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Deposition Time (deposition + time)
Selected AbstractsStudy of Magnesium Boride Films Obtained From Mg(BH4)2 by CVDCHEMICAL VAPOR DEPOSITION, Issue 8 2007L. Crociani Abstract Magnesium boride films are synthesized from Mg(BH4)2 by CVD. A new synthesis of the precursor is developed. Deposition time of the samples is varied to study its influence on film composition. The films are analyzed by means of X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The contributions of various chemical species (boride and oxides) in the depth profiles, carried out using Ar ion sputtering combined with cyclic XPS measurements, are separated by peak-fitting analysis of photoelectron B1s and Auger MgKLL spectra. The samples are composed of MgBx film covered by an overlayer of magnesium and boron oxides. [source] Silver Amalgam Film Electrode of Prolonged Application in Stripping ChronopotentiometryELECTROANALYSIS, Issue 18 2007Kapturski Abstract The utility of the cylindrical silver-based mercury film electrode of prolonged analytical application in stripping chronopotentiometry (SCP) was examined. This electrode allowed us to obtain good reproducibility of results owing to the special electrode design, which enables regeneration of the thin layer before each measurement cycle. The accessible potential window in KNO3 (pH,2), acetate and ammonia buffers was defined, and the optimal conditions (i.e., stripping current, deposition potential and deposition time) for the determination of Cd and Pb traces were selected. The detection limits, obtained for an accumulation time of 60,s, were 0.023,,g/L for Cd and 0.075,,g/L for Pb. The response increases linearly with Cd, Pb and Zn concentration, up to at least 100,,g/L. It was also shown that the proposed procedure ensures excellent separation of the In and Tl, Pb and Tl or the In and Cd signals. The method was tested with dolomite and lake sediment samples, and good agreement with reference values was achieved. The obtained results showed good reproducibility (RSD=5,6%) and reliability. [source] Anodic Stripping Voltammetry Using a Vibrating ElectrodeELECTROANALYSIS, Issue 13 2007Conrad Abstract This work proposes a vibrating microwire electrode as working electrode in stripping voltammetry. The vibration was found to maintain a constant and thin (1,2,,m) diffusion layer during the deposition step. The electrode vibration eliminated the need for external stirring of the solution, thus facilitating in situ detection in the environment. The vibration was effected by fixing a low-voltage (3,V), asymmetric, electrical rotor to the working electrode (a gold microwire of either 5 or 25,,m). The sensitivity of the vibrated electrode was ca. 22×greater than stationary. Measurements of copper (4,nM) by anodic stripping voltammetry using the vibrating electrode had a low standard deviation (1% for n=6) indicating that the diffusion layer had only minor variability. The agitation mechanism was unaffected by water moving at >2,m s,1 and by water pressure equivalent to a depth of >40,m, indicating its suitability for in situ measurements. The vibrating probe was used for in situ detection of copper by anodic stripping voltammetry to a depth of 6,m. Using a 5,min deposition time, the limit of detection for labile copper was 38,pM. [source] Enhanced Resolution of Copper and Bismuth by Addition of Gallium in Anodic Stripping Voltammetry with the Bismuth Film ElectrodeELECTROANALYSIS, Issue 24 2006Chad Prior Abstract This paper presents the enhanced analysis of copper on a bismuth electrode upon addition of gallium(III). The presence of gallium alleviates the problems of overlapping stripping signals usually observed between copper and bismuth when using the Bismuth Film Electrode. In addition, it has been found that the presence of gallium improves the reproducibility of the bismuth stripping signal. Simultaneous deposition of copper and bismuth at ,1500,mV for 2,minutes in a supporting electrolyte composed of 0.1,M pH,4.75 acetate buffer with 250,,g L,1 gallium yields well resolved copper and bismuth signals when analyzed with square-wave anodic stripping voltammetry. Simultaneous analysis of copper and lead yielded linear calibration plots in the range 10 to 100,,g L,1 with regression coefficients of 0.997 and 0.994 respectively. The theoretical detection limit for copper was calculated to be 4.98,,g L,1 utilizing a 2,minutes deposition time. The relative standard deviation for a copper concentration of 50,,g L,1 was 1.6% (n=10). [source] Mercury Detection in Seawater Using a Mercaptoacetic