Crystal-structure calculations with distorted ions

1993 ◽  
Vol 48 (5) ◽  
pp. 2889-2908 ◽  
Author(s):  
Daniel J. Lacks ◽  
Roy G. Gordon
Keyword(s):  
Crystal Structure ◽  
Structure Calculations ◽  
Crystal Structure Calculations

Vibrational properties of nanoparticles iron oxide by Raman spectroscopy

2020 ◽  
pp. 2150125
Author(s):  
T. A. Darziyeva ◽  
E. Sh. Alekperov ◽  
S. H. Jabarov ◽  
M. N. Mirzayev
Keyword(s):  
Crystal Structure ◽  
Raman Spectroscopy ◽  
Iron Oxide ◽  
Gaussian Function ◽  
High Symmetry ◽  
X Ray Diffraction ◽  
Cubic Crystal ◽  
Cubic Symmetry ◽  
Structure Calculations ◽  
Crystal Structure Calculations

The crystal structure and atomic dynamics of Fe3O4 nanoparticles have been studied. The crystal structure of iron oxide nanoparticles was determined by X-ray diffraction. The analysis showed that the crystal structure of [Formula: see text] 50–100 nm dimensional iron oxide corresponds to a high symmetry cubic crystal structure. Calculations have shown that there are four infrared active, five Raman active and seven hyper-Raman active modes in the space group Fd-3m with cubic symmetry. Four of these modes have been observed using Raman spectroscopy: 213, 271, 380 and 591 cm[Formula: see text]. The vibrational modes are interpreted by Gaussian function. It was found that these vibration modes correspond to the vibration of O–Fe–O bonds and iron-oxygen polyhedra.

scholarly journals NMR Crystallography at Fast Magic-Angle Spinning Frequencies: Application of Novel Recoupling Methods

Crystals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 231 ◽  
Author(s):  
Mukul G. Jain ◽  
Kaustubh R. Mote ◽  
Perunthiruthy K. Madhu
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Solid State Nmr ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Nmr Crystallography ◽  
Angle Spinning ◽  
Fast Magic Angle Spinning ◽  
Structure Calculations ◽  
Crystal Structure Calculations

Chemical characterisation of active pharmaceutical compounds can be challenging, especially when these molecules exhibit tautomeric or desmotropic behaviour. The complexity can increase manyfold if these molecules are not susceptible to crystallisation. Solid-state NMR has been employed effectively for characterising such molecules. However, characterisation of a molecule is just a first step in identifying the differences in the crystalline structure. 1 H solid-state Nuclear Magnetic Resonance (ssNMR) studies on these molecules at fast magic-angle-spinning frequencies can provide a wealth of information and may be used along with ab initio calculations to predict the crystal structure in the absence of X-ray crystallographic studies. In this work, we attempted to use solid-state NMR to measure 1 H - 1 H distances that can be used as restraints for crystal structure calculations. We performed studies on the desmotropic forms of albendazole.

Polymorphism and the influence of crystal structure on the luminescence of the opto-electronic material 4,4′-bis(9-carbazolyl)biphenyl

CrystEngComm ◽  
2014 ◽  
Vol 16 (33) ◽  
pp. 7621-7625 ◽  
Author(s):  
Cody J. Gleason ◽  
Jordan M. Cox ◽  
Ian M. Walton ◽  
Jason B. Benedict
Keyword(s):  
Crystal Structure ◽  
Electronic Structure ◽  
Electronic Material ◽  
Single Crystal ◽  
Charge Transport ◽  
Luminescent Properties ◽  
Electronic Structure Calculations ◽  
Electronic Charge ◽  
Single Crystal Structures ◽  
Structure Calculations

Single crystal structures, luminescent properties and electronic structure calculations of three polymorphs of the opto-electronic charge transport material 4,4′-bis(9-carbazolyl)biphenyl.

Crystal structure characterization and electronic structure of a rare-earth-containing Zintl phase in the Yb–Al–Sb family: Yb3AlSb3

2021 ◽  
Vol 77 (6) ◽  
Author(s):  
Rongqing Shang ◽  
An T. Nguyen ◽  
Allan He ◽  
Susan M. Kauzlarich
Keyword(s):  
Crystal Structure ◽  
Electronic Structure ◽  
Rare Earth ◽  
Electronic Structure Calculations ◽  
Structure Characterization ◽  
Charge Balance ◽  
X Ray Diffraction ◽  
Zintl Phase ◽  
X Ray ◽  
Structure Calculations

A rare-earth-containing compound, ytterbium aluminium antimonide, Yb3AlSb3 (Ca3AlAs3-type structure), has been successfully synthesized within the Yb–Al–Sb system through flux methods. According to the Zintl formalism, this structure is nominally made up of (Yb2+)3[(Al1−)(1b – Sb2−)2(2b – Sb1−)], where 1b and 2b indicate 1-bonded and 2-bonded, respectively, and Al is treated as part of the covalent anionic network. The crystal structure features infinite corner-sharing AlSb4 tetrahedra, [AlSb2Sb2/2]6−, with Yb2+ cations residing between the tetrahedra to provide charge balance. Herein, the synthetic conditions, the crystal structure determined from single-crystal X-ray diffraction data, and electronic structure calculations are reported.

Kristall- und elektronische Struktur von LaAlSi2 / Crystal and Electronic Structure of LaAlSi2

2001 ◽  
Vol 56 (7) ◽  
pp. 620-625 ◽  
Author(s):  
Christian Kranenberg ◽  
Dirk Johrendt ◽  
Albrecht Mewis ◽  
Winfried Kockelmann
Keyword(s):  
Crystal Structure ◽  
Electronic Structure ◽  
Neutron Diffraction ◽  
Structure Type ◽  
X Ray ◽  
Arc Melting ◽  
Band Structure Calculations ◽  
Ray Methods ◽  
Structure Calculations ◽  
Crystal And Electronic Structure

Abstract LaAlSi2 (a = 4.196(2), c = 11.437(7) Å; P3̄ml; Z = 2) was synthesized by arc-melting of preheated mixtures of the elements. The compound was investigated by means of X-ray methods and by neutron diffraction. The crystal structure can be described as a stacking variant of two different segments. The first one corresponds to the CaAl2Si2 structure type (LaAl2Si2), the second one with the A1B2 structure type (LaSi2). The segments are stacked along [001]. The electronic structure of the compound is discussed on the basis of LMTO band structure calculations.

scholarly journals Modelling of Atomic Imaging and Evaporation in the Field Ion Microscope

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Keith J. Fraser ◽  
John J. Boland
Keyword(s):  
Field Strength ◽  
Scanning Probe Microscopy ◽  
Finite Difference Methods ◽  
Scanning Probe ◽  
Voltage Distribution ◽  
Difference Methods ◽  
Field Ion Microscope ◽  
Structure Calculations ◽  
Crystal Structure Calculations ◽  
Strong Agreement

Imaging and evaporation of atoms in the field ion microscope (FIM) has been modelled by using finite difference methods to calculate the voltage distribution around a tip and hence the electric field strength experienced by individual atoms. Atoms are evaporated based on field strength using a number of different mathematical models which yield broadly similar results. The tip shapes and simulated FIM images produced show strong agreement with experimental results for tips of the same orientation and crystal structure. Calculations have also been made to estimate the effects on resolution of using a field-sharpened tip for scanning probe microscopy.

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