Control of epitaxial relationships of ZnO/SrTiO3 heterointerfaces by etching the substrate surface

In this work, the thermal expansion properties of carbon nanotube (CNT)-reinforced nanocomposites with CNT content ranging from 1 to 15 wt% were evaluated using a multi-scale numerical approach, in which the effects of two parameters, i.e., temperature and CNT content, were investigated extensively. For all CNT contents, the obtained results clearly revealed that within a wide low-temperature range (30°C ~ 62°C), thermal contraction is observed, while thermal expansion occurs in a high-temperature range (62°C ~ 120°C). It was found that at any specified CNT content, the thermal expansion properties vary with temperature - as temperature increases, the thermal expansion rate increases linearly. However, at a specified temperature, the absolute value of the thermal expansion rate decreases nonlinearly as the CNT content increases. Moreover, the results provided by the present multi-scale numerical model were in good agreement with those obtained from the corresponding theoretical analyses and experimental measurements in this work, which indicates that this multi-scale numerical approach provides a powerful tool to evaluate the thermal expansion properties of any type of CNT/polymer nanocomposites and therefore promotes the understanding on the thermal behaviors of CNT/polymer nanocomposites for their applications in temperature sensors, nanoelectronics devices, etc.     

Chemically attaching polyhydroxyethylmethacrylate brush on substrate surface,derivation, and the role in differential etching

This article reports the preparation and derivation of chemically tethered polyhydroxyethylmethacrylate (PHEMA) brush and its application in microfabrication. PHEMA brush was prepared by the surface‐initiated atomic transfer radical polymerization and derived by either organic reaction or sequence polymerization. The differential etching process was studied by atomic force microscope (AFM) and optical micrograph. PHEMA brush cannot prevent the underlying gold from dissolving in aqueous etchant KI/I₂ solution. Differential etching of UV‐patterned PHEMA template resulted in metal (gold) rings. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

化学刻蚀法制备黄铜基超疏水表面

采用含有三氯化铁和盐酸的水溶液刻蚀金属黄铜表面，在黄铜表面上得到了一层由不规则块状结构和更细小的乳突状结构相结合的具有双重粗糙度的阶层结构。该表面经氟化处理后表现出超疏水性，水在该表面上的接触角达到了157°，接触角滞后为5°。考察了不同刻蚀时间对表面疏水性的影响，结果表明，刻蚀时间对表面上这种阶层结构的形成和水滴在表面上的接触角数据都有十分重要的影响。随着刻蚀时间的增加，表面上逐渐开始形成粗糙结构，接触角数据也不断增加，增加到一定数值后，接触角变化开始不明显。接触角滞后随着接触角的增加而减小。初步分析了这种阶层结构的形成机制，并用Cassie理论对表面的润湿性进行了分析。     

Maskless micro/nanofabrication on GaAs surface by friction-induced selective etching

In the present study, a friction-induced selective etching method was developed to produce nanostructures on GaAs surface. Without any resist mask, the nanofabrication can be achieved by scratching and post-etching in sulfuric acid solution. The effects of the applied normal load and etching period on the formation of the nanostructure were studied. Results showed that the height of the nanostructure increased with the normal load or the etching period. XPS and Raman detection demonstrated that residual compressive stress and lattice densification were probably the main reason for selective etching, which eventually led to the protrusive nanostructures from the scratched area on the GaAs surface. Through a homemade multi-probe instrument, the capability of this fabrication method was demonstrated by producing various nanostructures on the GaAs surface, such as linear array, intersecting parallel, surface mesas, and special letters. In summary, the proposed method provided a straightforward and more maneuverable micro/nanofabrication method on the GaAs surface.     

Triangle pore arrays fabricated on Si (111) substrate by sphere lithography combined with metal-assisted chemical etching and anisotropic chemical etching

ABSTRACT: The morphological change of silicon macropore arrays formed by metal-assisted chemical etching using shape-controlled Au thin film arrays was investigated during anisotropic chemical etching in tetramethylammonium hydroxide (TMAH) aqueous solution. After the deposition of Au as the etching catalyst on (111) silicon through a honeycomb mask prepared by sphere lithography, the specimens were etched in a mixed solution of HF and H2O2 at room temperature, resulting in the formation of ordered macropores in silicon along the [111] direction, which is not achievable by conventional chemical etching without a catalyst. In the anisotropic etching in TMAH, the macropores changed from being circular to being hexagonal and finally to being triangular owing to the difference in etching rate between the crystal planes.     

