocations in NaCl single crystals
- Crystal structure of l(+)-cysteine hydrochloride monohydrate*
- Eighth International Congress of Crystallography
- Intercongress Meeting, 1968
