The role of substrates on the structural,optical, and morphological properties of zno nanotubes prepared by spray pyrolysis

ZnO films were deposited onto glass, ITO coated glass, and sapphire substrate by spray pyrolysis, and subsequently annealed at the same temperature of 400°C for 3 h. The role of substrate on the properties of ZnO films was investigated. The structural and optical properties of the films were investigated by X‐ray diffractometer (XRD) and photoluminescence (PL) spectrophotometer, respectively. The surface morphology of the nanostructured ZnO film was investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Crystallographic properties revealed that the ZnO films deposited on sapphire and ITO substrates exhibit a strong c‐axis orientation of grains with hexagonal wurtzite structure. Extremely high UV emission intensity was determined in the film on ITO. The different luminescence behaviors was discussed, which would be caused by least value of strain in the film. Films grown on different substrates revealed differences in the morphology. ZnO films on ITO and sapphire substrates revealed better morphology than that of the film on glass. AFM images of the films prepared on ITO show uniform distribution of grains with large surface roughness, suitable for application in dye sensitized solar cells. Microsc. Res. Tech. 77:211–215, 2014. © 2013 Wiley Periodicals, Inc.     

Microstructure of MmM(5)/Mg multi-layer hydrogen storage films prepared by magnetron sputtering

Multi-layer hydrogen storage thin films with Mg and MmNi3.5(CoAlMn)1.5 (here Mm denotes La-rich mischmetal) as alternative layers were prepared by direct current magnetron sputtering. Transmission electron microscopy investigation shows that the microstructure of the MmNi3.5(CoAlMn)1.5 and Mg layers are significantly different although their deposition conditions are the same. The MmNi3.5(CoAlMn)1.5 layer is composed of two regions: one is an amorphous region approximately 4 nm thick at the bottom of the layer and the other is a nanocrystalline region on top of the amorphous region. The Mg layer is also composed of two regions: one is a randomly orientated nanocrystalline region 50 nm thick at the bottom of the layer and the other is a columnar crystallite region on top of the nanocrystalline region. These Mg columnar crystallites have their [001] directions parallel to the growth direction and the average lateral size of these columnar crystallites is about 100 nm. A growth mechanism of the multi-layer thin films is discussed based on the experiment results.     

Adhesion and friction properties of hydrogenated amorphous carbon films measured by atomic force microscopy

Atomic force microscopy has been used to measure adhesion and friction forces at the interface between an oxidized metal probe tip and amorphous carbon films of varying hydrogen contents (12.3–39.0 atomic percent hydrogen). The interface of an oxide surface and a hard carbon coating models the unlubricated head-disk interface of current hard disk products. Adhesion forces normalized by the radius of curvature of the contacting tip range from 1.09 to 8.53 N/m. Coefficients of friction values, measured as the slope of the friction versus load plot, range from 0.33 to 0.87. A trend of increasing adhesion forces and coefficients of friction is observed for increasing hydrogen content in the films. We attribute the increase in adhesion and friction to increases in the surface free energy of the carbon films with the incorporation of hydrogen.     

Micromorphology analysis of TiO2 thin films by atomic force microscopy images: The influence of postannealing

This work describes an analysis of titanium dioxide (TiO₂) thin films prepared on silicon substrates by direct current (DC) planar magnetron sputtering system in O₂/Ar atmosphere in correlation with three‐dimensional (3D) surface characterization using atomic force microscopy (AFM). The samples were grown at temperatures 200, 300, and 400°C on silicon substrate using the same deposition time (30 min) and were distributed into four groups: Group I (as‐deposited samples), Group II (samples annealed at 200°C), Group III (samples annealed at 300°C), and Group IV (samples annealed at 400°C). AFM images with a size of 0.95 μm × 0.95 μm were recorded with a scanning resolution of 256 × 256 pixels. Stereometric analysis was carried out on the basis of AFM data, and the surface topography was described according to ISO 25178‐2:2012 and American Society of Mechanical Engineers (ASME) B46.1‐2009 standards. The maximum and minimum root mean square roughnesses were observed in surfaces of Group II (Sq = 7.96 ± 0.1 nm) and Group IV (Sq = 3.87 ± 0.1 nm), respectively.     

