Journal of Nano Research Vol. 4

Abstract: An attempt has been made to synthesize Ni1-xCoxFe2O4 by a simple technique of thermal evaporation with the help of egg white. The use of egg white (ovalbumin) in the synthesis process mainly helps to shape the particle during the reaction. The X-ray diffraction patterns reveal that the synthesized Ni1-XCoxFe2O4 ferrites are in nanocrystalline phase. The transmission electron microscopy observation confirmed that the average particle size of Ni1-xCoxFe2O4 has been varied from 7 nm to 30 nm. EDX spectrum gives account of the percentage composition of the products such as nickel, cobalt, Fe and O. Vibrating Samples Magnetometer (VSM) have been sued to study the saturation magnetization for variation of Ni substitution over CoFe2O4 and the influence of particle size in magnetic properties. Its analysis is based on the aspect of variation in coercivity with temperature. The FTIR spectra of the sample in the range 400 – 4000 cm-1 reveals the common feature of ferrites like high frequency band to the tetrahedral and low frequency band to the octahedral stretching vibrations.

Abstract: NMR nuclear relaxation times have been used by Tavares et al as a methodology to characterize the nano materials, especially nanocomposites, because NMR offers a great variety of relaxation parameters. The spin-lattice relaxation time, with a time constant T1, have been explored to get as much information as possible from the measurements of the spin-lattice proton relaxation (T1H), which can measure the fraction of available polymer/clay interface as well as the dispersion homogeneity of those interfaces actually formed. The spin-lattice has been evaluated since this relaxation time confirms the T1 and can give additional information to nanocomposite clay dispersion. The NMR relaxation times are sensitive to the chemical environmental, changes in the polymer matrix; chemical structure and interaction process, because they depend on the domain distribution and sample homogeneity, since they are measured in the solid state via intermolecular chains interaction and/or spin diffusion. The T1 relaxation time of the nanocomposite decreased very much in relation to the natural resin, according to the increase in the exfoliation clay process, forming a nanocomposite with polymer matrix around the clay lamella.

Abstract: Carbon Nanotubes (CNTs) are excellent material with a variety of physical, electrical, and mechanical properties. The average aspect ratio is evaluated for samples synthesized at different temperature and time of precursor flow. The experiments were conducted on calcium carbonate (CaCO3) substrate with iron-cobalt (Fe-Co) as a catalyst. Acetylene (C2H2) was used as a precursor gas and argon (Ar) as a carrier gas. The experiments were performed at temperatures ranging from 600 0C to 900 0C in step of 100 0C with time of precursor flow varying from 15 minutes to 75 minutes in the step of 15 minutes. The partial pressure of C2H2 and Ar kept constant during synthesis of CNT. The mass flow rate of C2H2 and Ar were 2 liters/hour and 60 liters/hour respectively during synthesis of CNT. The characterization of CNT was done with SEM, EDX, and TEM microscopes. Average aspect ratio of CNT is estimated using image analysis software. Most of nanotubes grown present an average diameter of 40 nm. The minimum and maximum diameter found are12.5 nm and 106 nm respectively. It is observed that average aspect ratio ranges from 25 to 58.

Abstract: Our present analysis will focus on the S(V)LS mechanism. In the S(V)LS process, silicon nanowires are grown by heating the metal-coated silicon substrate at high temperature in an argon and hydrogen atmosphere. Here, we demonstrate the origin of the driving force needed for the metal supersaturation and calculate the binary phase diagrams of Au-Si nanosystems involved in the growth of nanowires. These new diagrams can be used for other purposes helping to improve the understanding of the physical properties of nanostructures. We also answer the challenging question that many researchers have addressed on whether a minimum size limit of silicon nanowires exists. The nanowire size limit has been evaluated on the basis of thermodynamics and using silicon nanowires obtained via the S(V)LS rather than the VLS mechanism. At 1100°C, the temperature commonly used for the growth of nanowires by the S(V)LS mechanism, it has been found that there is no minimum size limit of nanowires.

Abstract: Copper nanorods and triangular nanoplates have been successfully generated by via a simple solution-phase approach by reducing CuCl2 with L-ascorbic acid (AsA) in aqueous solution in the presence of cetyltgrimethlammonium bromide (CTAB). The formation of self-assembled microstructures of CTAB molecules in aqueous solution is suggested to account for the anisotropic growth of one-dimensional copper nanorods and triangular nanoplates.