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Electrical characterization of electro-Ceramics
Published in Amit Sachdeva, Pramod Kumar Singh, Hee Woo Rhee, Composite Materials, 2021
X-ray crystallography is a technique in which the pattern produced by the diffraction of X-rays through the closely spaced atoms in a crystal is recorded and then analyzed to reveal the nature of that lattice (Figure 6.1). Geometrically, one may imagine that a crystal is made up of lattice planes and that the scattering from a given set of planes will only be strong if the X-ray reflected by each plane arrives at the detector in phase. This leads to a relationship between the order of diffraction pattern n, X-ray wavelength λ, the spacing between lattice planes d, and the angle of incidence θ known as Bragg’s law [11, 12]: 2dsinθ=nλ
An Introduction to Crystal Structures
Published in Elaine A. Moore, Lesley E. Smart, Solid State Chemistry, 2020
Elaine A. Moore, Lesley E. Smart
To understand the solid state, we need to have some insight into the structure of simple crystals and the forces that hold them together, so it is here that we start this book. Crystal structures are usually determined by the technique of X-ray crystallography. This technique relies on the fact that the distances between the atoms in the crystals are of the same order of magnitude as the wavelength of X-rays (of the order of 1 Å or 100 pm): a crystal thus acts as a three-dimensional diffraction grating to a beam of X-rays. The resulting diffraction pattern can be interpreted to give the internal positions of the atoms in the crystal very precisely, thus defining interatomic distances and angles. (Some of the principles underlying this technique are discussed in Chapter 2, where we review the physical methods available for characterising solids.) Most of the structures discussed in this book would have been determined in this way.
Mineral Crystals
Published in Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough, Earth Materials, 2019
Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough
Crystals, such as the huge ones in Cuevo de los Cristales, are solids with a fixed ratio of atoms held together by chemical bonds and arranged in an orderly and repeating way. The study of crystals and their formation is termed crystallography. Crystals may consist of a single element but, more commonly, they are compounds of two or more. The compositions of minerals, and how atoms bond together to create minerals, comprise the field of crystal chemistry. Because many natural materials are crystalline, crystallographic and crystal chemical studies today are directed at many kinds of materials—not just minerals. Among other applications, crystallography has been part of the semiconductor industry and the development of vitamins and drugs, and has allowed scientists to model the structure of DNA.
Synthesis of phosphoric triamide nanostructures, characterization, X-ray crystallography, and preparation of P2O5-RGO nanocomposites by solvothermal method
Published in Inorganic and Nano-Metal Chemistry, 2023
Tayebeh Charkhandaz, Niloufar Dorosti, Saeed Farhadi, Maciej Kubicki
Phosphorus pentoxide (P2O5) is a white crystalline material that is applied as a dehydrating agent in organic synthesis such the conversion of amides into nitriles, sulfuric acid into sulfur trioxide, and some other organic transformations.[16–18] It is also applied to fabricate phosphorus compounds, purifying sugar, optical glass, heat-insulating glass, medicine, pesticide, and surfactant manufacturing.[19] So far, phosphorus petnoxide reagent supported on different supports silica and alumina.[20] To our knowledge, this is the first report where P2O5 nanoparticles are decorated on RGO sheets via a solvothermal treatment with a phosphoric triamide as precursor. Therefore, we synthesized and characterized nano-phosphoric triamide with formula 4-NO2C6H4C(O)NHP(O)(NHC(CH3)3)2 under ultrasonic and microwave irradiation. Crystal structure of this compound was also determined by X-ray crystallography. The title phosphoric triamide in nano-size was used as an initial reagent to gain P2O5 nanoparticles with thermal decomposition. Finally, a P2O5-RGO nanocomposite was synthesized by a facile and one‐step solvothermal decomposition of 4-NO2C6H4C(O)NHP(O)(NHC(CH3)3)2 precursor over RGO. The structure of P2O5-RGO was thoroughly characterized by FTIR, SEM-EDS, XRD, and UV–vis spectroscopy.
Transition metal complexes incorporating lawsone: a review
Published in Journal of Coordination Chemistry, 2022
Freeda Selva Sheela Selvaraj, Michael Samuel, Arunsunai Kumar Karuppiah, Natarajan Raman
The molecular structure of a lawsone complex of zinc was investigated by Ali Dar and his team in detail. They prepared zinc complex with the formula [Zn(BrLw)2(H2O)2], where BrLw = Bromolawsone and characterized the complex with spectroscopic techniques such as UV, IR, 1H,13C-NMR and electrochemical studies such as cyclic voltammetry. The crystal structure had been evaluated by X-ray crystallography. Computational studies such as DFT have also been carried out using Gaussian-09 software. From X-ray diffraction studies, the ligand bromolawsone exists as an extended crystal network through π-π stacking interactions and the complex possesses intermolecular hydrogen bonding. The octahedral geometry and the coordination of lawsone to metals through cis, cis and trans, trans mode has been confirmed by X-ray diffraction studies. The trans, trans conformer possesses less energy and hence is more stable than the cis, cis conformer [34]. Kathawate et al. extended the same work to phthiocol (methylated lawsone) complex of zinc [71]. Neves et al. conducted structural studies on the metal complex of copper and zinc with the tridentate Mannich base ligand by X-ray crystallography [63]. The observed five-coordinate distorted square pyramidal geometry was in accordance with the theoretical DFT studies.
Binding polyprotic small molecules with second-sphere hydrogen bonds
Published in Journal of Coordination Chemistry, 2022
Morgan Hern, Rebecca Foley, John Bacsa, Christian M. Wallen
Reagents were purchased from Sigma-Aldrich, Oakwood Chemicals, or Ambeed and used without purification. Experiments run under anaerobic and anhydrous conditions were conducted in a VAC Genesis glovebox with solvents degassed under vacuum and dried using activated 3 Å molecular sieves. NMR data were collected on a Bruker 400 MHz instrument and referenced to residual solvent peaks. IR spectra were obtained using a Nicolet 6700 FT-IR with ATR attachment. Magnetic susceptibility was measured with an Evans balance. Electronic absorption data for characterization of isolated compounds were collected on a Shimadzu UV-2600 double-beam spectrophotometer using 1 cm pathlength quartz cuvettes. Electronic absorption data for photometric titrations were collected on a StellarNet BLACK-Comet-SR spectrometer with DP400-UVVIS-SR transmission dip probe fitted with a 10 mm path length tip. Crystal diffraction data were collected by Emory University Department of Chemistry X-Ray Crystallography Center. Additional crystallographic characterization information is included in the supplementary information. The precursor compounds N-(2-chloroethyl)-4-methylbenzene-1-sulfonamide [36] and para-toluenesulfonyl aziridine [37] have been previously characterized and published, but our modified synthetic procedures for these compounds are included here with select spectroscopic data for convenience.