Water-based Si3N4 suspensions: Part I. Effect of processing routes on the surface chemistry and particle interactions

2000 ◽  
Vol 15 (1) ◽  
pp. 155-163 ◽  
Author(s):  
C. Galassi ◽  
F. Bertoni ◽  
S. Ardizzone ◽  
C. L. Bianchi
Keyword(s):  
Photoelectron Spectroscopy ◽  
Surface Composition ◽  
Particle Surface ◽  
Great Influence ◽  
Particle Interactions ◽  
Mixing Process ◽  
Mixing Processes ◽  
X Ray ◽  
Solid Liquid ◽  
Nitride Particle

Si3N4 powders manufactured by two different preparative routes were characterized for the solid–liquid interfacial reactivity and surface composition. Three mixing processes were tried to investigate the modifications of silicon nitride particle surface in aqueous suspensions. The surfaces of the starting powders and the dried mixed powders were investigated by x-ray photoelectron spectroscopy to determine the nature and ratios of surface groups. Electroacoustic measurements show that no change occurs in the isoelectric point for the mixed Si3N4 powders while the milling/mixing process has a great influence on the zeta potential magnitude and particle size distribution.

Water-based Si3N4 suspensions: Part II. Effect of wet mixing/milling processes on the addition of the sintering aids

2000 ◽  
Vol 15 (1) ◽  
pp. 164-169 ◽  
Author(s):  
C. Galassi ◽  
F. Bertoni ◽  
S. Ardizzone ◽  
C. L. Bianchi
Keyword(s):  
Photoelectron Spectroscopy ◽  
Volume Fraction ◽  
Surface Composition ◽  
Great Influence ◽  
Sintering Aids ◽  
Mixing Processes ◽  
Mixing Energy ◽  
Solids Loading ◽  
Surface Behavior ◽  
Efficient Processing

Three mixing processes were used to introduce lanthanum oxide and yttrium oxide in silicon nitride suspensions. X-ray photoelectron spectroscopy (XPS) analysis was used to identify the surface composition and investigate the surface coverage by the added oxides. XPS results evidenced the protective effect against hydrolysis and oxidation of the coated layer. Electroacoustic measurements showed that the milling/mixing process and solids loading contents had a great influence on the isoelectric point (IEP) and on the dispersing degree for suspensions with sintering aids. With the change of solids load content and mixing energy, the IEP of mixed powders suspensions reflected a surface behavior dominated by the additives oxides. The attrition mixing and the ultrasonication resulted in the more efficient processing routes to distribute the sintering aids on the starting Si3N4 powders, especially at high solids volume fraction.

CO2 Reduction to Propanol by Copper Foams: A Pre- and Post-Catalysis Study

2020 ◽  
Author(s):  
Jennifer A. Rudd ◽  
Ewa Kazimierska ◽  
Louise B. Hamdy ◽  
Odin Bain ◽  
Sunyhik Ahn ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Photoelectron Spectroscopy ◽  
Carbon Capture ◽  
Surface Composition ◽  
Co2 Reduction ◽  
Structural Rearrangement ◽  
Copper Electrode ◽  
Ex Situ ◽  
X Ray ◽  
Copper Electrodes

The utilization of carbon dioxide is a major incentive for the growing field of carbon capture. Carbon dioxide could be an abundant building block to generate higher value products. Herein, we describe the use of porous copper electrodes to catalyze the reduction of carbon dioxide into higher value products such as ethylene, ethanol and, notably, propanol. For <i>n</i>-propanol production, faradaic efficiencies reach 4.93% at -0.83 V <i>vs</i> RHE, with a geometric partial current density of -1.85 mA/cm<sup>2</sup>. We have documented the performance of the catalyst in both pristine and urea-modified foams pre- and post-electrolysis. Before electrolysis, the copper electrode consisted of a mixture of cuboctahedra and dendrites. After 35-minute electrolysis, the cuboctahedra and dendrites have undergone structural rearrangement. Changes in the interaction of urea with the catalyst surface have also been observed. These transformations were characterized <i>ex-situ</i> using scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. We found that alterations in the morphology, crystallinity, and surface composition of the catalyst led to the deactivation of the copper foams.

