scholarly journals Large Single Crystal Graphene Manufacture

2017 ◽  
Vol 2 (1) ◽  
Keyword(s):  
Carbon Source ◽  
Single Crystal ◽  
Single Crystals ◽  
Large Single Crystal ◽  
Nickel Metal ◽  
Green House

Large single crystals of graphene ware made by using a solvent-catalyst of nickel metal. Both solid and liquid processes were experimented with graphene single crystals of mm demonstrated. The carbon source may be solid or gasses. For example, green house effected carbonaceous gasses could be used to strip carbon in forming large crystals of graphite that would be a source for making precious graphene.

scholarly journals MANUFACTURE OF SUPER LARGE TUNGSTEN SINGLE CRYSTALS IN THE FORM OF ROTATION BODIES

2020 ◽  
pp. 60-63
Author(s):  
V.O. Shapovalov ◽  
Yu.O. Nikitenko ◽  
V.V. Yakusha ◽  
O.M. Gnizdylo ◽  
I.V. Sheiko
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Refractory Metals ◽  
Large Single Crystal ◽  
Electric Welding ◽  
Material Studies ◽  
Further Development ◽  
Technology Of Production ◽  
Rotating Bodies

The results of researches made at creation of technology of production of super-large single crystals of tungsten in the form of plates and bodies of rotation are presented. In E.O. Paton Electric Welding Institute NAS of Ukraine created a unique technology for the production of single crystals of refractory metals in the form of plates 170x160x20 mm, worked out the technology and conducted material studies, which confirmed their quality and gave the basis for further development in this direction. In recent years, the technology of growing super-large single-crystal tungsten in the form of rotating bodies with a diameter of 85 mm has been created.

scholarly journals Adjustable Positive-Negative Signal in Self-Driven Photodetector based on Cubic CH3NH3PbI3 Large Single Crystal

2021 ◽  
Author(s):  
Xuewei Fu ◽  
Yunying Wang ◽  
Huawei Zhou ◽  
Yan Chen ◽  
Chen Wang ◽  
...  
Keyword(s):  
Response Time ◽  
Single Crystal ◽  
Band Gap ◽  
Single Crystals ◽  
Photocurrent Density ◽  
Large Single Crystal ◽  
Orientation Disorder ◽  
Octahedral Cavity ◽  
First Time ◽  
Negative Signal

<p><b>In this study, for the first time, self-driven photodetector based on cubic CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> large single crystal </b><b>(C-MAPbI<sub>3 </sub>LSC) </b><b>with adjustable positive-negative signal is fabricated. </b><b>The preparation of MAPbI<sub>3 </sub>large single crystal (MAPbI<sub>3 </sub>LSC) is realized by the method of growth-drop-growth (GDG). </b><b>The band gap of </b><b>MAPbI<sub>3 </sub></b><b>single crystals </b><b>with Pm-3m (221) space group (6.134×6.134×6.134 Å, 90.00 x 90.00 x 90.00) </b><b>is 1.58 eV.</b> <b>CH<sub>3</sub>NH<sub>3</sub><sup>+</sup> cation is orientation-disorder </b><b>within the perovskite cubo-octahedral cavity.</b><b> The photocurrent density at 803 nm of the</b><b> C-MAPbI<sub>3 </sub>LSC</b><b> photodetector under different bias voltages is the highest under different wavelength. The </b><b>responsivities (R), response time, external quantum efficiencies (EQE) and the detectivity (D) for </b><b>C-MAPbI<sub>3 </sub>LSC</b><b> photodetector at 803 nm wavelength with 1 W m<sup>-2</sup></b><b>, respectively, is </b><b>508.7 µA/mW, 0.1338 ms, 79.6% and 8.64*10<sup>11</sup> Jones. Notably, </b><b>the C-MAPbI<sub>3 </sub>LSC photodetector can be self-driven under 0 V bias voltage, in particular, the positive and negative values of the photocurrent can be adjusted. The proposed mechanism of poling inducing built-in potential is explained adjustable positive-negative signal in self-driven photodetector based on cubic CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> large single crystal.</b><b></b></p>

scholarly journals Adjustable Positive-Negative Signal in Self-Driven Photodetector based on Cubic CH3NH3PbI3 Large Single Crystal

2021 ◽  
Author(s):  
Xuewei Fu ◽  
Yunying Wang ◽  
Huawei Zhou ◽  
Yan Chen ◽  
Chen Wang ◽  
...  
Keyword(s):  
Response Time ◽  
Single Crystal ◽  
Band Gap ◽  
Single Crystals ◽  
Photocurrent Density ◽  
Large Single Crystal ◽  
Orientation Disorder ◽  
Octahedral Cavity ◽  
First Time ◽  
Negative Signal