Acid Modified Gold Microwire ElectrodeELECTROANALYSIS, Issue 10 2005Antje Widmann Abstract It is demonstrated here that it is possible to determine mercury in chloride containing media like seawater by anodic stripping voltammetry using a modified electrode. A gold microwire electrode is modified using mercaptoacetic acid (MAA) to eliminate the problem of calomel formation, allowing the mercury to become fully removed from the electrode surface after each scan. In a synthetic salt solution of KNO3 the sensitivity for mercury was found to be improved by the surface modification. In seawater the sensitivity was not significantly improved possibly because of complexation of the mercury by the abundant chloride; however, the MAA coating prevented the formation of calomel causing the background scan to be free of mercury. Measurements in seawater at various pH values demonstrated that mercury detection is possible at natural pH (around 8); however, best sensitivity was attained at pH,4.8 with a deposition time of 3,min. A peak for copper occurred at more negative potential but did not interfere at this pH. The calibration was linear between 0 and 37,nM mercury with a limit of detection of 1,nM mercury. [source] Integrated Microanalytical System Coupling Permeation Liquid Membrane and Voltammetry for Trace Metal Speciation.ELECTROANALYSIS, Issue 10 2004Optimization, Technical Description Abstract A new minicell coupling the liquid-liquid extraction technique called permeation liquid membrane (PLM) with an integrated Ir-based Hg-plated microelectrode array for voltammetric detection has been developed for the speciation of heavy metals in natural waters. Lead and cadmium have been used as model compounds. The PLM consists of a carrier (0.1,M 22DD+0.1,M lauric acid) dissolved in 1,:,1 mixture of toluene/phenylhexane held in the small pores (30,nm) of a hydrophobic polypropylene membrane (Celgard 2500). One side of this membrane is in contact with a flowing source solution, containing the metal ions of interest. An acceptor or strip solution (pyrophosphate) is placed on the other side of the PLM with the microelectrode array placed at 480,,m of the PLM. The analyte is transported by the carrier from the source solution to the strip solution. The originality of the new minicell is that accumulation in the strip solution is voltammetrically followed by the integrated microelectrode array in real time, and at low concentration level, using square-wave anodic stripping voltammetry (SWASV). In order to protect the Hg microelectrodes from the adsorption of the hydrophobic carrier, the microelectrodes are embedded in a thin gel layer (280,,m) of 1.5% LGL agarose gel containing 10% of hydrophobic silica particles C18. The choice of optimum conditions is discussed in details in this article. Due to the very small effective strip volume of the new cell (less than 1,,L), high enrichment factor can be obtained (e.g., 330 for Pb) after 2,hours of accumulation. No deaeration of the solutions is required for SWASV measurements. Detection limits under these conditions are 2,pM and 75,pM for Pb and Cd, respectively, using a voltammetric deposition time of 5,min. In addition, no fouling effects were observed with natural water samples. [source] Electrochemical Detection of Trace Concentrations of Cadmium and Lead with a Boron-Doped Diamond Electrode: Effect of KCl and KNO3 Electrolytes, Interferences and Measurement in River WaterELECTROANALYSIS, Issue 3 2004Carol Babyak Abstract Parts-per-billion levels of cadmium and lead were detected using square-wave anodic stripping voltammetry with a boron-doped diamond electrode. Calibration plots (10-minute deposition time) in KCl and KNO3 were non-linear at low concentrations (1,5,ppb) due to the deposition mechanism of these metals. The preferred electrolyte for cadmium was KCl, while lead could be measured in either electrolyte. The lowest concentrations included in the linear portion of the calibration plot (5,minute deposition time) for cadmium were 10,ppb and 50,ppb in KCl and KNO3, respectively, and 10,ppb for lead in KNO3. The presence of either lead or copper suppressed the cadmium stripping peak, but the lead stripping peak was unaffected by cadmium, and enhanced by the addition of copper. A river water sample was analyzed for cadmium and lead, and the cadmium results were confirmed using ICP-AES spectrometry. It was determined electrochemically that a fraction of lead in the river sample was bound by complexing material in the sample. [source] Fabrication of Density Gradients of Biodegradable Polymer Microparticles