Walter de Gruyter GmbH

Single-wall carbon nanotubes (SWNTs) as well as multi-wall carbon nanotubes (MWNTs) were characterized by Raman spectroscopy to observe the changes in their physical and structural properties on functionalization. When SWNTs or MWNTs are chemically treated, the defects are created. The analysis of radial breathing mode (RBM) showed that the diameter of the single wall carbon nanotubes changed after functionalization. In the carboxylated sample, the intensity of the disordered band (D-mode) increased more than in the pristine samples. The increase in the D-band intensity in SWNTs after functionalization can be attributed to carbon atoms excited from sp 2 to sp 3 hybridization. A higher intensity ratio in D-and G-mode (I D /I G ) was observed after functionalization with carboxylic group (COOH). The intensity ratio I D /I G increased on acid treatment which was evident from the Raman spectra and their analysis. In case of MWNTs, the intensity of D band became equal to the intensity of G band, which was due to the huge number of defects that had been introduced in the sidewalls. Moreover, it was found in this study that the MWNTs can be much easier chemically functionalized than SWNTs under the same physical conditions.

Four samples of austenite coatings deposited by reactive magnetron sputtering on silicon substrate at four different temperatures and pressures were investigated by ferromagnetic resonance (FMR) method at room temperature. The expanded austenite phase S (γ N ) layers with thickness in the 160–273 nm range and concentration of magnetic atoms: 72 % Fe, 18 % Cr and 10 % Ni, were obtained. The coatings with nanometric size grains were strongly textured and grown mostly in [100] direction, perpendicular to the sample surface. Intense FMR spectra were recorded at various angles between the static magnetic field direction and the sample surface. A strong magnetic anisotropy of the main uniform FMR mode was observed and the effective magnetization 4πM eff determined. Spin wave resonance (SWR) modes were observed in all investigated samples in out-of-plane geometry of the magnetic field. The resonance fields of SWR modes in our samples varied linearly with the spin wave mode number. The value of the effective magnon stiffness constant was determined assuming a parabolic shape of the magnetization variation across the sample thickness.

A rapid, safe and simple technique for the production of high purity strontium oxide powders via a chemical combustion process is reported. The combustion reactions were performed to optimize the fuel to oxidizer ratios in the reaction mixtures required to obtain pure SrO powders by varying the molar ratio of chemical precursors and the temperature. The synthesized powders were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectrometry, infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and N2-physisorption measurements. The results indicate that crystalline SrO was obtained using a 1:1 strontium nitrate: urea molar ratio at 1000 °C after 5 minutes. In addition, high-purity, homogeneous and crystalline SrO powders were easily produced in a short time via a chemical combustion process.

Tri-layer Au/Pd/Ni(P) films have been widely used as surface finish over the Cu pads in high-end packaging applications. It was found that a thin (Cu,Pd)6Sn5 IMC layer was beneficial in effective reducing inter-diffusion between a Cu substrate and a solder, and therefore the growth of the IMC layer and the EM (electromigration) processes. In this study, the structural properties and phase stability of monoclinic Cu6Sn5-based structures with Pd substitutions were studied by using the first-principles method. The (Cu,Pd)6Sn5 structure with the 4e site substituted by Pd has the lowest heat of formation and is the most stable among (Cu,Pd)6Sn5 structures. Hybridization of Pd-d and Sn-p states is a dominant factor for stability improvement. Moreover, Pd atoms concentration corresponding to the most stable structure of (Cu,Pd)6Sn5 was found to be 1.69 %, which is consistent with the experimental results.

2,3,9,10,16,17,23,24-copper octakis (octyloxy) phthalocyanine (CuPcOC8) thin films deposited at room temperature have exhibited a change in their surface morphology with the post deposition annealing temperature under normal atmosphere.These films have been characterised by optical absorption also. SEM images have shown densely packed nano particles and nano-rod like structures on the substrates annealed at different temperatures. The optical transition was found to be direct allowed and the direct energy gap changed with the annealing temperature. The results of optical and surface morphological studies on CuPcOC8 have been discussed.

