Showing papers in "Surface Review and Letters in 2008"
TL;DR: In this paper, the corrosion inhibition of mild steel in 1 M H2SO4 in the presence of polyvinylpyrollidone (PVP) and polyacrylamide (PA) as inhibitors at 30-60°C was studied using gravimetric and gasometric techniques.
Abstract: The corrosion inhibition of mild steel in 1 M H2SO4 in the presence of polyvinylpyrollidone (PVP) and polyacrylamide (PA) as inhibitors at 30–60°C was studied using gravimetric and gasometric techniques. The inhibition efficiency (1%) increased with increase in concentration of the inhibitors. Increase in temperature increased the corrosion rate in the absence and presence of inhibitors but decreased the inhibition efficiency. Both PVP and PA were found to obey Temkin adsorption isotherm and Kinetic-Thermodynamic Model of El-Awady at all the concentrations and temperatures studied. Phenomenon of physical adsorption is proposed from the activation parameters obtained. Thermodynamic parameters reveal that the adsorption process is spontaneous. PVP was found to be a better inhibitor than PA.
70 citations
TL;DR: In this article, 2,3-diaminonaphthalene (2,3DAN) was investigated for corrosion of aluminum in 1 M HCl using hydrogen evolution technique at 30 and 40°C.
Abstract: The inhibitive effect of 2,3-diaminonaphthalene (2,3-DAN) for corrosion of aluminum in 1 M HCl was investigated using hydrogen evolution technique at 30 and 40°C. Quantum chemical calculation results showed that 2,3-DAN molecule possessed planar structure with a number of active centers, which aided the adsorption process. The Mulliken charge density, the highest occupied molecular orbital (HOMO), and the lowest unoccupied molecular orbital (LUMO) were found mainly focused around nitrogen atoms and the cyclic of the benzene as well. The presence of 2,3-DAN molecules in the corrosive medium (1 M HCl solution) inhibits the corrosion process of aluminum and as the concentration of 2,3-DAN increases the inhibition efficiency also increases but decreases with rise in temperature. The corrosion inhibition of 2,3-DAN was discussed in terms of blocking of the Al surface by adsorption of the molecules of the inhibitor at the active centers. It was found that the adsorption of 2,3-DAN onto the Al surface followed t...
62 citations
TL;DR: In this paper, a wide set of experimental results on binding energy of photoelectrons emitted from P 2p, P 2s, and O 1s core levels has been observed for inorganic phosphate crystals and the parameters were compared using energy differences Δ(O 1s -P 2p) and Δ (O1s-P 2s) as most robust characteristics.
Abstract: Wide set of experimental results on binding energy of photoelectrons emitted from P 2p, P 2s, and O 1s core levels has been observed for inorganic phosphate crystals and the parameters were compared using energy differences Δ(O 1s - P 2p) and Δ (O 1s - P 2s) as most robust characteristics. Linear dependence of the binding energy difference on mean chemical bond length L(P–O) between phosphorus and oxygen atoms has been found. The functions are of the forms: Δ (O 1s - P 2p) (eV) = 375.54 + 0.146 · L(P–O) (pm) and Δ (O 1s - P 2s) (eV) = 320.77 + 0.129 · L(P–O) (pm). The dependencies are general for inorganic phosphates and may be used in quantitative component analysis of X-ray photoemission spectra of complex oxide compounds including functional groups with different coordination of P and O atoms.
36 citations
TL;DR: In this paper, the authors focused on cathodic arc physical vapor deposition (CAPVD), a technique used for the deposition of hard coatings for tooling applications, and which has many advantages.
Abstract: Titanium nitride (TiN) widely used as hard coating material, was coated on tool steels, namely on high-speed steel (HSS) and D2 tool steel by physical vapor deposition method. The study concentrated on cathodic arc physical vapor deposition (CAPVD), a technique used for the deposition of hard coatings for tooling applications, and which has many advantages. The main drawback of this technique, however, is the formation of macrodroplets (MDs) during deposition, resulting in films with rougher morphology. Various standard characterization techniques and equipment, such as electron microscopy, atomic force microscopy, hardness testing machine, scratch tester, and pin-on-disc machine, were used to analyze and quantify the following properties and parameters: surface morphology, thickness, hardness, adhesion, and coefficient of friction (COF) of the deposited coatings. Surface morphology revealed that the MDs produced during the etching stage, protruded through the TiN film, resulting in film with deteriorated surface features. Both coating thickness and indentation loads influenced the hardness of the deposited coatings. The coatings deposited on HSS exhibit better adhesion compared to those on D2 tool steel. Standard deviation indicates that the coating deposited with thickness around 6.7 μm showed the most stable trend of COF versus sliding distance.
