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Metal alloys are increasingly being used in the synthesis of nanostructures, such as nanotubes. This study was an attempt to expand the applicability of metallic nanotube arrays (MeNTAs) by fabricating structures with a high aspect ratio with the aim of increasing the active surface area. MeNTAs comprising thin-film metallic glass (TFMG) and bronze were fabricated via high-power impulse magnetron sputtering (HiPIMS) over a contact-hole array created using photoresist. MeNTAs were designed with 2 aspect ratios (2 and 4). MeNTAs with an AR of 2 were fabricated via single-layer deposition using both alloys. When fabricating MeNTA with an AR of 4, the resulting single-layer structures were unable to withstand the photoresist removal process, thereby necessitating the inclusion of a WNiB TFMG as the buffer layer for reinforcement. The percentage of intact AR 4 bronze MeNTA was far higher under multilayer deposition (98.4%) than under single-layer deposition (74%). Plasma diagnostic methods involving a Langmuir probe were used to monitor plasma properties (e.g., plasma potential, plasma density, electron temperature, and ion flux) during the deposition process. These results provide valuable reference for trench filling and the manufacture of nanostructures with a high aspect ratio using HiPIMS. • Fabrication of high aspect ratio metallic nanotube arrays (MeNTAs) is reported. • High-power impulse magnetron sputtering (HiPIMS) plasma properties are studied. • High aspect ratio MeNTAs can be prepared with HiPIMS. • The step coverage of deposition is increased with higher plasma density. • Survivability of MeNTA is higher by adding a buffer layer of W-based metallic glass. [ABSTRACT FROM AUTHOR]

A promising candidate for a top cell in a tandem solar cell setup is a superstate, high bandgap, CIGS (Copper Indium Gallium Diselenide) solar cell. To realize a tandem cell, both, front and back contact of the top cell must be transparent. In this work a molybdenum metal mesh electrode with four pattern derivatives is presented, which are designed towards this implementation in a tandem cell setup. The electrode consists of two-micron wide fingers arranged in an industry typical H-grid pattern and in a hexagonal shaped pattern, with each of these patterns being comprised of a derivative with and without tapered busbars. The electrode's micro structure, crystal orientation, surface roughness, electrical properties and optical properties are investigated. The manufacturing process as well as a comparison of this works electrodes with various competing electrode types is also presented. All electrode derivatives show excellent transmittance of up to 97% within and beyond the visible spectrum while retaining acceptable sheet resistances of about 30 Ω/□. [ABSTRACT FROM AUTHOR]

Abstract: The annealing-induced amorphization of a sputtered glass-forming Cu51Zr42Al4Ti3 thin film has been clarified by in-situ transmission electron microscopy in conjunction with ex-situ atomic force microscopy and X-ray diffractometry. Upon heating of the film at low temperatures, nanocrystallization and growth of metastable sputtered crystallites occur in the amorphous matrix. Heated to 438°C, within the supercooled liquid region (ΔT), the film becomes fully amorphous. At higher temperatures above ΔT, i.e. 525°C, crystalline Cu10Zr7 and AlTi2 phases appear as a result of crystallization. The annealing-induced nanocrystallization and amorphization appear to be rather general and applicable to a large number of systems. [Copyright &y& Elsevier]

The viscous flow typically plays an important role for the deformation of metallic glasses in the supercooled liquid region. This deformation behavior has been widely investigated for bulk metallic glasses. However, studies on the viscous flow and viscosity measurement of thin film metallic glasses (TFMGs) were sparse. In this work, we synthesized four compositions of fully amorphous AuCuSi TFMGs by magnetron sputtering. The glass transition temperature, which is also the temperature of the critical transition point from elastic/plastic deformation to time-dependent viscous flow, was determined using nanoindentation. The nanoindentation creep tests performed with hemispherical and Berkovich indenter tips in the temperature range of 50 to 170 °C were proven to be suitable for the viscosity measurements of AuCuSi TFMGs. The activation energy of the flow process was also evaluated from the indentation results and good agreement was obtained between the results evaluated from hemispherical and Berkovich tips. Finally, a nano-scaled imprinted AuCuSi TFMG showed great topological resolution. [ABSTRACT FROM AUTHOR]

