Hexagonal Boron Nitride Nanowalls Synthesized by Unbalanced RF Magnetron Sputtering

2011 ◽  
Vol 1307 ◽  
Author(s):  
Boumédiène BenMoussa ◽  
Jan D’Haen ◽  
Christian Borschel ◽  
Marc Saitner ◽  
Ali Soltani ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Film Thickness ◽  
Hexagonal Boron Nitride ◽  
Rf Magnetron Sputtering ◽  
Deposition Process ◽  
Dense Layer ◽  
Cross Sectional ◽  
X Ray ◽  
Optical And Electronic Properties ◽  
Film Interface

ABSTRACTA recurrent problem in the synthesis of hexagonal boron nitride (h-BN) is contamination with oxygen and carbon, leading to possible detrimental effects on optical and electronic properties. Here it is shown that the addition of H2 to the N2/Ar mixture used during the deposition process, clearly suppresses the incorporation of these elements, reducing their combined level below 5 %. The surface morphology, assessed with scanning electron microscopy (SEM), revealed the presence of h-BN nanowalls, i.e. vertically positioned 2D structures consisting out of several h-BN sheets. While Fourier transform infrared (FTIR) spectroscopy revealed the sp2 nature of the bonds, confirming the hexagonal nature of the nanowalls, the quasi-perfect stoichiometry of the material was evidenced by combining energy dispersive X-ray analysis (EDX) and Rutherford backscattering spectroscopy (RBS). The dimensions and density of these walls are clearly film thickness dependent and cross-sectional TEM images confirmed the increasing level of porosity with film thickness. A dense layer of material is present at the substrate-film interface, which gradually evolves into the 2D nanowall structures.

Effects of CaB2O4 Content on the Sintering Behavior of Hexagonal Boron Nitride

2011 ◽  
Vol 675-677 ◽  
pp. 131-134
Author(s):  
Yu Xia Cao ◽  
Ling Zhong Du ◽  
Wei Gang Zhang
Keyword(s):  
Boron Nitride ◽  
Diffraction Analysis ◽  
Apparent Density ◽  
Cross Sections ◽  
Hexagonal Boron Nitride ◽  
Sintering Behavior ◽  
Rockwell Hardness ◽  
X Ray Diffraction ◽  
X Ray ◽  
Grain Sizes

CaB2O4 was added into hexagonal boron nitride (hBN) to improve the sintering behaviors of hBN. CaB2O4 and hBN were mixed and then pressed into plates. The plates were sintered at 2000°C for 5h under a N2 ambience. The phase compositions with different CaB2O4 contents were examined with X-ray diffraction analysis. The fracture cross-sections of the hBN plates were investigated by SEM. The apparent density and Rockwell hardness were also measured. The results show that the hBN particles had a plate-like shape and the grain sizes of hBN increased with increasing CaB2O4 contents. The apparent density and Rockwell hardness decreased with increasing CaB2O4 contents. When the CaB2O4 content was 15(wt) %, the hBN has the average grain sizes of 3μm in diameter and 200nm in thickness, the apparent density of 1.06 g/cm3 and the Rockwell hardness of 3, respectively.

Crystallization of Germanium-Carbon Alloys - Structure and Electronic Transport

1997 ◽  
Vol 467 ◽  
Author(s):  
T.-M. John ◽  
J. Bläsing ◽  
P. Veit ◽  
T. Drüsedau
Keyword(s):  
Electron Microscopy ◽  
Crystallite Size ◽  
Electronic Transport ◽  
Cluster Formation ◽  
Electronic Conductivity ◽  
Rf Magnetron Sputtering ◽  
Cross Sectional ◽  
Structural Investigations ◽  
X Ray ◽  
Transmission Electron

ABSTRACTAmorphous Ge1-xCx alloys were deposited by rf-magnetron sputtering from a germanium target in methane-argon atmosphere. Structural investigations were performed by means of wide and small angle X-ray scattering, X-ray reflectometry and cross-sectional transmission electron microscopy. The electronic transport properties were characterized using Hall-measurements and temperature depended conductivity. The results of X-ray techniques together with the electron microscopy clearly proof the existence of a segregation of the components and cluster formation already during deposition. The temperature dependence of the electronic conductivity in the as-prepared films follows the Mott' T−1/4 law, indicating transport by a hopping process. After annealing at 870 K, samples with x≤0.4 show crystallization of the Ge-clusters with a crystallite size being a function of x. After Ge-crystallization, the conductivity increases by 4 to 5 orders of magnitude. Above room temperature, electronic transport is determined by a thermally activated process. For lower temperatures, the σ(T) curves show a behaviour which is determined by the crystallite size and the free carrier concentration, both depending on the carbon content.

