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A distributed parametric model of Brinson shape memory alloy based resonant frequency tunable cantilevered PZT energy harvester
摘要： This paper presents, an analytical model of piezoelectric vibration energy harvester consists of Brinson shape memory alloy (SMA) plate which can tune the resonant frequency. As the energy harvester should be tuned to excitation frequency in order to drive the maximum power, the temperature of SMA is varied to tune the natural frequency of the composite beam. In addition to SMA it also consists of piezoelectric layer and substructure layer. Using Euler–Bernoulli beam assumption, the expressions for frequency response of voltage, current and power outputs with temperature are obtained. From parametric study, it is observed that the tuning of natural frequency is 25–26%, for first three modes of vibration in short and open circuit conditions.
关键词： PZT,Energy harvester,Shape memory alloy,Tunable,Cantilever
更新于2025-09-23 15:22:29
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[ASME ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - San Francisco, California, USA (Monday 27 August 2018)] ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - Microstructural Evolution in SAC305 and SAC-Bi Solders Subjected to Mechanical Cycling
摘要： Fatigue failure of solder joints is one of the most common methods by which electronic packages fail. Electronic assemblies usually must cope with a temperature varying environment. Due to the mismatches in coefficients of thermal expansion (CTEs) of the various assembly materials, the solder joints are subjected to cyclic thermal-mechanical loading during temperature cycling. The main focus of this work is to investigate the changes in microstructure that occur in SAC305 and SAC+Bi lead free solders subjected to mechanical cycling. In this paper, we report on results for the SAC+Bi solder commonly known as SAC_Q or CYCLOMAX. Uniaxial solder specimens were prepared in glass tubes, and the outside surfaces were polished. A nanoindenter was then used to mark fixed regions on the samples for subsequent microscopy evaluation. The samples were subjected to mechanical cycling, and the microstructures of the selected fixed regions were recorded after various durations of cycling using Scanning Electron Microscopy (SEM). Using the recorded images, it was observed that the cycling induced damage consisted primarily of small intergranular cracks forming along the subgrain boundaries within dendrites. These cracks continued to grow as the cycling continued, resulting in a weakening of the dendrite structure, and eventually to the formation of large transgranular cracks. The distribution and size of the intermetallic particles in the inter-dendritic regions were observed to remain essentially unchanged.
关键词： Bismuth,Microstructure,SAC Alloy,Hysteresis,Evolution,Lead Free Solder,Cyclic Stress-Strain Curve
更新于2025-09-23 15:22:29
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In situ TiN-reinforced CoCr2FeNiTi0.5 high-entropy alloy composite coating fabricated by laser cladding
摘要： The fcc structural CoCr2FeNiTi0.5 high-entropy alloy (HEA) composite coating with TiN particles reinforced was acquired by laser cladding on the commercial 904L stainless steels. The results show that phase structure is mainly composed of fcc solid solution and TiN phases. The coating exhibits excellent structural stability below 850 °C. The microstructure consists of irregular dendrite and TiN particles. Transmission electron microscopy (TEM) results reveal that the close-packed plane of fcc phase is (111) with interplanar spacing of * 0.208 nm. The interface between TiN and fcc matrix is semi-coherent. And the angle of boundary between dendrite and matrix is * 65°. The hardness and corrosion resistance of coating have much improvement compared with those of substrate.
关键词： Semi-coherent interface,High-entropy alloy,Laser cladding,TiN particle reinforced
更新于2025-09-23 15:22:29
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Microstructure and Characteristic of Biomedical Titanium Alloy Based on Picosecond Laser Micromachining
摘要： Laser micromachining has become a hotspot in recent years due to its high precision, non-contact and adjustable parameter. In this paper, TC4 titanium alloy implant samples were conducted to obtain specific surface textures through picosecond laser. The laser parameters which directly influenced the microstructure and characteristic of surface textures were optimized within the context of laser power, scanning speed and scanning number via response surface methodology. The microstructure was evaluated using scanning electron microscope (SEM) while the feature size of the surface textures was measured through surface 3D profiler. In addition, endothelial cell culture was conducted to investigate the biofunctionalization of samples with specific surface textures. It demonstrated that well-structured textures played an important role in promoting cell adhesion and proliferation for titanium alloy implants.
关键词： Picosecond laser micromachining,Microstructure,Biofunctionalization,Titanium alloy
更新于2025-09-23 15:22:29
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Stability, Electronic and Magnetic Properties of Rare Earth (Eu, Tm) Implanted InGaN
摘要： The electronic structure and magnetic behavior of InGaN:RE (RE = Eu, Tm) have been studied by using scalar relativistic full-potential linear augmented-plane-wave plus local orbital (FPLAPW + lo) calculations with LSDA+U approximation. Band structure and density of states are analyzed. It appears that the In-site is the preferred site for doping InGaN alloy with rares earth (Eu, Tm) from the formation energy. Our study reveals that these materials are semiconductors with a direct band gap of 1.2345 eV and 1.3657 eV for InGaN:Eu and InGaN:Tm respectively. The total energy of the FM phase is lower than the AFM total energy; this confirms the fact that the ground state at zero temperature is ferromagnetic. A small-induced magnetic moment on other nonmagnetic atoms (Ga, In, and N) and the total magnetic moment of these compounds is mainly due to RE-4f states.
