The Preparation of Crystalline NbSe2/TiSe2 Superlattices from Modulated Elemental Reactants

1995 ◽  
Vol 382 ◽  
Author(s):  
Myungkeun Noh ◽  
James Thiel ◽  
David C. Johnson
Keyword(s):  
Diffraction Data ◽  
Substrate Surface ◽  
Domain Size ◽  
High Angle ◽  
High Quality ◽  
Rocking Curve ◽  
Modulated Elemental Reactants ◽  
Unit Cells ◽  
Controlled Crystallization ◽  
Elemental Reactants

ABSTRACTThree new crystalline NbSe2/TiSe2 superlattice compounds with 43.472±0.005A, 80.66±0.03A and 117.9±0.1Å unit cells in thec direction were prepared through controlled crystallization of Ti/Se/Nb/Se superlattice reactants with different compositional layer thicknesses. Theta-theta and rocking curve data were collected using a theta-theta diffractometer to study the evolution of the initially layered reactants into the crystalline superlattices as a function of temperature. Low angle diffraction data demonstrates that the initial layered reactant contracts in the c-axis direction upon initial annealing and suggests that the interfaces become smoother during this initial interdiffusion. High angle rocking curve diffraction data shows the development of caxis oriented NbSe2fTiSe2 crystal growth perpendicular to the substrate surface. Theta-theta scans show a gradual decrease of the (001) diffraction linewidths of the growing compound as a function of annealing time and temperature indicating an increase in the c-axis domain size. High quality caxis oriented TiSe2/NbSe2 crystalline superlattices result from annealing at the relatively low temperature of 500ºC. The rational synthesis of intergrowth compounds from superlattice reactants as described herein will permit the tailoring of physical properties as a function of compositional layer thicknesses and nativeproperties of the parent compounds.

The Synthesis and Superconducting Behavior of Crystalline Superlattices: (TiSe2)m(NbSe2)n

1996 ◽  
Vol 441 ◽  
Author(s):  
Myungkeun Noh ◽  
David C. Johnson
Keyword(s):  
Annealing Temperature ◽  
Substrate Surface ◽  
Domain Size ◽  
Bragg Diffraction ◽  
Conductivity Measurements ◽  
High Quality ◽  
Rocking Curve ◽  
Integral Number ◽  
Controlled Crystallization ◽  
Diffraction Peaks

AbstractA series of kinetically stable, crystalline superlattices containing an integral number of intergrown TiSe2 and NbSe2 layers have been synthesized by controlled crystallization of elementally modulated reactants. Theta-theta and rocking curve data were collected to study the evolution of the initially layered reactants into the crystalline superlattices as a function of temperature. Nucleation of the dichalcogenide structure occurs upon annealing at temperatures above 200°C with the c-axis oriented perpendicular to the substrate surface. The [00l] diffraction linewidths decrease with increased annealing time and temperature suggesting growth of the c-axis domain size. High quality c-axis oriented dichalcogenide crystalline superlattices result from extended annealing at the relatively low annealing temperature of 500°C. The large number of well resolved [00l] Bragg diffraction peaks confirm the well developed crystal structure of the product superlattices in this direction. Four probe electrical conductivity measurements were used to determine the variation of the superconducting critical temperature as a function of the number of TiSe2 and NbSe2 layers in the superlattice.

Topological insulator bismuth selenide grown on black phosphorus for sensitive broadband photodetection

2021 ◽  
Author(s):  
Dae-Kyoung Kim ◽  
Seok-Bo Hong ◽  
Jonghoon Kim ◽  
Mann-Ho Cho
Keyword(s):  
Topological Insulator ◽  
Black Phosphorus ◽  
Bismuth Selenide ◽  
High Quality ◽  
Modulated Elemental Reactants ◽  
Elemental Reactants

We investigate a high-quality Bi2Se3/black phosphorus (BP) heterostructure prepared through the modulated elemental reactants (MER, annealed in situ at 220 °C for 20 min under a vacuum of 10−9 Torr)...

Growth of SnS van der Waals Epitaxies on Layered Substrates

2013 ◽  
Vol 1493 ◽  
pp. 213-217 ◽  
Author(s):  
S.F. Wang ◽  
W.K. Fong ◽  
W. Wang ◽  
K.K. Leung ◽  
C. Surya
Keyword(s):  
Molecular Beam ◽  
Crystal Size ◽  
Substrate Surface ◽  
Van Der Waals ◽  
Layered Materials ◽  
Substantial Improvement ◽  
High Quality ◽  
Rocking Curve ◽  
Large Lattice ◽  
Unit Layer

ABSTRACTIn this paper we present systematic investigations on the growth of SnS van der Waals epitaxies (vdWEs) on different substrates, including crystalline and layered substrates, by molecular beam epitaxy (MBE). Experimental growth of SnS on conventional 3D substrates, such as GaAs, indicates strong interaction between the SnS layer and the substrate resulting in poor crystallinity in general. Substantial improvement in the film crystallinity can be obtained when the deposition is made on layered substrates, with saturated surface bonds, as observed in SnS films deposited on mica and crystalline substrates with a graphene buffer layer. Crystal size as large as one micron and rocking curve FWHM of 0.118° was observed despite the large lattice mismatches. This represents significant improvement over the reported value of ∼3°. Several symmetric growth orientations are observed for films grown on mica substrates. The results indicate that weak vdW interactions between the saturated bonds of the substrate surface and the SnS unit layer which is an important factor for achieving high quality epitaxy layered materials.

