scholarly journals Water mediated growth of oriented single crystalline SrCO3 nanorod arrays on strontium compounds

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Junsung Hong ◽  
Su Jeong Heo ◽  
Prabhakar Singh
Keyword(s):  
Structural Evolution ◽  
Earth Metal ◽  
Nanorod Arrays ◽  
Liquid Droplets ◽  
X Ray Diffraction ◽  
In Situ Raman Spectroscopy ◽  
Simple Method ◽  
Metal Carbonates ◽  
Transmission Electron ◽  
Trace Water

AbstractMorphology-controlled strontianite nanostructures have attracted interest in various fields, such as electrocatalyst and photocatalysts. Basic additives in aqueous strontium solutions is commonly used in controlling strontianite nanostructures. Here, we show that trace water also serves an important role in forming and structuring vertically oriented strontianite nanorod arrays on strontium compounds. Using in situ Raman spectroscopy, we monitored the structural evolution from hydrated strontium to strontianite nanorods, demonstrating the epitaxial growth by vapor–liquid–solid mechanism. Water molecules cause not only the exsolution of Sr liquid droplets on the surface but also the uptake of airborne CO2 followed by its ionization to CO32−. The existence of intermediate SrHO+–OCO22− phase indicates the interaction of CO32− with SrOH+ in Sr(OH)x(H2O)y cluster to orient strontianite crystals. X-ray diffraction simulation and transmission electron microscopy identify the preferred-orientation plane of the 1D nanostructures as the (002) plane, i.e., the growth along the c-axis. The anisotropic growth habit is found to be affected by the kinetics of carbonation. This study paves the way for designing and developing 1D architecture of alkaline earth metal carbonates by a simple method without external additives at room temperature.

scholarly journals Electrochemical Glucose Oxidation Using Glassy Carbon Electrodes Modified with Au-Ag Nanoparticles: Influence of Ag Content

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Nancy Gabriela García-Morales ◽  
Luis Alfonso García-Cerda ◽  
Bertha Alicia Puente-Urbina ◽  
Leonor María Blanco-Jerez ◽  
René Antaño-López ◽  
...  
Keyword(s):  
Glassy Carbon ◽  
Electrode Surface ◽  
Glucose Oxidation ◽  
Modified Electrodes ◽  
Alkaline Media ◽  
Carbon Electrodes ◽  
X Ray Diffraction ◽  
Simple Method ◽  
Glassy Carbon Electrodes ◽  
Transmission Electron

This paper describes the application of glassy carbon modified electrodes bearing Aux-Agynanoparticles to catalyze the electrochemical oxidation of glucose. In particular, the paper shows the influence of the Ag content on this oxidation process. A simple method was applied to prepare the nanoparticles, which were characterized by transmission electron microscopy, Ultraviolet-Visible spectroscopy, X-ray diffraction spectroscopy, and cyclic voltammetry. These nanoparticles were used to modify glassy carbon electrodes. The effectiveness of these electrodes for electrochemical glucose oxidation was evaluated. The modified glassy carbon electrodes are highly sensitive to glucose oxidation in alkaline media, which could be attributed to the presence of Aux-Agynanoparticles on the electrode surface. The voltammetric results suggest that the glucose oxidation speed is controlled by the glucose diffusion to the electrode surface. These results also show that the catalytic activity of the electrodes depends on the Ag content of the nanoparticles. Best results were obtained for the Au80-Ag20nanoparticles modified electrode. This electrode could be used for Gluconic acid (GA) production.

scholarly journals Structural Evolution in Wet Mechanically Alloyed Co-Fe-(Ta,W)-B Alloys

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 800
Author(s):  
Vladimír Girman ◽  
Maksym Lisnichuk ◽  
Daria Yudina ◽  
Miloš Matvija ◽  
Pavol Sovák ◽  
...  
Keyword(s):  
Structural Changes ◽  
Magnetic Measurements ◽  
Structural Evolution ◽  
High Energy ◽  
Control Agent ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
X Ray ◽  
Transmission Electron ◽  
X Ray Absorption

In the present study, the effect of wet mechanical alloying (MA) on the glass-forming ability (GFA) of Co43Fe20X5.5B31.5 (X = Ta, W) alloys was studied. The structural evolution during MA was investigated using high-energy X-ray diffraction, X-ray absorption spectroscopy, high-resolution transmission electron microscopy and magnetic measurements. Pair distribution function and extended X-ray absorption fine structure spectroscopy were used to characterize local atomic structure at various stages of MA. Besides structural changes, the magnetic properties of both compositions were investigated employing a vibrating sample magnetometer and thermomagnetic measurements. It was shown that using hexane as a process control agent during wet MA resulted in the formation of fully amorphous Co-Fe-Ta-B powder material at a shorter milling time (100 h) as compared to dry MA. It has also been shown that substituting Ta with W effectively suppresses GFA. After 100 h of MA of Co-Fe-W-B mixture, a nanocomposite material consisting of amorphous and nanocrystalline bcc-W phase was synthesized.

