Growth and CO chemisorption study of platinum nanoparticle on α-Al2O3

Pt nanoparticles sputter-deposited on α-Al2O3 support were investigated by FE-SEM measurement and CO chemisorption studies. Pt nanoparticles formed in the early stages of sputter deposition were well isolated, and the particle size distribution of Pt nanoparticles evaluated by FE-SEM measurements was narrow. Longer sputter deposition resulted in growth and coalescence of Pt nanoparticles. Such a transition of Pt from nanoparticles to film by sputter deposition was properly evaluated by CO chemisorption studies

Functionalized platinum nanoparticles with surface charge trigged by pH: synthesis, characterization and stability studies

In this work, the synthesis and characterization of functionalized platinum nanoparticles (PtNPs) have been investigated. PtNPs were obtained by a wet redox procedure using 2-diethylaminoethanethiol hydrochloride (DEA) as capping agent. By varying the Pt/thiol molar ratio, monodispersed and stable particles with diameters in the range of 3-40 nm were isolated. The amino functionality allows neutral particles to be obtained in basic water solution and positive charged nanoparticles in neutral or acidic water solution (pH 7-2), as confirmed by DLS and ζ-potential measurements. FTIR spectroscopy, FE-SEM, DLS and ζ-potential measurements confirmed the size and showed long term water stability (up to three months) of the colloidal system

Technique of failure analysis for gate oxide defect of Bi-polar CMOS Diffuse (BCD) technology

This research presents failure analysis (FA) works on gate oxide defect of Bi�polar CMOS Diffuse (BCD) technology. The latent problem with electrical degradation in the CMOS performance is due to gate oxide defect. The defect was well known affects the CMOS reliability after certain period of time, temperatures and stress. The FA techniques used for this research were developed using a combination of IDDQ scan test pattern, photo localization by the emission microscope and Field Emission Scanning Electron Microscopy (FE-SEM) for defect inspection. The FA methods successfully evaluated on few failing samples which were taken from customer return with IDDQ failure range from 50µA until less than 1mA. Concurrently, the spotted excessive emission found on the defective samples during photo localization step indicates of gate oxide defect. The defect well observed with FE-SEM analysis on all tested samples after the physical analysis accomplishment until oxide layer. The proposed technique shows an effective method to compensate the existing FA difficulty on gate oxide defect faced by IC manufacturer in micrometer and nanometer scale technology, which having more metal interconnection layers with higher dense. The proposed technique able to construct promising result compared to the conventional techniques which used in the current FA practice due to certain extends of limitation

Phase Analysis and Micro Structure of Zinc Oxide Nanoparticles

ZnO nanoparticles were prepared by precipitation method and calined at at 400°C, 600°C, and 800°C. The synthesized as well as calcined ZnO nanoparticles were characterized by DSC TG, X-ray diffraction (XRD) and FE SEM. X-ray diffraction result indicates that the sample is having a crystalline wurtzite phase. Crystallite size of ZnO nanoparticles calcined at different temperatures was determined using Scherrer’s formula. Field Emission Scanning Electron Microscopy (FE SEM) result reveals that the ZnO sample is spherical in shape, rod like structure and polycrystalline nature. Crystallite sizes and lattice strain were also analyzed using Williamson-Hall (W-H) analysi

Bimetallic Au-Cu Nanoparticles Anchored Reduced Graphene Oxide as Efficient Catalyst for Reduction of Nitro Aromatic Compounds

In the present work an efficient nanocomposite Au-Cu/rGO has been synthesised by decorating Au-Cu bimetallic nanoparticles on reduced graphene oxide surface via co-reduction method. The nanocomposite was characterized using X-ray diffraction (XRD), Field-emission Scanning electron microscopy (FE-SEM), Energy dispersive X-ray spectroscopy (EDS), Transmission electron microscopy (TEM) and UV-Visible spectroscopy. The FE-SEM and TEM images demonstrate the uniform distribution of the Au-Cu bimetallic nanoparticles on the GO surface and transmission electron microscopy (TEM) confirms an average particle size of 6-8 nm. The Au-Cu/rGO nanocomposite has been found to be an extremely efficient catalyst for the reduction of nitroaromatic compounds into nitroamine compounds. The Au-Cu/rGO nanocomposites exhibited synergistically more superior catalytic efficiency compared to monometallic Au nanoparticles doped reduced graphene oxide and monometallic Cu nanoparticles doped reduced graphene oxide. The reaction conditions were optimized by changing different parameters such as catalyst dose and reducing agent concentratio

