Novel Technique For Synthesis Research Articles

Decomposition-adsorption-deposition: An effective and novel technique for synthesis of hexagonal boron nitride microsheets

Magnesium diboride as a precursor with dual role of Nitrogen introduces a simple “decomposition-adsorption-deposition (DAD)” technique for the synthesis of Hexagonal Boron nitride microsheets (BNMSs) on silicon (Si) substrate at 1100 °C. The synthesized BNMSs has the apparent morphology like the white dispersed feathers on a plate surface with diameter in the range of 3–15 µm and lengt greater than 30 µm. All the BNMSs has the characteristics of h-BN lattice with an interlayer spacing of 0.34 nm. Boron and Nitrogen elemental compositions and h-BN phase of the synthesized BNMSs are verified from its characterization by X-ray photoelectron spectroscopy (XPS), Fourier transformed infrared (FTIR) spectroscopy and Raman.

Reaction synthesis of ultrafine titanium diborides and nitrides reinforced steel matrix composites in situ by spark plasma sintering

A novel technique for synthesis of in situ titanium diborides and nitrides reinforced steel matrix composite (TiB2–TiN/Fe) was put forward. In situ TiB2–TiN/Fe composite was synthesised by spark plasma sintering of mechanically mixed ferrotitanium and boron nitride (BN) powders. The phase evolution during sintering indicates that the TiB2–TiN reinforcements are formed in situ as follows: first step, the solid/solid interface reaction between ferrotitanium and BN, resulting in the formation of a small amount of TiB2 and TiN below 1000°C; second step, the solid–liquid solution precipitation reaction in the Fe–Ti–B–N system, resulting in most of TiB2 and TiN reinforcement formation at ∼1100°C. The microstructure investigation reveals that utrafine TiB2 and TiN reinforcements with a size of ∼1 μm are homogeneously distributed in the Fe matrix.

Catalyst free self-assembled growth of InN nanorings on stepped Si (5 5 3) surface

A novel technique for synthesis of high crystalline quality self-assembled InN nanorings, by nitriding the bulk deposited In/Si (553)-1×4 system using low energy N2+ ions at 520°C, has been demonstrated. Scanning electron microscopy images reveal the formation of ring shaped InN structures with average size ∼500nm. Anisotropic strain relaxation via self assembly could be the driving force for the formation of these InN rings on reconstructed Si (553) surface. High resolution X-ray diffraction analysis indicates high crystalline quality of these wurtzite InN nanostructures with c-plane. A strong downward band bending was observed in X-ray photoelectron spectroscopy valence band spectra which signify the large electron accumulation in the InN nanostructures.

Graphene nanosheets by low-temperature thermal reduction of graphene oxide using RF-CVD

A novel technique for synthesis of thin-layered graphene sheets (GNS) were established by hydrogen-induced reduction of graphene oxide at low temperature of 200°C, using radio frequency chemical vapour deposition. The functional group and microstructures of the prepared GNS were characterised by various techniques such as Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, Raman spectroscopy and particle-size analyser. Further the as-prepared GNS with an average diameter of 528.8 nm was confirmed by particle-size analyser. This GNS-generation process is rapid with high efficiency of exfoliation process, non-toxic, environmental friendly and ideal for large-scale production for industrial applications.

Fabrication of monodisperse silica microspheres using synechocystis cell as a template

A novel technique for synthesis of monodisperse silica microparticles (MSMs), using spherical synechocystis sp. PCC 6803 as bio-templates, has been successfully developed. Various approaches including FESEM, TEM, FTIR and Small-angle X-ray scattering were used to characterize the intermediate and the final products. The results showed that MSMs retained the original morphology and uniformity of the PCC 6803 cells, and the average diameter of MSMs is almost the same with the cells. The possible mechanism for the formation of MSMs is proposed. With the surface modification by Sepharose CL-6B, the resultant MSMs were demonstrated as the good chromatography packings for protein separation. Therefore, this convenient, low cost and reproducible synthesis process may be used to prepare the MSMs with various sizes and shapes by the proper selection of original bio-templates.

Double Pulse Electrodeposition of Cu-Ga Precursor Layer for CuGaS2 Solar Energy Thin Film

A novel technique for synthesis of CuGaS2 solar energy thin film is presented. It is associated with double pulse electrodeposition of Cu-Ga precursor layer followed by thermal annealing treatment in sulfur atmosphere. The influence of several flexible parameters including pulse deposition potential and agitation rate on the compositions, crystal structure and morphology of the films were investigated. A relative negative shift of the higher pulse deposition potential results in the increasement of Ga content. A higher agitation rate results in higher Cu/Ga ratio and the emergence of CuS secondary phase after annealing in sulfur atmosphere. The crystal size increases with decreasing the higher pulse deposition potential. Several characterization methods including X-ray diffraction (XRD), scanning electron microscope (SEM), energy diffraction spectrum (EDS), ultraviolet–visible (UV–vis) spectra, impedance spectroscopy, and Raman spectrum are used to characterize the synthesized CuGaS2 polycrystalline thin films. Based on the experimental results, a probable formation mechanism of the CuGaS2 thin films was proposed and briefly discussed.