Synthesis and Characterization of Nanometer Copper Ferrite by Auto-Combustion

2011 ◽  
Vol 347-353 ◽  
pp. 3472-3476
Author(s):  
Guang Xiu Cao ◽  
Tian Liu ◽  
Qing Hong Zhang ◽  
Hong Zhi Wang
Keyword(s):  
Raw Materials ◽  
Combustion Process ◽  
Copper Nitrate ◽  
Copper Ferrite ◽  
X Ray Diffraction ◽  
Uniform Size ◽  
Simple Method ◽  
Transmission Electron ◽  
Auto Combustion ◽  
Average Size

A simple method for preparing nanoscale copper ferrite particles with narrow distribution and uniform size was developed by auto-combusting the precursor using copper nitrate, iron nitrate, and malic acid as raw materials. The constituents and the thermal decomposition process of the precursor were studied by Fourier transform infrared (FT-IR), thermogravimetry-differental thermal analysis (TG-DTA) and X-ray diffraction (XRD). The results showed that the carboxyl and nitrate ion take part in the reaction during the auto-combustion process. The precursor decomposed completely at about 199 °C, to yield single phase product. Transmission electron microscopy (TEM) indicated that the average size of the as-burnt sample was about 90 nm.

A structural analysis of the Pd/GaN ohmic contact annealing behavior

2002 ◽  
Vol 743 ◽  
Author(s):  
C. C. Kim ◽  
P. Ruterana ◽  
J. H. Je
Keyword(s):  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Structural Evolution ◽  
Electron Beam Evaporation ◽  
Intermetallic Phases ◽  
X Ray Diffraction ◽  
Annealing Behavior ◽  
X Ray ◽  
Transmission Electron ◽  
The Relationship

AbstractFor ohmic contact on p GaN, palladium is one of the best candidates showing ohmic characteristics already without annealing. To be realized in devices, it is necessary to know the behavior of the ohmic contacts at accelerated conditions, especially for high temperatures and power. We report on the structural evolution of palladium layers (30 nm) deposited on GaN (0001) by electron beam evaporation without intentional annealing. They were next cut into various pieces which were individually submitted to rapid thermal annealing at 400, 500, 600, 700 and 800°C for 10 sec. We investigate the differences in the microstructure and the location of interfacial phases and their relationships as determined by X-ray diffraction and transmission electron microscopy, we then suggest the formation mechanism based on the relationship. It is shown that the interface is disrupted at annealing above 600°C and by 800°C only very small patches of Pd are still present, however they area completely imbedded in a matrix of intermetallic phases (gallides) formed by the reaction with GaN.

scholarly journals GRAPHENE QUANTUM DOTS AS A REDUCING REAGENT AND STABILIZER FOR GREEN SYNTHESIS OF SILVER NANOPARTICLES: TOWARDS A HYDROGEN PEROXIDE AND GLUCOSE SENSOR

2018 ◽  
Vol 56 (1A) ◽  
pp. 146 ◽  
Author(s):  
Tran Vinh Hoang
Keyword(s):  
Hydrogen Peroxide ◽  
Quantum Dots ◽  
Silver Nanoparticles ◽  
Glucose Sensor ◽  
Graphene Quantum Dots ◽  
X Ray Diffraction ◽  
Simple Method ◽  
Transmission Electron ◽  
Sensitivity And Selectivity ◽  
Signal Probe

In this work, we have developed a simple method for preparation of silver nanoparticles/graphene quantum dots hybrid (AgNPs/GQDs) using graphene quantum dots (GQDs) as reducing reagent and stabilizer. The synthesized GQDs and AgNPs/GQDs hybrid have been characterized by ultraviolet–visible spectroscopy (UV-Vis), photoluminescence (PL), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Results indicated that mono-dispersed AgNPs were obtained with particles size around 30 nm. Based on the etching of silver nanoparticles by hydrogen peroxide (H2O2), we have constructed a colorimetric sensor for H2O2 and glucose sensors basing on the use of AgNPs/GQDs hybrid as capture probe and signal probe. The fabricated sensors performed excellent sensitivity and selectivity, high reproducibility for H2O2 and glucose detection with a low detection limit of 100 nM and 0.1 mM for hydrogen peroxide and glucose, respectively.