30 citations
TL;DR: In this paper, the processes of nickel electrodeposition on Pt/Si(100) substrate from an aqueous sulfate, Watts, and chloride solution have been studied using electrochemical techniques and atomic force microscopy (AFM).
Abstract: The processes of nickel electrodeposition on Pt/Si(100) substrate from an aqueous sulfate, Watts, and chloride solution have been studied using electrochemical techniques and atomic force microscopy (AFM). It was found that hydrogen evolution reaction (HER) was shifted more cathodically and the nickel electrodeposition obeys to inhibition process, caused by adsorbed species in surface substrate. At early stage of the deposition chronoamperometric results were compared with Sharifker and Hills theoretical model. The nucleation was in agreement with progressive mode followed by 3D diffusion growth mechanism. The nucleation is generally slow at low over potentials, in all studied baths. AFM images show distribution nickel clusters, with different sizes.
27 citations
TL;DR: In this article, the surface modification mechanism of polyvinyl chloride (PVC) by ozonation was investigated to study the selective hydrophilization of PVC surface among other plastics.
Abstract: The surface modification mechanism of polyvinyl chloride (PVC) by ozonation was investigated to study the selective hydrophilization of PVC surface among other plastics. Infrared analysis confirmed the increase of hydrophilic groups. XPS analysis revealed that the increase was due to the structural change in chlorine group in PVC to hydroxylic acid, ketone, and carboxylic groups by ozonation. This chemical reaction by ozone could occur only for polymers with chlorides in its structure and resulted in the selective hydrophilization of PVC among various polymers.
21 citations
TL;DR: In this paper, the effective elastic modulus and fracture toughness of the nanofilm were derived with the surface relaxation and the surface energy taken into consideration by means of the interatomic potential of an ideal crystal.
Abstract: The effective elastic modulus and fracture toughness of the nanofilm were derived with the surface relaxation and the surface energy taken into consideration by means of the interatomic potential of an ideal crystal. The size effects of the effective elastic modulus and fracture toughness were discussed when the thickness of the nanofilm was reduced. And the dependence of the size effects on the surface relaxation and surface energy was also analyzed.
18 citations
TL;DR: In this paper, the most stable form of aluminum oxide, i.e. α-Al2O3, is obtained when samples are heated up to a temperature of as low as 350°C.
Abstract: Bayerite sol is spun onto single crystal Si substrate, after synthesis and optimization, to obtain films of thickness ~ 0.2 μm. The deposited films are room temperature dried and then heated up to a temperature of 350°C in order to obtain Al2O3. Surface and structural changes, during heating, are observed with optical microscopy. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) are used for post-treatment analyses/characterization. The as-deposited and heated samples' surfaces are smooth as seen with optical and scanning electron microscope in case of optimized conditions. XRD patterns show the change from amorphous to crystalline behavior of these films when heated under various conditions. The most stable form of aluminum oxide, i.e. α-Al2O3, is obtained when samples are heated up to a temperature of as low as 350°C. The thin films are also deposited onto sodalime glass substrates in order to confirm Al2O3 formation through band gap probing. Photoconduction is used to find the energy band gap, which comes out to be 4.7 eV; lower value is correlated to the defect induced states in the band gap.
18 citations
TL;DR: In this article, XRD spectra of lead zirconate titanate Pb(Zr0.53Ti0.47)O3 with europium doping concentration of 0, 0.5, 1.5 and 3 mol% (PEZT) were fabricated by sol-gel method.