Computerized simulation of shortened ingots with a controlled crystallization for manufacturing of high-quality forgings

2019 ◽  
Vol 103 (5-8) ◽  
pp. 3057-3065 ◽  
Author(s):  
Oleg E. Markov ◽  
Oleksiy V. Gerasimenko ◽  
Alexander A. Shapoval ◽  
Oleksandr R. Abdulov ◽  
Roman U. Zhytnikov
Keyword(s):  
High Quality ◽  
Controlled Crystallization ◽  
Computerized Simulation

scholarly journals Crystallographic features of ammonium fluoroelpasolites: dynamic orientational disorder in crystals of (NH4)3HfF7 and (NH4)3Ti(O2)F5

2017 ◽  
Vol 73 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Anatoly A. Udovenko ◽  
Alexander A. Karabtsov ◽  
Natalia M. Laptash
Keyword(s):  
Single Crystal ◽  
Electron Density ◽  
Diffraction Data ◽  
Central Atom ◽  
X Ray Diffraction ◽  
Dynamic Nature ◽  
Orientational Disorder ◽  
High Quality ◽  
Structural Units ◽  
X Ray

A classical elpasolite-type structure is considered with respect to dynamically disordered ammonium fluoro-(oxofluoro-)metallates. Single-crystal X-ray diffraction data from high quality (NH4)3HfF7 and (NH4)3Ti(O2)F5 samples enabled the refinement of the ligand and cationic positions in the cubic Fm \bar 3 m (Z = 4) structure. Electron-density atomic profiles show that the ligand atoms are distributed in a mixed (split) position instead of 24e. One of the ammonium groups is disordered near 8c so that its central atom (N1) forms a tetrahedron with vertexes in 32f. However, a center of another group (N2) remains in the 4b site, whereas its H atoms (H2) occupy the 96k positions instead of 24e and, together with the H3 atom in the 32f position, they form eight spatial orientations of the ammonium group. It is a common feature of all ammonium fluoroelpasolites with orientational disorder of structural units of a dynamic nature.

scholarly journals Characterization of Cr-rich Cr-Sb multilayer films: Syntheses of a new metastable phase using modulated elemental reactants

2015 ◽  
Vol 230 ◽  
pp. 254-265 ◽  
Author(s):  
Matthias Regus ◽  
Sergiy Mankovsky ◽  
Svitlana Polesya ◽  
Gerhard Kuhn ◽  
Jeffrey Ditto ◽  
...  
Keyword(s):  
Metastable Phase ◽  
Multilayer Films ◽  
Modulated Elemental Reactants ◽  
Elemental Reactants

scholarly journals Image Simulations of Ge Twin Boundaries.

1992 ◽  
Vol 295 ◽  
Author(s):  
Stuart Mckernan ◽  
C. Barry Carter
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
High Angle ◽  
Structural Units ◽  
Twin Boundaries ◽  
Large Unit ◽  
Unit Cells ◽  
The Individual ◽  
Image Simulations

AbstractGeneral high-angle tilt grain boundaries may be described by an arrangement of repeating structural units. Some grain-boundary defects may also be modeled by the incorporation of structural units of related boundary structures into the boundary. The simulation of these structures requires the use of prohibitively large unit cells. The possibility of modeling these boundaries by the superposition of image simulations of the individual structural units isinvestigated.

scholarly journals Growth of Ordered Graphene Ribbons by Sublimation Epitaxy

Crystals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 449
Author(s):  
Shuxian Cai ◽  
Xingfang Liu ◽  
Xin Zheng ◽  
Zhonghua Liu
Keyword(s):  
Substrate Surface ◽  
Graphene Film ◽  
Graphene Ribbon ◽  
High Quality ◽  
Graphene Layers ◽  
Force Microscopy ◽  
Layer Graphene ◽  
Micro Raman Spectroscopy ◽  
Atomic Force ◽  
Few Layer Graphene

Ordered graphene ribbons were grown on the surface of 4° off-axis 4H-SiC wafers by sublimation epitaxy, and characterized by using scanning electron microscopy (SEM), atomic force microscopy (AFM) and micro-Raman spectroscopy (μ-Raman). SEM showed that there were gray and dark ribbons on the substrate surface, and AFM further revealed that these ordered graphene ribbons had clear stepped morphologies due to surface step-bunching. It was shown by μ-Raman that the numbers of graphene layers of these two types of regions were different. The gray region was composed of mono- or bilayer ordered graphene ribbon, while the dark region was of tri- or few-layer ribbon. Meanwhile, ribbons were all homogeneous and had a width up to 40 μm and a length up to 1000 μm, without micro defects such as grain boundaries, ridges, or mono- and few-layer graphene mixtures. The results of this study are useful for optimized growth of high-quality graphene film on silicon carbide crystal.

Sign in / Sign up

Export Citation Format

Share Document