Coupled-Resonator Filters With Frequency-Dependent Couplings: Coupling Matrix Synthesis

This letter presents a novel technique for synthesis of coupled-resonator filters with inter-resonator couplings varying linearly with frequency. The values of non-zero elements of the coupling matrix are found by solving a nonlinear least squares problem involving eigenvalues of matrix pencils derived from the coupling matrix and reference zeros and poles of scattering parameters. The proposed method was verified by numerical tests carried out for various coupling schemes including triplets and quadruplets for which the frequency-dependent coupling was found to produce an extra zero.

Novel technique for synthesis of silicon nitride nanowires

Silicon nitride nanowires have been prepared by carbothermal reduction followed by nitridation of silica gel by in situ generation of ultrafine carbon as well as nitrogen over a temperature range of 1200–1350°C. Before the heat treatment dry silica gel is subjected to repeated evacuation followed by purging with ammonia. Ammonia is adsorbed on the silica gel surface and forms a ≡Si–NH2 bond which acts as a source of in situ generation of nitrogen and decomposition of dextrose provides ultrafine carbon respectively at the reaction temperature. During a high temperature heat treatment ultrafine carbon reduces the partial pressure of oxygen required for the generation and stabilisation of silicon nitride nanowires. The nanowires synthesised by this process are of 20–40 nm diameter and ∼1 μm length. The nanowires are characterised by XRD and filed emission SEM and EDAX.

Synthesis of single-walled carbon nanotubes in oxy-fuel inverse diffusion flames with online diagnostics

A novel technique for synthesis of single-walled carbon nanotubes (SWNTs) in diffusion flames is presented, as is a diagnostic tool that can provide online information about nanotube size, number density, and purity. An inverse diffusion flame with a high stoichiometric mixture fraction ( Z st) is used to produce SWNTs with an average length of 1 μm. The high Z st flame allows nanotubes to be produced in a fuel-rich region that is void of soot and polycyclic aromatic hydrocarbons (PAH). In addition, by operating as an inverse diffusion flame the carbon nanotubes (CNTs) are not exposed to oxygen and thus, can be collected downstream. Consequently, this flame provides a potential approach to large-scale synthesis of pure SWNTs. In addition, a differential mobility analyzer (DMA) is employed as an online diagnostic tool. The DMA can distinguish between excess catalyst particles and CNTs due to the differences in their electrical mobilities. Thus, the presence of CNTs as well as their size, number density, and purity relative to excess catalyst particles can be identified from the size distribution of the aerosol sampled downstream of the flame. This tool allows for rapid identification of the effect of changing process variables on nanotube growth and thus, the production process can be quickly optimized.

Novel technique for synthesis and characterization of nanosized Ba1?xSrxSn0.15Ti0.85O3 ceramics

Nanosized Ba1−xSrxSn0.15Ti0.85O3 (BSST; x = 0, 0.03, 0.06 and 0.09) was prepared by a method involving the decomposition of a metal complex-based aqueous precursor solution. Preliminary X-ray structural analysis confirmed the formation of single-phase compounds with tetragonal structures. Transmission electron microscopy of the compounds showed the distribution of nanosized spherical grains. Detailed dielectric studies as a function of temperature at three different frequencies (10, 50 and 100 kHz) showed that on increasing the Sr concentration in BSST, the Curie temperature was shifted to higher temperature. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Novel technique for synthesis and consolidation of aluminium nitride nanopowders

In this paper, the use of a microwave plasma method for the synthesis of aluminium nitride nanopowders is described. The powders were consolidated to near theoretical densities using the unique rapid consolidation technique, plasma pressure consolidation (P2C), developed by MMI. Rapid consolidation of nanopowders is an ideal requirement for better mechanical and thermal properties in the consolidated part, as it retains the fine microstructure preventing anomalous grain growth. Microwave plasma synthesis resulted in aluminium nitride nanopowders (85–200 nm), which were consolidated to near theoretical density using P2C in <5 min without sintering additives. The effect of yttria (3 wt-%) as a sintering additive on the thermal conductivity (TC) of aluminium nitride was also evaluated and compared with TC values obtained from additive free AlN consolidated samples.

A novel technique for synthesis of silver nanoparticles by laser-liquid interaction

Ultrafine particles of many materials have received much attention over the last few years by researchers because of their unique physical and mechanical properties due to increased surface area to volume ratio. A novel laser–liquid interaction technique has been developed to synthesize silver nanoparticles from inexpensive silver nitrate solution in distilled water. The shape, size distribution, microchemistry and crystal structure of the silver nanoparticles were studied using X-ray diffraction, scanning electron microscopy and electron probe X-ray microanalysis.

Novel Porous Films Having Low Dielectric Constants Synthesized by Liquid Phase Silylation of Spin-On Glass Sol for Intermetal Dielectrics

A novel technique for synthesis of highly porous inorganic SOG films such as aerogels using conventional spin-on processing has been developed. The porous films exhibit dielectric constants as low as 2.3 and the average pore diameter was about 80 nm. The relative dielectric constants of the films compare favorably with those of organic polymers, and the films were demonstrated to exhibit relatively low hygroscopic characteristics. This novel technique for synthesis of porous film is the first step in the development of nanofoam materials for future low k dielectrics.