Abstract: Samples of lead zirconate titanate Pb(Zr0.53Ti0.47)O3 with europium (Eu) doping concentration of 0, 0.5, 1.5, 3 mol% (PEZT) were fabricated by sol–gel method. XRD spectra showed that the introduction of Eu into PZT favored the growth of (100) orientation. With 3% Eu content, the preferential orientation of the film converted from (111) to (100) orientation. The Eu-doped PZT films exhibited lower leakage current less than 10-9 A/cm2 and the behavior of leakage current was discussed in terms of defect chemistry theorem. When Eu content was 1.5%, the remanent polarization (Pr) increased to 28 μ C/cm2 which was much higher than that of undoped PZT film.
18 citations
TL;DR: In this article, the contamination and growth mechanisms of macrodroplets were investigated in TiN coatings over high-speed steel, as a function of metal ion etching, substrate bias, and nitrogen gas flow rate.
Abstract: Cathodic arc physical vapor deposition (CAPVD) a technique used for the deposition of hard coatings for tooling applications has many advantages. The main drawback of this technique is the formation of macrodroplets (MDs) during deposition resulting in films with rougher morphology. The MDs contamination and growth mechanisms was investigated in TiN coatings over high-speed steel, as a function of metal ion etching, substrate bias, and nitrogen gas flow rate; it was observed that the latter is the most important factor in controlling the size and number of the macrodroplets.
17 citations
TL;DR: In this paper, the precursors for BaTiO3 sol are synthesized using research grade materials and locally available facilities, in order to obtain a suitable sol for BaO3, which is then spun onto Cu substrates to obtain films of thickness 0.5 μm.
Abstract: Synthesis of the precursors, using research grade materials and locally available facilities, is optimized in order to obtain a suitable sol for BaTiO3. The optimally synthesized BaTiO3 sol is then spun onto Cu substrates to obtain films of thickness ~0.5 μm. The deposited BaTiO3 films are heated up to a temperature of 300°C. Surface and structural changes, with heating, are observed by optical microscope, scanning electron microscope, atomic force microscope, and X-ray diffraction. The surface cracked in some cases but is generally uniform, as seen with SEM and AFM, in case of optimized conditions. The SEM images reveal large crystallites, which are correlated to the XRD observation of tetragonal perovskite structure of these sol–gel films. The AFM scan, however, shows an rms roughness of 35.6 nm for an area of 3 μm × 3 μm. Tetragonal perovskite BaTiO3 is obtained at a temperature of as low as 300°C. The dielectric constant and loss angle, in the 30 Hz–3 MHz range, are calculated at room temperature and up to 200°C. At high frequencies the dielectric constant (~290) and loss angle (~2 × 10-6) values indicate the usefulness of such films in electronic applications. The leakage current is also measured at room temperature and a conductivity of 2.0 × 10-15S/cm is obtained.
TL;DR: In this article, Monte Carlo simulations of the kinetics of migration and coalescence of nm-sized metal particles on a uniform surface and a surface with traps in the physically reasonable case when the diffusion coefficient of particles varies inversely as the fourth power of the particle size are presented.
Abstract: Monte Carlo simulations of the kinetics of migration and coalescence of nm-sized metal particles on a uniform surface and a surface with traps in the physically reasonable case when the diffusion coefficient of particles varies inversely as the fourth power of the particle size are presented. The Monte Carlo kinetics are demonstrated to be in good agreement with the mean-field results. The size distribution of particles is found to be nearly symmetrical with respect to the average value.
TL;DR: In this paper, the formation mechanism and surface evolution of thin silver films deposited on silicone oil substrates by a DC-magnetron sputtering method are reported, and the evolution behaviors and underlying physical mechanisms of the cracks and wrinkles are presented and discussed in detail.
Abstract: The formation mechanism and surface evolution of thin silver films deposited on silicone oil substrates by a DC-magnetron sputtering method are reported. As the film thickness increases, the deposited silver atoms first form compact clusters, then transfer to ramified aggregates and finally form a continuous film on the liquid substrate. After deposition, the surface morphology of the silver film is susceptible to evolve successively in the atmosphere condition, resulting in the formation of broad cracks and straight-sided (or worm-like) wrinkles. The evolution behaviors and underlying physical mechanisms of the cracks and wrinkles are presented and discussed in detail.
TL;DR: An improved chemical bath deposition (CBD) technique has been provided to prepare zinc sulfide (ZnS) thin films on glass substrates deposited at 80-82°C using a mixed aqueous solution of zinc sulfate, ammonium sulfate and thiourea, hydrazine hydrate, and ammonia at the alkaline conditions.
