Nanosized Copper Particles Research Articles

Metallic Copper Nanoparticle Synthesis in AOT Reverse Micelles in Compressed Propane and Supercritical Ethane Solutions

In this articles, we present the formation of nanosized metallic copper particles synthesized in sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles in compressed propane and supercritical fluid (SCF) ethane solutions. Specifically, copper particles (<20 nm) were produced by the reduction of copper ions from copper bis(2-ethylhexyl) sulfosuccinate, Cu(AOT)2, incorporated within AOT reverse micelles dispersed in compressed propane and SCF ethane solvent along with small amounts of isooctane cosolvent. The effects of the compressed solvents on the particle characteristics and particle growth rate are discussed and comparisons are made with growth rates in normal liquid solvents. The metallic nanoparticles were characterized using both in situ UV−vis spectroscopy and transmission electron microscopy. The UV−vis spectrum of these nanosized copper particles is sensitive to particle size, and hence time-resolved spectral measurements were used to monitor the particle growth process. The particle growth rate in AOT reverse micelles in SCF ethane is faster than in either of the two normal liquid solvents partly because of intermediate physical and transport properties of the SCF solvent (e.g. increased mass transfer, decreased viscosity and density, lower dielectric constant), which results in increased collision frequencies and exchange rates between micelles.

Ultrasonic Force Microscopic Characterization of Nanosized Copper Particles

ABSTRACTAn Ultrasonic Force Microscope capable of imaging elastic modulus variations with nanometer resolution has been developed by modifying a Scanning Probe Microscope. Images of ultrasonic properties have been simultaneously obtained with the topography images. The technique has been utilized to characterize nanoscale copper droplets and grains deposited on a quartz substrate by ionized cluster beam deposition. Images of the same region obtained with atomic force microscope, lateral force microscope, and ultrasonic force microscope are compared. The origin of image contrast in ultrasonic force microscopy and its utilization for quantitative elastic property measurement of nanometer particles are discussed.

Fabrication of nano-sized particles of metallic copper and copper sulfide in Langmuir–Blodgett films

Langmuir monolayers of arachidic acid on a subphase of 0.3 mM CuSO 4/17 mM NH 3 were transferred to hydrophobic glass and mica substrates to give Langmuir–Blodgett films of cupric arachidate (CuAr). Transfer ratios of close to 1 were observed and regular “Y”-type deposition was demonstrated with hydrophobic glass. With mica as the substrate, “Z”-type deposition occurred. The films were exposed to H 2S and hydrazine, and evidence for the formation of copper sulfide and metallic copper particles, respectively, was obtained by ultraviolet/visible spectrophotometry, X-ray photoelectron spectroscopy and atomic force microscopy.

Sol-gel prepared copper doped SiO2 glasses

SiO2 glasses doped with nano-sized copper particles were prepared through sol-gel method. Samples with nominal composition xCu−(1−x)SiO2 (x=0.02, 0.05, 0.1, 0.2, 0.4) were prepared by hydrolyzing tetraethylorthosilicate with various amounts of Cu(NO3)2. The dried gels were heat treated at 400, 500, 600, 700°C for 10 hrs under flowing 5% H2-95% N2 mixture gas to reduce Cu+2 ions to metallic copper. The amorphous nature of the SiO2 matrix was confirmed by powder X-ray diffraction. The size of particulate copper metal, which was determined by transmission electron microscopy, increases with the temperature of heat treatment and the copper content. The local structure of SiO2 matrix was probed by FTIR. The silica matrix has no major structural change for gels heat treated at different temperatures and with different copper contents.

Iron nanoparticles in copper matrix prepared by sol-gel route

Iron particles having diameters around 8 nm and loosely packed with nanosized copper particles have been prepared by a sol-gel route. The samples exhibit coercivities in the range 200 to 500 Oe that are typical of single-domain iron grains. The Mössbauer spectrum is consistent with the presence of α-Fe particles in the system. However, a finite value of the isomer shift is obtained that is ascribed to possible electron transfer between the iron atoms and the surrounding copper matrix.

Cross-sectional TEM observation of copper-implanted SiO 2 glass

Transmission electron microscopic observation has been made on SiO2 glass implanted to a dose of 6 × 1016 ions/cm2 at an energy of 160 keV and in a sample implanted to 6 × 1016 ions/cm2 at 169 keV and to 2 × 1016 ions/cm2 at 35 keV. In the sample with 6 × 1016 ions/cm2, the depth distribution of implanted Cu is bimodal in shape. It has been found that nano-sized particles of copper are formed in both depth regions of the bimodal distribution and the distribution of Cu colloid diameters has a shape that is close to that of implanted Cu concentrations. A triple layer of Cu colloid particles has been formed by sequential implantation using differing acceleration voltages (160 keV followed by 35 keV).