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Optimal target sputtering mode for aluminum nitride thin film deposition by high power pulsed magnetron sputtering
摘要： Low surface roughness, low residual stress, and (002) textured aluminum nitride (AlN) thin films are favored for applications in microelectronic and optoelectronic devices. In this paper, AlN thin films were deposited by reactive high power pulsed magnetron sputtering (HPPMS). The effect of aluminum target sputtering mode and sputtering power on thin film residual stress, crystalline structure, surface roughness, and morphology of AlN thin films was studied. The results indicate that, with Al target sputtering mode transfer from metallic mode to transitional and compound modes, respectively, the number of Al species decrease, and ion-to-neutral ratio of Al species increase. Comparing the AlN thin film deposited in compound mode with that deposited in transitional mode, the latter exhibited lower surface roughness and residual stress. In addition, AlN thin film with (002) texture and lower residual stress is obtained by increasing sputtering power in transitional mode. For fabricating AlN film via reactive HPPMS with a particular (002) texture, low surface roughness, and residual stress, sputtering the target in the transitional mode with high sputtering power is optimal.
关键词： Aluminum nitride,Microstructure,Texture,High power pulsed magnetron sputtering,Sputtering modes,Sputtering power
更新于2025-09-23 15:23:52
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Polar surface dominated octagonal Sn doped ZnO nanowires and their room-temperature photoluminance properties
摘要： Polar surface dominated Sn doped ZnO nanowires (NWs) with an octagonal shaped cross section have been fabricated by chemical vapor deposition method. The NWs grew along [01 0] direction, and were wrapped by non-polar surface (2 0) and polar surfaces (0001) and (1 1). Planar defects in (0001) plane were formed in the middle of the doped NWs, and strain concentration occurred around the planar defects, which might lower the energy in the wurtzite lattice and thus maintain polar surface dominated configuration. X-ray photoelectron spectroscopy (XPS) and Raman tests reveal that the concentration of Oxygen vacancy (VO) was significantly lowered after doping, which led to the reduced deep level emission (DLE).
关键词： Polar surface,Photoluminance,Sn-doped ZnO Nanowires,Microstructure
更新于2025-09-23 15:23:52
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Corrosion study of laser cladded Ti-6Al-4V alloy in different corrosive environments
摘要： Laser cladding of Ti-6Al-4V powder on a substrate with the same chemical composition was performed at different laser powers. The effect of laser power on the microstructure and corrosion behavior was then investigated. Electrochemical studies were performed by potentiodynamic polarization tests in different corrosive environments (3.5% NaCl, 2% H2SO4 and 5% HCl solutions). Microstructural investigation together with phase characterization revealed that laser cladded Ti-6Al-4V coatings were composed of needle-like martensite (ɑ/) and coaxial hexagonal compact (ɑ) phases. The coatings were crack-free; however, some cavities were observed in the coatings produced at high laser powers. In all three corrosive environments, the coatings showed a more noble corrosion behavior compared to the untreated substrate. The results showed that corrosion potential increases from ?410 (mV) to ?130 (mV) in NaCl and from ?50 (mV) to ?20 (mV) in H2SO4 enviroments but decreases from ?60 (mV) to ?270 (mV) in HCl solution. Increasing laser power had a positive effect on the corrosion behavior in NaCl and H2SO4 solutions; however, it had a negative effect on the corrosion behavior in HCl solution.
