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AbstractInformation on the lattice parameter of single crystals with known crystallographic structure allows for estimations of sample quality and composition. In many cases it is sufficient to determine one lattice parameter or the lattice spacing along a certain, high- symmetry direction, e.g.
In order to determine the composition in a substitution series by taking advantage of Vegard’s rule. Here we present a guide to accurate measurements of single crystals with dimensions ranging from 200 μm up to several millimeter using a standard powder diffractometer in Bragg-Brentano geometry. The correction of the error introduced by the sample height and the optimization of the alignment are discussed in detail. Finally, in particular for single crystals with a plate-like habit, the described procedure allows for measurement of the lattice spacings normal to the plates with high accuracy on a timescale of minutes. Of Augsburg, Augsburg (Germany). Of Physics, Center for Electronic Correlations and Magnetism; Ames Lab., Ames, IA (United States).
I find that using a low background sample holder for an acetone smear of a. Set delivered with the instrument, we got a so-called 'zero-background holder',.
Univ. Of Augsburg, Augsburg (Germany). Of Physics, Center for Electronic Correlations and Magnetism. Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States). We report the growth of single crystals of SrCu2As2, SrCu2Sb2, SrCu2(As0.84Sb0.16)2, and BaCu2Sb2 using the self-flux technique and their structural, magnetic, thermal, and transport properties that were investigated by powder x-ray diffraction (XRD), magnetic susceptibility χ, specific heat Cp, and electrical resistivity ρ measurements versus temperature T from 1.8 to 350 K. Rietveld refinements of XRD patterns for crushed crystals confirm that SrCu2As2 crystallizes in the ThCr2Si2-type body-centered tetragonal structure (space group I4/mmm) and SrCu2Sb2 crystallizes in the CaBe2Ge2-type primitive tetragonal structure (space group P4/nmm).
However, as reported previously, BaCu2Sb2 is found to have a large unit cell consisting of three blocks. Here a ThCr2Si2-type block is sandwiched between two CaBe2Ge2-type blocks along the c axis with an overall symmetry of I4/mmm, as reported, but likely with a monoclinic distortion. The χ data of all these compounds are diamagnetic and reveal nearly T-independent anisotropic behavior. The χ of SrCu2As2 is found to be larger in the ab plane than along the c axis, as also previously reported for pure and doped BaFe2As2, whereas the χ values of SrCu2Sb2 and BaCu2Sb2 are larger along the c axis. This difference in anisotropy appears to arise from the differences between the crystal structures. The finite values of the Sommerfeld linear specific heat coefficients γ and the T dependences of ρ reveal metallic character of all four compounds. The electronic and magnetic properties indicate that these compounds are sp metals with Cu in the nonmagnetic 3d10 electronic configuration corresponding to the oxidation state Cu+1, as previously predicted theoretically for SrCu2As2 by Singh Phys.
B 79 153102 (2009). We present a brief review of theoretical and experimental work on the doping character of transition metals for Fe in BaFe2As2. The As–As covalent interlayer bond distances in the collapsed-tetragonal (Ca,Sr,Ba)Cu2As2 compounds are much shorter than the nonbonding As–As distances in BaFe2As2.
Thus, the electronic character of the Cu and the strength of the As–As interlayer bonding are both expected to drastically change between weakly Cu-substituted BaFe2As2 and pure BaCu2As2, perhaps via a first-order lattice instability such as a miscibility gap in the Ba(Fe1−xCux)2As2 system.
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Specifications:. Crystal: Si, P-type B-doped. Resistivity:10-15 ohm.cm. Size: 24.6 mm diameter x 1.0 mm thickness. Surface: one side optical polished.
Cavity zero diffraction plate is made of Silicon cut at special orientation. Perfect for sample holder of powder XRD, which has no background noise from 20 to 120 degree ( 2 θ angle Cu Ka X-Ray).
Fit with XRD of Siemens, Scintag, Rugaku and many more. Typical XRD of Si zero plate.Please click pictures below to find other size zero diffraction plates and related products.