Hydrogen activation of spectroscopic graphite surface by argon plasma etching

Argon plasma bombardment was successfully used for the hydrogen activation of spectroscopic graphite electrodes. The hydrogen evolution reaction (HER) in 1m KOH was investigated using electrochemical techniques such as galvanostatic polarization and a.c. impedence spectroscopy; the electrode surface was characterized by SEM. It is shown that the rate of HER at a given hydrogen overpotential value increases exponentially with the etching time (ET), up to ETs of 30min, and slightly decreases from 30 to 60min. The double-layer capacity (Cdl) was established against the hydrogen overpotential for different ETs, with Cdl reaching its maximum for ETs of 30min. Moreover, it is shown that the etching process also leads to a significant increase in intrinsic activity toward HER.     

Visualization and functions of surface defects on carbon nanotubes created by catalytic etching

Surface defects were created on carbon nanotubes (CNTs) by catalytic steam gasification or catalytic etching with iron as catalysts. The structure and morphology of the etched CNTs were studied by transmission electron microscopy (TEM) and scanning tunneling microscopy (STM). The electronic structure of the etched CNTs was investigated by ultraviolet photoelectron spectroscopy (UPS). The etched CNTs were treated by nitric acid to obtain oxygen-containing functional groups. The amount and the thermal stability of these groups were studied by temperature-resolved X-ray photoelectron spectroscopy (XPS). Temperature-programmed desorption with ammonia as a probe molecule (NH₃-TPD) was employed to investigate the interaction of the surface defects with foreign molecules in gas phase. TEM and STM studies disclosed the presence of surface defects especially edge planes on the etched CNTs. Etching of CNTs led to a less pronounced p-π band than the as-is CNTs, as evidenced by UPS studies. The XPS and NH₃-TPD studies demonstrated that the defects on the CNTs enhanced the reactivity of the exposed surfaces allowing obtaining a higher degree of oxygen functionalization and more active adsorption sites.     

Optimized route for the production of zirconia structures with controlled surface porosity for biomedical applications

Zirconia structures with controlled surface porosity may be used in several biomedical and engineering applications. This work aimed at developing a processing route for the production of zirconia structures with porous surfaces, using the dip coating method and without pore forming additives. Zirconia powders (~ 40?µm diameter) were used in the dip coating suspensions in three different forms: agglomerates (as received), pre-sintered (1150?°C, 1?h) and sintered (1500?°C, 2?h). The addition of fine particles (< 10?µm diameter) to the suspensions, in different contents, were tested to act as binder for the larger particles. Zirconia disk-shape compacts were dipped in the different suspensions and sintered. Pre-sintered powders were found to be the most adequate for producing the porous surface. The optimized binder content was determined as a function of the porous layer strength. A feasible route could be successfully established for the production of zirconia structures with porous surface.     

辊式涂布法构建纸基牢固超疏水表面

采用辊式涂布的方法在纸基材料上构建超疏水表面,并对超疏水表面的牢固性、自清洁性和疏水性能进行评价。用γ-氨丙基三乙氧基硅烷和1H,1H,2H,2H-全氟辛基三乙氧基硅烷（POTS）对微米级和纳米级两种尺寸的TiO₂粒子进行疏水改性处理,然后将改性后的微/纳米TiO₂涂布在纸基材料表面。采用红外光谱（FTIR）对改性后的微/纳米TiO₂的化学组成进行了分析,采用扫描电镜（SEM）对涂布纸表面结构进行了表征,通过接触角、耐磨性和自洁净测试评价了涂层表面的超疏水性、牢固性和自清洁性。改性TiO₂的FTIR分析显示在1000～1500cm^-1之间出现多个C—F键的伸缩振动峰,表明POTS通过化学键与TiO₂表面发生了结合。涂布纸表面的SEM分析可以看出,纸基材料表面上均匀分布了微米和纳米尺寸的TiO₂颗粒,具备了类似荷叶表面微-纳结构的粗糙表面。涂层表面的水接触角为153°±1.5°,滚动角为3.5°±0.5°,水滴在涂层表面呈球形,极易滑落,涂层在水中浸泡7天后,接触角没有发生明显变化,表明纸张表面具备了优异的超疏水性能,且疏水稳定性较好。涂层表面经过10次循环磨损试验后,接触角仍能达到150°,滚动角为9°,表明机械摩擦没有对涂布纸表面的化学成分和粗糙结构造成明显的破坏,超疏水表面的牢固性较好。自洁净测试表明,涂布纸表面具有良好的自清洁和防污性能。该工艺过程操作简单,易于实现工业化生产,为在纸基表面构建综合性能优异的超疏水表面提供了一种新的便利途径。     

Antireflective grassy surface on glass substrates with self-masked dry etching

Although recently developed bio-inspired nanostructures exhibit superior optic performance, their practical applications are limited due to cost issues. We present highly transparent glasses with grassy surface fabricated with self-masked dry etch process. Simultaneously generated nanoclusters during reactive ion etch process with simple gas mixture (i.e., CF₄/O₂) enables lithography-free, one-step nanostructure fabrication. The resulting grassy surfaces, composed of tapered subwavelength structures, exhibit antireflective (AR) properties in 300 to 1,800-nm wavelength ranges as well as improved hydrophilicity for antifogging. Rigorous coupled-wave analysis calculation provides design guidelines for AR surface on glass substrates.     