scholarly journals Removal of hexavalent chromium from wastewater by Cu/Fe bimetallic nanoparticles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jien Ye ◽  
Yi Wang ◽  
Qiao Xu ◽  
Hanxin Wu ◽  
Jianhao Tong ◽  
...  
Keyword(s):  
Hexavalent Chromium ◽  
Removal Efficiency ◽  
Photoelectron Spectroscopy ◽  
Bimetallic Nanoparticles ◽  
Chemical Reduction ◽  
Particle Surface ◽  
Zerovalent Iron ◽  
Order Model ◽  
X Ray ◽  
Nanoscale Zerovalent Iron

AbstractPassivation of nanoscale zerovalent iron hinders its efficiency in water treatment, and loading another catalytic metal has been found to improve the efficiency significantly. In this study, Cu/Fe bimetallic nanoparticles were prepared by liquid-phase chemical reduction for removal of hexavalent chromium (Cr(VI)) from wastewater. Synthesized bimetallic nanoparticles were characterized by transmission electron microscopy, Brunauer–Emmet–Teller isotherm, and X-ray diffraction. The results showed that Cu loading can significantly enhance the removal efficiency of Cr(VI) by 29.3% to 84.0%, and the optimal Cu loading rate was 3% (wt%). The removal efficiency decreased with increasing initial pH and Cr(VI) concentration. The removal of Cr(VI) was better fitted by pseudo-second-order model than pseudo-first-order model. Thermodynamic analysis revealed that the Cr(VI) removal was spontaneous and endothermic, and the increase of reaction temperature facilitated the process. X-ray photoelectron spectroscopy (XPS) analysis indicated that Cr(VI) was completely reduced to Cr(III) and precipitated on the particle surface as hydroxylated Cr(OH)3 and CrxFe1−x(OH)3 coprecipitation. Our work could be beneficial for the application of iron-based nanomaterials in remediation of wastewater.

Solid-liquid interfaces studied with synchrotron-based ambient pressure X-ray photoelectron spectroscopy

2021 ◽  
Author(s):  
David Starr ◽  
Marco Favaro ◽  
Pip Clark ◽  
Rossella Yivlialin ◽  
Maryline Ralaiarisoa ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
Liquid Interfaces ◽  
X Ray ◽  
Solid Liquid

scholarly journals Dual Light- and pH-Responsive Composite of Polyazo-Derivative Grafted Cellulose Nanocrystals

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1725 ◽  
Author(s):  
Xiaohong Liu ◽  
Ming Li ◽  
Xuemei Zheng ◽  
Elias Retulainen ◽  
Shiyu Fu
Keyword(s):  
Cellulose Nanocrystals ◽  
Photoelectron Spectroscopy ◽  
Surface Composition ◽  
X Ray Diffraction ◽  
Responsive Materials ◽  
X Ray ◽  
Ph Response ◽  
Transmission Electron ◽  
Ft Ir ◽  
Hexyl Methacrylate

As a type of functional group, azo-derivatives are commonly used to synthesize responsive materials. Cellulose nanocrystals (CNCs), prepared by acid hydrolysis of cotton, were dewatered and reacted with 2-bromoisobuturyl bromide to form a macro-initiator, which grafted 6-[4-(4-methoxyphenyl-azo) phenoxy] hexyl methacrylate (MMAZO) via atom transfer radical polymerization. The successful grafting was supported by Fourier transform infrared spectroscopy (FT-IR) and Solid magnetic resonance carbon spectrum (MAS 13C-NMR). The morphology and surface composition of the poly{6-[4-(4-methoxyphenylazo) phenoxy] hexyl methacrylate} (PMMAZO)-grafted CNCs were confirmed with Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The grafting rate on the macro-initiator of CNCs was over 870%, and the polydispersities of branched polymers were narrow. The crystal structure of CNCs did not change after grafting, as determined by X-ray diffraction (XRD). The polymer PMMAZO improved the thermal stability of cellulose nanocrystals, as shown by thermogravimetry analysis (TGA). Then the PMMAZO-grafted CNCs were mixed with polyurethane and casted to form a composite film. The film showed a significant light and pH response, which may be suitable for visual acid-alkali measurement and reversible optical storage.

