scholarly journals Crystal structure and chemistry of topological insulators

2013 ◽  
Vol 1 (19) ◽  
pp. 3176 ◽  
Author(s):  
R. J. Cava ◽  
Huiwen Ji ◽  
M. K. Fuccillo ◽  
Q. D. Gibson ◽  
Y. S. Hor
Keyword(s):  
Crystal Structure ◽  
Topological Insulators ◽  
Crystal Structure And Chemistry

ChemInform Abstract: Crystal Structure and Chemistry of a Complex Indium Phosphate Framework Material, (Ethylenediammonium)In3P3O12(OH)2.

ChemInform ◽  
2013 ◽  
Vol 44 (5) ◽  
pp. no-no
Author(s):  
Robert W. Broach ◽  
Robert L. Bedard ◽  
Lisa M. King ◽  
Joseph J. Pluth ◽  
Joseph V. Smith ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Crystal Structure And Chemistry

scholarly journals Crystallinity of tellurium capping and epitaxy of ferromagnetic topological insulator films on SrTiO3

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Jihwey Park ◽  
Yeong-Ah Soh ◽  
Gabriel Aeppli ◽  
Xiao Feng ◽  
Yunbo Ou ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electronic Structure ◽  
Transport Properties ◽  
Topological Insulator ◽  
Topological Insulators ◽  
Surface States ◽  
Crystal Quality ◽  
X Rays ◽  
Capping Layer ◽  
Subtle Effect

Abstract Thin films of topological insulators are often capped with an insulating layer since topological insulators are known to be fragile to degradation. However, capping can hinder the observation of novel transport properties of the surface states. To understand the influence of capping on the surface states, it is crucial to understand the crystal structure and the atomic arrangement at the interfaces. Here, we use x-ray diffraction to establish the crystal structure of magnetic topological insulator Cr-doped (Bi,Sb)2Te3 (CBST) films grown on SrTiO3 (1 1 1) substrates with and without a Te capping layer. We find that both the film and capping layer are single crystal and that the crystal quality of the film is independent of the presence of the capping layer, but that x-rays cause sublimation of the CBST film, which is prevented by the capping layer. Our findings show that the different transport properties of capped films cannot be attributed to a lower crystal quality but to a more subtle effect such as a different electronic structure at the interface with the capping layer. Our results on the crystal structure and atomic arrangements of the topological heterostructure will enable modelling the electronic structure and design of topological heterostructures.

The crystal structure and chemistry of mereheadite

2009 ◽  
Vol 73 (1) ◽  
pp. 103-117 ◽  
Author(s):  
S. V. Krivovichev ◽  
R. Turner ◽  
M. RumseY ◽  
O. I. Siidra ◽  
C. A. Kirk
Keyword(s):  
Crystal Structure ◽  
Lead Oxide ◽  
Direct Methods ◽  
Structural Formula ◽  
The Other ◽  
Naturally Occurring ◽  
Pb Ions ◽  
Oriented Parallel ◽  
Crystal Structure And Chemistry ◽  
The Ideal