Abstract: An improved chemical bath deposition (CBD) technique has been provided to prepare zinc sulfide (ZnS) thin films on glass substrates deposited at 80–82°C using a mixed aqueous solution of zinc sulfate, ammonium sulfate, thiourea, hydrazine hydrate, and ammonia at the alkaline conditions. Both the traditional magnetic agitation and the substrates vibration by hand frequently were done simultaneously during the deposition. The substrates vibration reduced the formation and residence of gas bubbles on the glass substrates during growth and resulted in growth of clean ZnS thin films with high quality. Ammonia and hydrazine hydrate were used as complexing agents. It is found that hydrazine hydrate played an important role in growth of ZnS films. The structure and microstructure of ZnS films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV-vis spectroscopic methods. The XRD showed a hexagonal structure. The formed ZnS films exhibited good optical properties with high transmittance in the visible region and the band gap value was estimated to be 3.5–3.70 eV.
TL;DR: In this paper, the water repellence and physical properties such as gas permeability, bending properties, beetling properties, tensile strength, elongation at break, abrasion resistance, and anti-crease properties of the cotton fabrics were investigated.
Abstract: The properties of the cotton fabric with water-repellence finishing by sol method with the hexadecyltrimethoxysilane as additive were observed. The cotton fabrics were immersed in the prepared sols with double dip and double nip dried at 90°C, annealed at 160°C for 3 min. The water repellence and the physical properties such as gas permeability, bending properties, beetling properties, tensile strength, elongation at break, abrasion resistance, and anti-crease properties of the cotton fabrics were investigated. The results showed that anti-crease and tensile strength were improved. However, the abrasion resistance of the cotton fabrics decreased in some way. Both the bending and beetling properties measurement proved that the handle of the treated cotton fabrics changed stiffness. For the dyed fabrics by the water-repellent finishing, the hue was slightly changed, the deeper color was achieved. There is no adverse effect for treated fabric by water-repellent finishing on the fastness.
TL;DR: In this article, a high-energy ball milling method was used to construct Li/FeS cells, and the surface of the FeS powder was coated with metallic nickel to obtain high initial discharge capacity of 581 mAh/g-FeS.
Abstract: In order to investigate the electrochemical properties of Li/FeS cell, FeS powder was fabricated by using a high-energy ball milling method. Then, surface of FeS powder was coated with metallic nickel. Nickel coating was conducted by using electroless nickel plating method. Nickel chloride (NiCl2 · 6H2O) was used as the nickel ion source for electroless nickel plating. The effects of nickel coating on the electrochemical properties of FeS electrode for Li/FeS cell were investigated by CV measurement and charge/discharge tests. Then, cells for electrochemical tests were assembled by stacking a lithium anode, separator containing liquid electrolyte, and FeS cathode in turn. From the results, electroless nickel plated FeS electrode showed very high initial discharge capacity of 581 mAh/g-FeS. And also, it showed higher discharge capacity than that of bare FeS electrode until the 29th cycle. Therefore, it is found that metallic nickel gives beneficial effects on enhancing the electrical conductivity of FeS cathode material. 82.47.Cb.
TL;DR: In this paper, the effect of concentration and temperature on inhibition properties of chromium-nickel steel in different concentrations of dimethyl 2-(2-hydroxy phenyl amino)-3-(triphenyl phosphoranilidin) butane dioate (L-OH) was investigated by potentiostatic polarization measurements.
Abstract: The corrosion behavior of the austenitic chromium–nickel steel in different concentrations (0.001, 0.002, 0.005, and 0.01 M) of dimethyl 2-(2–hydroxy phenyl amino)-3-(triphenyl phosphoranilidin) butane dioate (L–OH) in 0.5 M H2SO4 was investigated by potentiostatic polarization measurements. The effect of concentration and temperature on inhibition properties was determined. It was found that the presence of L–OH reduces markedly the corrosion rate of steel in the acid solution. The inhibition efficiency increases as the L–OH concentration is increased. Maximum inhibition efficiency (95%) was obtained for alloy in acid solution containing 0.01 M of L–OH. Thermodynamic parameters for adsorption of L–OH are calculated. It was found that the inhibitor is adsorbed on the steel surface and the experimental results are in agreement with Timken's isotherm. Negative values of the free energy of adsorption were obtained indicating the spontaneity of adsorption process. Scanning electron microscopy was done from the surface of exposed sample indicating uniform film on the surface of the alloy.