Differences in the nanoscale electrical properties of GaN films grown on sapphire and ZnO substrates by molecular beam epitaxy

Gallium nitride (GaN) films were grown on sapphire and zinc oxide (ZnO) single crystal substrates using plasma‐assisted molecular beam epitaxy. As ZnO for GaN have a better lattice match, the coverage ratio of the GaN (002) plane on the ZnO substrate was significantly higher by about 45%. According to conducting atomic force microscopy and scanning surface potential microscopy measurements, the surface of GaN films grown on the ZnO substrate had two excellent physical characteristics: (a) an 18% reduction of the high contact current region, and (b) a highly uniform work function distribution. Therefore, for future applications in GaN‐based light‐emitting diodes, the use of ZnO as a substrate will prolong the luminescence lifetime and enhance the luminescent monochromaticity.     

A scanning conduction microscopic method for probing abrasion of insulating thin films

The use of scanning force microscopy (SFM) to probe wear processes at interfaces is of considerable interest. We present here a simple modification of the SFM which allows us to make highly spatially resolved measurements of conductivity changes produced by abrasion of thin insulating films on metal substrates. The technique is demonstrated on fluorocarbon polymer thin films deposited on stainless steel substrates.     

Measurement of edge verticality of optical recording bits on blu‐ray discs using scanning probe microscopy

This work investigates recording bits on recordable and rewritable blu‐ray discs using atomic force microscopy and conducting atomic force microscopy with high contrast, respectively. The geometric structure of the recording bits is clearly observed in images, which, when coupled with cross‐section analysis, yields precise bit dimensions, and edge horizontal extended length values. The microscopic results are a valuable reference for increasing the recognition rate of digital signals in optical storage media. Furthermore, such a rapid and convenient measuring mode is an indispensable research tool for developing new recording materials and improving formation mechanisms. Microsc. Res. Tech., 2009. © 2009 Wiley‐Liss, Inc.     

Topography and nanomechanical properties of tribochemical films derived from zinc dialkyl and diaryl dithiophosphates

In this paper we present recent results from an on‐going effort to characterize the nanomechanical properties of a variety of tribochemical, antiwear films through the use of modern scanning probe techniques. The two types of antiwear wear films studied, derived from zinc dialkyl dithiophosphate (alkyl ZDDP) and zinc diaryl dithiophosphate (aryl ZDDP), were chosen because they possess significantly different wear characteristics. High resolution AFM topographic images showed significant differences between the two types of films. More interestingly, high resolution imaging and quantitative mechanical properties testing using the interfacial force microscope (IFM), revealed different elastic and plastic properties between the two types of films; in addition each type of film possessed several distinct regions with respect to mechanical properties. The maximum values for elastic modulus and hardness were located on the highly loaded regions of the alkyl ZDDP films which exhibited the best tribological performance. In contrast, the aryl ZDDP films, which exhibited poorer antiwear behaviour, were devoid of such resilient regions. Our results correlate the macroscopic wear behavior of the tribochemical films to differences in the mechanical properties on a nanometer scale. This revised version was published online in July 2006 with corrections to the Cover Date.     

Structural investigations on green culms and charcoal of Bambusa multiplex

Green culms of Bambusa multiplex and the bamboo charcoal carbonized from the green culms at 700°C have been studied by means of X‐ray diffraction, X‐ray fluorescent element analysis, analytical scanning electron microscopy, and analytical scanning transmission electron microscopy (STEM), aiming at industrial applications as raw materials for functional devices and substances. It is revealed that the green culms and the charcoal contain a significant amount of Si, in particular, ～18 wt % in the skin. The green culms comprise amorphous and crystalline celluloses. The charcoal has a so‐called amorphous structure which is composed of randomly distributed carbon nanotubes and fibers. The growth of Ag‐doped activated charcoal powders that were produced by two different methods using this charcoal powder has also been studied.     

