scholarly journals Synthesis and characterization of nanoscale composite particles formed by 2D layers of Cu-Fe sulfide and Mg-based hydroxide

2022 ◽  
Author(s):  
Yuri Mikhlin ◽  
Roman Borisov ◽  
Sergey Vorobyev ◽  
Yevgeny Tomashevich ◽  
Alexander Romanchenko ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Magnetic Behavior ◽  
Hyperfine Fields ◽  
Minority Spin ◽  
Dielectric Resonance ◽  
Magnetic Dynamic ◽  
Potential Applications ◽  
20 Nm ◽  
Electron Energy Loss

We introduce here a multifunctional material composed of alternating atomic sulfide sheets close to CuFeS2 and Mg-based hydroxide ones (valleriite), which are assembled due to their electric charges of opposite sign. Valleriite particles of 50-200 nm in the lateral size and 10-20 nm thick were synthesized via a simple hydrothermal pathway using various concentrations of precursors and dopants, and examined with XRD, TEM, EDS, X-ray photoelectron spectroscopy, reflection electron energy loss spectroscopy (REELS), Mössbauer, Raman and UV-vis-NIR spectroscopies, magnetic, dynamic light scattering, zeta potential measurements. The electronic, magnetic and optical characteristics are found to be critically dependent of the charge (electron density) at the narrow-gap sulfide layers containing Cu+ and Fe3+ cations, and can be tuned via the composition of hydroxide part. Particularly, substitution of Mg2+ with Al3+ increases the negative charge of the hydroxide layers and reduces the content of Fe3+-OH centers (10-45% of total iron); the effects of Cr and Co dopants entering both layers are more complicated. Mössbauer doublets of paramagnetic Fe3+ detected at room temperature transform to several Zeeman sextets at 4.2 K; the hyperfine fields up to 500 kOe and complex magnetic behavior, but not pure paramagnetism or antiferromagnetism, were observed for valleriites with the higher positive charge of the sulfide sheets, probably due to the depopulation of the minority-spin 3d states of S-bonded Fe3+ ions. Aqueous colloids of valleriite show optical absorption at 500 - 750 nm, which, along with the peaks at the same energies in REELS, may arise due to quasi-static dielectric resonance involving the vacant Fe 3d band and being dependent on the composition of both layers too. These and other findings call attention to the of valleriites as a new rich family of 2D materials for a variety of potential applications.

scholarly journals Synthesis and characterization of nanoscale composite particles formed by 2D layers of Cu-Fe sulfide and Mg-based hydroxide

2021 ◽  
Author(s):  
Yuri Mikhlin ◽  
Roman Borisov ◽  
Sergey Vorobyev ◽  
Yevgeny Tomashevich ◽  
Alexander Romanchenko ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Localized Surface Plasmon ◽  
X Ray ◽  
Zeta Potentials ◽  
Dielectric Resonance ◽  
Magnetic Dynamic ◽  
20 Nm ◽  
Electron Energy Loss

Two-dimensional phenomena are attracting enormous interest at present and the search for novel 2D materials is very challenging. We propose here the layered material valleriite composed of altering atomic sheets of Cu-Fe sulfide and Mg-based hydroxide synthesized via a simple hydrothermal pathway as particles of 50-200 nm in the lateral size and 10-20 nm thick. The solid products and aqueous colloids prepared with various precursor ratios were examined using XRD, TEM, EDS, X-ray photoelectron spectroscopy (XPS), reflection electron energy loss spectroscopy (REELS), Raman, Mössbauer, UV-vis-NIR spectroscopies, magnetic, dynamic light scattering, zeta potential measurements. The material properties are largely determined by the narrow-gap (less than 0.5 eV) sulfide layers containing Cu+ and Fe3+ cations, monosulfide and minor polysulfide anions but are strongly affected by the hydroxide counterparts. Particularly, Fe distribution between sulfide (55-90%) and magnesium hydroxide layers is controlled through insertion of Al into the hydroxide part and by Cr and Co dopants entering both layers. Room-temperature Mössbauer signals of paramagnetic Fe3+ transformed to several Zeeman sextets with hyperfine magnetic fields up to 500 kOe in the sulfide layers at 4 K. Paramagnetic or more complicated characters were observed for valleriites with higher and lower Fe concentrations in hydroxide sheets, respectively. Valleriite colloids showed negative zeta potentials, suggesting negative electric charging of the hydroxide sheets, and optical absorption maxima between 500 nm and 700 nm, also depended on the Fe distribution. The last features observed also in the REELS spectra may be due to localized surface plasmon or, more likely, quasi-static dielectric resonance. The tunable composition, electronic, magnetic, optic and surface properties highlight valleriites as a rich platform for novel 2D composites promising for numerous applications.