High-power impulse magnetron sputtering (HiPIMS) is a thin film deposition technique that combines the advantages of energetic deposition methods with magnetron sputtering. HiPIMS has so far mostly been utilized for the growth of crystalline coatings. Here we offer a study devoted to metallic glasses, in which we compare Zr 60 Cu 25 Al 10 Ni 5 (target composition) thin films deposited by conventional direct current magnetron sputtering (DC) and HiPIMS. Film microstructure is strongly dependent on the choice of the sputtering method. The DC layers show a columnar structure with intra-columnar porosity, which provides a pathway for oxygen diffusion into the film. In contrast, HiPIMS films are column-free and possess about 4% higher density, as revealed by X-ray reflectivity. Electron diffraction reveals a decrease in average atomic spacing for the latter film of about 12%. These differences in film properties and morphology can be attributed to an increase in ad-atom mobility during HiPIMS caused by an increase in ion energy and flux of the film-forming species enabling a more efficient energy and momentum transfer to the growing film surface. The relative contribution of metallic and hence film forming ions to the overall ion flux of the DC plasma compared to the HiPIMS plasma is 13% and 96%, respectively. Additionally, a substrate bias causes the ionized film forming species during HiPIMS to arrive close to the substrate normal reducing shadowing effects. Different microstructures have a direct effect on the average roughness values, which for DC and HiPIMS films are 1.4 nm and 0.2 nm, respectively. The indentation hardness H and Young's modulus E are higher for the HiPIMS sample, at 9.2 ± 0.3 GPa and 131.6 ± 3.6 GPa, respectively. The increase in hardness for the HiPIMS sample as compared to the DC sample (~35%) can be attributed to higher film density, compressive (HiPIMS) as opposed to tensile (DC) stress and the lack of a columnar structure. • High-power impulse magnetron sputtering (HiPIMS) is used to deposit metallic glass. • The metallic glass Zr 60 Cu 25 Al 10 Ni 5 shows column-free microstructure by HiPIMS. • The coating by HiPIMS is about 4% higher density with roughness value of 0.2 nm. • Indentation hardness H and Young's modulus E are higher for the HiPIMS sample. [ABSTRACT FROM AUTHOR]

Selecting electrolytes is critical before assembling a cell to achieve good performance in a Li metal battery. An Ag-coated groove with hill and valley features is prepared by magnetron sputtering on a 3D structure array pattern laying on a commercial Cu foil to act as a platform to evaluate liquid electrolytes in Li//Cu half-cell configuration. The 3D Ag-coated groove with hill and valley feature provides the capability to determine the uniformity in terms of throwing power (TP) of various electrolytes, which is correlated with their electrochemical performance. The increase in TP value after applying fluoroethylene carbonate (FEC) (−3.59%) and tris(trimethylsilyl) phosphite (TMSP) (−49.60%) as an additive is in contrast to the TP value of the pristine electrolyte w/o additive (−66.84%), which is in line with the higher average coulombic efficiency achieved (95.39% for FEC and 94.87% for TMSP) compared to LiPF 6 alone (91.89%). Moreover, the FEC-contained electrolyte achieves the lowest value of resistance (18.76 Ω and 10.92 Ω) and average surface roughness Ra (24.8 and 22.4 nm) on hill and valley, respectively, among the investigated electrolytes. Applying the design of an Ag-coated groove gives significant insight into how a platform can be built to comply with the effort in screening the good options for liquid electrolytes in Li metal battery application. [Display omitted] • Photolithography and magnetron sputtering are used for 3D structure modification on Cu foil. • An electrolyte evaluating platform is designed based on the throwing power of hill and valley of 3D Ag-coated groove. • AFM and EIS characterizations are conducted on hills and valleys and then correlated with the throwing power capability. [ABSTRACT FROM AUTHOR]