Study of cellular architecture and micromechanical properties of cuajilote fruits (Parmentiera edulis D.C.) using different microscopy techniques

The cuajilote (Parmentiera edulis D.C.) tree produces fibrous fruits with a high content of lignocellulosic compounds. However, this fruit and their fibers have been scarcely studied. For this reason, an integral study of their cellular architecture, physicochemical, micromechanical, and structural properties in two maturity stages were carried out. Physicochemical tests, light, confocal and electron microscopy, microindentation, and X‐ray diffraction were used for the characterization of fruit and their fibers. Chemical analysis showed that the unripe fruits have the highest cellulose content (42.17%), but in ripe fruit the cellulose content decreases (32.76%) while lignin content increases from 35.26 to 40.79%, caused by the lignification of the sclerenchyma fibers. Microstructural and micromechanical studies in the different regions of the fruit provided relevant information about its cellular architecture, distribution of lignocellulosic compounds and its role in the micromechanical properties of their fibers. The thickening cell wall of sclerenchyma fibers was caused by the cellular lignification of the ripe fruits. According to the physicochemical and structural studies, cuajilote fibers are comparable to other fibers obtained from crops rich in lignocellulosic compounds. The current study provided new knowledge about the cellular architecture of fruit and criteria for selecting the ripening stage adequate for the extraction of cellulose or lignin. Furthermore, information regarding the micromechanical properties of their fibers and which structural arrangement could be more convenient for mechanical reinforcement of biodegradable materials was obtained.     

Effect of in‐office bleaching agents on the surface roughness and morphology of different dental composites: An AFM study

The aim of this study was to evaluate, using atomic force microscopy, the effect of two different bleaching agents on the modification of dental composites materials. This modification will be judged by analyzing the variation of surface roughness and surface morphology of two different composites: one containing nanoparticles and other consisting of microhybrid resin. The bleaching was performed by using two different concentrations of hydrogen peroxide: HP Blue (20% hydrogen peroxide) and Whiteness HP Maxx (35% hydrogen peroxide). Disks of Esthet X and Filtek? Z350 composites were used. Atomic force microscopy was used for analyses of the same place of the sample before and after treatment. A total of 12 analyses were performed per group (n = 12). The samples were analyzed qualitatively by evaluating morphological changes in the images and quantitatively by using roughness parameters (Ra). Data were analyzed statistically using Kruskal–Wallis, Mann–Whitney, and Friedman tests (P < 0.05). Changes were observed both qualitatively and quantitatively only in the groups where Esthet X resin was used. The use of hydrogen peroxide bleaching agents caused changes only in the surface of microhybrid composites, with no changes being observed in the composite containing nanoparticles. Despite being even significant, these alterations are clinically slight and can be eliminated by polishing them. Microsc. Res. Tech. 76:481–485, 2013. © 2013 Wiley Periodicals, Inc.     

薄膜厚度对直流脉冲磁控溅射Mo薄膜光电性能的影响

采用直流脉冲磁控溅射方法在SLG衬底上沉积CIGS太阳电池背接触Mo薄膜,研究了薄膜的光学和电学性能随厚度的变化关系。结果表明,随着薄膜厚度的增加,薄膜的电阻率先降低后增加,在厚度284.3nm处电阻率最低,为7.3×10-4Ω.cm。不同厚度的Mo薄膜在各个波长处(200~840nm)反射率都随波长的增加而增大。随着薄膜厚度的增加,平均反射率总的呈下降趋势,在薄膜厚度284.3nm时出现一反射率高峰,其在200~840nm波长范围内的平均反射率达43.33%。     

柔性衬底直流磁控溅射ZnO基高性能透明导电薄膜的制备及性能研究

采用直流磁控溅射法,以柔性PET(聚对苯二甲酸乙二醇酯)为基底,通过参数优化以求在室温下制备高性能ZnO/Ag/ZnO多层薄膜。实验中,使用X射线衍射仪(XRD)、原子力显微镜(AFM)、紫外-可见分光光度计、四探针电阻测试仪等仪器分别对ZnO/Ag/ZnO多层薄膜的微观结构、表面形貌、透过率及方块电阻进行测试及表征。结果表明,随着Ag层厚度增加,薄膜方块电阻急剧下降,通过改变ZnO层厚度,可有效调节薄膜光学性能,随着ZnO层厚度增加,可见光区平均透过率先增大后减小。引入品质因子FTC作为评价指标可知,当依次沉积ZnO、Ag、ZnO厚度为50nm、8nm、50nm时,薄膜光电性能最佳,其在可见光平均透过率为82.3%、方块电阻为2.8Ω/、禁带宽度为3.332eV。     