<p><b>In this study, for the first time, self-driven photodetector based on cubic CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> large single crystal </b><b>(C-MAPbI<sub>3 </sub>LSC) </b><b>with adjustable positive-negative signal is fabricated. </b><b>The preparation of MAPbI<sub>3 </sub>large single crystal (MAPbI<sub>3 </sub>LSC) is realized by the method of growth-drop-growth (GDG). </b><b>The band gap of </b><b>MAPbI<sub>3 </sub></b><b>single crystals </b><b>with Pm-3m (221) space group (6.134×6.134×6.134 Å, 90.00 x 90.00 x 90.00) </b><b>is 1.58 eV.</b> <b>CH<sub>3</sub>NH<sub>3</sub><sup>+</sup> cation is orientation-disorder </b><b>within the perovskite cubo-octahedral cavity.</b><b> The photocurrent density at 803 nm of the</b><b> C-MAPbI<sub>3 </sub>LSC</b><b> photodetector under different bias voltages is the highest under different wavelength. The </b><b>responsivities (R), response time, external quantum efficiencies (EQE) and the detectivity (D) for </b><b>C-MAPbI<sub>3 </sub>LSC</b><b> photodetector at 803 nm wavelength with 1 W m<sup>-2</sup></b><b>, respectively, is </b><b>508.7 µA/mW, 0.1338 ms, 79.6% and 8.64*10<sup>11</sup> Jones. Notably, </b><b>the C-MAPbI<sub>3 </sub>LSC photodetector can be self-driven under 0 V bias voltage, in particular, the positive and negative values of the photocurrent can be adjusted. The proposed mechanism of poling inducing built-in potential is explained adjustable positive-negative signal in self-driven photodetector based on cubic CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> large single crystal.</b><b></b></p>

The diffraction of thermal neutrons by single crystals

1951 ◽  
Vol 209 (1098) ◽  
pp. 397-407 ◽  
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Structure Analysis ◽  
Experimental Measurements ◽  
Thermal Neutrons ◽  
Large Single Crystal ◽  
Structure Factors ◽  
Accurate Comparison ◽  
Secondary Extinction

Experimental measurements of the intensity of neutron reflexion by large single-crystal slices are shown to be in agreement with previously published calculations. It is demonstrated that accurate comparison can be made of the structure factors of planes in a zone by the use of cylindrical or pillar crystals, sufficiently small in diameter to give negligible secondary extinction effects. The use of single crystals for structure analysis is discussed.

The observation of defects on (100) CdTe surfaces by chemical etching

1992 ◽  
Vol 50 (2) ◽  
pp. 1424-1425
Author(s):  
M.E. Lee
Keyword(s):  
Single Crystal ◽  
Grain Boundaries ◽  
Single Crystals ◽  
Chemical Etching ◽  
Crystalline Perfection ◽  
Crystalline Defects ◽  
High Incidence ◽  
Crystallographic Defects ◽  
Cdznte Substrates ◽  
Device Technology

The crystalline perfection of bulk CdTe substrates plays an important role in their use in infrared device technology. The application of chemical etchants to determine crystal polarity or the density and distribution of crystallographic defects in (100) CdTe is not well understood. The lack of data on (100) CdTe surfaces is a result of the apparent difficulty in growing (100) CdTe single crystal substrates which is caused by a high incidence of twinning. Many etchants have been reported to predict polarity on one or both (111) CdTe planes but are considered to be unsuitable as defect etchants. An etchant reported recently has been considered to be a true defect etchant for CdTe, MCT and CdZnTe substrates. This etchant has been reported to reveal crystalline defects such as dislocations, grain boundaries and inclusions in (110) and (111) CdTe. In this study the effect of this new etchant on (100) CdTe surfaces is investigated.The single crystals used in this study were (100) CdTe as-cut slices (1mm thickness) from Bridgman-grown ingots.

