scholarly journals Identification of promising chemical systems for the synthesis of new materials structure types: An ab initio minimization data mining approach

2013 ◽  
Vol 7 (1) ◽  
pp. 37-41 ◽  
Author(s):  
Dejan Zagorac ◽  
Johann Schön ◽  
Martin Jansen
Keyword(s):  
Ab Initio ◽  
Theoretical Work ◽  
Structure Type ◽  
Alkaline Metal ◽  
New Materials ◽  
Chemical Systems ◽  
Data Mining Approach ◽  
The Earth ◽  
Alkali Metal Halides ◽  
Binary Compounds

In this research we performed data exploring for binary compounds with elements from groups V, IV-VI, and III-VII, with the goal to identify chemical systems where the recently proposed ?5-5? structure type might be experimentally accessible. Among others, TlF, SnO, SnS, SnSe, GeS, GeSe, PbO, PbS, ZnO and ZnS, were chosen for the study. For each of these systems, a local optimization on ab initio level with the LDA functional was performed for the 5-5 structure type, plus other experimentally observed and theoretically proposed structure types, for comparison. Afterwards, the results were combined with earlier theoretical work involving the 5-5 structure in the earth alkaline metal oxides and the alkali metal halides. As a result, we suggest the GeSe and the ZnO systems as the most suitable ones for synthesizing the 5-5 structure type.

The Earth Mover’s Distance as a Metric for the Space of Inorganic Compositions

2020 ◽  
Author(s):  
Cameron Hargreaves ◽  
Matthew Dyer ◽  
Michael Gaultois ◽  
Vitaliy Kurlin ◽  
Matthew J Rosseinsky
Keyword(s):  
Euclidean Distance ◽  
Nearest Neighbor ◽  
Nearest Neighbor Search ◽  
Inorganic Crystal Structure Database ◽  
Earth Mover’S Distance ◽  
Chemical Similarity ◽  
Earth Mover's Distance ◽  
Neighbor Search ◽  
The Earth ◽  
Binary Compounds

It is a core problem in any field to reliably tell how close two objects are to being the same, and once this relation has been established we can use this information to precisely quantify potential relationships, both analytically and with machine learning (ML). For inorganic solids, the chemical composition is a fundamental descriptor, which can be represented by assigning the ratio of each element in the material to a vector. These vectors are a convenient mathematical data structure for measuring similarity, but unfortunately, the standard metric (the Euclidean distance) gives little to no variance in the resultant distances between chemically dissimilar compositions. We present the Earth Mover’s Distance (EMD) for inorganic compositions, a well-defined metric which enables the measure of chemical similarity in an explainable fashion. We compute the EMD between two compositions from the ratio of each of the elements and the absolute distance between the elements on the modified Pettifor scale. This simple metric shows clear strength at distinguishing compounds and is efficient to compute in practice. The resultant distances have greater alignment with chemical understanding than the Euclidean distance, which is demonstrated on the binary compositions of the Inorganic Crystal Structure Database (ICSD). The EMD is a reliable numeric measure of chemical similarity that can be incorporated into automated workflows for a range of ML techniques. We have found that with no supervision the use of this metric gives a distinct partitioning of binary compounds into clear trends and families of chemical property, with future applications for nearest neighbor search queries in chemical database retrieval systems and supervised ML techniques.

ChemInform Abstract: Synthesis, Structural Characterization, and ab Initio Study of Cu5+δIn2+xSb2-x: A New B8-Related Structure Type.

ChemInform ◽  
2013 ◽  
Vol 44 (1) ◽  
pp. no-no
Author(s):  
Carola J. Mueller ◽  
Sven Lidin ◽  
Susana Ramos de Debiaggi ◽  
Crispulo E. Deluque Toro ◽  
Armando Fernandez Guillermet
Keyword(s):  
Ab Initio ◽  
Structural Characterization ◽  
Structure Type ◽  
Related Structure ◽  
Ab Initio Study

scholarly journals Darstellung und Kristallstruktur von K2Sn2S5 und K2Sn2Se5 / Preparation and Crystal Structure of K2Sn2S5 and K2Sn2Se5