Properties of GaN-based light-emitting diodes on patterned sapphire substrate coated with silver nanoparticles prepared by mask-free chemical etching

This study reports on the use of a template that is made of silver nanoparticles (ANPs) that are dispersed on a patterned sapphire substrate (PSS) to improve the light output power of GaN-based light-emitting diodes (LEDs). The dipping of a sapphire substrate in hot H₂SO₄ solution generates white reaction products that are identified as a mixture of polycrystalline aluminum sulfates. These white reaction products can act as a natural etching mask in the preparation of an ANP-coated PSS (PSS-ANP) template. The optimal annealing temperature and time, surface morphology, and optical characteristics of the PSS-ANP template were investigated. The light output power of an LED that is bonded to the PSS-ANP template is approximately double than that of an LED that is not.     

Structure in metallurgical cokes and carbons as studied by etching with atomic oxygen and chromic acid

Anisotropie carbons and cokes exhibit an optical texture or micro-texture in the size range 0.5–300 μm in polished surfaces using optical microscopy. Structure within this optical texture can be studied as the topography created by etching surfaces with atomic oxygen and chromic acid. Atomic oxygen preferentially etches an isotropic carbon layer which exists between the grains of the fine-grained mozaics. Chromic acid oxidizes or etches selectively the surfaces of anisotropic carbon to create fissures parallel to basal plane orientation. Structural components within petroleum cokes, carbon fibres and carbon/carbon fibre composites are revealed. Chromic acid oxidizes isotropic components in metallurgi-cal cokes more slowly and so reveals the structure of cokes as prepared from co-carbonizations of coal with petroleum pitch. It is considered that these etching techniques augment our knowledge of internal structure within carbons and cokes and of considerations of strength and fracture in these materials.     

The effect of sputter etching on the surface characteristics of dyed aramid fabrics

Three kinds of aramid fabrics, Technora (modified p-aramid), Conex (m-aramid) and Kevlar (p-aramid), were subjected to sputter etching and argon low-temperature plasma treatments after dyeing in black with disperse dyes. The depth of shade increased considerably on Technora and Kevlar with the sputter etching treatment, but not on Conex fabrics. Argon low-temperature plasma treatment had virtually no effect on the depth of shade on the aramid fabrics.     

Graphene materials with different structures prepared from the same graphite by the Hummers and Brodie methods

Graphene materials containing different functional groups were prepared from a natural graphite, by means of two different oxidation methods (Hummers and Brodie). It was observed that the differences in the structure of the resultant graphite oxides (GOs) greatly affect the structure of the graphenes resulting from their thermal exfoliation/reduction. Although the oxidation of the graphite was more effective with the modified Hummers method than with Brodie’s method (C/O of 1.8 vs 2.9, as determined by XPS), the former generated a lower residual oxygen content after thermal exfoliation/reduction and a better reconstruction of the 2D graphene structure (with fewer defects). This is explained by the presence of conjugated epoxy and hydroxyl groups in the GO obtained by Brodie’s method, which upon thermal treatment, lead to the incorporation of oxygen into the carbon lattice preventing its complete restoration. Additionally, graphene materials obtained with Brodie’s method exhibit, in general, smaller sheet size and larger surface area.     

蒙砂粉熟化过程与蚀刻玻璃表面的研究

固体蒙砂粉的熟化质量是决定玻璃蚀刻效果的重要因素。用X射线衍射（XRD）、能谱仪（EDS）、拉曼光谱、粘度计、Zeta电位和碱滴定等方法研究了用柠檬酸和氟化氢铵为主要成分配制的蒙砂粉的理化性质随熟化时间的变化规律,考察和评价了熟化时间对GG6手机盖板玻璃蚀刻效果的影响。结果表明：熟化时间为36 h,得到的熟化液的黏度和氢离子浓度最大,GG6玻璃蚀刻后的粗糙度为265 nm、雾度为84%、透光率为92.4%、光泽度为11.7%,符合工业上手机玻璃盖板的蚀刻加工质量要求,蚀刻后的GG6玻璃表面形成一层微量的氟硅酸物晶体,构成的微纳蚀孔结构更均匀。测定蒙砂液的理化性质能有助于更好地了解蒙砂粉的熟化过程,对蒙砂粉蚀刻工艺具有指导作用,提高玻璃防眩工艺的生产效率。     

