Examination Of Surface Morphology Research Articles

Effect of Hydrodynamic Condition on the Electrochemical Behavior of Various Metals in 3.5 wt% NaCl Solution

The electrochemical behaviors of various metals with and without diamond-like-carbon (DLC) coating in 3.5 wt% NaCl solution were investigated. The effect of hydrodynamic conditions was focused by employing a rotating disc electrode (RDE). The experimental results showed that each bare metal had a more positive corrosion potential and a higher corrosion rate due to enhanced oxygen transport at the higher rotating speed of the RDE. DLC coating caused a substantial increase in the corrosion resistance of all metals studied. However, localized corrosion was still found in the DLC-coated metal at sites where deposition defects existed. Surface morphology examination was performed after the electrochemical test to confirm the roles of hydrodynamic conditions and DLC coating.

Surface coating of α-Al2O3 nanoparticles with poly(vinyl alcohol) as biocompatible coupling agent for improving properties of bio-active poly(amide-imide) based nanocomposites having l-phenylalanine linkages

Nanocomposites (NCs) containing metal oxide nanoparticles (NPs) as fillers are used in a wide range of applications and in various fields. Poly(vinyl alcohol) (PVA) is an attractive polymer because of its many desirable applications and characteristics. In this investigation, at first, the surface of alumina (α-Al2O3) NPs was modified with PVA as a biocompatible modifier. Then, the optically active poly(amide-imide) (PAI) nanostructure was prepared by using molten tetrabutylammonium bromide as a molten ionic liquid and triphenyl phosphite as the condensing agent. Finally, the modified α-Al2O3 (α-Al2O3-PVA) NPs were incorporated into the PAI matrix for the preparation of PAI/Al2O3-PVA NCs (PAPNCs). To investigate effect and nature of coating on the surface of the α-Al2O3 NPs and preparation of PAPNCs, the samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and thermogravimetric analysis. The surface morphology examination demonstrated the monodispersed characteristics of α-Al2O3 NPs after surface modification with the PVA and incorporation into the PAI matrix.

Sonochemical production and characterization of d-fructose functionalized MWCNTs/alanine-based poly(amide-imide) nanocomposites

This study presents the preparation of d-fructose covalently functionalized multiwalled carbon nanotube (MWCNT-Fr) and its application in the synthesis of polymer nanocomposites (NCs). Poly(amide-imide) (PAI) as matrix of NCs was synthesized from polycondensation reaction between N-trimellitylimido-l-alanine diacid and 4,4′-diamino diphenyl methane under green conditions. Different percents of functionalized multiwalled carbon nanotube (MWCNT-Fr) were dispersed in the PAI using a solution mixing technique. Increased outer diameter and rough surface of the MWCNT-Fr showed the coating of fructose on the surface of MWCNTs. X-ray diffraction analysis was performed in order to confirm the presence of MWCNT-Fr in the PAI matrix. Surface morphology examination showed that the MWCNT-Fr was very well dispersed in the PAI matrix. The thermal properties of the blends were also evaluated. Our results demonstrated according to the limited oxygen index values that these NCs could be classified as self-extinguishing materials.

Tetraphosphonic acid as eco-friendly corrosion inhibitor on carbon steel in 3 % NaCl aqueous solution

The inhibition activity of a new tetraphosphonic acid (TPA), 2-hydroxy-5-[4-hydroxy-3,5-bis(phosphonomethyl)benzyl]-3-(phosphonomethyl)benzylphosphonic acid, for carbon steel in aerated 3 % NaCl solution, at 1000 rpm, was investigated using open circuit potential (OCP), potentiodynamic polarizations, and electrochemical impedance spectroscopy (EIS) to evaluate the TPA inhibition efficiency. The steel surface was also examined by SEM observations and energy-dispersive X-ray (EDX) analysis. The inhibition efficiency increased with TPA increasing concentration up to 10−3 mol L−1 where the highest inhibition efficiency (88 %) was obtained. The thermodynamic parameters—adsorption equilibrium constant, standard free energy, and activation energy—were calculated to determine the corrosion inhibition mechanism. Results from potentiodynamic polarization and electrochemical impedance spectroscopy revealed the mode of inhibitive action and adsorption of inhibitor molecules. Further, surface morphological examination supports the protective film formation by TPA on carbon steel surface. Inhibitor adsorption was spontaneous (ΔG < 0), supported the physical/chemical adsorption mechanism, and obeyed to the Langmuir adsorption isotherm.