and Their Use in Guiding Neurite OutgrowthADVANCED FUNCTIONAL MATERIALS, Issue 10 2010Xiaoran Li Abstract A new method for generating both continuous and discrete density gradients in microparticles of biodegradable polymers via an electrospray technique is reported. The gradients are generated by spatially varying the deposition time of electrosprayed microparticles. The substrate coated with a density gradient of microparticles has varying surface roughness, offering a unique system for studying the effect of physical cues on neurite outgrowth from dorsal root ganglia. An optimal surface roughness for promoting neuron adhesion and neurite extension in vitro is obtained. Furthermore, this capability of approach is extended to generate a gradient of fluorescein isothiocyanate labeled bovine serum albumin by encapsulating it in the polymer microparticles in situ during electrospray. Taken together, this new class of substrates with gradients of microparticle density can potentially be used in various biomedical applications such as neural tissue engineering. [source] Carbon Nanotube Coatings on Bioglass-Based Tissue Engineering ScaffoldsADVANCED FUNCTIONAL MATERIALS, Issue 15 2007R. Boccaccini Abstract The coating of highly porous Bioglass® based 3D scaffolds with multi-walled carbon nanotubes (CNT) was investigated. Foam like Bioglass® scaffolds were fabricated by the replica technique and electrophoretic deposition was used to deposit homogeneous layers of CNT throughout the scaffold pore structure. The optimal experimental conditions were determined to be: applied voltage 15,V and deposition time 20 minutes, utilizing a concentrated aqueous suspension of CNT with addition of a surfactant and iodine. The scaffold pore structure remained invariant after the CNT coating, as assessed by SEM. The incorporation of CNTs induced a nanostructured internal surface of the pores which is thought to be beneficial for osteoblast cell attachment and proliferation. Bioactivity of the scaffolds was assessed by immersion studies in simulated body fluid (SBF) for periods of up to 2 weeks and the subsequent determination of hydroxyapatite (HA) formation. The presence of CNTs can enhance the bioactive behaviour of the scaffolds since CNTs can serve as template for the ordered formation of a nanostructured HA layers, which does not occur on uncoated Bioglass® surfaces. [source] A promising method for electrodeposition of aluminium on stainless steel in ionic liquidAICHE JOURNAL, Issue 3 2009Guikuan Yue Abstract A promising method for aluminium deposition was proposed by using AlCl3/[bmim]Cl (1-butyl-3-methylimidazolium chloride) ionic liquid as electrolyte. By using this novel method, the volatile and flammable organic solvent systems and the high corrosive inorganic molten salts with high temperature can be substituted, and the deposit microstructure can be easily adjusted by changing the current density, temperature and electrolyte composition. The study was performed by means of galvano-static electrolysis and the optimum operating conditions were determined based on the systematic studies of the effects of current density, temperature, molar ratio of AlCl3 to [bmim]Cl, stirring speed and deposition time on the quality of deposited coatings. The electrical conductivities of electrolytes were also investigated as a function of temperature (298,358 K) and molar ratio of AlCl3 to [bmim]Cl (from 0.1:1 to 2.0:1). Dense, bright and adherent aluminium coatings were obtained over a wide range of temperature (298,348 K), current densities (8,44 mA/cm2) and molar ratio (1.6:1,2.0:1). Results from the analysis of crystal structure show that all of the electrodeposits exhibit a preferred (200) crystallographic orientation. Temperature has significant influence on the crystallographic orientation and there does not appear to be an apparent impact of current density on it. Analyses of the chronoamperograms indicate that the deposition process of aluminium on stainless steel was controlled by three-dimension nucleation with diffusion-controlled growth and there is a conversion from progressive nucleation to instantaneous nucleation. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Kinetics of Electrophoretic Deposition for Nanocrystalline Zinc Oxide CoatingsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2004Yuan-Chung Wang An integrated process combining the preparation of ZnO nanoparticles and the formation of ZnO coatings using electrophoretic deposition (EPD) is reported. The work focuses on the deposition kinetics of nanocrystalline ZnO coatings on copper electrodes during EPD by direct measurement of the thickness of the deposited layer. The experimental results show that the EPD process is a powerful route to fabricate uniform coatings with desired thickness and excellent surface smoothness, which might be attributed to small particle size and narrow size distribution. On the other hand, the deposition kinetics changes with applied voltage and deposition time. The deposition thickness increases with increasing applied voltage and deposition time. In a short deposition time, the deviation of deposition rate between the theoretical and experimental values is caused by voltage drops during deposition, and the discrepancy increases with the applied voltage. Moreover, the increasing voltage drop and depletion of the suspension lead to decreasing current and lower deposition rate after longer deposition time. The critical transition time of deposition kinetics is found to exponentially decrease with increasing applied voltage. [source] Nanocrystalline Tin Oxide Thin Films via Liquid Flow DepositionJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2003Sitthisuntorn Supothina Nanocrystalline films of SnO2 were deposited by liquid flow deposition (LFD), i.e., by flowing aqueous solutions of SnCl4·5H2O and HCl over single-crystalline silicon substrates at 80°C. The substrates were either oxidized and fully hydrolyzed (bare silicon) or oxidized, hydrolyzed, and then coated with siloxy-anchored organic self-assembled monolayers (SAMs). Continuous, adherent films formed on sulfonate- and thioacetate-functionalized SAMs; adherent but sometimes discontinuous films formed on bare silicon and methyl-functionalized SAMs. The films contained equiaxed cassiterite crystals, ,4,10 nm in size. The film thickness increased linearly with deposition time. The maximum growth rate observed was 85 nm·h,1 on sulfonate SAM, and the maximum film thickness obtained was 1 ,m. A new dimensionless parameter, the normalized residence time, ,, was introduced for the purpose of interpreting the influence of solution conditions (i.e., degree of supersaturation, as controlled via pH, and tin concentration) and flow characteristics (flow rate and the configuration of the deposition chamber) on the growth rate in LFD processes. The results were consistent with a particle attachment mechanism for film growth and inconsistent with heterogeneous nucleation on the substrate. [source] Growth and electrical properties of ZnO films prepared by chemical bath deposition methodPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 4 2009Dewei Chu Abstract The influence of the choice of temperature, pH value, counter-ion, deposition time, and seed layer on the morphology as well as electrical properties of ZnO films grown from chemical bath deposition (CBD) are discussed. Consequently, oriented ZnO films with various microstructures can be synthesized by controlling the solution pH value and counter-ions. Besides, the point at which the seed layer is pre-heated at higher temperature is crucial and can lead to a significant difference in the width of crystals and electrical properties of ZnO films. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Two-step growth of InGaN quantum dots and application to light emittersPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2007T. Yamaguchi Abstract A two-step growth method for creating InGaN quantum dots (QDs) was developed by using a combination of an InxGa1,xN nucleation layer (NL) without island structures and an InyGa1,yN formation layer (FL) with an indium content lower than that of the InxGa1,xN NL. The realization of QDs was confirmed by micro-photoluminescence (,-PL) measurements only for the sample with both the InxGa1,xN NL and the InyGa1,yN FL. The spectral position of the QD ensemble recombination was controlled mainly by the deposition time of the InxGa1,xN NL. Green (,520 nm) and amber (,600 nm) LEDs with the QD layers grown by the two-step growth method as the active region were also fabricated and compared with that having InGaN QW layers, reported previously. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Optical effect of diamond-like carbon film coating of long-period optical fiber gratingsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2007M. Smietana Abstract The paper presents diamond-like carbon (DLC) film as a coating for long-period grating (LPG) optical fiber structure. The spectral response of a DLC-coated LPG structure is strictly dependent on Radio Frequency Plasma Chemical Vapour Deposition (RF PCVD) process parameters. The paper discusses the influence of DLC deposition time and self-bias voltage to shift of the LPG resonance peak and explores the possibility of using the structure as a refractometric sensor. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effect of Substrate Temperature and RF Biasing on the Optical Properties of Titania-Like Thin Films Obtained by Plasma Enhanced Chemical Vapor DepositionPLASMA PROCESSES AND POLYMERS, Issue S1 2009Axel Sonnenfeld Abstract A low pressure radio frequency (RF) discharge (200,W) was operated in argon/oxygen with small admixtures of titanium(IV)isopropoxide (TTIP). By regulating the cooling temperature of the RF driven electrode, the influence of the substrate temperature and of the ion bombardment caused by the negative DC self-bias of the RF electrode was investigated comparatively. Thin titania-like films were obtained and characterized with respect to their cut-off wavelength and their spectral absorption coefficient in the UV range. Accordingly, the cut-off wavelength was found to be higher for films obtained on the DC-self-biased electrode. Here, its value appears independent of the substrate temperature and attained successively its maximum at 340,nm with deposition time. Furthermore, the absorption coefficients of films deposited on the DC self-biased electrode are well superior to those obtained on the grounded substrate holder. [source] Deposition of SnO2:F Thin Films on Polycarbonate Substrates by PECVD for Antifouling PropertiesPLASMA PROCESSES AND POLYMERS, Issue S1 2007Marie Jubault Abstract SnO2:F thin films were deposited on polycarbonate and glass substrates by RF capacitively coupled plasma enhanced chemical vapor deposition (PECVD) using a mixture of tetramethyltin (TMT) [Sn(CH3)4], argon, oxygen as precursors. The effects of the substrate temperature, deposition time and doping on the resistivity and the morphology of the films have been studied. The as-deposited films appear to have higher carrier mobilities than amorphous ones, in the range of 5 and 7.5 cm2,·,V,1,·,s,1, which could be explained by the presence of nanocrystallites. In order to understand the nanostructure of the films, we studied the formation of nanoparticles and dust particles in the discharge. Finally, we have shown that the incorporation of less than 3% of F in the tin oxide layer could decrease the resistivity down to 3,·,10,3 ,,·,cm. [source] Immersion Deposition of Pt Nanoparticles on Porous Silicon for Methanol OxidationCHINESE JOURNAL OF CHEMISTRY, Issue 9 2009Xu Su Abstract Porous silicon (PS) was chosen as the substrate for supporting the Pt particles because of great surface area, good conductivity and stability. Pt nanoparticles have been successfully prepared on the substrate by immersion deposition, which is convenient. The component and morphological properties of the films have been investigated by means of X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM), which shows that the Pt particles have small size and big specific surface. Cyclic voltammetry (CV) research showed that the Pt nanoparticles had novel catalytic activity for methanol when the immersion deposition time was past 24 min. [source] Iridium Oxide Film-Enhanced Impedance Immunosensor for Rapid Detection of Carcinoembyronic AntigenCHINESE JOURNAL OF CHEMISTRY, Issue 9 2007Yan-Jun Ding Abstract A simple, rapid and sensitive impedance immunosensor based on iridium oxide (IrOx) thin film for the detection of carcinoembyronic antigen (CEA) in human sera has been proposed. Gold electrode was electrochemically modified with IrOx thin film and simultaneously functionalized with protein A (PA) to bind anti-CEA antibodies in an orientated way. It has been found that the antibody loading amount was dependent on the PA concentration and the deposition time of IrOx matrix. Under the optimized experimental conditions, the electron transfer resistances obtained were linearly related to the CEA concentration ranging from 36.2 to 460.0 ng/mL, with a detection limit of 28.0 ng/mL. Analytical results of clinical samples from cancer patients show that the proposed immunoassay is reasonably comparable with the chemiluminescence immunoassay (CLIA), indicating the feasibility of using the proposed method for CEA immunoassay in clinical laboratory. [source] Screen Printed Electrodes and Screen Printed Modified Electrodes Benefit from InsonationELECTROANALYSIS, Issue 9 2006Biljana, ljuki Abstract The synergy of power ultrasound with screen printed electrodes and screen printed modified electrodes is shown to be possible and beneficial. Proof-of-concept is shown for the anodic stripping voltammetry of lead at screen