Preparation and Characterization of Chitosan-Casein Phosphopeptides Biocomposite Coatings on the Medical Titanium Alloy

2011 ◽  
Vol 480-481 ◽  
pp. 1065-1069
Author(s):  
Bin Liu ◽  
Lin Wang ◽  
Yin Zhong Bu ◽  
Sheng Rong Yang ◽  
Jin Qing Wang
Keyword(s):  
Photoelectron Spectroscopy ◽  
Attenuated Total Reflectance ◽  
Ti Alloy ◽  
Force Microscopy ◽  
Implant Materials ◽  
Atomic Force ◽  
Casein Phosphopeptides ◽  
Potential Applications ◽  
First Time

Titanium (Ti) and its alloys have been applied in orthopedics as one of the most popular biomedical metallic implant materials. In this work, to enhance the bioactivity, the surface of Ti alloy pre-modified by silane coupling agent and glutaraldehyde was covalently grafted with chitosan (CS) via biochemical multistep self-assembled method. Then, for the first time, the achieved surface was further immobilized with casein phosphopeptides (CPP), which are one group of bioactive peptides released from caseins in the digestive tract and can facilitate the calcium adsorption and usage, to form CS-CPP biocomposite coatings. The structure and composition of the fabricated coatings were characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and atomic force microscopy (AFM). As the experimental results indicated, multi-step assembly was successfully performed, and the CS and CPP were assembled onto the Ti alloy surface orderly. It is anticipated that the Ti alloys modified by CS-CPP biocomposite coatings will find potential applications as implant materials in biomedical fields.

Energetic Deposition and Surface Characterization of Thin Carbon Films on Nickel

1998 ◽  
Vol 12 (10) ◽  
pp. 383-391
Author(s):  
K. P. Adhi ◽  
A. K. Sharma ◽  
S. S. Wagal ◽  
D. S. Joag ◽  
S. K. Kulkarni
Keyword(s):  
Photoelectron Spectroscopy ◽  
Surface Characterization ◽  
Carbon Films ◽  
Polycrystalline Nickel ◽  
Thin Carbon ◽  
Nickel Substrates ◽  
Phase Surface ◽  
Electron Energy Loss ◽  
Deposited Films

Thin films deposited by rapidly quenching the energetic carbon species impinging onto polycrystalline nickel substrates were studied by X-ray photoelectron spectroscopy (XPS), electron energy loss spectroscopy (EELS), and field ion microscopy (FIM). XPS and EELS of the deposited films, when compared with those recorded for graphite and synthetic diamond, indicated the growth of diamond like carbon films and amorphic diamond (a-D) phase. Surface atomic arrangement in the film is observed by FIM which magnifies the surface ~105 to 106 times. Facetting, lack of graphitic ordering, stability of the image inspite of raising or lowering the voltage about the field evaporation voltage indicate that the field ion micrograph is that of a-D.