Atomic force microscopy and energy dispersive X‐ray spectrophotometry analysis of reciprocating and continuous rotary nickel‐titanium instruments following root canal retreatment

The aim was to examine the effect of retreatment process on the surface roughness and nickel titanium (NiTi) composition of ProTaper Universal Retreatment (PTUR; consists of 3 files; D1, D2, D3) and WaveOne Gold (WOG) (primary) instruments. Twenty extracted mandibular molar teeth with severe curved (30–40°) mesial roots were selected and divided into two groups (n = 10) based on the instrument used for the removal of the root canal filling. Before and after using the instruments in two canals, they were subjected to atomic force microscopy (AFM) and energy dispersive X‐ray spectrophotometry (EDX) analysis. The EDX analysis data and roughness average (Ra) and root mean square (RMS) values were analyzed statistically using a one‐way analysis of variance and post hoc Tukey's test at the 5% significant level. There was no significant difference between the new and used D1 and D2 PTUR and WOG instruments in terms of the Ni composition (p > .05). The Ti contents of the used D2 and D3 PTUR instruments were lower those of the new instruments (p < .05). In both new and used instruments, PTUR and WOG have no difference in terms of Ra and RMS values. (p > .05). The Ra and RMS values of the PTUR and WOG systems significantly increased after removal of the root canal filling (p < .05). The use of PTUR and WOG instruments for removal of root canal filling in severely curved root canals affected the surface topography of the files. The NiTi composition of the WOG instruments was unaffected by the retreatment process.     

Erosion effects on chemical composition and morphology of dental materials and root dentin

Purpose: This work aims to study the erosion on restorative materials and on surrounding dentin. Fifty root dentin samples were obtained from bovine incisors. Methods: Twenty samples were not restored and thirty received cavity preparations. Samples were assigned to five groups: G1, G2: sound dentin (D); G3: composite resin (CR); G4: resin‐modified glass‐ionomer cement (RMGIC); G5: glass‐ionomer cement (GIC). The samples of groups 2–5 were submitted to six cycles (demineralization–remineralization). Samples were analyzed by micro energy‐dispersive X‐ray fluorescence spectrometry (μ‐EDXRF) and by scanning electron microscopy (SEM). Results: Mineral loss was greater in G2 samples than in RMGI > CR > GIC > D (control). SEM images showed pronounced dentin demineralization in groups 2 and 4. The acid erosion has a significant effect on mineral loss (Ca and P) of root dentin without restoration. Conclusions: Composite resin had the best chemical resistance to erosion among all the materials. Fluoride contained in GIC seemed to cause some protection, however, with material degradation. Chemical interaction of tooth‐colored dental materials with root dentin could be assessed by μ‐EDXRF. Microsc. Res. Tech. 75:703–710, 2012. © 2011 Wiley Periodicals, Inc.     

Effects of film thickness and contact load on nanotribological properties of sputtered amorphous carbon thin films

The nanotribological properties of amorphous carbon (a-C) films of thickness in the range of 5-85 nm sputtered on Si(1 0 0) substrates were investigated with a surface force microscope (SFM), using a Berkovich diamond tip of nominal radius of curvature approximately equal to 200 nm and contact (normal) loads between 10 and 1200 μN. The dependence of the friction and wear behaviors of the a-C films on normal load and film thickness was studied in terms of nanomechanical properties, images of scratched surfaces, and numerical results obtained from a previous analytical friction model. The increase of the contact load caused the coefficient of friction to decrease initially to a minimum value and, subsequently, to increase to a maximum value, after which, it either remained constant or decreased slightly. The dominant friction mechanism in the low-load range was adhesion, while both adhesion and plowing mechanisms contributed to the friction behavior in the intermediate- and high-load ranges. Thinner (thicker) a-C films yielded higher (lower) friction coefficients for normal loads less than 50 μN (low-load range) and lower (higher) friction coefficients for normal loads greater than 150 μN (high-load range). Elastic and plastic deformation, microcracking, and delamination of the a-C films occurred, depending on the contact load and film thickness ranges. The reduced load-carrying capacity, relatively low effective hardness (strength) obtained with thinner films, and dominant friction and wear mechanisms at each load range illustrate the film thickness and contact load dependence of the nanotribological properties of the sputtered a-C films.     