The adhesion of platelet cells is viewed as a first step in thrombus formation, and cancer cell attachment can lead to cancer seeding. In this study, we examined the feasibility of utilizing Zr 53 Cu 33 Al 9 Ta 5 thin film metallic glass (TFMG) to minimize the adhesion of human cancer cells (breast cancer cell, colon cancer cell, and esophageal cancer cell), human and animal platelets. TFMG and pure titanium (Ti) were respectively grown on glass substrates to a thickness of 200 nm using magnetron sputtering. TFMG was shown to reduce surface roughness of approximately 27% than Ti coating did on glass samples. The concentrations of all major ions released from the TFMG were well below toxic levels. TFMG surfaces were more effective than Ti in increasing the contact angle of water, phosphate buffer saline (PBS) and blood from different animal species. The application of TFMG to bare surfaces was shown to reduce the attachment area of human platelets by 77% and that of pig platelets by 63%. TFMG also reduced the attachment of cancer cells by up to ~87%. These characteristics can be attributed to a low surface free energy of TFMG-coated surfaces (31.89 mN/m), which is far below that of Ti-coated (39.25 mN/m) and bare glass (47.80 mN/m). These findings demonstrate the considerable potential of TFMG coatings in the fabrication of medical instruments aimed at preventing the adhesion of platelet and cancer cells. [ABSTRACT FROM AUTHOR]

Abstract: Recently thin film metallic glass represents a class of promising engineering materials for structural applications. In this work, the Zr-based thin film metallic glass (TFMG) was fabricated on the Si and AISI 420 substrates using a Zr–Cu–Ni–Al alloy and pure Zr metal targets by a pulsed DC magnetron sputtering system. The chemical compositions, crystalline structures, microstructures and corrosion behavior in hydrochloric (HCl) aqueous solutions of Zr-based TFMGs were investigated. The results showed that the surface morphologies of Zr-based TFMG were very smooth. A compact and dense structure without columnar structure was observed. The amorphous structure of Zr-based TFMG was characterized by the X-ray diffractometer and transmission electron microscopy analyses. After the potentiodynamic polarization test, the better corrosion resistance was achieved for the Zr-based TFMG coated AISI 420 in 1mM HCl aqueous solution. Based on the surface morphologies and chemical analysis results of the corroded surfaces, the pitting, crevice corrosion and filiform corrosion were found. The corrosion mechanisms of the Zr-based TFMG were discussed in this work. [Copyright &y& Elsevier]

Abstract: Recently metallic glass thin films represent a class of promising engineering materials for structural applications. In this work, a series of Zr-based thin film metallic glass (TFMG) were fabricated by sputtering process. The nitrogen was introduced during deposition by using a plasma emission monitoring (PEM) control system at different degrees of target poisoning rates. The structures, surface and cross-sectional morphologies, and surface roughness of thin films were explored. A nanoindenter, a scratch tester and pin-on-disk wear tests were used to evaluate the hardness, adhesion and tribological properties of thin films, respectively. The Zr-based TFMGs with nitrogen content ranging from 0 to 17.7at.% were achieved by field emission electron probe microanalyzer (FE-EPMA). The supercooled liquid region can be found when the TFMG contained less than 7.1at.% nitrogen. The nanocrystalline ZrN phase was observed as the nitrogen content was higher than 11.1at.%. The surface roughness increased with an increase of nitrogen content. On the other hand, the deposition rate decreased instead. The hardness, wear resistance and adhesion critical loads were enhanced by the addition of nitrogen. According to the Daimler Benz Rockwell-C (HRC-DB) analysis, sufficient adhesion quality was achieved for each TFMG. It can be concluded that the 13.8at.% N contained TFMG and fabricated under the Zr target poisoning rate of 50%, and having a microstructure consisting of ZrN nanograins provided a combination of high hardness, good wear resistance and excellent adhesion properties. [Copyright &y& Elsevier]