The crystal structure of mereheadite (monoclinic, Cm, a = 17.372(1), b = 27.9419(19), c = 10.6661(6) Å, β = 93.152(5)°, V = 5169.6(5) Å3) has been solved by direct methods and refined to R1 = 0.058 for 6279 unique observed reflections. The structure consists of alternating Pb–O/OH blocks and Pb–Cl sheets oriented parallel toth e (201) plane and belongs toth e 1:1 type of lead oxide halides with PbO blocks. It contains 30 symmetrically independent Pb positions, 28 of which belong to the PbO blocks, whilst two positions (Pb12 and Pb16) are located within the tetragonal sheets of the Cl– anions. Mereheadite is thus the first naturally occurring lead oxychloride mineral with inter-layer Pb ions. The coordination configurations of the Pb atoms of the PbO blocks are distorted versions of the square antiprism. In one half of the coordination hemisphere, they are coordinated by hard O2– and OH– anions whose number varies from three to four, whereas the other coordination hemisphere invariably consists of four soft Cl– anions located at the vertices of a distorted square. The Pb12 and Pb16 atoms in between the PbO blocks have an almost planar square coordination of four Cl– anions. These PbCl4 squares are complemented by triangular TO3 groups (T = B, C) so that a sevenfold coordination is achieved. The Pb–O/OH block in mereheadite can be obtained from the ideal PbO block by the following list of procedures: (1) removal of some PbO4 groups that results in the formation of square-shaped vacancies; (2) insertion of TO3 groups into these vacancies; (3) removal of some Pb atoms (that correspond to the Pb1A and Pb2A sites), thus transforming coordination of associated O sites from tetrahedral OPb4 tot riangular OHPb3; and (4) replacement of two O2– anions by one OH– anion with twofold coordination; this results in formation of the 1×2 elongated rectangular vacancy. The structural formula that can be derived on the basis of the results of single-crystal structure determination is Pb47O24(OH)13Cl25(BO3)2(CO3). Welch et al. (1998) proposed the formula Pb2O(OH)Cl for mereheadite, which assumes that neither borate nor carbonate is an essential constituent of mereheadite and their presence in the mineral is due to disordered replacements of Cl– anions. However, our study demonstrates that this is not the case, as BO3 and CO3 groups have well-defined structural positions confined in the vacancies of the Pb–O/OH blocks and are therefore essential constituents. Our results also show that mereheadite is not a polymorph of blixite, but is in fact related to symesite. Symesite thus becomes the baseline member of a group of structurallyrelated minerals.

ChemInform Abstract: Preparation, X-Ray Crystal Structure, and Chemistry of Stable Azidoiodinanes - Derivatives of Benziodoxole.

ChemInform ◽  
2010 ◽  
Vol 27 (38) ◽  
pp. no-no
Author(s):  
V. V. ZHDANKIN ◽  
A. P. KRASUTSKY ◽  
C. J. KUEHL ◽  
A. J. SIMONSEN ◽  
J. K. WOODWARD ◽  
...  
Keyword(s):  
Crystal Structure ◽  
X Ray ◽  
Derivatives Of ◽  
Crystal Structure And Chemistry

Crystal structure and chemistry of natural kutinaite from Černý Důl, Krkonoše, Czech Republic

2015 ◽  
Vol 79 (5) ◽  
pp. 1099-1109 ◽  
Author(s):  
Luca Bindi ◽  
Emil Makovicky
Keyword(s):  
Crystal Structure ◽  
Czech Republic ◽  
Metal Contacts ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Metal Metal ◽  
Crystal Structure And Chemistry

AbstractWe have characterized the crystal structure of natural kutinaite, a rare mineral from the ores of Černý Důl, Czech Republic, by single-crystal X-ray diffraction and chemical analysis. We found that the structure of natural kutinaite is not identical to that of synthetic Cu14Ag6As7, previously reported to be cubic, space group Pm3m. Although topologically similar, the structure of natural kutinaite is indeed tetragonal, space group P4/mmm, with cell parameters: a = 11.789(2), c = 11.766(2) Å, V = 1635.5(4) Å3 and Z = 4. Electron microprobe analyses pointed to the (K,Tl)0.25Cu14Ag6As6.75 stoichiometry (Z = 4), or (K, Tl)Cu56Ag24As27 with Z = 16. The crystal structure of an untwinned crystal has been refined to R1 = 2.61%. It consists of clusters of eight edge-sharing tetrahedra of Cu, which alternate in a 3D chess-board manner with octahedral clusters of six Ag atoms. The latter are surrounded by triangularly coordinated copper in eight faces of a cuboctahedron. The last structure components are large cavities containing partly occupied (K,Tl) sites, coordinated by 18 Ag and As ligands. The structure is full of direct metal-metal contacts although As plays the role of anion, associating especially with copper.

Orthometalation of m-bis(dimethylaminomethyl)benzene: crystal structure and chemistry of trans-Rh(III)Cl2[C6H3(CH2NMe2)2-o,o'](H2O)

1988 ◽  
Vol 27 (6) ◽  
pp. 1014-1019 ◽  
Author(s):  
Adolphus A. H. Van der Zeijden ◽  
Gerard Van Koten ◽  
Ronald Luijk ◽  
Kees Vrieze ◽  
Cees Slob ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Crystal Structure And Chemistry
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