Surface Review and Letters

Bi_0.95La_0.05FeO₃(BLFO_x=0.05) film was fabricated on indium tin oxide/glass substrate using a metal organic decomposition method. No secondary phase can be observed in the well crystallized and predominantly (110)-oriented BLFO_x=0.05 film. Well-saturated P - E hysteresis loops with the remanent polarization of 60.7 μC/cm² can be obtained in BLFO_x=0.05 film due to the low leakage currents as well as the preferred orientation of the (110) peak. The content of oxygen vacancies in the film is considered to be the dominant factor affecting the asymmetry ferroelectric properties and leakage currents.

By taking into account two types of boundary conditions (BC), free boundary condition (FBC) and zero boundary condition (ZBC), an improved transverse Ising model with the consideration of surface transition layers (STL) is used to describe the polarization properties of ferroelectric thin films in the framework of the mean field approximation. Functions representing the intra-layer and inter-layer couplings are introduced to characterize the BC and STL, which reflect the structure variation of film surface. Comparing the results obtained by employing FBC and ZBC, some effects of BC are derived in the model, which demonstrated that the BC play important roles on the properties of ferroelectric thin films. It is shown that the effect of ZBC can extend to deeper film than that of FBC. When different BC are adopted, competition between the fields (depolarization field and transverse field) and BC induces some different and interesting phenomena. Some theoretical results in this paper are found to be in reasonable accordance with experimental data and have some application importance.

A simple hydrothermal growth process was developed to deposit conformal manganese oxide nanospheres with a diameter of 10 to 20 nm on mesoporous carbon paper. The coating of nanospheres increased the cyclic-voltammogramic response of carbon paper by a factor of 5 with a slight dependence on the scan rate. For comparison, a related chemistry was also developed to fabricate a dense packing of manganese oxide nanorods with a diameter of 20 to 50 nm and a length of approximately 500 nm. The nanorods also increased the cyclic-voltammogramic response of carbon paper but only by a factor of approximately 3.

A self-assembled monolayer (SAM) of octanethiol was vapor-deposited onto the surface of copper (Cu) nanoparticles as a means of preventing oxidation. The presence of octanethiol on the surface of Cu nanoparticles was verified using Fourier transform infrared spectroscopy and transmission electron microscopy. The electrical resistance of copper nanoparticles with deposition of a 12-nm thickness of octanethiol on the surface was found to be 100 times greater than that of uncoated powders, indicating uniform SAM coating of the particles.

The viability of facile oxidation and cycloaddition of fullerene C₆₀ with ruthenium tetraoxide (RuO₄) has been confirmed by means of density functional theory calculations. Owing to the powerful capability of RuO₄ as an oxidant, the addition process has been found to occur readily in the absence of organic base as a catalyst, which is in remarkable contrast to the base-catalyzed osmylation of C₆₀ with osmium tetraoxide (OsO₄). Significantly, we have found that boron can be employed as an effective promoter for enhancing the cycloaddition and complexation of transition metal oxides, e.g. RuO₄ and OsO₄, with C₆₀, in which the base is not needed at all. Our results suggest that boron doping into the lattice of fullerenes and carbon nanotubes would provide a well-defined approach for anchoring transition metal oxides.

A manganese oxide contained coating was prepared on biodegradable AZ31B magnesium alloy to control the degradation of AZ31B and improve its biocompatibility. Morphology, composition, and corrosion resistance of the coating were studied. The SEM observations showed that the coating was approximately 4–6 μm in thickness with net-like microcracks. The XPS analysis indicated that the coating was mainly composed of MgO, Mg(OH)₂, MnO₂, Mn₂O₃, and Mn₃O₄. It was found that AZ31B with such coating showed better corrosion resistance in simulated blood plasma through electrochemical and immersion tests. The hemolytic assay indicated that the treated AZ31B had no hemolytic effect.

Well-dispersed Prussian blue (PB) nanoparticles were successfully prepared by reverse micelle. This method is based on one-step rapid formation in different sizes of nano-pool with water/oil system, which leads to a homogeneous distribution of PB nanoparticles. Scanning electronic microscopy, UV–vis, and Fourier infrared spectra give supportive evidence of PB nanoparticles. Electrochemical study shows that PB nanoparticles are modified onto cysteine-assembled Au electrodes and exhibit high efficiency of electron transfer.

In this paper, we derive analytical formulations of the elastic energy of a stressed domain on a crystalline substrate. Taking care of the singularity of the elastic Green function at r = 0, we obtain a universal expression for the isotropic case. By using the analogy between electric dipolar and elastic interactions, we developed similar analytical calculations for the (001) surface of a cubic crystal.