Mounting an individual submicrometer sized single crystal

1996 ◽  
Vol 211 (6) ◽  
Author(s):  
R. B. Neder ◽  
M. Burghammer ◽  
Th. Grasl ◽  
H. Schulz
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Single Crystal ◽  
Single Crystals ◽  
High Vacuum ◽  
Nanometer Resolution ◽  
Micro Manipulator ◽  
Scanning Electron

AbstractWe developed a new micro manipulator for mounting individual sub-micrometer sized single crystals within a scanning electron microscope. The translations are realized via a commercially available piezomicroscope, adapted for high vacuum usage and realize nanometer resolution. With this novel instrument it is routinely possible to mount individual single crystals with sizes down to 0.1

Study of potential oscillations during reaction of an aluminium single crystal with an aqueous KOH solution

1990 ◽  
Vol 55 (2) ◽  
pp. 345-353 ◽  
Author(s):  
Ivan Halaša ◽  
Milica Miadoková
Keyword(s):  
Aqueous Solutions ◽  
Single Crystal ◽  
Single Crystals ◽  
Periodic Potential ◽  
Optimum Conditions ◽  
Potential Oscillations ◽  
Dilute Aqueous Solutions ◽  
Experimental Findings ◽  
Kinetics Of

The authors investigated periodic potential changes measured on oriented sections of Al single crystals during spontaneous dissolution in dilute aqueous solutions of KOH, with the aim to find optimum conditions for the formation of potential oscillations. It was found that this phenomenon is related with the kinetics of the reaction investigated, whose rate also changed periodically. The mechanism of the oscillations is discussed in view of the experimental findings.

Measurement of growth rates for single crystals and pressed tablets of CuSO4.5 H2O on a rotating disc

1989 ◽  
Vol 54 (11) ◽  
pp. 2951-2961 ◽  
Author(s):  
Miloslav Karel ◽  
Jaroslav Nývlt
Keyword(s):  
Growth Rate ◽  
Single Crystal ◽  
Single Crystals ◽  
Growth Rates ◽  
Diffusion Coefficients ◽  
Preferred Orientation ◽  
Rotating Disc ◽  
Dissolution Rates ◽  
Rates Of Growth ◽  
Good Agreement

Measured growth and dissolution rates of single crystals and tablets were used to calculate the overall linear rates of growth and dissolution of CuSO4.5 H2O crystals. The growth rate for the tablet is by 20% higher than that calculated for the single crystal. It has been concluded that this difference is due to a preferred orientation of crystal faces on the tablet surface. Calculated diffusion coefficients and thicknesses of the diffusion and hydrodynamic layers in the vicinity of the growing or dissolving crystal are in good agreement with published values.

scholarly journals Single Crystal Growth and Physical Properties of Pyroxene CoGeO3

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 378
Author(s):  
Li Zhao ◽  
Zhiwei Hu ◽  
Hanjie Guo ◽  
Christoph Geibel ◽  
Hong-Ji Lin ◽  
...  
Keyword(s):  
High Pressure ◽  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Crystal Growth ◽  
Physical Properties ◽  
Single Crystal ◽  
Single Crystals ◽  
Magnetic Moments ◽  
Single Crystal Growth ◽  
The Impact

We report on the synthesis and physical properties of cm-sized CoGeO3 single crystals grown in a high pressure mirror furnace at pressures of 80 bar. Direction dependent magnetic susceptibility measurements on our single crystals reveal highly anisotropic magnetic properties that we attribute to the impact of strong single ion anisotropy appearing in this system with TN∼33.5 K. Furthermore, we observe effective magnetic moments that are exceeding the spin only values of the Co ions, which reveals the presence of sizable orbital moments in CoGeO3.

scholarly journals Growth of sillenite Bi12FeO20 single crystals: structural, thermal, optical, photocatalytic features and first principle calculations

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Durga Sankar Vavilapalli ◽  
Ambrose A. Melvin ◽  
F. Bellarmine ◽  
Ramanjaneyulu Mannam ◽  
Srihari Velaga ◽  
...  
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Photoelectron Spectroscopy ◽  
Diffraction Method ◽  
Lattice Parameter ◽  
First Principle ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Principle Calculations ◽  
Photodegradation Efficiency

AbstractIdeal sillenite type Bi12FeO20 (BFO) micron sized single crystals have been successfully grown via inexpensive hydrothermal method. The refined single crystal X-ray diffraction data reveals cubic Bi12FeO20 structure with single crystal parameters. Occurrence of rare Fe4+ state is identified via X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The lattice parameter (a) and corresponding molar volume (Vm) of Bi12FeO20 have been measured in the temperature range of 30–700 °C by the X-ray diffraction method. The thermal expansion coefficient (α) 3.93 × 10–5 K−1 was calculated from the measured values of the parameters. Electronic structure and density of states are investigated by first principle calculations. Photoelectrochemical measurements on single crystals with bandgap of 2 eV reveal significant photo response. The photoactivity of as grown crystals were further investigated by degrading organic effluents such as Methylene blue (MB) and Congo red (CR) under natural sunlight. BFO showed photodegradation efficiency about 74.23% and 32.10% for degrading MB and CR respectively. Interesting morphology and microstructure of pointed spearhead like BFO crystals provide a new insight in designing and synthesizing multifunctional single crystals.

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