关键词： Corrosion,Laser cladding,Ti-6Al-4V alloy,Microstructure
更新于2025-09-23 15:23:52
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Dielectric and Transport Properties of Strontium Modified Calcium Copper Titanate
摘要： The present article provides the detailed study of the effect of strontium on the structural, microstructural, dielectric and electrical characteristics of strontium modified calcium copper titanate (i.e. Ca0.95Sr0.05Cu3Ti4O12, referred as CSCTO further) synthesized by a cost-effective ceramic processing technology. The structural analysis carried out suggests a cubic symmetry in the prepared sample. The dielectric relaxation and electrical conduction mechanism of CSCTO were studied using various powerful spectroscopic tools (i.e dielectric and impedance). Study of temperature dependence of dielectric permittivity exhibits very high (giant) dielectric permittivity (5 (cid:1) 103) and low loss factor at low frequency (1 kHz) at an intermediate temperature (315 (cid:3)C). Structure–properties relationship and conduction mechanism have been studied in a wide frequency (103–106 Hz) and temperature (25–315 (cid:3)C) range. At region of low frequency and high temperatures, there is a dominant role of the interface and Maxwell–Wagner dielectric relaxation mechanism in CSCTO bulk ceramic. The grain, grain boundary and electrode contributes towards the capacitive and resistive property of the sample are discerned from Nyquist plot. The ferroelectric (P–E) loop of the sintered CSCTO bulk sample at room temperature showed a lossy hysteresis loop. These findings further promote the capabilities of CSCTO as a base for supercapacitor.
关键词： X-Ray diffraction,supercapacitor,ferroelectric phase,microstructure,dielectric properties
更新于2025-09-23 15:23:52
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Effects of Calcination Temperature on Morphology and Structure of CeO2 Nanofibers and their Photocatalytic Activity
摘要： Calcination temperature plays a critical role on morphology and structure of CeO2 nanofibers, thus affecting its photocatalytic activity. CeO2 nanofibers with diameter of 95 nm were successfully fabricated by electrospinning combining with calcination. The calcination temperature was determined by TGA results ranging from 500℃ to 800℃. The morphology and structure of samples obtained with different calcination temperatures, have been characterized by SEM and XRD. Meanwhile, the specific surface area of samples were checked by BET, that was decreased 17 times from 56.3 m2/g to 3.3 m2/g, as the temperature increasing from 500℃ to 800℃. Normally, the higher specific surface area, the more efficiency photocatalytic activity. But it was interesting that the photodegradation rate of methylene blue was increased from 67% to 98% for CeO2 catalyst obtained at 500℃ and 800℃, with 4 times higher kinetic constant reaction rate under UV irradiation for 60 min. It demonstrates that the photocatalytic activity of CeO2 nanofibers catalyst is not directly related to the specific surface area, and increasing the calcination temperature has a positive effect for the photocatalytic efficiency.
关键词： Calcination,Porous Materials,Microstructure,CeO2 Nanofiber,Photocatalysis
更新于2025-09-23 15:23:52
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A comparative study on single-laser and multi-laser selective laser melting AlSi10Mg: defects, microstructure and mechanical properties
摘要： AlSi10Mg samples fabricated by using a multi-laser beam selective laser melting system have been studied in this paper. The relative density, defects, microstructure and mechanical properties of the isolated and overlap samples are investigated. It is found that the width and depth of the melt pools in overlap area are larger than that in isolated area, which leads to an obvious boundary between the overlap area and isolated area. Moreover, a few small pores are found in the melt pools along the overlap boundary. The isolated and overlap area in as-built samples have similar microstructure, microhardness and tensile strengths. The morphology and distribution of Si changed into particles from continuous dendrite after annealing treatment. However, it did not cause the grains to grow up. The microhardness and tensile strengths have little difference due to almost the same grain size. The slight difference in strength and elongation of isolated and overlap samples are supposed to be caused by small pores. It can be concluded that the microstructure significantly influences the microhardness and strengths of the AlSi10Mg samples, while the small pores have limited influences. There are a few smooth surfaces on the fractures of both isolated and overlap samples, which turn out to be the melt pool boundaries, indicating that the cracks mainly propagate along the melt pool boundaries.
