A5047089569- Crystal Structures and Properties
- X-ray Diffraction in Crystallography
- Zeolite Catalysis and Synthesis
- Catalytic Processes in Materials Science
- Mineralogy and Gemology Studies
- Chemical Synthesis and Characterization
- Geological and Geochemical Analysis
- Catalysis and Oxidation Reactions
- Solid-state spectroscopy and crystallography
- Clay minerals and soil interactions
- Mesoporous Materials and Catalysis
- Polyoxometalates: Synthesis and Applications
- High-pressure geophysics and materials
- Crystallography and molecular interactions
- Inorganic Fluorides and Related Compounds
- Crystal structures of chemical compounds
- Nuclear materials and radiation effects
- Crystallization and Solubility Studies
- Chemical Thermodynamics and Molecular Structure
- Radioactive element chemistry and processing
- Glass properties and applications
- Methane Hydrates and Related Phenomena
- Thermal and Kinetic Analysis
- Magnetic and transport properties of perovskites and related materials
- Catalysis and Hydrodesulfurization Studies
University of Turin
2011-2021
Accademia Nazionale dei Lincei
2021
Sapienza University of Rome
2003-2014
Institute of Nanostructured Materials
2012-2014
Institute for Complex Systems
2005-2009
Institute of Geosciences and Earth Resources
2002-2007
Max Planck Institute for Solid State Research
2007
LMU Klinikum
2007
Ludwig-Maximilians-Universität München
2007
University of Oxford
2005
Abstract The introduction of a fifth amphibole group, the Na-Ca-Mg-Fe-Mn-Li defined by 0.50 < B (M g ,Fe 2+ ,Mn ,Li) 1.50 and ≤ (Ca,Na) a.f.p.u. (atoms per formula unit), with members whittakerite ottoliniite, has been required recent discoveries (LiNa) amphiboles. This, other new discoveries, such as sodicpedrizite (which, here, is changed slightly, but significantly, from original idealized formula), necessitate amendments to IMA 1997 definitions M -Fe-Mn-Li, calcic, sodic-calcic sodic...
1. Modular series - principles and types 2. Ordered derivative structures 3. Polytypes polytype categories 4. Application of modularity to structure description modelling 5. Modularity at crystal scale twinning
The total valence of the bonds between acceptors and H atoms bonded to a water molecule (s d) is taken equal bond (st) received by donor 0 atom from coordination bonds. For an OH- group, s d = sr-l. Plots for H...O as functions O...O, O-H distances are fitted with function (R/Ro)-b+ k. most reliable fitting obtained vs O...O; minimum value O...O ~_2.55 A hydrogen donated predicted. Similar curves literature compared discussed.
A survey of the geometry and environment water molecules in crystalline hydrates is presented. Histograms correlation analyses are based on 97 crystal structures accurately determined by neutron diffraction, include data from 183 molecules, each donating two hydrogen bonds. The sample analyzed according to nature hydrogen-bond acceptors coordinated cations. Cases bifurcated bonds also discussed. tend be linear located close plane. tendency coordination collinear with direction one lone pairs...
1972) The bond lengths and angles in water molecules, derived from over 40 neutron-diffraction studies of crystalline hydrates, are analysed statistically. A 'quasi-normal' spread the dimensions con- sequent deviations an average model, affecting both molecules their environment, is associated with strains due to local failures Pauling's second rule. This interpretation consistent linear correlations between pairs and/or angles. new, more general classification based on cation coordination,...
The introduction of a fifth group amphiboles, the Na–Ca–Mg–Fe–Mn–Li group, defined by 0.50 < B(Mg,Fe2+,Mn2+,Li) 1.50 and ≤ B(Ca,Na) atoms per formula unit, with members whittakerite ottoliniite, has been required recent discoveries B(Li,Na) amphiboles. These, other new discoveries, such as sodicpedrizite (which is herein slightly, but significantly, changed from original idealized formula), necessitate amendments to IMA 1997 definitions Mg–Fe–Mn–Li, calcic, sodic-calcic sodic groups....
The crystal structure of the mineral analcime, NaAlSi2O6 · H2O, known from x-ray analysis to approximate closely cubic space-group symmetry Ia3d, has been examined by neutron diffraction. Intensity data a single were collected for one octant so as be representative and some lower symmetries. In general, systematic absences consistent with space group Ia3d; within experimental error, six reflections equivalent Laue m3m equal in intensity. From Fourier difference syntheses least-squares...
MgNH4PO4.6H20 (struvite), Mr=245'4, Pmn2, a=6.955(1), b=6.142(1), c=11.218(2)A, V= 479.2 (2) ]k 3, Z = 2, Dx 1.70 Mg m -3, neutrons, A 1.179/~, /z 0.03 mm -t, room temperature. The structure was refined from 685 unique neutron diffraction data to R -- 0.032. ammonium group is completely ordered and linked by one single several polyfurcated N...O hydrogen bonds varying 2.800 (5) 3498 ~. Six out of eight W...O donated the water molecules are in range 2.630 (4)-2.649 A. survey studied reveals, on
Twins by merohedry can be usefully divided in two classes. Class I: the twin operation is contained Laue symmetry of crystal and twin-related reflexions have equal intensities; this case set intensities collected from a indistinguishable that on single crystal. II: at least one independent operations lattice but not (twin-related differ intensity); knowledge fractional volumes crystals necessary to solve structure. The solution refinement structure measurements performed class I are discussed.
It is shown that one of the main reasons for most failures methods calculating distance-dependent bond strengths related to distortion coordination polyhedra. The charge distribution (CD) method which depends on only universal empirical parameter (contraction parameter) modified include: (i) an iterative calculation effective number (ECoN), deal with structures containing very distorted polyhedra; (ii) a specific contraction treat any type hydrogen bond; (iii) scale factors subshells,...
The charge distribution (CD) method, previously introduced as a development of the bond-valence (BV) approach, is applied for first time to mineral structures, and specifically pyroxenes. CD essentially involves Effective Coordination Number (ECoN) cation among all neighboring anions. This then interpreted in terms 'charges', where 'charge' represents formal oxidation state. Differently from BV, description depends upon geometry each coordination polyhedron, which characterized through ECoN...