We showed that the anisotropy of the boundary energy and the anisotropy of the substrate govern the shape of the domains, favoring either compact shapes or stripe configurations. The analytical approach adopted in this paper also allows us to discuss the role of elastic anisotropy for the existence of attractive interactions between domains.

TiO₂ samples with different crystal forms were treated in flowing NH₃ at elevated temperatures to fabricate N-doped TiO₂ photocatalysts with different crystal forms. The resulting N-doped TiO₂ photocatalysts were characterized by means of X-ray diffraction, transmission electron microscopy, diffusion reflectance spectrometry, and X-ray photoelectron spectroscopy. The visible-light photocatalytic activity of the catalysts was evaluated by measuring the photocatalyzed removal rate of propylene. Results indicate that the visible-light activity of N-doped TiO₂ photocatalysts is highly dependent on the crystal form. Namely, N-doped anatase TiO₂ has the highest visible-light activity, while the visible-light activity of N-doped TiO₂ photocatalysts decreases with decreasing content of anatase phase and increasing content of rutile phase. In addition N-doped rutile TiO₂ has no visible-light photocatalytic activity.

The structural and morphology of copper-stabilized zirconia samples prepared by sol–gel techniques in different calcination time and temperature are reported. This research work has been proposed and verified that the calcination temperature and time strongly influenced the morphology as well as interaction between the active species and the support. The results obtained from the laboratory test indicate that cubic ZrO₂ and copper oxide are present in the structure if the calcination temperature is under 400°C. Cubic ZrO₂, tetragonal ZrO₂ with small amount of monoclinic ZrO₂, and CuO are formed after calcination at 500°C. Heating under 500°C will result in amorphous compounds being formed, suggesting that 500°C could be a phase transition point. The effect of calcination time is investigated by morphology and structural changes of CuO–ZrO₂ at 600°C during 2, 3.5, 5.5, 7.5, and 10 h. Incorporation of copper in ZrO₂ lattice results in a loss of order in the ZrO₂ structure when it is calcined. A further increase in the temperature of calcination leads to the phase changes in ZrO₂ structure.

A specialized high-precision thermal gradient furnace with a rotating stage was developed for in situ observation of the equilibrated grain boundary groove shapes at multiple crystallographic orientations in transparent materials. Anisotropies of solid–liquid interfacial free energy for the distillated succinonitrile (SCN) and pivalic acid (PVA) are determined experimentally through direct observation of the equilibrated grain boundary grooves at the multiple crystallographic orientations stabilized within a controlled thermal gradient. The average anisotropies of solid–liquid interfacial energy for distillated SCN and PVA are found to be 0.42 and 3.12% from observed grain boundary groove shapes at multiple crystallographic orientations. Details related to the experimental apparatus and experimental procedures are given.

Periodic, self-consistent, density functional theory calculations have been performed to investigate Li adsorption on Mo(110) surface. It turns out that the long-bridge site is the most stable site and the Li–Mo surface alloy forms easily at high coverage with the substitution of Mo by Li atoms in the outermost layer. Work function analysis showed that the work function decreases dramatically as the coverage from 0 to 0.5 ML, and finally increases again at the coverage of 1 ML, which agrees well with the experimental finding of Kroger et al. (Surf. Sci.449 (2000) 227–235). Vibrational properties, diffusion barrier of Li along the Mo(110) surface, and the energy of formation of the surface have also been investigated for Li adsorption at various coverages.

Molecular interaction dynamics at liquid–liquid interface (LLI), involved nondispersive solution as compared with the interaction in bulk phase. Thereby, interfacial tension (IFT, mN/m) of LLI for four saturated hydrocarbons, six alcohols, and three cationic surfactants are reported at 298.15 K. The pentane, hexane, heptane, octane hydrocarbons and pentanol, hexanol, heptanol, 1-octanol, 2-octanol, and 1-decanol alcohols were used and IFT data were compared with 4 mm kg^-1 dodecyltrimethylammoniumbromide (DTAB), trimethylsulfoxoniumiodide (TMSOI), methyltrioctylammoniumchloride (MTOAC) surfactants studied in benzene–water LLI. The IFT data are noted as hydrocarbons > DTAB > TMSOI > alcohols > MTOAC. The hydrocarbons and alcohols decreased IFT within 16 to 49% and 87 to 92%, respectively, whereas the surfactants within 78.3 to 95.9%. The alcohols developed interaction similar to surfactants and are denoted as nonionic surfactants for making mixtures of low IFT with hydrophilic and hydrophobic interactions to the level of the surfactants. The pentanol and MTOAC caused similar decrease in IFT so the pentanol developed the hydrophilic and hydrophobic interactions of the strength of MTOAC. Comparatively, the hydrocarbons showed lower decrease but the octane showed 49% decrease in IFT. Thus, the hydrocarbon with longer alkyl chain and the alcohol with shorter behave as good surfactants. The hydrocarbons with inductive effect on sigma bond between carbon atoms in alkyl chain also weakened the IFT and influenced the hydrophobic interactions. The MTOAC with four octyl units reduced 96% IFT so inductive effects monitor LLI dynamics.