TL;DR: In this paper, the surface effect of gold nanoparticles (AuNPs) has been investigated in two-round PCR and the results showed that, except 5.02 nm AuNPs, the AuNs that could achieve the similar enhancement happened to have nearly the same total surface area.
Abstract: Recently, gold nanoparticles (AuNPs) were reported to increase the specificity and efficiency of the polymerase chain reaction (PCR). In this paper, we tested the enhancement of AuNPs with five different sizes on the specificity of two-round PCR. The results showed that, except 5.02 nm AuNPs, the AuNPs that could achieve the similar enhancement happened to have nearly the same total surface area. The surface effect seems to be the key factor of nanogold-assisted PCR.
TL;DR: In this paper, the localization of surface plasmons polariton is reviewed in the context of experiments and modeling of near-field optical images, and approaches for the correct image interpretation are outlined.
Abstract: Localization of surface plasmons polariton is reviewed in the context of experiments and modeling of near-field optical images. Near-field imaging of elastic (in-plane) surface plasmon scattering is discussed, and approaches for the correct image interpretation are outlined. Nonlinear effects related to localized surface plasmons are pressented. Surface plasmon localization opens up numerous possibilities for application in biosensing, nanophotonics, and in general in the area of surface optics properties.
TL;DR: In this article, electron energy loss spectroscopy in the low energy range of the primary electron energy was used to study surface and bulk plasmon excitations from the ordering Pt80Co20(111) alloy surface.
Abstract: Surface and bulk plasmon excitations from the ordering Pt80Co20(111) alloy surface are studied by means electron energy loss spectroscopy in the low energy range of the primary electron energy E0. Deviation of the plasmon excitations from the theoretical value was found for Pt, Co metals, and Pt80Co20(111) alloy as calculated in the free-electron gas model. For the ordered alloy, the bulk plasmon energy is 2–3 eV more than for the disordered alloy, whereas the difference for surface plasmon energy is 4–7 eV in the range E0 = 150–800 eV. The ration of intensity lines of plasmons η from E0 was investigated for the (dis)ordered state of the Pt80Co20(111) alloy surface. For the ordered alloy, η has prolonged dependence from energy E0 in comparison with the disordered alloy. The relationship between layer-by-layer surface concentration and surface plasmon damping was observed.
TL;DR: In this article, the tribo-performance of a new engineering composite material based on coconut fibers was investigated by using pin-on-disc machine under dry and wet sliding contact condition against smooth stainless steel counterface.
Abstract: The tribo-performance of a new engineering composite material based on coconut fibers was investigated. In this work, coconut fibers reinforced polyester (CFRP) composites were developed. The tribo-experiments were conducted by using pin-on-disc machine under dry and wet sliding contact condition against smooth stainless steel counterface. Worn surfaces were observed using optical microscope. Friction coefficient and specific wear rate were presented as a function of sliding distance (0–0.6 km) at different sliding velocities (0.1–0.28 m/s). The effect of applied load and sliding velocity was evaluated. The results showed that all test parameters have significant influence on friction and wear characteristics of the composites. Moreover, friction coefficient increased as the normal load and speed increased, the values were about 0.7–0.9 under dry contact condition. Meanwhile, under wet contact condition, there was a great reduction in the friction coefficient, i.e. the values were about 0.1–0.2. Furthermore, the specific wear rates were found to be around 2–4 (10-3) mm3/Nm under dry contact condition and highly reduced under wet condition. In other words, the presence of water as cleaner and polisher assisted to enhance the adhesive wear performance of CFRP by about 10%. The images from optical microscope showed evidence of adhesive wear mode with transition to abrasive wear mode at higher sliding velocities due to third body abrasion. On the other hand, optical images for wet condition showed less adhesive wear and smooth surfaces.
TL;DR: In this article, the effect of various laser processing parameters on the kerf width and cut quality of Si wafer as well as encapsulated si wafer was investigated and the parameters were then optimized to minimize the heat affect zone and obtain the best possible cut quality.