Effects of Titanium Doping Concentration on the Structural and Electrical Properties of Sputtered Indium Oxide Films.

The surface structure and electrical properties of titanium-doped indium oxide (ITiO) films prepared by RF magnetron sputtering were investigated. The doping concentration of TiO2 in the In2O3 target was changed from 1.0 wt.% to 10.0 wt.% with increments of 1.0 wt.%. At a Ti content of 5.0 wt.%, the optimum growth conditions were achieved. The finest value of hall mobility, carrier concentration, and resistivity of the deposited film reached 47.03 cm2Ns, 1.148 x 10(21) cm-3 and 1.14 x 10(-4) Ωcm, respectively. Then the transmittance was achieved up to 82% at 570 nm. The peaks of the XRD spectra became more intense and sharp as the Ti concentration increased up to 2.5 wt.% but a higher Ti content of 10.0 wt.% retarded a growth of In2O3 grains. The surface roughness of the films by examination of surface morphology using AFM also rose with increase of Ti doping concentration.

Synthesis and Study of Corrosion Protection Efficiency of Silica Nanoparticles on Aluminium

Monodispersed silica nanoparticles (SNPs) were synthesized by cost effective aqueous-ethanolic route. The particle size was controlled by optimizing the synthetic conditions. The synthesized different size SNPs were used to study the corrosion protection efficiency on aluminium (Al) in alkaline medium by weight loss, Potentiodynamic polarization and surface morphology examination methods. It was found that SNPs with smaller particle sizes showed better protection efficiency compared to those of larger particles. The results were explained in terms of effective surface coverage by smaller sized SNPs.

Structure and formation of anoxic granular sludge—A string-bag hypothesis

Anoxic granular sludge was developed in a laboratory-scale sequencing batch reactor which was fed with sodium acetate and sodium nitrate as electron donor and accepter. The sludge in the reactor was almost granulated after approximately 90 days of cultivation. In the present study, a detailed examination of surface morphology and internal structure of anoxic granular sludge was conducted using scanning electron microscope. It showed that the bacteria inside the granules had a uniform, coccus-like shape. By contrast, filamentous bacteria were predominant outside the granules. These bacteria were woven and had wrapped the coccus bacteria together to form granules. The small amounts of DO in the liquid bulk promoted the growth of filamentous bacteria on the surface of the granules. A string-bag hypothesis was proposed to elucidate the structure and formation of the anoxic granular sludge. It suggested that micro-aeration could be a method to promote granulation in practical anoxic treatment systems.

Effectiveness of BaTiO3 dielectric patches on YBa2Cu3O7 thin films for MEM switches

A micro-electro-mechanical (MEM) switch built on a superconducting microstrip filter will be utilized to investigate BaTiO3 dielectric patches for functional switching points of contact. Actuation voltage resulting from the MEM switch provokes static friction between the bridge membrane and BaTiO3 insulation layer. The dielectric patch crystal structure and roughness affect the ability of repetitively switching cycles and lifetime. A series of experiments have been performed using different deposition methods and RF magnetron sputtering was found to be the best deposition process for the BaTiO3 layer. The effect examination of surface morphology will be presented using characterization techniques as x-ray diffraction, SEM and AFM for an optimum switching device. The thin film is made of YBa2Cu3O7 deposited on LaAlO3 substrate by pulsed laser deposition. For this work, the dielectric material sputtering pressure is set at 9.5×10−6 Torr. The argon gas is released through a mass-flow controller to purge the system prior to deposition. RF power is 85 W at a distance of 9 cm. The behavior of Au membranes built on ultimate BaTiO3 patches will be shown as part of the results. These novel surface patterns will in turn be used in modelling other RF MEM switch devices such as distributed-satellite communication system operating at cryogenic temperatures.