This paper describes the inhibition effect of 1-benzyl piperazine (P1) and bis(1-benzyl piperazine) thiuram disulfide (P2) towards the corrosion of C38 steel in 5.5 M H₃PO₄ solution by potentiodynamic polarization and weight loss methods. The influence of inhibitor concentration and temperature on inhibitory behavior of P2 were investigated. The inhibition efficiency (IE) was found to be dependent on the type of piperazine and its concentration. The IE for 10^-3 M P2 in 5.5 M H₃PO₄ is greater than 98%. Polarization studies clearly revealed that both P1 and P2 act as mixed-type inhibitors. Adsorption isotherms were fitted by the Langmuir isotherm. Adsorption energies ( and ) were evaluated. Kinetic parameters were determined.

Bifunctional Fe/ZrO₂ was prepared by mechanical mixing method, and its bifunctional effect on reductive dechlorination of chlorobenzene in subcritical water was studied. Dechlorination efficiency increased with increasing iron content in catalyst and catalyst amount. Dechlorination efficiency slowed when the iron content in catalyst reached 30%; bifunctional catalyst of Fe/ZrO₂ was more efficient in dechlorination of chlorobenzene than Fe alone. Catalyst of Fe (30%)/ZrO₂ was characterized by means of X-ray diffraction (XRD), H₂ temperature programmed desorption (H₂-TPD), and N₂ adsorption. The possible mechanism of dechlorination in subcritical water by this bifunctional catalyst was proposed. H⁺ produced in the water dissociation formed the highly reactive spillover hydrogen on the surface of catalyst, and then reacted with chlorobenzene adsorbed on the catalyst surface by ZrO₂ to form benzene and chloride ions.

Substrates of Ti-based coatings were investigated regarding wear resistance and refractoriness. Substrates with and without the TiAl₃ coating formed by the ion plating method with evaporation of Al are considered. Additionally, the paper briefly presents principles of kinetics of the formation of the TiAl₃ coating.

A two-dimensional sub-wavelength grating (SWG) is fabricated on light-emitting diodes (LEDs). The SWG is simulated by finite-difference time-domain (FDTD) method. The SWG surface has silver-coated dielectric materials with sinusoidal structures, 175 nm period and 125 m depth of groove. When the incident wave is in the red light region of 600–700nm, the transmission efficiency of TM propagated light will reach 0.82. If this SWG structure is applied in LCD direct backlight module, the lower polarization piece can be replaced and fluorescence efficiency of LED can be improved.

An alkaline bath was developed for electroless deposition of Co–W–P thin films on a copper substrate. Effects of pH values, various concentrations of reducing agent, and different powers of ultrasonic on composition, microstructure, and magnetic properties of the films were investigated. It was found out that higher pH could improve cobalt atomic percentage and reduce amounts of phosphorus and tungsten in the film while larger amounts of NaH₂PO₂ would decrease the cobalt content but increase the tungsten and phosphors content. The ultrasonic was introduced during the electroless deposition. Few effects of ultrasonic on the cobalt content were observed. X-ray diffraction showed that almost all of the deposited films were crystalline and contained hexagonal cobalt with a preferred crystallographic orientation (002). However, a typical amorphous Co–W–P film, which has smooth surface, and no crystallite with definite grains could be obtained when the concentration of NaH₂PO₂ in the bath was over 1.2 mol/L. The films with rougher and agglomerate nodular structures would be formed in the bath with a higher pH value. Certain power (60 W, 40 kHz) of ultrasonic could smash the grains and led to the formation of a denser and smoother surface. Cracks appeared at the surface of the film when the ultrasonic power was 150 W. Vibration sample magnetometer results showed that the film with maximum magnetization (600 emu/g) and coercivity (1000 Oe) could be achieved when introducing ultrasonic (60 W, 40 kHz) during the deposition.