Abstract: The effect of various laser processing parameters on the kerf width and cut quality of Si wafer as well as encapsulated Si wafer is investigated. The parameters are then optimized to minimize the heat affect zone and obtain the best possible cut quality. It has been found that oxygen is the most suitable assist gas for laser dicing and that the highest gas pressure may not produce the best cut quality. The effect of laser repetition rate, pump energy, feed rate, and number of passes are also studied. Under optimized parameters, the cut quality of Si wafer using laser dicing is found to be comparable to diamond saw dicing.
TL;DR: In this article, 4-Amino-decylpyridinium bromide (ADPBr), an antimicrobial surface active agent, was synthesized by quaternization of 4-aminopyridine (AP) with decyl bromides (DBr).
Abstract: 4-Amino-decylpyridinium bromide (ADPBr), an antimicrobial surface active agent, was synthesized by quaternization of 4-aminopyridine (AP) with decyl bromide (DBr). The reaction was carried out at 1:1.2 molar ratio of reactants (4-aminopyridine and decyl bromide, respectively) at 200°C for 10 min. The maximum yield of the product was 74.6%. The structure of the synthesized product was characterized by using modern analytical techniques, such as FT-IR, 1H NMR, and 13C NMR. The antimicrobial activity of the salt was evaluated with minimum inhibition concentration method and showed good activity against gram-negative bacteria. The MIC of the salt was found to be 600 ppm for 2 × 104 CFU/mL of E. coli.
TL;DR: In this article, the performance of EL Ni-B coated brass contacts under fretting conditions was evaluated and the contact resistance was measured as a function of fretting cycles, and the surface profile and wear depth of the fretted zone were measured using a laser scanning microscope.
Abstract: The performance of electroless (EL) Ni–B coated brass contacts under fretting conditions was evaluated. The contact resistance of EL Ni–B coated brass contact was measured as a function of fretting cycles. The surface profile and wear depth of the fretted zone were measured using laser scanning microscope. The study reveals that EL Ni–B coated contacts exhibit better performance under fretting conditions. However, at conditions which are prone for severe oxidation such as, low frequency (3 Hz) or high temperature (155°C), EL Ni–B coated contacts fail to exhibit a better stability. The quick removal of the oxide film by fretting motion, rapid oxidation of the fresh metallic particles and trapping of the oxidation products in the remaining coating, cause the contact resistance to increase to unacceptable levels at such conditions. The study concludes that EL Ni–B coating is not a suitable choice for connector contacts that could experience fretting under highly oxidizing conditions.
TL;DR: In this article, the surface pressure area per molecule isotherm (π-A) of the pyrene and stearic acid mixed films was analyzed and it was observed that the pyrenes are miscible in the mixed monolayer, which leads to phase separation between the constituent components.
Abstract: In the present communication, the monolayer characteristics of pyrene mixed with stearic acid (SA) at the air–water interface have been reported. The monolayer properties are investigated by recording and analyzing the surface pressure–area per molecule isotherm (π–A) of the pyrene–SA mixed films. It is observed that the pyrene and SA are miscible in the mixed monolayer. This miscibility/nonideality leads to phase separation between the constituent components (pyrene and SA). BAM image of the mixed monolayer confirms the miscibility or nonideal mixing at the mixed monolayer.
TL;DR: In this article, the thermodynamic properties of polyvinylidene fluoride (PVDF) thin films with a high content of β-phase were shown by controlling heat-treatment temperature using casting from the poled solvents.
Abstract: The Poly(vinylidene) fluoride (PVDF) thin films with a high content of β-phase were prepared by controlling heat-treatment temperature using casting from the poled solvents. The crystallite microstructure of thin films was depicted by the techniques of X-ray diffraction and FTIR. The results showed that heat treatment was favorable for inducing the β- and γ-phase formation of PVDF. The β phase films were obtained with heat treatment at temperatures ranging from 60°C to 120°C and annealing at 120°C after casting from DMF. The thermo-optical effect of β phase PVDF films was investigated using a spectroscopic ellipsometer. At temperatures ranging from 20°C to 100°C, the refractive index of PVDF was negatively correlated with the temperature between 350 and 1500 nm. The value of the t.o. coefficient of PVDF films was calculated at all temperatures. The maximum value of the t.o. coefficient was about 3.3 × 10-4/°C at the ascending stage of temperature and 3.0 × 10-4/°C at the descending stage of temperature. Therefore, it is possible to use the thermo-optic effect of the β phase PVDF for long wavelength infrared imaging.