Single crystals of good optical quality, made of potassium dihydrogen phosphate (KDP) doped with urea were grown by slow evaporation solution growth technique at a constant temperature of 35 °C. Optical absorption and dielectric properties were studied for pure and urea doped KDP crystals. Using powder XRD studies, crystalline nature of pure and urea doped KDP crystals was confirmed. AC conductivity was measured for the grown crystals. DC electrical conductivity and photoconductivity studies were carried out for pure and urea doped KDP crystals and the differences caused by the dopant were also discussed.

Nghiên cứu này đánh giá tác động của các thông số trong quá trình anod hóa lớp cứng bằng axit sulfuric, chẳng hạn như nồng độ axit, nhiệt độ dung môi, mật độ dòng điện và thời gian, đến độ cứng và độ dày của các lớp anod hóa thu được. Một cơ sở anod hóa quy mô nhỏ đã được thiết kế và thiết lập để tạo điều kiện cho việc nghiên cứu thực nghiệm các thông số anod hóa. Thiết kế thực nghiệm sử dụng phương pháp Taguchi để tối ưu hóa các thông số trong một khoảng hoạt động đã được thiết lập đã được thực hiện. Các phương pháp định tính và định lượng để xác định các lớp anod hóa thu được đã được thực hiện. Độ dày và hình thái của lớp anod hóa được xác định bằng kính hiển vi ánh sáng (LOM) và kính hiển vi điện tử quét phát xạ trường (FEG-SEM). Các phép đo độ cứng được thực hiện bằng cách sử dụng máy đo độ cứng nano. Mối tương quan giữa các thông số anod hóa khác nhau và tác động của chúng đến độ cứng và độ dày của các lớp anod hóa đã được thiết lập. Việc đánh giá cẩn thận các tác động này đã cho phép xác định các thông số tối ưu bằng cách sử dụng phương pháp Taguchi, điều này đã được xác thực qua thực nghiệm. Các lớp anod hóa có độ cứng thay đổi từ 2.4–5.2 GPa và độ dày từ 20–80 μm đã được sản xuất. Phương pháp Taguchi đã chứng tỏ tính ứng dụng trong anod hóa. Phát hiện này có thể tạo điều kiện cho các nghiên cứu và phát triển tương lai về anod hóa, lĩnh vực đang thu hút sự quan tâm đáng kể từ học thuật cũng như công nghiệp.

CdS and Zn-doped CdS (CdS:Zn) thin films have been deposited on glass substrates by spray pyrolysis technique using a perfume atomizer. The influence of Zn incorporation on the structural, morphological, optical and electrical properties of the films has been studied. All the films exhibit hexagonal phase with (0 0 2) as preferential orientation. A shift of the (0 0 2) diffraction peak towards higher diffraction angle is observed with increased Zn doping. The optical studies confirmed that the transparency increases as Zn doping level increases and the film coated with 2 at.% Zn doping has the maximum transmittance of about 90 %. The sheet resistance (R sh ) decreases as the Zn-doping level increases and a minimum value of 1.113 × 103 Ω/sq is obtained for the film coated with 8 at.% Zn dopant. The CdS film coated with 8 at.% Zn dopant has the best structural, morphological and electrical properties.

Porous anodic aluminium oxide (AAO) template is commonly used in the synthesis of one-dimensional nanostructures, such as nanowires and nanorods, due to its simple fabrication process. Controlling the anodizing conditions is important because of their direct influence on the size of AAO template pores; it affects the size of nanostructures that are fabricated in AAO template. In present study, several alumina templates were fabricated by a two-step electrochemical anodization in different conditions, such as the time of first process, its voltage, and electrolyte concentration. The effect of these factors on pore diameters of AAO templates was investigated using scanning electron microscopy (SEM).

The functionalized graphene (GO) was fabricated by a simple method of chemical reduction in a polar aprotic solvent. This paper therefore, describes a versatile and synthetic route for the preparation of reduced graphene oxide (RGO) and its behavior when exposed to magnetic field environment. The characterization results of transmission electron microscopy (TEM), scanning electron microscopy (SEM), Raman spectroscopy and the attenuated total reflectance-Fourier transform infra-red (ATR-FTIR) analysis indicate that graphite was exfoliated and reduced to graphene layers.