printed electrodes and screen printed calomel modified electrodes offering shorter deposition times and increased sensitivity. [source] Catalytic Effect on Silver Electrodeposition of Gold Deposited on Carbon ElectrodesELECTROANALYSIS, Issue 19 2004Alfredo de, Escosura-Muñiz Abstract A new methodology, based on silver electrocatalytic deposition and designed to quantify gold deposited onto carbon paste electrode (CPE) and glassy carbon electrode (GCE), has been developed in this work. Silver (prepared in 1.0,M NH3) electrodeposition at ,0.13,V occurs only when gold is previously deposited at an adequate potential on the electrode surface for a fixed period of time. When a CPE is used as working electrode, an adequate oxidation of gold is necessary. This oxidation is carried out in both 0.1,M NaOH and 0.1,M H2SO4 at oxidation potentials. When a GCE is used as working electrode, the oxidation steps are not necessary. Moreover, a cleaning step in KCN, which removes gold from electrode surface, is included. To obtain reproducibility in the analytical signal, the surface of the electrodes must be suitably pretreated; this electrodic pretreatment depends on the kind of electrode used as working electrode. Low detection limits (5.0×10,10,M) for short gold deposition times (10,min for CPE and 5,min for GCE) were achieved with this novel methodology. Finally, sodium aurothiomalate can be quantified using silver electrocatalytic deposition and GCE as working electrode. Good linear relationship between silver anodic stripping peak and aurothiomalate concentration was found from 5.0×10,10,M to 1.0×10,8,M. [source] A Study of the Determination of Cu(II) by Anodic Stripping Voltammetry on a Novel Nylon/Carbon Fiber ElectrodeELECTROANALYSIS, Issue 7 2004A. Mylonakis Abstract In this work we report a new electrode material formed by injection-moulding of a conducting polymer consisting of carbon fibers in a Nylon matrix. This material is highly conductive, inexpensive, easy to mould in different shapes and requires minimal pretreatment. The electrode was tested as a mercury-free sensor for the trace determination of Cu(II) by anodic stripping voltammetry (ASV). The deposition and stripping behavior of copper on the conducting material was initially studied by cyclic voltammetry and the chemical and instrumental parameters of the determination were investigated. The electrode has been shown to be suitable for the determination of Cu(II) in the range 8,,g L,1 to 30,mg,L,1 (with deposition times ranging from 30,s to 10,min) with a relative standard deviation of 2.2% (at the 0.5,mg,L,1 level) and a limit of detection of 8,,g L,1 Cu(II) for 10,min of accumulation (at a S/N ratio of 5). The electrode was, finally, applied to the determination of copper in tap-water, pharmaceutical tablets and bovine serum with recoveries of 97.4, 94.9 and 93.4%, respectively [source] Electrodeposition of Thermoelectric Superlattice Nanowires,ADVANCED MATERIALS, Issue 2 2007B. Yoo Bi2Te3/(Bi0.3Sb0.7)2Te3superlattice thermoelectric nanowires are synthesized by using a template-directed electrodeposition method. Adjustment of the deposition times and potentials enables precise control over the composition and length of each segment of the nanowires. Characterization of the superlattice nanowires by, amongst others, energy dispersive X-ray analysis (see figure) reveals their periodically varying structure. [source] Structural Characterization of Cobalt Thin Films Grown by Metal-Organic CVD,CHEMICAL VAPOR DEPOSITION, Issue 5 2005F. Chioncel Abstract Cobalt thin films were produced by metal-organic CVD from C5H5Co(CO)2, at various temperatures and for various deposition times. The films have been grown onto glass substrates with no buffer. The crystalline structure, morphology, and composition of the films were analyzed by X-ray diffractometry (XRD), field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and Auger electron spectroscopy (AES). Routine XRD patterns were collected in symmetric geometry for phase identification and the sin2, diffraction technique was employed to calculate the average in-plane stress. Structural studies indicate that the films tend to grow in island mode, as predicted by theory, and have a structure between that of face-centered cubic (fcc) and hexagonal close-packed (hcp) cobalt. There is significant in-plane tensile stress at the interface with the substrate, which relaxes to a compressive stress an order of magnitude lower at the surface. The films have a relatively low impurity content, as determined by AES, except near the surface. [source] | ||||||||||||||||