Synthesis and Characterization of FePt Nanoparticle/Single Walled Carbon Nanotube Composites

2009 ◽  
Vol 620-622 ◽  
pp. 505-508 ◽  
Author(s):  
Yan Wang ◽  
Lian Gao ◽  
Jing Sun ◽  
Yang Qiao Liu
Keyword(s):  
Carbon Nanotube ◽  
Synthesis And Characterization ◽  
Fept Nanoparticles ◽  
Single Walled Carbon Nanotube ◽  
Single Walled Carbon ◽  
Nanotube Composites ◽  
Potential Applications ◽  
Carbon Nanotube Composites ◽  
20 Nm

We report the synthesis and characterization of FePt nanoparticles (NPs)/single walled carbon nanotube (SWNTs) nanocomposites, which might have important potential applications to orient CNTs and the development of new catalysts. The crystallite size of FePt NPs is about 2.5-4 nm and the Fe atom content ranges from 50% to 65%. HiPCO SWNTs have been decorated with FePt nanoparticles under mild conditions without any pretreatment. When the bundle size of HiPCO SWNTs is about 20 nm, FePt NPs mostly attach on the sidewalls of SWNTs. The loading of FePt nanoparticles on the SWNTs bundles can be conveniently controlled by adjusting the initial amount of FePt NPs. The nanocomposite showed magnetic properties in a magnetic field. TEM, HRTEM, and EDS spectra were performed to observe the nanostructure of these nanocomposites.

Preparation and Characterization of Silica-Coated ZnSe Nanowires with Thermal Stability and Photoluminescence

2007 ◽  
Vol 7 (12) ◽  
pp. 4494-4500 ◽  
Author(s):  
Shenglin Xiong ◽  
Baojuan Xi ◽  
Weizhi Wang ◽  
Hongyang Zhou ◽  
Shuyuan Zhang ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Volume Ratio ◽  
Silica Coating ◽  
Sol Gel Process ◽  
High Resolution Tem ◽  
Potential Applications ◽  
Znse Nanowires

Silica-coated ZnSe nanowires with well-controlled the thickness of sheath in the range of 10–60 nm have been synthesized through a simple sol–gel process. The thickness of silica coating could be controlled through altering reaction parameters such as volume ratio of TEOS and ammonia. XRD, high-resolution TEM, X-ray photoelectron spectroscopy (XPS), Raman spectra, thermogravimetric analysis (TGA), and photoluminescence (PL) spectra were used to characterize the core/sheath nanostructures. Room-temperature PL measurements indicate these silica-coated ZnSe nanowires remarkably improve the PL intensity. Meanwhile, the thermal stability has been enhanced greatly, which is useful for their potential applications in advanced semiconductor devices.

Preparation and Characterization of Skin-Colored N-Doped ZnO Nanocrystals

2010 ◽  
Vol 663-665 ◽  
pp. 243-246
Author(s):  
Han Mei Hu ◽  
Chong Hai Deng ◽  
Qiang Fang ◽  
Ya Gao ◽  
Meng Wei Song
Keyword(s):  
Photoelectron Spectroscopy ◽  
X Ray Diffraction ◽  
Visible Absorption ◽  
X Ray ◽  
Zno Nanocrystals ◽  
Uv Visible ◽  
Doped Zno ◽  
20 Nm ◽  
Strong Absorption Peak

In this paper, we report a simple two-step approach (microwave-calcinating) to prepare skin-colored N-doped ZnO nanocrystals. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS) and UV-visible absorption were used to characterize the as-synthesized products. The FESEM results reveal the products mainly take on the morphology of porous flake constructed by 20 nm nanoparticles. UV-Vis spectrum shows a strong absorption peak located at 384nm.

Growth and Characterization of Self-Aligned Erbium Silicide on N-Type, (100) Oriented Silicon

1998 ◽  
Vol 514 ◽  
Author(s):  
Suhit R. Das ◽  
Les LeBrun ◽  
G. Irwin Sproule
Keyword(s):  
Schottky Barrier ◽  
Barrier Height ◽  
Ohmic Contacts ◽  
Hexagonal Phase ◽  
Infrared Detector ◽  
Bulk Composition ◽  
Ex Situ ◽  
Potential Applications ◽  
20 Nm