One-step preparation and characterization of core-shell SiO2/Ag composite spheres by pulse plating

2017 ◽  
Vol 24 (3) ◽  
pp. 423-427 ◽  
Author(s):  
Li Xiong ◽  
Xiangping Huang ◽  
Ya Liu ◽  
Liqing Pan
Keyword(s):  
Structural Characteristics ◽  
Pulse Plating ◽  
Core Shell ◽  
X Ray Diffraction ◽  
Simple Method ◽  
Transmission Electron ◽  
Surface Enhanced Raman ◽  
One Step ◽  
Enhanced Raman Scattering ◽  
20 Nm

AbstractA simple method of one-step pulse plating was used in the fabrication of core-shell SiO2/Ag composite spheres. Structural characteristics and morphologies of the prepared SiO2/Ag composite spheres are characterized by means of X-ray diffraction, scanning electron microscope, and transmission electron microscopy. The Ag shell is uniformly coated on the surface of SiO2 spheres with the thickness of about 20 nm. Photoluminescence (PL) spectrum has revealed that PL of the core-shell samples is much stronger than that of bare SiO2 spheres. Raman spectrometer measurements show that the SiO2/Ag composite spheres have excellent surface-enhanced Raman scattering performance. In addition, the current-voltage characteristic of SiO2/Ag composite spheres has improved at the same time.

Synthesis and Characterization of ZrO2/Graphene Nanocomposite Materials

2012 ◽  
Vol 531 ◽  
pp. 161-164 ◽  
Author(s):  
Zong Hua Wang ◽  
Fu Qiang Zhu ◽  
Jan Fei Xia ◽  
Fei Fei Zhang ◽  
Yan Zhi Xia ◽  
...  
Keyword(s):  
High Surface ◽  
High Surface Area ◽  
Nitrogen Adsorption ◽  
X Ray Diffraction ◽  
Simple Method ◽  
Transmission Electron ◽  
Ft Ir ◽  
Graphene Nanocomposite ◽  
Adsorption Desorption

Zirconia/graphene (ZrO2/graphene) nanocomposite has been successfully synthesized by a simple method. The as-prepared nanocomposite was characterized using transmission electron microscopy (TEM), FT-IR spectroscopy, power X-ray diffraction (XRD) and nitrogen adsorption-desorption. It was found that tetragonal ZrO2was uniformly deposited on graphene, which resulted in the formation of two-dimensional nanocomposite, it showed a high surface area of 165 m2/g.

A Simple Method to Synthesize Nano-Sized 3C-SiC Powder Using Hexamethyldisilane in a CVD Reactor

2006 ◽  
Vol 527-529 ◽  
pp. 767-770 ◽  
Author(s):  
Aparna Gupta ◽  
Chacko Jacob
Keyword(s):  
Growth Parameters ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
Cold Region ◽  
Simple Method ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
High Resolution Tem ◽  
Cubic Silicon Carbide ◽  
Shaped Pattern

In this paper, we report a novel route to synthesize nano-sized cubic silicon carbide (3CSiC) powder by a chemical vapor deposition (CVD) technique in a resistance-heated furnace. The nanoparticles were deposited on the relatively cold region of a hot-wall quartz reactor. Hexamethyldisilane (HMDS) was used as the source material for both silicon and carbon. The presence of crystalline 3C-SiC was identified using powder x-ray diffraction (XRD) technique. From the XRD data, the crystallite size was also estimated to be in the range of nanometers (nm). A clear evidence of the particle size (~ 10 - 30 nm) was obtained by transmission electron microscopy (TEM). Selected area electron diffraction (SAED) was carried out on the nanoparticle assembly. The ring shaped pattern is a clear indication of polycrystalline particle formation. High resolution TEM (HRTEM) of nanoparticles was performed to study the crystal structure in detail. The nanoparticles were also characterized by Raman spectroscopy at room temperature. Finally, the influence of the growth parameters is also reported in the present study.

On the Structural Evolution of the Amorphous Al75Cu15V10 Alloy to the Icosahedral Phase

1988 ◽  
Vol 43 (5) ◽  
pp. 505-506 ◽  
Author(s):  
E. Matsubara ◽  
Y. Waseda ◽  
A. P. Tsai ◽  
A. Inoue ◽  
T. Masumoto
Keyword(s):  
Electron Microscopy ◽  
Structural Evolution ◽  
Icosahedral Phase ◽  
X Ray Diffraction ◽  
Bright Field ◽  
Continuous Growth ◽  
X Ray ◽  
Transmission Electron ◽  
Icosahedral Clusters ◽  
Peak Widths

The transformations occurring on annealing an as-spun amorphous Al75Cu15V10 alloy are studied by X-ray diffraction and transmission electron microscopy (TEM). A continuous growth of icosahedral clusters, which are present already in the as-spun sample, is revealed. The size of the clusters estimated from the diffuse X-ray peak widths is consistent with the size of the modulation observed in the bright field TEM images.

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