1992 ◽  
Vol 47 (2) ◽  
pp. 197-200 ◽  
Author(s):  
Kurt O. Klepp
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structure Type ◽  
Slow Cooling ◽  
Bond Lengths ◽  
Trigonal Bipyramidal ◽  
Equatorial Bond ◽  
Binary Compounds ◽  
R Factors ◽  
Distorted Trigonal Bipyramidal

K2Sn2S5 and K2Sn2Se5 were prepared by reacting stoichiometric powdered mixtures of the binary compounds K2S or K2Se with Sn and the corresponding chalcogen at 1070 K, followed by slow cooling of the melt. The two compounds are isostructural and crystallize with the Tl2Sn2S5 structure type, s.g. C 2/c, Z = 4 with a = 11.072(5) Å, b = 7.806(3)Å, c = 11.517(5)Å, β = 108.43(2)° for K2Sn2S5 and a = 11.613(5)Å, b = 8.189(3) Å, c = 11,897(6) Å, β = 108.28(2)° for K2Sn2Se5. The crystal structures were refined to conventional R-factors of 0.032 and 0.031, respectively. Sn-atoms are in a distorted trigonal-bipyramidal chalcogen coordination. The average equatorial bond lengths are Sn -S: 2.427 Å and Sn -Se: 2.552 Å , the axial ones are Sn -S: 2.600 Å and Sn -Se: 2.774 Å.

ISSUES OF STUDYING AND PRESERVING OF KAZAKH WINTERINGS

2021 ◽  
Vol 27 ◽  
pp. 7-16
Author(s):  
BEISENOV A. ◽  
Keyword(s):  
New Materials ◽  
The Earth ◽  
The Face ◽  
Comprehensive Study

The report provides new materials on the Kazakh winterings of the 19th - early 20th centuries, located in the eastern regions ofCentral Kazakhstan. Winterings were built using stone, wood and adobe bricks, and at present they are represented only by ruins of varying preservation. Winterings is a type of poorly explored sites. Currently, the need to develop a methodology for their comprehensive study is especially growing. It is important to carry out work to identify and permanently fix these sites. Winterings belong to the category of rapidly decaying sites, most of them have already disappeared from the face of the earth. According to the author, the Kazakh winterings mark the locations of the settlements of the Saka time and very often they overlap the sites of ancient dwellings. Among the new data, such facts were noted in the tracts ofDosbolay, Mauke, Malmak, Tungatar. In modern studies of the ruins of Kazakh winterings, old photographs and paintings stored in the funds of museums can be used as important additional materials. Keywords: Kazakh winterings, Kazakh Upland, settlements of the Saka time, topography, S.M. Dudin

Multi-Species Multi-Channel (MSMC): An Ab Initio- based Parallel Thermodynamic and Kinetic Code for Complex Chemical Systems

2015 ◽  
Vol 47 (9) ◽  
pp. 564-575 ◽  
Author(s):  
Minh V. Duong ◽  
Hieu T. Nguyen ◽  
Nghia Truong ◽  
Thong N.-M. Le ◽  
Lam K. Huynh
Keyword(s):  
Ab Initio ◽  
Complex Chemical ◽  
Chemical Systems

scholarly journals Geometrical parameterization of the crystal chemistry of P63/m apatites: comparison with experimental data and ab initio results

2005 ◽  
Vol 61 (6) ◽  
pp. 635-655 ◽  
Author(s):  
Patrick H. J. Mercier ◽  
Yvon Le Page ◽  
Pamela S. Whitfield ◽  
Lyndon D. Mitchell ◽  
Isobel J. Davidson ◽  
...  
Keyword(s):  
Single Crystal ◽  
Ab Initio ◽  
Minimum Energy ◽  
Structure Type ◽  
Chemical Model ◽  
Crystal Chemical ◽  
Chemical Parameters ◽  
Rietveld Refinements ◽  
Cell Parameters ◽  
Cell Data