[Display omitted] • SUS316 stainless steel sputter target was used to deposit Fe-Cr-Ni thin film. • Deposition pressure was varied to create a nano-pyramid surface structure. • The growth of such texture can be explained by Thronton's structural zone diagram. • From low to high working pressure there was a drastic change in the grain growth morphology. • Fine-tuning of surface texture by deposition pressure allows manipulation of surface wetting property. In this article a series of Stainless steel thin films are fabricated by DC power magnetron sputtering of a SUS316 stainless steel target at various argon working pressure. The sample film compositions retain that of an austenitic stainless steel, while XRD spectra reveal that all films possess a single phase, body-centered cubic ferrite crystal structure. At working pressure 6 mTorr and above, the film exhibits a textured surface morphology made up of nano-sized pyramids. Cross-sectional images show that increasing argon pressure cause a microstructural evolution from dense, fibrous grain to coarse tapered grains. This observation agrees with the prediction by Thornton's structural zone model and causes a drastic reduction in static water contact angle (WCA) from ~65° to ~17°. With further increase of argon pressure, a minimum WCA of 11° at 8 mTorr can be achieved. In addition, our textured film deposited at 12 mTorr exhibits both excellent hydrophilicity and low contact angle hysteresis (CAH) at the same time. In summary, this work reports a convenient way of depositing a stainless steel-like hydrophilic coating, in which the wetting properties are tunable via working pressure control. [ABSTRACT FROM AUTHOR]

In this work Fe 39 Co 39 Si 8 B 14 thin film metallic glasses (TFMGs) of thickness ranged between 122– 475 nm were deposited by magnetron sputtering on a commercial filter paper to act as a peroxymonosulfate (PMS) activator for degradation of Orange G (OG) azo dye. Degradation of 98.6% was achieved in 16 min. The influence of parameters such as catalyst dosage, light irradiation intensity, dye and PMS concentration to the efficiency of degradation were also investigated. SEM and XPS results revealed that the outstanding performance was attributed to the abundance of amorphous zero valent metals given by the amorphous atomic packing structure of TFMG. Zero valent metals readily activated PMS and favored the generation of SO4• and •OH radicals, which were the responsible species in degrading OG dye molecules. Another contribution was from the fibrous and porous texture of the filter paper substrate which provides specific surface area as high as 1.152 m2/g. TFMG-coated filter paper also showed good reusability that repeated degradation was possible. Results suggests that applying TFMG on a textured substrate could drastically reduce the dosage of Fe-based metallic glass needed compared to its powder or foil counterparts, which is significantly more cost effective. • Fe-based thin film metallic glass (TFMG) was used to degrade Orange G azo dye. • Degradation of 98.6% was achieved in 16 min and its reusability was also tested. • Such performance was due to TFMG's large surface area and rich in zero valent iron. • Zero valent iron and other ferrous iron significantly promoted radical generation. • Effect of dosage, illumination and concentration on degradation rate were reported. [ABSTRACT FROM AUTHOR]

• Membranes modified by activated oxygen and metallic glass deposition. • High flux, rejection, and antifouling ultrafiltration composite membranes. • Ultrafiltration performance improving mechanism for modified PSf membrane. Polysulfone (PSf) composite ultrafiltration membranes were subjected to Ar/O 2 plasma assisted oxygen activation and then coated with various forms of metallic glass (W 50 Ni 25 B 25 , Zr 60 Cu 25 Al 10 Ni 5 , and Pd 74 Si 14 Cu 12). The activated oxygen treated PSf ultrafiltration membrane was strongly hydrophilic, with pure water flux (PWF) of 350.7 L m−2 h−1 and bovine serum albumin (BSA) rejection of 83%. The application of metallic glass (MG) to the surface of the polysulfone composite membrane using low-power radio-frequency magnetron sputtering improved the BSA rejection rate (ranging from 98.6 to 99.9%) with only a slight reduction in PWF: tungsten-based MG (321.5 L m−2 h−1), zirconium-based MG (215.6 L m−2 h−1), and palladium-based MG (181.3 L m−2 h−1). The membrane with the tungsten-based coating achieved remarkable PWF, BSA rejection, and antifouling performance, due primarily to high surface hydrophilicity (water contact angle of 24.2°) and a strongly negative surface charge. Overall, the proposed metallic glass/polysulfone composite membranes achieved moderately high PWF and protein rejection with incredible antifouling competence, even under extended (multi-cycle) fouling conditions. [ABSTRACT FROM AUTHOR]