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

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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Grafting of TiO2 on PMMA Film and Reusability in Photodegradation of Organic Dye

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.99.17 ◽

2016 ◽

Vol 99 ◽

pp. 17-21

Author(s):

Rachan Klaysri ◽

Sopita Wichaidit ◽

Piyasan Praserthdam ◽

Okorn Mekasuwandumrong

Keyword(s):

Photoelectron Spectroscopy ◽

Surface Composition ◽

Bulk Composition ◽

Pmma Film ◽

Glass Temperature ◽

Scanning Calorimetry ◽

X Ray ◽

H Nmr ◽

Ft Ir ◽

Novel Method

Grafting TiO2 on PMMA was studied by atom-transfer radical-polymerization (ATRP). Each step in grafting process was monitored by fourier transform infrared spectroscopy (FT-IR), 1H NMR and 13C NMR spectra. The glass temperature of grafted-PMMA film was determined by using differential scanning calorimetry (DSC). The morphology and bulk composition were characterized by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). The surface composition was characterized by X-ray photoelectron spectroscopy (XPS). As results, a novel method of grafting TiO2 on PMMA was successfully grafted and confirmed in various techniques. The photocatlytic activity was evaluated under UV and visible light irradiation. The reusability of TiO2-g-PMMA films was studied in details.

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Effects of Rapid Thermal Annealing on CdTe/CdS Solar Cell Fabrication

MRS Proceedings ◽

10.1557/proc-426-379 ◽

1996 ◽

Vol 426 ◽

Author(s):

Y. A. Cho ◽

W. J. Nam ◽

H. S. Kim ◽

G. Y. Yeom ◽

J. K. Yoon ◽

...

Keyword(s):

Thin Films ◽

Thermal Annealing ◽

Rapid Thermal Annealing ◽

Photoelectron Spectroscopy ◽

Surface Composition ◽

Bulk Composition ◽

Cross Sectional ◽

Transmission Microscopy ◽

X Ray ◽

Cdte Thin Films

AbstractRapid thermal annealing (RTA) was applied to anneal polycrystalline CdTe thin films evaporated on CdS/ITO substrate and the effects of rapid thermal annealing temperatures and gas environments were studied. X-ray diffractometer (XRD), X-ray photoelectron spectroscopy(XPS), energy dispersive X-ray spectroscopy(EDX), cross-sectional transmission microscopy(TEM), and micro-EDX in TEM were used to characterize physical and chemical properties of rapid thermal annealed CdTe thin films. Complete CdTe/CdS photovoltaic cells were fabricated and I-V characteristics of these cells were measured under the illumination. Results showed that the bulk composition of CdTe remained stoichiometric to 550°C in the air environment and surface composition became Cd-rich. Cross-sectional TEM and micro-EDX showed columnar grains and micro-twins remained even after RTA, however, sulfur content in rapid thermal annealed CdTe caused by sulfur diffusion from CdS during the annealing was much smaller than that by furnace annealing. Among the investigated RTA temperatures and gas environments, the cell made with CdTe annealed at 550°C in the air showed the best solar energy conversion efficiency.

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Low Temperature Film Growth by Supersonic Jets of CBr4

MRS Proceedings ◽

10.1557/proc-388-233 ◽

1995 ◽

Vol 388 ◽

Author(s):

Douglas A. A. Ohlberg ◽

Garry Rose ◽

James Ren ◽

R. Stanley Williams

Keyword(s):

Photoelectron Spectroscopy ◽

Film Growth ◽

Surface Composition ◽

Bulk Composition ◽

High Vacuum ◽

Depth Profiling ◽

Deposition Efficiency ◽

Supersonic Jets ◽

X Ray

AbstractPulsed, supersonic jets of CBr4 seeded in a hydrogen bath gas have been used to deposit films on silicon at low temperatures (c A. 100° C) in a high vacuum chamber. IN situ analysis of the films using x-ray photoelectron spectroscopy (XPS) and depth profiling indicate a surface composition of 34% Br and 66 % C and a bulk composition of 88% C and 12% Br. the deposition efficiency of CBr4 was found to drop dramatically when seeded in bath gases of deuterium, helium, and argon, suggesting that the film growth is an activated process, requiring precursor energies of at least 3.6 eV.

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Synthesis and Characterization of p-n Junction Ternary Mixed Oxides for Photocatalytic Coprocessing of CO2 and H2O

Catalysts ◽

10.3390/catal10090980 ◽

2020 ◽

Vol 10 (9) ◽

pp. 980

Author(s):

Davide M. S. Marcolongo ◽

Francesco Nocito ◽

Nicoletta Ditaranto ◽

Michele Aresta ◽

Angela Dibenedetto

Keyword(s):