Experimental structure refinements and ab initio simulation results for 18 published, fully ordered P63/m (A^{\rm I}_4)(A^{\rm II}_6)(BO4)6 X 2 apatite end-member compositions have been analyzed in terms of a geometric crystal-chemical model that allows the prediction of unit-cell parameters (a and c) and all atom coordinates. To an accuracy of ± 0.025 Å, the magnitude of c was reproduced from crystal-chemical parameters characterizing chains of …–A II–O3–B–O3–A II–... atoms, whereas that of a was determined from those describing (A IO6)–(BO4) polyhedral arrangements. The c/a ratio could be predicted to ±0.2% using multi-variable functions based on geometric crystal-chemical model predictions, but could not be ascribed to the adjustment of a single crystal-chemical parameter. The correlations observed between algebraically independent crystal-chemical parameters representing the main observed polyhedral distortions reveal them as the minimum-energy solution to accommodate misfit components within this flexible structure type. For materials with given composition, good agreement (within ± 0.5–2.0%) of ab initio crystal-chemical parameters was observed with only those from single-crystal refinements with R ≤ 4.0%. Agreement with single-crystal work with R > 4.0% was not as good, while the scatter with those from Rietveld refinements was considerable. Accordingly, ab initio cell data, atomic coordinates and crystal-chemical parameters were reported here for the following compositions awaiting experimental work: (Zn,Hg)10(PO4)6(Cl,F)2, (Ca,Cd)10(VO4)6Cl2 and (Ca,Pb,Cd)10(CrO4)6Cl2.

Ab initio structure determination of nanosized θ-KAlF4 with edge-sharing AlF6 octahedra

2009 ◽  
Vol 24 (3) ◽  
pp. 185-190 ◽  
Author(s):  
A. Le Bail
Keyword(s):  
Crystal Structure ◽  
Ab Initio ◽  
Fluorite Structure ◽  
Structure Type ◽  
Powder Diffraction Data ◽  
Orthorhombic Unit Cell ◽  
Common Edge ◽  
X Ray ◽  
Ab Initio Structure

θ-KAlF4 is a new nanosized potassium tetrafluoroaluminate metastable polymorph (13×18×55 nm3). The crystal structure is solved ab initio from X-ray powder diffraction data in direct space [orthorhombic unit cell with a=8.3242(3) Å, b=7.2502(3) Å, c=11.8875(4) Å, V=717.44(5) Å3, Z=8, and space group Pnma]. This new structure type, unique in the whole AIMIIIF4 family, is related to the fluorite structure and consists of AlF6 octahedra linked via a common edge forming a bioctahedral motif which is trans-connected through the corner-shared fluorine, resulting in the formation of infinite ladderlike double file of octahedra ([Al2F8]2−)n running along the b axis.

scholarly journals Use of Precession Electron and X Powder for solution and refinement of materials

2014 ◽  
Vol 70 (a1) ◽  
pp. C927-C927
Author(s):  
Marie Colmont ◽  
Lukas Palatinus ◽  
Marielle Huvé ◽  
Olivier Mentré ◽  
Pascal Roussel
Keyword(s):  
Ab Initio ◽  
Title Compound ◽  
Rietveld Method ◽  
Structural Type ◽  
A Posteriori ◽  
New Materials ◽  
X Ray ◽  
3D Tomography ◽  
System A

This communication will present the case study of ALa5O5(VO4)2 (A= Li, Na, K, Rb), example of the use of a combination of Precession Electron and X-ray Powder Data for the solution and the refinement of new materials. Indeed, an original structural type has been evidenced in the system (A, La, V, O) with A=Li, Na, K, Rb. Attempts to solve the structure ab initio on X-ray powder data were unsuccessful (more particularly because the powder was a mixture of the title compound and of unreacted precursors). The structure was finally solved by charge flipping using Precession Electron Data (3D tomography) on a nanocrystal, enabling a posteriori the good formulation of a pure powder. This powder was then classically refined by Rietveld method showing the correctness of the electron-solved structure. It crystallizes in a monoclinic unit cell with space group C2/m and a=20.2282(14) b=5.8639(4) c=12.6060(9) Å and β=117.64(1)0. The ALa5O5(VO4)2 structure is built of (OLa4) tetrahedral units creating Crenel-like 2D ribbons. These ribbons, surrounded by four isolated VO4 tetrahedra, are creating channels parallel to b axis in which A+ ions are located.

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