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Structure Refinement and Vibrational Spectroscopy of Vauxite From the Type Locality, Llallagua (Bolivia)
- Publication Year :
- 2016
-
Abstract
- A crystal-chemical investigation of vauxite, ideally FeAl 2 (PO 4 ) 2 (OH) 2 ·6H 2 O, from Llallagua (Bolivia) has been performed using a multi-methodological approach based on WDS-electron microprobe, single-crystal X-ray diffraction, and vibrational spectroscopies (Raman and FTIR). The structure was refined in the triclinic P space group, with the following unit-cell constants: a 9.1276(2), b 11.5836(3), c 6.15960(10) A, α 98.3152(10)°, β 92.0139(10)°, γ 108.1695(9)°, and V 610.05(2) A 3 . The vauxite structure is based on a building unit oriented parallel to the c axis and composed of a chain of Fe2 and Al2 edge-sharing octahedra and two chains of corner-sharing P2 tetrahedra and Al1 octahedra, interconnected via corners and P1 tetrahedra. Neighboring building units are interconnected by Al3 octahedra and via Fe1 octahedra. The framework is completed with two non-coordinated water molecules. The latter, together with the two hydroxyl groups and the other four coordinated water molecules, form a complex hydrogen bonding network whose interactions further compact the whole framework. Both FTIR and Raman spectra show, in the H 2 O stretching region, a broad absorption consisting of several overlapping components due to the six water molecules plus the OH groups. The band multiplicity observed in the low-wavenumber region ( −1 ) is compatible with the presence of two distorted PO 4 tetrahedra.
- Subjects :
- Infrared spectroscopy
Phosphate
02 engineering and technology
Triclinic crystal system
engineering.material
010502 geochemistry & geophysics
01 natural sciences
EMPA
symbols.namesake
Geochemistry and Petrology
Single-crystal X-ray structure refinement
Vauxite
Multiplicity (chemistry)
0105 earth and related environmental sciences
Hydrogen bond
Chemistry
EMPA, FTIR and Raman spectroscopy, Hydrogen bonding network, Phosphate, Single-crystal X-ray, structure refinement, Vauxite
021001 nanoscience & nanotechnology
Hydrogen bonding network
Crystallography
Octahedron
engineering
symbols
Tetrahedron
FTIR and Raman spectroscopy
0210 nano-technology
Raman spectroscopy
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....ab9fb781a600d87c4538b3eace8b8f3d