Magnetic Force Microscopy Characterization of Superparamagnetic Iron Oxide Nanoparticles (SPIONs)

The present study was aimed to develop dimethylaminoethyl methacrylate based nanoparticulate drug delivery system using nanoprecipitation method and optimize the process parameters using Plackett-Burman factorial design to yield least average particle size and narrow sized particle distribution without filtration or centrifugation process. Twelve experimental runs involving 11 process parameters at higher and lower levels were generated using Design-Expert. Factorial design result has shown that (a) Except stirring duration all other process parameters significantly influence the average particle size; (B) Except β-cyclodextrin concentration, aqueous phase volume and organic phase volume, all other process parameters significantly influence the polydispersity index; and (C) Except polymer concentration and poloxamer 407 concentration, all other process parameters do not significantly influence the zeta potential. The average particle size, polydispersity index and zeta potential of the prepared dual drug loaded nanoparticles were well within acceptable limits and found to be in the range of 47 to 87 nm, 0.14 to 0.28 and 22 to 39 mV, respectively. Surface morphology examination has shown that the prepared nanoparticles were spherical in shape. The developed dimethylaminoethyl methacrylate based nanoparticulate drug delivery system can be routinely used to fabricate narrow sized polymeric nanoparticles without filtration or centrifugation process.

Development of Dimethylaminoethyl Methacrylate Based Nanoparticulate Drug Delivery System Using Nanoprecipitation Method and Optimization of Process Parameters Using Plackett-Burman Factorial Design

The present study was aimed to develop dimethylaminoethyl methacrylate based nanoparticulate drug delivery system using nanoprecipitation method and optimize the process parameters using Plackett-Burman factorial design to yield least average particle size and narrow sized particle distribution without filtration or centrifugation process. Twelve experimental runs involving 11 process parameters at higher and lower levels were generated using Design-Expert. Factorial design result has shown that (a) Except stirring duration all other process parameters significantly influence the average particle size; (B) Except β-cyclodextrin concentration, aqueous phase volume and organic phase volume, all other process parameters significantly influence the polydispersity index; and (C) Except polymer concentration and poloxamer 407 concentration, all other process parameters do not significantly influence the zeta potential. The average particle size, polydispersity index and zeta potential of the prepared dual drug loaded nanoparticles were well within acceptable limits and found to be in the range of 47 to 87 nm, 0.14 to 0.28 and 22 to 39 mV, respectively. Surface morphology examination has shown that the prepared nanoparticles were spherical in shape. The developed dimethylaminoethylmethacrylate based nanoparticulate drug delivery system can be routinely used to fabricate narrow sized polymeric nanoparticles without filtration or centrifugation process.

Dependence of the Capacitive Deionization Performance on Potential of Zero Charge Shifting of Carbon Xerogel Electrodes during Long-Term Operation

In order to examine the reliability of carbon xerogel (CX) materials for capacitive deionization (CDI), long-term operation of a CDI cell with CX electrodes was performed in a dilute NaCl solution. During operation at 1.2/0 V, the deionization performance gradually degraded, and a growing inversion peak formed at the beginning of each adsorption step. When the polarity of the electrode was reversed, the use of −1.2/0 V significantly boosted deionization performance. However, this enhancement was not sustained with continued cycling. In this study, we also reported the use of a four-electrode cell, in which the potential distribution for a pair of electrodes could be measured, and the potential of zero charge (PZC) for a single electrode could be located. Based upon the PZC location for the used electrodes with respect to the corresponding potential distribution, performance variation and the formation of the inversion peak for long-term CDI operation were interpreted. In addition, N2 adsorption-desorption measurements and surface morphology examinations indicated that there was little variation in the porosity of the cycled electrodes with long-term operation.