ABSTRACTIn view of its low barrier height to n-type Si, ErSi2 has potential applications as an infrared detector, as low-resistance ohmic contacts and as source/drain regions in Schottky barrier MOSFETs. Although there is a substantial body of work on ErSi2 grown on Si(111), there are relatively few published papers on the growth and properties of ErSi2 on Si(100). In order to develop a CMOS-compatible process, we have studied the growth of ErSi2 using a multi-source, UHV magnetron system to sputter-deposit 20 nm Ti/(10–50) nm Er bilayers on chemically cleaned n-Si(100) substrates followed by ex-situ rapid thermal annealing in N2. Highly oriented ErSi2 in the hexagonal phase was formed at an annealing temperature of 400°C with ErSi2 (100) Si(100). The Ti overlayer and the unreacted Er were selectively etched in HF and HNO3, respectively, leaving behind an ErSi2 layer with a smooth surface morphology, a uniform bulk composition and a planar ErSi2/Si interface. Results of electrical sheet resistance and Schottky barrier height measurements on these layers will be reported.

scholarly journals Hydrogenation of terminal and internal olefins using a biowaste-derived heterogeneous cobalt catalyst

2018 ◽  
Vol 4 (9) ◽  
pp. eaau1248 ◽  
Author(s):  
Florian Korbinian Scharnagl ◽  
Maximilian Franz Hertrich ◽  
Francesco Ferretti ◽  
Carsten Kreyenschulte ◽  
Henrik Lund ◽  
...  
Keyword(s):  
Magnetic Behavior ◽  
Magnetic Composite ◽  
Metal Composite ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Water As Solvent ◽  
Scanning Transmission ◽  
Product Separation ◽  
Electron Energy Loss

Hydrogenation of olefins is achieved using biowaste-derived cobalt chitosan catalysts. Characterization of the optimal Co@Chitosan-700 by STEM (scanning transmission electron microscopy), EELS (electron energy loss spectroscopy), PXRD (powder x-ray diffraction), and elemental analysis revealed the formation of a distinctive magnetic composite material with high metallic Co content. The general performance of this catalyst is demonstrated in the hydrogenation of 50 olefins including terminal, internal, and functionalized derivatives, as well as renewables. Using this nonnoble metal composite, hydrogenation of terminal C==C double bonds occurs under very mild and benign conditions (water or methanol, 40° to 60°C). The utility of Co@Chitosan-700 is showcased for efficient hydrogenation of the industrially relevant examples diisobutene, fatty acids, and their triglycerides. Because of the magnetic behavior of this material and water as solvent, product separation and recycling of the catalyst are straightforward.

Characterization of Antimony-Doped TIN Oxide Catalysts

2001 ◽  
Vol 7 (S2) ◽  
pp. 1094-1095
Author(s):  
K. Sun ◽  
J. Liu ◽  
N.D. Browning
Keyword(s):  
Tin Oxide ◽  
Photoelectron Spectroscopy ◽  
Contrast Imaging ◽  
X Ray ◽  
Catalytic Activities ◽  
Valence States ◽  
Z Contrast ◽  
Electron Energy Loss ◽  
X Ray Absorption

Antimony-doped tin oxide (ATO) catalysts are used for the oxidation of propylene to acrolein, the ammoxidation of propylene to acrylonitrile and the oxidative dehydrogenation of butanes to 1,3- butadiene. The distribution and valence states of Sb in ATOs are key in determining their catalytic activities. While these materials have been subjects of intensive studies for more than 20 years, X-ray photoelectron spectroscopy, Mössbauer spectrometry, and X-ray absorption spectroscopy4 have so far provided only indirect data for the distribution of Sb and its valence states. in particular, while has been hypothesized that the tin (IV) oxide contains Sb (V) within the bulk lattice and Sb (III) located at surface sites, no direct experimental evidence for this has been provided.Here we use electron energy loss spectroscopy (EELS) combined with Z-contrast imaging in a JEOL 2010F field emission STEM/TEM operating at 200 KV to analyze ATO catalysts.

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