Advanced Materials Research Vols. 287-290

Abstract: Ferroelectric thin films Bi_3.25La_0.75Ti₃O₁₂,Bi_3.15Nd_0.85Ti₃O₁₂ and Bi_3.15(La_0.5Nd_0.5)_0.85Ti₃O₁₂ of A-site substitution of Bi₄Ti₃O₁₂ were fabricated by sol-gel method in the paper. X-ray diffraction pattern shows the prepared thin films exhibit a highly random orientation with predominantly (117) and (00l) orientation. Pr values of Bi_3.25La_0.75Ti₃O₁₂ 、Bi_3.15Nd_0.85Ti₃O₁₂ and Bi_3.15(La_0.5Nd_0.5)_0.85Ti₃O₁₂ thin films were respectively 13.14μC/cm2, 20.65μC/cm2 and 21.23μC/cm2 at the voltage of 10V.FE-SEM shows that the BNT thin film has a dense and homogeneous microstructure without any crack. The BNT thin film thickness is about 300nm.

Abstract: Fe doped up-graded and down-graded PST thin films were prepared on Pt/Ti/SiO₂/Si with sol–gel method. Crystal structure and surface morphology of graded PST thin films were characterized by X-ray diffraction (XRD) and atom force microscope (AFM). The dielectric measurements were conducted on metal-insulator-metal capacitors at the frequency from 100 Hz to 1M Hz and at room temperature. It was found that the up-graded PST thin film had a larger dielectric constant and lower figure of merit (FOM) than the down-graded film. At 1M Hz, the tunability of up-graded PST thin film was about 65.48%, which was higher than that (about 41.84%) of down-graded PST thin film. The FOM of up-graded and down-graded PST thin films were 16.3 and 9.2, respectively. Our results showed that the dielectric tunable properties of the Fe doped graded PST films depended strongly on the direction of the composition gradient of the graded PST films.

Abstract: The absence of stable oxide/GaAs interface greatly holds back the step of GaAs-based MOSFETs fabrication. In this letter, we report on the chemical passivation of n-type GaAs surface by introducing a new sulfuration method. X-ray photon-electron spectroscopy (XPS) analyses indicate that most GaAs native oxides and elemental arsenic (As) can be more effectively removed by treating the GaAs surface in CH₃CSNH₂ solution compared to the traditional (NH₄)₂S solution. Capacitance-Voltage characteristics of the CH₃CSNH₂ treated MOS capacitors also presents reduced interfacial layer and equivalent oxide thickness which are well consisted with the conclusion obtained by XPS.

Abstract: The properties of corrosion scale on P110 carbon steel in the saltwater solution containing CO₂ have been examined by electrochemical impedance spectroscope (EIS). The change of electrode reaction process on the corrosion scale has been discussed in the present work. It is found that the corrosion rate decreases with the increasing of the experimental time, and the reducing tendency of corrosion rate becomes low as the experimental time was 72 hours, EIS results indicate that the polarization resistance increases gradually and the electrode reaction is controlled by both diffusion and activation in comparison with activation only at the beginning.

Abstract: The contact at head/disk interface in hard disk drives subject to an external shock has been studied using the finite element method. A rigid cylinder moving over a two-layered thin film was implemented to simulate the contact between the recording slider and the disk. The effects of different friction coefficients on the von Mises stress of two-layered thin film were investigated. The relation between pressed depth and width of deformation has been obtained. Results show that the amplitude decreases with increase of friction coefficient while the period of slider motion is diminution. In addition, the stress distribution fits Hertzian contact theory.

Abstract: WO3/Pd layered composite films were prepared by magnetron Sputtering on glass substrate. After deposition, samples were annealed with different condition. The hydrogen sensitive response of the composite film was measured by home-made measurement system. The results indicated that suitable annealing could increase the response sensitivity of the layered composite film to hydrogen detect, Exorbitant annealing temperature will damage Pd layer on the WO3 suface, then decrease the hydrogen detect sinsitivity badly.

Abstract: ZnO thin films were deposited by radio frequency (R. F.) magnetron sputtering on various diamond film substrates with different surface roughness. The influence of surface roughness on structural properties and surface morphology of ZnO thin films was investigated by X-ray diffraction (XRD) and atom force microscopy (AFM), respectively. Only on the nanocrystalline and free-standing diamond substrates, ZnO films with preferential c-axis orientation and smooth surface were obtained.

Abstract: Continuous CO₂ laser irradiation is exploited to realize nanocrystallization of Fe based amorphous alloys Fe_73.5Cu₁Nb₃Si_13.5B₉ by overlapping of the heated areas, and to get homogeneous ultrafine grains of about 10nm with a bcc α-Fe(Si) structure, which is the foundation of the excellent soft magnetic property. X-ray diffraction and transmission electron microscopy(TEM) are used for microstructure analysis and observation, and the results show that irradiation power of 71w~99w gives the heat shock to the transformation from the metastable amorphous state to crystallized state, and proper time of about 20~30 seconds is necessary for optimum microstructure and soft magnetic properties.

Abstract: Large area graphene oxide (GO) film was prepared by vacuum filtration method through a membrane with a pore size of 25 nm, using GO sheets suspension as raw materials. The film was thermal treated in Ar/H₂ atmosphere at 600°C to make the film electrical conductive. The structure and morphology of the obtained film were investigated by XRD, Raman, FT-IR and SEM. Results showed that most oxygen-containing functional groups in GO film were reduced during the thermal annealing process. The obtained reduced film showed excellent electrical conductivity and the average sheet resistance of the reduced film was 11.3 Ω□^-1.

Abstract: Bonded structure are commonly of three types, purely adhesive bonded, weld-bonded and adhesive/mechanical structures. Present work concern with experimental set-up of double containment joint with circular cross-section support using photoelasticity techniques. The experimental results were found to be within 5% when compared with the numerical analysis.