Ablation and spectroscopic characteristics of thin CuIn1-xGaxSe2 solar cell films fabricated by co-evaporation and co-sputtering processes

The influence of fabrication processes on the LIBS (Laser Induced Breakdown Spectroscopy) spectra of major and minor chemical constituents in CuIn1-xGaxSe2 (CIGS) absorber films produced by co-sputtering and co-evaporation techniques on Mo-coated soda lime glass (SLG) is reported. It was found that the ablation rate per pulse of CIGS layers fabricated by the co-sputtering technique is higher than those fabricated by the co-evaporation technique, resulting in higher LIBS signal intensities of the constituent elements. The examination of surface morphology of irradiated surfaces and changes in LIBS signal intensities revealed evidences of elemental fractionation for the CIGS films fabricated by co-sputtering technique but not for those by co-evaporation technique. From x-ray diffraction measurements, it was confirmed that the differences in the ablation and spectroscopic characteristics of the two different types of CIGS absorber films were contributed to the differences in crystalline properties. Furthermore, it was demonstrated that LIBS can effectively determine a depth profile of sodium concentration in CIGS thin films, diffused from SLG.

Structure–property correlation of pure and Sn-doped ZnO nanocrystalline materials prepared by co-precipitation

The structural, optical and electrical properties of pure and tin (Sn) doped zinc oxide (ZnO) nanocrystalline materials prepared by co-precipitation method have been studied as a function of Sn doping concentration. The phase identification through powder X-ray diffraction methods confirmed that pure and Sn-doped zinc oxide powder have typical hexagonal wurtzite structure (a = 3.407 Å and c = 4.592 Å) with slight change in lattice parameters. The surface morphological examination with field emission scanning electron microscopy revealed the fact that the grains are closely and densely packed and pores/voids between the grains decrease with increasing the doping concentration of Sn from 0% to 15%. The energy bandgap of pure ZnO was found to be 3.35 eV from optical absorption spectra obtained by ultraviolet–visible (UV–Vis) absorption spectrophotometer. The variation of energy bandgap and electrical resistivity of Sn-doped ZnO were also determined with tin doping. Upon increasing the Sn dopant concentration from 0 to 15 wt%, the optical bandgaps of ZnO increases from 3.35 to 3.42 eV. The electrical resistivity of Sn-doped ZnO has been decreased at least two orders of magnitude, i.e. from 1263.17 to 28.64 Ω cm. This decrement in electrical resistivity may be due to the partial substitution of divalent Zn2+ ions with tetravalent Sn4+ ions, generating more free electrons for conduction.

Microstructural, optical and electrical investigations of Sb-SnO2 thin films deposited by spray pyrolysis

The structural, optical and electrical properties of spray deposited antimony (Sb) doped tin oxide (SnO2) thin films, prepared from SnCl4 precursor, have been studied as a function of antimony doping concentration. The doping concentration was varied from 0 to 1.5wt.% of Sb. The analysis of X-ray diffraction patterns revealed that the as deposited doped and undoped tin oxide thin films are pure crystalline tetragonal rutile phase of tin oxide which belongs to the space group P42/mnm (number 136). The surface morphological examination with field emission scanning electron microscopy (FESEM) revealed the fact that the grains are closely packed and pores/voids between the grains are very few. The resistivity (ρ) and mobility (μ) are in the range of 1.512×10−3–6.624×10−3Ωcm and 9.75–22.96cm2V−1s−1. The electron density lies between 4.11×1019 and 4.24×1020cm−3. A thorough electrical investigation reveals that the film's resistivity depends on carrier concentration. It is found that ionized impurity scattering is the dominant mechanism, which limits the mobility of the carriers. The transmittance spectra for as-deposited films were recorded in the wavelength range of 200–1000nm. The transmittance of the films was observed to increase from 57% to 68% (at 800nm) on initial addition of Sb (up to [Sb]/[Sn]=0.5wt.%) and then it is decreased for higher level of antimony doping ([Sb]/[Sn] >0.5wt.%).