Fabrication of superhydrophilic surface on copper substrate by electrochemical deposition and sintering process

Superhydrophilic surfaces were fabricated on copper substrates by an electrochemical deposition and sintering process. Superhydrophobic surfaces were prepared by constructing micro/nano-structure on copper substrates through an electrochemical deposition method. Conversion from superhydrophobic to superhydrophilic was ob-tained via a suitable sintering process. After reduction sintering, the contact angle of the superhydrophilic sur-faces changed from 155° to 0°. The scanning electron microscope (SEM) images show that the morphology of superhydrophobic and superhydrophilic surfaces looks like corals and cells respectively. The chemical composi-tion and crystal structure of these surfaces were examined using energy dispersive spectrometry (EDS) and X-ray diffraction (XRD). The results show that the main components on superhydrophobic surfaces are Cu, Cu2O and CuO, while the superhydrophilic surfaces are composed of Cu merely. The crystal structure is more inerratic and the grain size becomes bigger after the sintering. The interfacial strength of the superhydrophilic surfaces was investigated, showing that the interfacial strength between superhydrophilic layer and copper substrate is considerably high.     

Enhancing adhesion by ion beam-induced atomic mixing at the interface between copper film and polyimide substrate

Ion beam mixing was used to improve the adhesion between deposited Cu film (400 Å) and polyimide (PI) substrate. Ar⁺ ion with the energy levels between 180 and 200 keV, and the dose between 10¹⁴ to 4 × 10¹⁶ ions/cm² were used. The surface analyses were carried out by Rutherford Backscattering Spectroscopy (SEM). RBS analysis, using 2 MeV He⁺ ions, showed mixing of Cu and FI and the mixing depended on the Ar⁺ energy and dose. The X-ray study showed a very broad halo for deposited Cu film but the (111) peak appeared after the Ar⁺ implantation and the peak increased with Ar⁺ ion dose. Optical micrographs showed that Cu film formed circular bubbles after many thermal cycles when adhesion was poor and fracture cracks when adhesion was good.     

Effect of simultaneous etching and N-doping on the surface and electrochemical properties of AC

To improve the electrical performance of activated carbon (AC)-based electric double-layer capacitors (EDLCs), the surface of AC was modified with gas phase ammonia treatment at 1073 K with different treatment times to carry out simultaneous etching and N-doping. The effects of the treatment on AC surfaces and their electrochemical properties were investigated. The specific capacitances of samples treated for 22 min were increased to 426 F/g at scan rates of 10 mV/s, which corresponded to a 76.8% increase as compared with 241 F/g of samples measured as received from the manufacturer. The increase is attributed to an increase in the specific surface area and the total pore, micro- and mesopore volumes due to the etching effect of the high-temperature ammonia gas reaction. Moreover, N-functional groups, which were introduced by the treatment, also aided to improve the electrochemical properties of the resulting AC-based electrode. Therefore, the simultaneous etching and N-doping method with ammonia gas at high temperature can easily introduce nitrogen functional groups on the AC surface. In addition, the reaction of nitrogen gas with AC can affect its specific surface area and surface pore structure, which is very effective in preparing AC for EDLCs with improved electrochemical properties.     

Fabrication of mechanically robust superhydrophobic aluminum surface by acid etching and stearic acid modification

The aluminium surface with multi-scale structure has been fabricated via a facile and rapid solution-phase etching method by HCl/H₂O₂ etchants. After modification with stearic acid solution, the wettability of the etched aluminum surface turns into superhydrophobicity with an optimal water contact angle of 160° ± 2° and a sliding angle of 4° ± 1°. The processing conditions, such as the etching time, modifier types and the concentration of H₂O₂ are investigated to determine their effects on the surface morphology and wettability. As a result, the obtained sample shows excellent anti-adhesion property and bouncing phenomenon of water droplet. It can withstand mechanical abrasion for at least 100 cm under 12.3 kPa, or hydrostatic pressure under 24 ± 1 kPa without losing its superhydrophobicity, suggesting superior mechanical durability. Moreover, the surface also remains superhydrophobicity even after contacting corrosive liquids or long-term exposure in air over 100 days. Such a mechanically durable superhydrophobic aluminum surface can provide a promising practical application in various fields.     

Recent advances in preparation of metallic superhydrophobic surface by chemical etching and its applications

In the past few decades,inspired by the superhydrophobic surfaces(SHPS) of animals and plants such as lotus leaves,rose petals,legs of water striders,and wings of butterflies,preparing metal materials with metallic SHPS(MSHPS) have attracted great research interest,due to the great prospect in practical applications.To obtain SHPS on conventional metal materials,it is necessary to construct rough surface,followed by modification with low surface energy substances.In this paper,the action mechani...