Determination of Optimum Annealing Time Durations of Nano Boron Nitride Added MgB2 Superconductors

2018 ◽  
Vol 2 (2) ◽  
Author(s):  
Asaf Tolga Ulgen
Keyword(s):  
Boron Nitride ◽  
Annealing Time ◽  
Hexagonal Boron Nitride ◽  
Superconducting Magnet ◽  
Solid State Reaction Method ◽  
Lattice Parameter ◽  
Residual Resistivity ◽  
Conventional Solid State Reaction ◽  
Cross Sectional ◽  
Sintering Time

In the present study, I have investigated the effect of different annealing time durations of 0.5h, 1h, 2h and 4h (annealing temperature at 700oC) on the electrical, micro structural and superconducting properties of the nano hexagonal boron nitride (hBN) added/doping magnesium diboride (MgB2) superconducting samples. The aim of this work, hBN added MgB2 superconducting bulk samples are determined to find out the optimum sintering time, also investigated how BN addition effects the optimum fabrication conditions. These superconducting samples were prepared by the conventional solid-state reaction method. Experimental techniques of X-ray diffraction (XRD) were used for structural and microstructural examinations. Critical transition temperatures, difference between Tc-onset and Tc-offset, a and c lattice parameter, grain size, bulk density, residual resistivity ratios (RR) and cross-sectional area fractions (AF) of the pure and nano-hBN added MgB2 materials are obtained using a cryostat equipped with a superconducting magnet. All the experimental results notice that the characteristic features improve regularly with the increment in sintering time durations. 

Effects of Oxygen Flow Rate on Nanostructured ZnO Thin Films

2013 ◽  
Vol 667 ◽  
pp. 333-337
Author(s):  
S. Ahmad ◽  
N.D. Md Sin ◽  
M.N. Berhan ◽  
Mohamad Rusop Mahmood
Keyword(s):  
Thin Films ◽  
Flow Rate ◽  
Volume Ratio ◽  
Rf Magnetron Sputtering ◽  
Deposition Process ◽  
Oxygen Flow Rate ◽  
Oxygen Flow ◽  
Zno Thin Films ◽  
Average Thickness ◽  
X Ray

Zinc Oxide (ZnO) thin films were deposited on thermally oxidized SiO2 by varying the oxygen flow rate. The deposition process were done using radio frequency (RF) magnetron sputtering at various oxygen flow rate ranging from 0 to 40 sccm. The surface morphology and crystallinity were analyzed by field emission scanning electron microscopy (FESEM) and X-Ray Diffractometer (XRD) respectively. The average thickness and deposition rate decreases with an increase of oxygen content. The grain size was measured by FESEM and it was found that it is also decreasing with the increased of oxygen flow rate. The films grown with 10 sccm oxygen shows the highest (002) peak however it is expected that the sample deposited with 40 sccm oxygen exhibit the highest sensitivity toward NH3 gas due to the highest surface to volume ratio.

Effects of Growth Parameters on Surface-morphological, Structural and Electrical Properties of Mo Films by RF Magnetron Sputtering

2008 ◽  
Vol 1123 ◽  
Author(s):  
Shou-Yi Kuo ◽  
Liann-Be Chang ◽  
Ming-Jer Jeng ◽  
Wei-Ting Lin ◽  
Yong-Tian Lu ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Magnetron Sputtering ◽  
Film Thickness ◽  
Growth Parameters ◽  
Soda Lime ◽  
Rf Magnetron Sputtering ◽  
Soda Lime Glass ◽  
Working Pressure ◽  
Soda Lime Glass Substrate ◽  
X Ray