TL;DR: In this paper, the effects of thermal expansion coefficient mismatch on structure and electrical properties of TiO2 film deposited on Si substrate by ion beam assistant electron beam evaporation have been investigated.
Abstract: Effects of thermal expansion coefficient (CTE) mismatch on structure and electrical properties of TiO2 film deposited on Si substrate by ion beam assistant electron beam evaporation have been investigated. Because of a high CTE mismatch between TiO2 film and Si substrate, microcracks appeared in the TiO2 film deposited directly on Si substrate after the as-deposited film was annealed at 600°C. In order to decrease the CTE mismatch, TiO2 film was deposited on Si substrate which was covered by a ZrO2 thin layer. As a result, crack–free TiO2 film after annealed at the same temperature was obtained. Meanwhile, corresponding to the crack–free structure, the TiO2 thin film has more stable dielectric properties and excellent I–V characteristics.
TL;DR: In this paper, a TEM analysis revealed the transition from polycrystalline structure to single crystal from the bottom to the top, probably due to the competition growth of the adjacent grains and the confinement of growth in the nano-sized hole of the AAO template.
Abstract: Ferromagnetic (Ni, Co, Fe) nanowires were electrodeposited using AAO template. XRD analysis indicated that the ferromagnetic wires had preferred orientation. For longer deposition time, the nanowires with textured structure changed to single crystal. The investigation on the growth mechanism showed that in the initial stage, the nanowires were polycrystalline. Our TEM analysis revealed the transition from polycrystalline structure to single crystal from the bottom to the top. The growth mechanisms are probably due to the competition growth of the adjacent grains and the confinement of growth in the nano-sized hole of the AAO template.
TL;DR: In this article, a Ti-pillared montmorillonite with high thermal stability has been prepared by using a Na-montmorillonites as the host clay and polyhydroxy-titania ions as the pillaring precursor, which has been confirmed from the characterizations through X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric differential scanning calorimeter, and specific surface area analyses.
Abstract: In this work, a Ti-pillared montmorillonite with high thermal stability has been prepared by using a Na-montmorillonite as the host clay and polyhydroxy-titania ions as the pillaring precursor. The formation of Ti-pillared montmorillonite has been confirmed from the characterizations through X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric–differential scanning calorimeter, and specific surface area analyses. In the preparation of Ti-pillared montmorillonite several parameters, such as the type of solvent in which the synthesis is realized, the ratio of polyhydroxy-titania ions and montmorillonite, the intercalation time, the calcining temperature, and calcining time, were tested to understand their effects on the basal spacing. It was shown that this method could produce a Ti-pillared montmorillonite with the basal spacing of 3.74 nm, specific surface area of 409 m2/g, and mean pore size of 2.94 nm, as well as a high thermal stability up to 900°C.
TL;DR: In this paper, a simply modified bath deposition technique has been successfully used to deposit uniform CdS thin films using cadmium chloride and thiourea as the sulfur source on glass substrates.
Abstract: A simply modified bath deposition technique has been successfully used to deposit uniform CdS thin films using cadmium chloride or cadmium acetate as the cadmium ion source, and thiourea as the sulfur source on glass substrates. Both the traditional magnetic agitation and the frequent substrate vibration by hand were done simultaneously during the deposition. Various properties of the deposited films such as surface morphology, crystallinity, and optical properties were investigated. The CdS films deposited from cadmium acetate show a good crystallinity and exhibit a preferential orientation along the hexagonal (002) direction. Their surface morphologies are more homogeneous with smaller grains than those from cadmium chloride. The CdS films prepared from both cadmium ion sources present a high optical transmission (more than 80%) in the visible range with the band gap value of about 2.4 eV. The substrate vibration reduces the formation and residence of gas bubbles on the glass substrate during growth and resulted in deposition of CdS thin films with high quality. XRD, SEM, and UV–Vis measurements have provided the supported data. The fundamental CBD growth mechanisms involving different cadmium salts are discussed.