Photoelectron Spectroscopy ◽

Mixed Oxides ◽

Surface Composition ◽

Diffuse Reflectance Spectroscopy ◽

Bulk Composition ◽

High Energy ◽

Synthesis And Characterization ◽

X Ray ◽

Uv Visible

In the present paper, we report the synthesis and characterization of both binary (Cu2O, Fe2O3, and In2O3) and ternary (Cu2O-Fe2O3 and Cu2O-In2O3) transition metal mixed-oxides that may find application as photocatalysts for solar driven CO2 conversion into energy rich species. Two different preparation techniques (High Energy Milling (HEM) and Co-Precipitation (CP)) are compared and materials properties are studied by means of a variety of characterization and analytical techniques UV-Visible Diffuse Reflectance Spectroscopy (UV-VIS DRS), X-ray Photoelectron Spectroscopy (XPS), X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and Energy Dispersive X-Ray spectrometry (EDX). Appropriate data elaboration methods are used to extract materials bandgap for Cu2O@Fe2O3 and Cu2O@In2O3 prepared by HEM and CP, and foresee whether the newly prepared semiconductor mixed oxides pairs are useful for application in CO2-H2O coprocessing. The experimental results show that the synthetic technique influences the photoactivity of the materials that can correctly be foreseen on the basis of bandgap experimentally derived. Of the mixed oxides prepared and described in this work, only Cu2O@In2O3 shows positive results in CO2-H2O photo-co-processing. Preliminary results show that the composition and synthetic methodologies of mixed-oxides, the reactor geometry, the way of dispersing the photocatalyst sample, play a key role in the light driven reaction of CO2–H2O. This work is a rare case of full characterization of photo-materials, using UV-Visible DRS, XPS, XRD, TEM, EDX for the surface and bulk analytical characterization. Surface composition may not be the same of the bulk composition and plays a key role in photocatalysts behavior. We show that a full material knowledge is necessary for the correct forecast of their photocatalytic behavior, inferred from experimentally determined bandgaps.

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

10.26434/chemrxiv.12022623.v1 ◽

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 n-propanol production, faradaic efficiencies reach 4.93% at -0.83 V vs RHE, with a geometric partial current density of -1.85 mA/cm2. 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 ex-situ 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.

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Effect of calcination temperature on rare earth tailing catalysts for catalytic methane combustion

Green Processing and Synthesis ◽

10.1515/gps-2020-0053 ◽

2020 ◽

Vol 9 (1) ◽

pp. 734-743

Author(s):

Ran Zhao ◽

ZiChen Tian ◽

Zengwu Zhao

Keyword(s):

Rare Earth ◽

Mine Tailings ◽

Photoelectron Spectroscopy ◽

Methane Combustion ◽

Space Velocity ◽

High Catalytic Activity ◽

Reduction Peak ◽

X Ray ◽

Different Temperatures ◽

Bayan Obo

AbstractBayan Obo tailings are rich in rare earth elements (REEs), iron, and other catalytic active substances. In this study, mine tailings were calcined at different temperatures and tested for the catalytic combustion of low-concentration methane. Upon calcination at 600°C, high catalytic activity was revealed, with 50% CH4 conversion at 587°C (space velocity of 12,000 mL/g h). The physicochemical properties of catalysts were characterized using thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, hydrogen temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS). Compared to the raw ore sample, the diffraction peak intensity of Fe2O3 increased post calcination, whereas that of CeCO3F decreased. A porous structure appeared after the catalyst was calcined at 600°C. Additionally, Fe, Ce, Ti, and other metal elements were more highly dispersed on the catalyst surface. H2-TPR results revealed a broadening of the reduction temperature range for the catalyst calcined at 600°C and an increase in the reduction peak. XPS analysis indicated the presence of Ce in the form of Ce3+ and Ce4+ oxidation states and the coexistence of Fe in the form of Fe2+ and Fe3+. Moreover, XPS revealed a higher surface Oads/Olatt ratio. This study provides evidence for the green reuse of Bayan Obo mine tailings in secondary resources.

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Low-Temperature Synthesis of Solution Processable Carbon Nitride Polymers

Molecules ◽

10.3390/molecules26061646 ◽

2021 ◽

Vol 26 (6) ◽

pp. 1646

Author(s):

Junyi Li ◽

Neeta Karjule ◽

Jiani Qin ◽

Ying Wang ◽

Jesús Barrio ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Carbon Nitride ◽

Spatial Organization ◽

Surface Display ◽

Liquid Media ◽

Low Temperature Synthesis ◽

Temperature Synthesis ◽

X Ray ◽

N2 Atmosphere ◽

Carbon Nitride Materials

Carbon nitride materials require high temperatures (>500 °C) for their preparation, which entails substantial energy consumption. Furthermore, the high reaction temperature limits the materials’ processability and the control over their elemental composition. Therefore, alternative synthetic pathways that operate under milder conditions are still very much sought after. In this work, we prepared semiconductive carbon nitride (CN) polymers at low temperatures (300 °C) by carrying out the thermal condensation of triaminopyrimidine and acetoguanamine under a N2 atmosphere. These molecules are isomers: they display the same chemical formula but a different spatial distribution of their elements. X-ray photoelectron spectroscopy (XPS) experiments and electrochemical and photophysical characterization confirm that the initial spatial organization strongly determines the chemical composition and electronic structure of the materials, which, thanks to the preservation of functional groups in their surface, display excellent processability in liquid media.

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

Materials ◽

10.3390/ma11091725 ◽

2018 ◽

Vol 11 (9) ◽

pp. 1725 ◽

Cited By ~ 5

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.

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