AbstractThis work reports on the fabrication and characterization of Mo thin films on soda-lime glass substrate grown by reactive RF magnetron sputtering. Film thickness was measured by x-ray step surface profiler. The structural properties and surface morphology were analyzed by x-ray diffraction (XRD), atomic force microscope (AFM) and scanning electron microscopy (SEM). Electrical properties were measured by four-point probe. It was found that the growth parameters, such as argon flow rate, RF power, film thickness, have significant influences on properties of Mo films. The strain on films revealed the complicated relationship with the working pressure, which might be associated with micro structures and impurities. In order to improve the adhesion and electricity, we adopted a two-pressure deposition scheme. The optimal thickness and sheet resistance are νm and 0.12 ω The mechanisms therein will be discussed in detail. Furthermore, we also investigated the diffusion property of Na ion of double Mo films sputtered on soda-lime glass. Our experimental results could lead to better understanding for improving further CIGS-based photovoltaic devices.

scholarly journals AB-stacked nanosheet-based hexagonal boron nitride

2021 ◽  
Vol 77 (2) ◽  
Author(s):  
Jae-Kap Lee ◽  
Jin-Gyu Kim ◽  
K. P. S. S. Hembram ◽  
Seunggun Yu ◽  
Sang-Gil Lee
Keyword(s):  
Boron Nitride ◽  
Hexagonal Boron Nitride ◽  
Metastable Phase ◽  
Stacking Sequence ◽  
Lateral Growth ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Pressure High Temperature ◽  
Crystalline Growth

Hexagonal boron nitride (h-BN) has been generally interpreted as having an AA stacking sequence. Evidence is presented in this article indicating that typical commercial h-BN platelets (∼10–500 nm in thickness) exhibit stacks of parallel nanosheets (∼10 nm in thickness) predominantly in the AB sequence. The AB-stacked nanosheet occurs as a metastable phase of h-BN resulting from the preferred texture and lateral growth of armchair (110) planes. It appears as an independent nanosheet or unit for h-BN platelets. The analysis is supported by simulation of thin AB films (2–20 layers), which explains the unique X-ray diffraction pattern of h-BN. With this analysis and the role of pressure in commercial high-pressure high-temperature sintering (driving nucleation and parallelizing the in-plane crystalline growth of the nuclei), a growth mechanism is proposed for 2D h-BN (on a substrate) as `substrate-induced 2D growth', where the substrate plays the role of pressure.

scholarly journals Improving Corrosion Resistance of Magnesium Alloy in Cl- Containing Simulated Concrete Pore Solution by Ultrasound-Assisted Chemical Deposition

Scanning ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Ye Wang ◽  
Guosong Wu
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloys ◽  
Pore Solution ◽  
Chemical Deposition ◽  
Deposition Process ◽  
Cross Sectional ◽  
X Ray ◽  
Electrochemical Tests ◽  
Reaction Solution ◽  
Building Engineering

Coatings are playing an important role in corrosion mitigation of magnesium alloys, and in this study, a facile and eco-friendly chemical deposition process is proposed to improve the corrosion resistance of magnesium-neodymium alloys. The mixture of 1.5 mol/L KH2PO4 solution and 1.2 mol/L CaCl2 solution is used for reaction solution, and ultrasound is introduced into the process for assisting the chemical deposition. After 40 minutes of the surface treatment, the surface and cross-sectional morphologies are observed by scanning electron microscope (SEM), which reveals that a layer of dense coating is formed on Mg alloy. Energy-dispersive X-ray spectroscopy (EDS) and X-ray Diffraction (XRD) are further combined to analyze the coating, and it is thereby confirmed that this coating mainly consists of CaHPO4·2H2O. Electrochemical tests and soaking experiments are conducted to evaluate the corrosion resistance of the treated samples in simulated concrete pore solutions. Both the untreated and treated samples have a good corrosion resistance in the Cl- free simulated concrete pore solution, but their corrosion behavior is influenced by the introduction of Cl- in this study. Fortunately, the coating can protect the substrate effectively in the Cl- containing simulated concrete pore solution. In summary, it provides a possible way for magnesium alloys to improve their corrosion resistance when they are used in building engineering.

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