InGaN-based multi-quantum well light-emitting diode structure with the insertion of superlattices under-layer

This paper reports on the improved crystalline quality of In0.11Ga0.89N/In0.02Ga0.98N multi-quantum well (MQW) light-emitting diode (LED) structure with the insertion of n-AlN/n-GaN multilayer (ML) and n-Al0.06Ga0.94N/n-GaN strained-layer superlattices (SLSs) cladding under-layer. The LED sample structure was epitaxially grown on Si (111) substrate by metal organic chemical vapor deposition (MOCVD) system with laminar-flow horizontal growth reactor. From X-ray rocking curves (XRCs) omega-scan (ω-scan), the n-Al0.06Ga0.94N/n-GaN SLS under-layer facilitate in improving the crystalline quality of the LED sample structures by reducing the threading dislocation density (TDD). Reciprocal space mapping (RSM) confirms the strain state of the GaN epitaxial layers. Triple axis (TA) X-ray diffraction (XRD) omega-2Theta (ω-2θ) scan reveals a higher-order fringes indicate the ML and MQW layers with sharp layer interfaces. Photoluminescence (PL) measurement of the sample with n-Al0.06Ga0.94N/n-GaN SLS under-layer shows band-to-band photon energy of 2.97eV with narrower full-width at half-maximum (FWHM) as compared to the sample with n-Al0.03Ga0.97N under-layer. Surface morphology examination by atomic force microscopy (AFM) demonstrate smoother sample surface for the sample with n-Al0.06Ga0.94N/n-GaN SLS as compared to conventional sample without the SLS layer.

Cell biological responses of osteoblasts on anodized nanotubular surface of a titanium‐zirconium alloy

Anodization of titanium and its alloys, under controlled conditions, generates a nanotubular architecture on the material surface. The biological consequences of such changes are poorly understood, and therefore, we have analyzed the cellular and molecular responses of osteoblasts that were plated on nanotubular anodized surface of a titanium-zirconium (TiZr) alloy. Upon comparing these results with those obtained on acid etched and polished surfaces of the same alloy, we observed a significant increase in adhesion and proliferation of cells on anodized surfaces as compared to acid etched or polished surface. The expression of genes related to cell adhesion was high only on anodized TiZr, but that of genes related to osteoblast differentiation and osteocalcin protein and extracellular matrix secretion were higher on both anodized and acid etched surfaces. Examination of surface morphology, topography, roughness, surface area and wettability using scanning electron microscopy, atomic force microscopy, and contact angle goniometry, showed that higher surface area, hydrophilicity, and nanoscale roughness of nanotubular TiZr surfaces, which were generated specifically by the anodization process, could strongly enhance the adhesion and proliferation of osteoblasts. We propose that biological properties of known bioactive titanium alloys can be further enhanced by generating nanotubular surfaces using anodization.

Electrochemical Formation of Functional Silver Coatings: Nanostructural Peculiarities

The microstructure of silver coatings electrodeposited from different types of baths without brightening agents had been studied. The principal formulations of baths were following: cyanide: 0.75M KAg(CN)2+1.5M KCN+0.2M KOH; dicyanoargentate-thiocyanate (DCAT): 0.75M KAg(CN)2+6M KCNS + 1M K2CO3; dicyanoargentate-borate-phosphate-carbonate (BPC): 0.75M KAg(CN)2+0.82M KH2PO4+ 0.41M H3BO3+0.15M K2CO3+0.69M KOH; thiocyanate: 0.75M AgNO3 + 6M KCNS. The values of grain size was evaluated based on the XRD examination and are in the range 60 nm (for coatings electrodeposited from cyanide baths at current densities (15-40 mA cm-2) to 100 nm (for thiocyanate and BPC baths). The values of lattice parameter and interplanar distance obtained for Ag coatings are higher than that obtained for metallurgically prepared silver. Regardless on the type of bath, the obtained coatings were polycrystalline and nanocrystalline. The coatings electrodeposited at low current densities (< 10 mA cm-2) are rather crystalline that evidently was confirmed by SEM examination of surface morphology.

