SEARCH · Engineering Papers
Results for “CRYSTAL STRUCTURE”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
The seventh blind test of crystal structure prediction: structure generation methods
A seventh blind test of crystal structure prediction was organized by the Cambridge Crystallographic Data Centre featuring seven target systems of varying complexity: a silicon and iodine-containing molecule, a copper coordination complex, a near-rigid molecule, a cocrystal, a polymorphic small agrochemical, a highly flexible polymorphic drug candidate, and a polymorphic morpholine salt. In this first of two parts focusing on structure generation methods, many crystal structure prediction (CSP) methods performed well for the small but flexible agrochemical compound, successfully reproducing the experimentally observed crystal structures, while few groups were successful for the systems of higher complexity. A powder X-ray diffraction (PXRD) assisted exercise demonstrated the use of CSP in successfully determining a crystal structure from a low-quality PXRD pattern. The use of CSP in the prediction of likely cocrystal stoichiometry was also explored, demonstrating multiple possible approaches. Crystallographic disorder emerged as an important theme throughout the test as both a challenge for analysis and a major achievement where two groups blindly predicted the existence of disorder for the first time. Additionally, large-scale comparisons of the sets of predicted crystal structures also showed that some methods yield sets that largely contain the same crystal structures.
Crystal structure and orientation of organic semiconductor thin films by microcrystal electron diffraction and grazing-incidence wide-angle X-ray scattering
Explore the source record for details and available documents.
Crystal structure and luminescence properties of lead-free metal halides (C 6 H 5 CH 2 NH 3 ) 3 MBr 6 (M = Bi and Sb)
Organic–inorganic hybrid metal halides have received extensive attention owing to their versatile structures and optoelectronic properties. Herein, we report two lead-free metal halides, (PMA) 3 BiBr 6 and (PMA) 3 SbBr 6 [PMA + : (C 6 H 5 CH 2 NH 3 ) + , as the abbreviation of phenylmethylammonium], which possess iso-structural zero-dimensional structures and crystallize in the monoclinic space group P2 1 /c. (PMA) 3 BiBr 6 and (PMA) 3 SbBr 6 exhibit optical band gaps of ~3.50 and 3.40 eV, respectively, and density functional theory calculations reveal their indirect bandgap behaviors. Upon 350 and 425 nm excitation, (PMA) 3 BiBr 6 and (PMA) 3 SbBr 6 exhibit broadband emission peaking at 510 nm and 625 nm with wide full-widths at half-maximum of ~153 and 175 nm, respectively. The emission mechanism of the metal halides is attributed to self-trapped exciton emission. The relationship between the crystal structure and luminescence intensity is also discussed. Lastly, both metal halides have high decomposition temperatures and are stable for long-term storage under ambient conditions, demonstrating their potential for optoelectronic applications.
Comparing crystal structures with symmetry and geometry
Abstract Measuring the similarity between two arbitrary crystal structures is a common challenge in crystallography and materials science. Although there are an infinite number of ways to mathematically relate two crystal structures, only a few are physically meaningful. Here we introduce both a geometry-based and a symmetry-adapted similarity metric to compare crystal structures. Using crystal symmetry and combinatorial optimization we describe an algorithm to arrive at the structural relationship that minimizes these similarity metrics across all possible maps between any pair of crystal structures. The approach makes it possible to (i) identify pairs of crystal structures that are identical, (ii) quantitatively measure the similarity between crystal structures, and (iii) find and rank structural transformation pathways between any pair of crystal structures. We discuss the advantages of using the symmetry-adapted cost metric over the geometric cost. Finally, we show that all known structural transformation pathways between common crystal structures are recovered with the mapping algorithm. The methodology presented in this study will be of value to efforts that seek to catalogue crystal structures, identify structural transformation pathways or prune large first-principles datasets used to parameterize on-lattice Hamiltonians.
The crystal structure of dipotassium tetranitroethide
Crystal structure of dipotassium tetranitroethide determined by single crystal X-ray diffraction techniques
THE CRYSTAL STRUCTURE OF SODIUM BICARBONATE
Crystal structure of sodium bicarbonate
Crystal structure of aqua(citric acid)(hydrogen citrato)calcium monohydrate, [Ca(HC[subscript 6]H[subscript 5]O[subscript 7])(H[subscript 3]C[subscript 6]H[subscript 5]O[subscript 7])(H[subscript 2]O)]·H[subscript 2], from synchrotron X-ray powder data, and DFT-optimized crystal structure of existing calcium hydrogen citrate trihydrate, [Ca(HC[subscript 6]H[subscript 5]O[subscript 7])(H[subscript 2]O)[subscript 3]]
Abstract not provided
The crystal structure of strontium bromide.
Crystal structure analysis of strontium bromide, determining bromine atom positions
The crystal structure of strontium bromide
Crystal structure analysis of strontium bromide, determining bromine atom positions
THE CRYSTAL STRUCTURE OF PROPIONIC ACID
Crystal structure of propionic acid by x-ray diffraction
THE CRYSTAL STRUCTURE OF VALERIC ACID
Crystal structure of valeric acid - hydrogen bonding of fatty acids determined by x-ray diffraction
Crystal structure of beta-Mg2SiO4 - Crystal-chemical and geophysical implications
Crystal-chemical and geophysical implications concerning earth mantle phase transitions from beta magnesium silicate crystal structure
Crystal structure engineering in multimetallic high-index facet nanocatalysts
Significance Crystal structure engineering in nanoparticles represents an important strategy in catalyst design, as catalytic performance is highly dependent on atomic arrangement. However, realizing crystal structure engineering in high-index facet nanocatalysts has been a synthetic challenge for decades. Here, we first employed density functional theory calculations to determine whether surface modifications can stabilize high-index facets during crystal structure transformations and then synthesized a library of multimetallic high-index facet tetrahexahedral (THH) nanoparticles with controllable crystal structures. Importantly, the crystal structural transition between the intermetallic and chemically disordered states is reversable, and the THH morphology of nanocatalysts is maintained during this transformation. This approach broadens the synthetic scope of nanocatalysts available for use in diverse chemical processes.
CSD 2078665: Experimental Crystal Structure Determination
An entry from the Inorganic Crystal Structure Database, the world’s repository for inorganic crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the joint CCDC and FIZ Karlsruhe Access Structures service and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
CSD 2312746: Experimental Crystal Structure Determination
An entry from the Inorganic Crystal Structure Database, the world’s repository for inorganic crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the joint CCDC and FIZ Karlsruhe Access Structures service and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
CSD 2374310: Experimental Crystal Structure Determination
An entry from the Inorganic Crystal Structure Database, the world’s repository for inorganic crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the joint CCDC and FIZ Karlsruhe Access Structures service and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.