CeAsSeSynthesis, Crystal Structure, and Physical Properties

Abstract

Single crystals of CeAsSe were synthesized by a reaction of the elements using iodine as a mineralization agent at 900 degrees C. The crystal structure was established from single crystal X-ray diffraction data and obtained from a pseudomerohedrically twinned specimen (space group Pnma, a = 5.7969(1) A, b = 5.7664(1) A, and c = 17.8196(6) A; Z = 8). CeAsSe crystallizes in the GdPS type of structure and contains infinite cis-trans chains of arsenic atoms, packed between two-dimensional slabs of alternating Ce and Se atoms. The chemical composition of the investigated crystals was determined to be CeAs(1.01(1))Se(0.99(3)). High-resolution diffraction experiments with synchrotron radiation clearly evidence the orthorhombic metric. However, variations in composition or temperature profile in the synthesis procedure lead to vanishing distortion, that is, disappearance of reflection splitting and superstructure reflections, and thus to a tetragonal metric within the resolution of the synchrotron-based diffraction experiments. CeAsSe can be expressed as consisting of Ce(3+), As(1-), and Se(2-) as an electronic precise Zintl-type compound. This interpretation is consistent with the results of X-ray absorption spectroscopy at the Ce-L(III) edge and magnetic susceptibility data. The temperature dependence of a semiconductor was observed in electrical resistivity measurements.

Synthesis and Crystal Growth of Tetragonal β‐Fe1.00Se

“…Thus, the symmetry of the projections is consistent with the selected space group of the crystal structure. The observed plate‐like morphology of β‐Fe x Se crystals and the obtained diffraction data are in accordance with the layered atomic pattern28 implying that the compound grows preferentially perpendicular to the c axis as observed in other layered chalcogenides 29,30. According to the results of crystal structure refinements, large crystals exhibit pronounced extinction.…”

“…The observed plate-like morphology of β-FexSe crystals and the obtained diffraction data are in accordance with the layered atomic pattern [28] implying that the compound grows preferentially perpendicular to the c-axis as observed in other layered chalcogenides. [29][30] According to the results of crystal structure refinements, large crystals exhibit pronounced extinction. Thus, the given results (Tables 2 and 3 [a] Lattice parameters were calculated from X-ray powder diffraction data using TiO2 as an internal standard.…”

Twisted nodal wires and three-dimensional quantum spin Hall effect in distorted square-net compounds

“…S1 and Table S1 in SM B], which allows us to adopt various chemical doping. In particular, crystals of CeAs 1+x Se 1−y and EuCdSb 2 compounds with an insulating behavior have been synthesized successfully in P nma structure [27,28].…”

Crystal Chemistry and Physical Properties of the Nonmagnetic Kondo Compound HfAs1.7Se0.2

“…[16,17] For example, for CeAsSe significant distortion due to formation of infinite cis-trans As chains was analyzed only recently . [11] This distortion can be clearly recognized due to reflection splitting and superstructure reflections in high-resolution diffraction experiments for samples with chemical compositions close to the ideal atomic ratio of 1:1:1. Any deviation from this ideal atomic ratio leads to reduced distortion.…”

“…In the respective Hf system we succeeded in the synthesis of HfAs 1.7 Se 0.2 only recently. [8] This system exemplifies the close chemical, physical, and crystallographic relations with the zirconium, [9,10] cerium, [11] and thorium arsenide selenides. [12,13] The intensively studied metallic phase ZrAs 1.4 Se 0.5 crystallizes in the PbFCl structure type without indications for any deviation from the ideal tetragonal metric.…”