Surface Composition of Free Mixed NaCl/Na2SO4 Nanoscale Aerosols Probed by X-ray Photoelectron Spectroscopy

2018 ◽  
Vol 122 (10) ◽  
pp. 2695-2702 ◽  
Author(s):  
E. Antonsson ◽  
C. Raschpichler ◽  
B. Langer ◽  
D. Marchenko ◽  
E. Rühl
Keyword(s):  
Photoelectron Spectroscopy ◽  
Surface Composition ◽  
X Ray

Surface composition and electronic structure of Ni2+xMn1−xGa studied by X-ray photoelectron spectroscopy

2006 ◽  
Vol 600 (18) ◽  
pp. 3749-3752 ◽  
Author(s):  
C. Biswas ◽  
S. Banik ◽  
A.K. Shukla ◽  
R.S. Dhaka ◽  
V. Ganesan ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Photoelectron Spectroscopy ◽  
Surface Composition ◽  
X Ray

scholarly journals Succinic acid in aqueous solution: connecting microscopic surface composition and macroscopic surface tension

2014 ◽  
Vol 16 (39) ◽  
pp. 21486-21495 ◽  
Author(s):  
Josephina Werner ◽  
Jan Julin ◽  
Maryam Dalirian ◽  
Nønne L. Prisle ◽  
Gunnar Öhrwall ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Surface Tension ◽  
Succinic Acid ◽  
Photoelectron Spectroscopy ◽  
Surface Composition ◽  
Md Simulations ◽  
Vapor Interface ◽  
X Ray ◽  
Ph Values ◽  
Microscopic Surface

The water–vapor interface of aqueous solutions of succinic acid, where pH values and bulk concentrations were varied, has been studied using surface sensitive X-ray photoelectron spectroscopy (XPS) and molecular dynamics (MD) simulations.

Effect of Microstructural Characteristics of Electroless Nickel Metallisation on Solderability to Pb-Free Solder Alloys

2005 ◽  
Author(s):  
Changqing Liu ◽  
David A. Hutt ◽  
Dezhi Li ◽  
Paul P. Conway
Keyword(s):  
Photoelectron Spectroscopy ◽  
Surface Composition ◽  
Bulk Composition ◽  
Industrial Process ◽  
Surface Characteristics ◽  
Electroless Nickel ◽  
X Ray ◽  
N2 Atmosphere ◽  
Different Temperatures ◽  
Free Solder

This paper aims to gain an insight into the correlation between the microstructure and surface composition of electroless Ni-P and its behaviour during soldering with Pb free alloys including Sn-3.8Ag-0.7Cu, Sn-3.5Ag and Sn-0.7Cu. Ni-P coatings with different P contents were produced through an industrial process on copper metal substrates. The surface morphology of these coatings was observed by Scanning Electron Microscopy (SEM) and the bulk composition was analyzed by means of Energy Dispersive X-ray analysis (EDX). The mechanical properties of the coatings were evaluated by nano-indentation testing under different maximum loads. However, to understand the behaviour of P in Ni-P coatings and deterioration of the coating surfaces during exposure to air, the surfaces of the coatings were also characterised by X-ray Photoelectron Spectroscopy (XPS) for storage at different temperatures. The dependence of the solderability of Ni-P coatings on the storage time and temperature was investigated by wetting balance testing, using an inactive or active flux with or without an inert N2 atmosphere. Finally, the solderability of Ni-P coatings to Pb free solders is correlated with their composition and microstructure (e.g. surface characteristics).

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