关键词： Defects,Microstructure,Mechanical properties,Multi-laser beam,Overlap area
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - Kiev (2018.4.24-2018.4.26)] 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - Investigation of the Structure and Optical Properties of Thin Copper Films
摘要： Copper nanolayers were formed using the vacuum magnetron-assisted sputtering in various technological modes (sedimentation speed, working pressure, discharge power). Results of microstructural study of the 1 nm to 65 nm thick copper nanofilms deposited on quartz, glass and silicon substrates are presented. Spectra of transmission and reflection coefficients of the copper nanofilms were studied in the wavelength range from 0.2 μm to 1.1 μm. The transmission and reflection spectra of films correspond well to the known spectra of bulk materials. The obtained results are of practical importance for development of nanostructural systems with the preset optical properties and for design of functional devices to be used in optoelectronics, information and energy-saving technologies.
关键词： transmission spectrum,microstructure,nanofilms,reflection spectrum
更新于2025-09-23 15:23:52
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Effect of laser forming on mechanical properties of multiple-phase steels by using a thermal–microstructure–mechanical model
摘要： Based on a forming temperature-controlled mixed strain-hardening law, a temperature-controlled thermal–microstructure–mechanical model was developed to predict the deformation in ferrite–martensite dual-phase steel before and after complex laser forming. Phase transformation in dual phase steel was predicted by coupling a kinetic transformation model with the developed model during laser forming. The corresponding algorithm of the constitutive model was used in three-dimensional finite element method to simulate the material deformation and mechanical properties during the laser forming. The simulated results agree well with the experimental results. Laser forming influences the mechanical properties of the material significantly, leads to bending deformation of the scanned sample and induces a ferrite-to-martensite transformation. The influence of scanning line number on the tensile strength and bending deformation of the scanned specimen was investigated. The tensile strength and bending angle are related positively to the number of scanning lines on the sample.
关键词： Stress-strain curve,Phase transformation,Thermal–microstructure–mechanical model,Sheet metal,Laser forming
更新于2025-09-23 15:23:52
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Microstructure and Properties of Graphene Oxide-doped TiO2 Coating on Titanium by Micro Arc Oxidation
摘要： Micro arc oxidation (MAO) coatings doped with graphene oxide (GO) were prepared on pure titanium by adding GO and sodium dodecyl benzene sulfonate (SDBS) into a sodium silicate solution. The as-deposited coatings were comparatively analyzed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The binding forces of the MAO, MAO+GO and MAO+GO+SDBS three coatings were measured by a scratch tester. The mechanical property of the three coatings was analyzed using the nano-indentation technique. The corrosion resistance of the coatings was tested by the electrochemical system in 3.5% NaCl solution. The photocatalytic activity of the prepared samples was evaluated by determining the degradation of methylene blue (MB) solution. The results showed that compared to the MAO coating, the morphologies and phase compositions of MAO+GO and MAO+GO+SDBS composite coatings were significantly different. These two composite coatings all had superior photocatalytic activity. Especially, the MAO+GO composite coating still had enhanced binding force and excellent corrosion resistance. Furthermore, the relationship between the microstructure and the properties of these three MAO coatings was analyzed.
关键词： pure titanium,graphene oxide,micro arc oxidation,properties,microstructure
更新于2025-09-23 15:23:52
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Fabrication and enhanced photocatalytic property of TiO2-ZnO composite photocatalysts
摘要： TiO2 nanotube and TiO2-ZnO composite photocatalysts were fabricated by simple hydrothermal method, and the photocatalytic property of as-prepared samples were analyzed by the photo degradation of rhodamine B water solutions under visible light irradiation. The prepared TiO2-ZnO composite photocatalysts exhibited excellent property in photo degradation of rhodamine B water solution, which is better than that of P25. The enhancement photocatalytic property of target photocatalysts could be attributed to the reduced band gap energy, the enhanced-surface physic-chemical properties, the separation of photo induced electron-hole pairs and the decreased recombination rate. In addition, TiO2-ZnO composite photocatalysts showed good stability for rhodamine B photo degradation under visible light.
关键词： Microstructure,TiO2-ZnO,Photocatalytic property,Hydrothermal method,Composite materials
更新于2025-09-23 15:23:52