Liquid-phase hydrogenation of bio-refined succinic acid to 1,4-butanediol using bimetallic catalysts

open access articleDevelopment of a Crotalaria juncea based biorefinery produce large quantity of waste glycerol after trans-esterification of the juncea seeds. This glycerol, after purification, is used as a substrate for producing succinic acid on a microbial route. Hydrogenation of this bio-refined succinic acid is carried out under high pressure in order to produce 1,4- butanediol (BDO) using a batch slurry reactor with cobalt supported ruthenium bimetallic catalysts, synthesized inhouse. It is demonstrated that, using small amounts of ruthenium to cobalt increases the overall hydrogenation activity for the production of 1,4-butanediol. Hydrogenation reactions are carried out at various operating temperatures and pressures along with changes in the mixing ratios of ruthenium chloride and cobalt chloride hexahydrate, which are used to synthesize the catalyst. The Ru-Co bimetallic catalysts are characterized by XRD, FE-SEM and TGA. Concentrations of the hydrogenation product are analyzed using Gas chromatography-Mass spectrometry (GC-MS). Statistical analysis of the overall hydrogenation process is performed using a Box-Behnken Design (BBD)

Nanostructured Zinc Oxide as a Prospective Room Temperature Thermoelectric Material

Nanostructured Zinc oxide (ZnO) was synthesized via a ball milling for 10 hours using high energy planetary ball mill. Phase purity and homogeneity of all the samples have been investigated by X-ray diffraction (XRD) and Field Emission Scanning Electron Microscopy (FE-SEM). All the diffraction peaks can be indexed to the hexagonal phase ZnO with hexagonal symmetry (space group P63mc). Average crystallite size was observed to be 20 nm. There was a remarkable suppression in thermal conductivity ({\kappa}) compared to the bulk values by a factor of ~50 at room temperature. This suggests to the possibility of using nanostructured ZnO as a prospective room temperature thermoelectric material.Comment: submitted to DAE SSPS 201

Sintering Effects on Microstructure and Electrical Properties of CaCu3Ti4O12 Ceramics

CCTO powders were prepared by solid state reaction and mechanochemically, respectively. Synthesized powders were characterized by XRD, FE-SEM and PSA techniques. The sinterability of CCTO powders was investigated by heating microscopy. Powders were uniaxially pressed into pellets and sintered up to 1100 °C, with heating rates of 2, 5, 10 and 20 °/min. The recorded shrinkage curves were used for choosing conventional and two step sintering (TSS) conditions. By TSS the samples were heated up to 1070 °C and after retention for 10 min cooled down to 1020 °C and kept for 20 h. The microstructure of CCTO ceramics sintered by conventional and TSS techniques was examined by FE-SEM method; the electrical properties were investigated in medium frequency (MF) range (42 Hz-5 MHz) and in the microwave (MW) range of frequencies. Electrical properties of the sintered CCTO ceramics were correlated to the samples microstructure. Finally, we have shown that appropriate choice of sintering conditions is important for preparation of high-quality CCTO ceramics with high dielectric permittivity in the kilohertz range as well as at the resonant frequency

Graphene-based dental adhesive with anti-biofilm activity

BACKGROUND: Secondary caries are considered the main cause of dental restoration failure. In this context, anti-biofilm and bactericidal properties are desired in dental materials against pathogens such as Streptococcus mutans. To this purpose, graphene based materials can be used as fillers of polymer dental adhesives. In this work, we investigated the possibility to use as filler of dental adhesives, graphene nanoplatelets (GNP), a non toxic hydrophobic nanomaterial with antimicrobial and anti-biofilm properties. RESULTS: Graphene nanoplatelets have been produced starting from graphite intercalated compounds through a process consisting of thermal expansion and liquid exfoliation. Then, a dental adhesive filled with GNPs at different volume fractions has been produced through a solvent evaporation method. The rheological properties of the new experimental adhesives have been assessed experimentally. The adhesive properties have been tested using microtensile bond strength measurements (µ-TBS). Biocidal activity has been studied using the colony forming units count (CFU) method. The anti-biofilm properties have been demonstrated through FE-SEM imaging of the biofilm development after 3 and 24 h of growth. CONCLUSIONS: A significantly lower vitality of S. mutans cells has been demonstrated when in contact with the GNP filled dental adhesives. Biofilm growth on adhesive-covered dentine tissues demonstrated anti-adhesion properties of the produced materials. µ-TBS results demonstrated no significant difference in µ-TBS between the experimental and the control adhesive. The rheology tests highlighted the necessity to avoid low shear rate regimes during adhesive processing and application in clinical protocol, and confirmed that the adhesive containing the 0.2%wt of GNPs possess mechanical properties comparable with the ones of the control adhesive

On the path to a new generation of cement-based composites through the use of lignocellulosic micro/nanofibers

Due to its high biocompatibility, bio-degradability, and low cost, cellulose finds application in disparate areas of research. Here we focus our attention on the potential applications of cellulose nanofiber in cement-basedmaterials for the building sector. We first describe the chemical/morphological composition of cellulose fibers, their process and treatment, the characterization of cement-based composites, and their flexural strengthPeer ReviewedPostprint (published version