Fundamental Studies of Electrochemically Controlled Surface Oxidation and Hydrophobicity of Natural Enargite

The surface oxidation and hydrophobicity of natural enargite (Cu(3)AsS(4)) and the formation of oxidation species at the mineral surface have been examined by a novel experimental approach that combines electrochemical techniques and atomic force microscopy (AFM). This approach allows for in-situ, synchronized electrochemical control and examination of the oxidative surface morphology of enargite. Combined with ex-situ cryo X-ray photoelectron spectroscopy surface analysis, the surface speciation of enargite surface oxidation has been obtained, comparing the newly fractured natural enargite surface with those that have been electrochemically oxidized at pHs 4 and 10. At pH 4, surface layer formations consisting of metal-deficient sulfide and elemental sulfur were identified, associated with a limited increase in root-mean-square (rms) roughness (1.228 to 3.143 nm) and apparent heterogeneous distribution of surface products as demonstrated by AFM imaging. A mechanism of initial rapid dissolution of Cu followed by diffusion-limited surface layer deposition was identified. At pH 10, a similar mechanism was identified although the differences between the initial and diffusion-limited phases were less definitive. Surface species were identified as copper sulfate and copper hydroxide. A significant increase in surface roughness was found as rms roughness increased from 0.795 to 9.723 nm. Dynamic (receding) contact angle measurements were obtained by a droplet evaporation method. No significant difference in the contact angle on a surface oxidized at pH 10 and the freshly polished surface was found. A significant difference was found between the polished surface and that oxidized at pH 4, with an increase in contact angle of about 13° (46° to 59°) after oxidation. Competing effects of hydrophilic (copper oxides and hydroxides) and hydrophobic (elemental sulfur) species on the mineral surface under oxidizing conditions at pH 4 and the change in surface roughness at pH 10 may contribute to the observed effects of electrochemically controlled oxidation on enargite hydrophobicity.

Thermal-induced growth of RuO2nanorods from a binary Ru–Ti oxide composite and alteration in supercapacitive characteristics

The growth of crystalline RuO2 nanorods has been thermally induced from a binary Ru–Ti oxide prepared by oxidative precipitation in an aqueous solution consisting of RuCl3·xH2O, TiCl3 and H2O2. X-ray diffraction results show the formation of RuO2 nanocrystals as the annealing temperature is above/equal to 250 °C. The examination of surface morphology by transmission electron microscopic analysis confirms that the growth of RuO2 nanorods takes place in the high annealing temperature region. X-ray absorption spectroscopy (XAS) demonstrates that a minor amount of Ti atoms have been incorporated into crystalline RuO2, which partially occupy Ru sites in the octahedral RuO6 structure. The electrochemical results show that the binary Ru–Ti oxide annealed at 200 °C exhibits a much higher specific capacitance (ca. 2.5-fold improvement) and better capacitance retention in comparison with RuO2. Introducing Ti into RuO2 not only facilitates RuO2 utilization, but also enhances capacitance retention for the high-rate charge–discharge process. A schematic model is proposed to describe the growth mechanism of RuO2 nanorods from the binary Ru–Ti oxide and the function of Ti atoms within such composites for promoting the capacitive characteristics.

Studies on Ervatinine – The anticorrosive phytoconstituent of Ervatamia coronaria

The inhibition of corrosion of mild steel in 1M HCl and H2SO4 acid solutions by Ervatamia coronaria has been evaluated by a weight loss method. The results indicate that the plant extract possesses a significant anticorrosion effect. Ervatinine, the alkaloid present in the leaves of the plant has been isolated and its anti-corrosive potential has been investigated using weight loss, electrochemical impedance, Tafel polarization, scanning electron microscope and X-ray diffraction techniques. The results suggest that ervatinine acts as a good corrosion inhibitor. The adsorption of ervatinine on mild steel surface obeyed Langmuir adsorption isotherm following physisorption mode. The thermodynamic parameters such as adsorption equilibrium constant, standard free energy of adsorption and activation energy have been calculated to determine the mechanism of corrosion inhibition. Results of electrochemical measurements such as potentiodynamic polarization and electrochemical impedance spectroscopy revealed the mode of inhibitive action and adsorption of inhibitor molecules. Further, surface morphological examination supports the protective film formation by ervatinine on mild steel surface. The results confirmed the influencing role of ervatinine in the inhibition of corrosion of mild steel in acid media by extract of E. coronaria.