关键词： InGaN alloy,Europium,DMS,Direct band gap,Thulium
更新于2025-09-23 15:22:29
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Half-metallic, Magnetic, and Optical Properties for the (001) Surface of Binary Heusler Alloy MgCl3
摘要： The half-metallic (HM), magnetic, and optical properties for the (001) surface of binary Heusler alloy MgCl3 were investigated by the first-principles method. The Mg*Mg*-term and Mg*Mg-term had the lower surface energies among the ClCl-term, Mg*Mg*-term, ClMg-term, ClCl*-term, and Mg*Mg-term (001) surfaces, thus, they were the more stable surfaces. The band decomposed charge density showed clearly the valence band maximum was contributed not only by the ClB-3p states but also the ClA-3p and ClC-3p states. The HM character was destroyed in all the five terminations of the (001) surface. The stable Mg*Mg*-term (001) surface had the largest spin polarization (≈ 83.0%). The hydrogen-termination effect showed an effective method to enlarge the spin polarizations for the ClCl-term and ClCl*-term surfaces to produce thin films which had potential applications in spintronics. There were great changes of atomic magnetic moments for Cl atoms in any layer. In energy range of 1.6–3.1 eV for the visible light, the Mg*Mg*-term had superiority in the absorption for purple light.
关键词： binary Heusler alloy,Half-metallic property,magnetic property,optical property
更新于2025-09-23 15:22:29
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Epitaxial Growth and Magnetic Properties of NiMnAs Films on GaAs Substrates
摘要： Single-phase Ni0.92Mn1.08As films with strained C1b symmetry are grown on GaAs (001) substrates. In addition, a preferred epitaxial configuration of (110)-orientated Ni0.92Mn1.08As on (001)-orientated GaAs is revealed by synchrotron radiation measurement. The magnetic properties of the films are found to be significantly influenced by the growth temperature and the optimized growth temperature is determined to be ～370°C. According to the results of x-ray absorption spectroscopy, these phenomena can be attributed to the variation of the local electronic structure of the Mn atoms. Our work provides useful information for the further investigations of NiMnAs, which is a theoretically predicted half-metal.
关键词： epitaxial growth,half-metal,Heusler alloy,magnetic properties,NiMnAs
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 8th International Conference on Consumer Electronics - Berlin - Berlin (2018.9.2-2018.9.5)] 2018 IEEE 8th International Conference on Consumer Electronics - Berlin (ICCE-Berlin) - Development of a Mobile App for training health professionals in diagnostic imaging: a progress report
摘要： The paper discusses the development and application of a Noble Metal Alloy (NMA) for enhancing heat transfer processes in diagnostic imaging, specifically designed for use in optoelectronics. It presents a novel approach to improving the efficiency and reliability of imaging devices through advanced material science.
关键词： Noble Metal Alloy,Heat Transfer,Optoelectronics,Material Science,Diagnostic Imaging
更新于2025-09-23 15:22:29
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PdEr-Silicide Formation and Contact Resistivity Reduction to n-Si(100) Realized by Dopant Segregation Process
摘要： In this paper, we have investigated the PdEr-silicide formation utilizing a developed PdEr-alloy target for sputtering, and evaluated the contact resistivity of PdEr-silicide layer formed on n-Si(100) by dopant segregation process for the first time. Pd2Si and ErSi2 have same hexagonal structure, while the Schottky barrier height for electron (Φbn) is different as 0.75 eV and 0.28 eV, respectively. A 20 nm-thick PdEr-alloy layer was deposited on the n-Si(100) substrates utilizing a developed PdEr-alloy target by the RF magnetron sputtering at room temperature. Then, 10 nm-thick TiN encapsulating layer was in-situ deposited at room temperature. Next, silicidation was carried out by the RTA at 500°C for 5 min in N2/4.9%H2 followed by the selective etching. From the J-V characteristics of fabricated Schottky diode, qΦbn was reduced from 0.75 eV of Pd2Si to 0.43 eV of PdEr-silicide. Furthermore, 4.0x10?8Ωcm2 was extracted for the PdEr-silicide to n-Si(100) by the dopant segregation process.
关键词： contact resistivity,PdEr-alloy target,RF magnetron sputtering,schottky barrier height,silicide
更新于2025-09-23 15:22:29
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Structure and cathodoluminescent properties of ultraviolet emitting Zn(Al<inf>1-x</inf> Ga<inf>x</inf>)<inf>2</inf> O<inf>4</inf> alloy phosphor
摘要： The goal is to control the band gap by replacing the Al site of zinc aluminate having a spinel structure with Ga, and to control the emission wavelength, and aim for application as a light source in sterilization, skin treatment and the like. Zn(Al1-xGax)2O4 phosphor was prepared by a solid phase synthesis method. A plurality of samples with different Al/Ga ratio were prepared, and their crystal structures and luminescent properties were evaluated. In X-ray diffraction, formation of a single phase was confirmed in the sample fired at 1300 oC. It was confirmed that the diffraction peak shifted to the lower angle side by increasing the Ga ratio. In the cathode luminescence method, it was confirmed that ultraviolet emission of ZnAl2O4 was confirmed at about 250 nm, and it was confirmed that the emission wavelength shifted to the long wavelength side by increasing the Ga ratio. It is suggested that substituting Ga for the Al site of ZnAl2O4 is useful for shifting the emission wavelength although the emission intensity is unstable.
关键词： Cathodoluminescence,Zn(Al,Ga)2O4,Alloy phosphor,Ultra-Violet emission
更新于2025-09-23 15:21:21