Topography of four different endodontic rotary systems, before and after being used for the 12th time

Root canal preparation may damage NiTi instruments resulting in wear and deformation. The aim of this study was to make a comparative evaluation of the surface topography of the cervical third of four different rotary systems, before and after being used twelve times, in 1.440 resin blocks with simulated root canals with standardized 45° curvatures, and analyzed by atomic force microscopy &#150; AFM. The blocks were divided into four groups and prepared according to the manufacturers recommendations: Group 1 ‐ K3®; Group 2 ‐ Protaper Universal®; Group 3 ‐ Twisted Files® and Group 4 ‐ Biorace®. After each preparation, the instruments were washed and autoclaved. A total of 240 instruments were selected, being 30 new instruments and 30 after having been used for the 12th time, from each group. These instruments were analyzed by AFM and for quantitative evaluation, the mean RMS (Root mean square) values of the cervical third of the specimens from the four groups were used. The result showed that all the rotary files used for the 12th time suffered wear with change in the topography of the cervical region of the active portion of the file (ANOVA p < 0.01). Classifying the specimens in increasing order, from the least to the greatest wear suffered, Group 3 (2.8993 nm) presented the least wear, followed by Group 4 (12.2520 nm), Group 1 (36.0043 nm) and lastly, Group 2 (59.8750 nm) with the largest amount of cervical surface wear. Microsc. Res. Tech., 2012. © 2011 Wiley Periodicals, Inc.     

Influence of ethyl acetate and alkyl phosphate adsorption on the frictional properties of VC(100)

This report presents ultrahigh vacuum measurements of the frictional properties of the non-polar (100) surface of vanadium carbide (VC) as a function of the room temperature uptake and reaction of ethyl acetate, triethyl phosphate, and trimethyl phosphate. Atomic force microscopy, employing a silicon nitride probe tip, has been used to determine the changes in friction and interfacial adhesion as a function of adsorbate uptake. Changes in surface morphology have been monitored with scanning tunneling microscopy while the composition of the surface species formed through the reaction of these adsorbates with the VC surface has been determined by X-ray photoelectron spectroscopy. Adsorption and reaction of ethyl acetate leads to an increase in friction with little change in interfacial adhesion. The adsorption and reaction of triethyl phosphate and trimethyl phosphate have no influence on either the friction or adhesion properties of VC. The observed results are discussed in terms of the surface chemical composition, the extent of surface coverage, and the molecular details of the adsorbed species.     

Effects of atopic dermatitis on the morphology and water content of scalp hair

The effects of atopic dermatitis (AD) on scalp hair properties, such as morphology and water content, were investigated using atomic force microscopy (AFM) and thermogravimetric analyzer. Hairs from lesional and nonlesional scalp regions of eight patients with AD were investigated. The severity of the disease, which was evaluated using the SCORing Atopic Dermatitis index, was 48.75 (range, 40-80). Hairs from 15 normal adults were also examined as controls. The surface images were taken in an area of 20 × 20 μm(2) with 512 × 512 pixels and a scan speed of 0.8 line/s. AD affected the cuticle structures and scales of scalp hair. The edges of cuticles were torn and collapsed, and the scales were very thick. The water contents of both types of AD hair were less than the control: 12% ± 0.7%, 11.7% ± 0.4%, and 13% ± 0.8% for lesional AD hair, nonlesional AD hair, and control hair, respectively. The scalp hair of patients with AD can be characterized by thick and globular scale patterns. The hair of patients with AD has less water content than normal hair showing a good agreement with the property of skin having AD.     

基底温度对YbF3薄膜缺陷和光学性能影响研究

采用热蒸发法镀制了单层Y bF3薄膜,观察了薄膜表面主要的微观结构缺陷,研究了沉积温度对薄膜折射率与表面缺陷的影响,测量了薄膜施加沉积温度前后的粗糙度变化。结果表明:通过加温可以降低薄膜的表面粗糙度与缺陷密度大小。