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Introduction
Education
September 2005 - December 2009
Publications
Publications (50)
AgSbTe2 plays a pivotal role in mid-temperature thermoelectric generators (TEGs). Leveraging the seminal advances in cation manipulation within AgSbTe2, this study demonstrates an enhanced TE power factor (PF = S2σ) of 1.5 mWm-1 K-2 and a peak zT of 1.5 at 583 K in an off-stoichiometric Ag1.04Sb0.96Te2 crystal. The introduction of Ge in place of Ag...
This study reports a simplified method to grow CuAlO2 crystals of submillimeter sizes with a highly anisotropic shape of a platelet. The solid-state reaction of forming CuAlO2 at ca. 1373 K in the first stage of the conventional flux method is no longer required. The CuAlO2 platelets nucleated directly onto the (0001)sapphire surface in a melt of C...
Thermoelectrics
In article number 2201802 by I-Lun Jen, Kuang-Kuo Wang, and Hsin-Jay Wu, aliovalent cation substitution fulfilling by dilute gallium (Ga) ions diminishes the highly-mobile zinc (Zn) ions in zinc antimonide (Zn4Sb3) and optimizes the hole carriers, leading to an ultrahigh thermoelectric power factor. The interstitial metallic Ga elic...
Thermoelectric (TE) generators have come a long way since the first commercial apparatus launched in the 1950s. Since then, the β‐Zn4Sb3 has manifested its potential as a cost‐effective and environmentally friendly TE generator compared with the tellurium‐bearing TE materials. Although the β‐Zn4Sb3 features an intrinsically low thermal conductivity...
Cubic β-GeTe alloys are apt to hoist the conversion efficiency for mid-temperature thermoelectric (TE) generators with their remarkably high peak figure-of-merit (zT) values at T > 700 K. Nevertheless, the TE device that consolidated by β-GeTe alloys have existed concerns as the rhombohedral α-GeTe to β-GeTe phase-transition leverage over the worka...
Mechanical energy-induced deposition on NiTi shape memory alloys (SMAs) is difficult to accomplish due to the pseudoelasticity of NiTi SMAs. In this study, a high-frequency ball-bombardment method called ultrasonic mechanical coating and armouring (UMCA) is introduced to synthesize a hydroxyapatite (HA)-containing coating on a NiTi SMA. The effects...
In the present work, nanostructured hydroxyapatite (HA)-containing coating was prepared on a Ti surface by ultrasonic mechanical coating and armoring (UMCA). A Ti plate was pre-coated with HA slurry, followed by UMCA, which was achieved by high-frequency ZrO2 ball bombardment. The UMCA process comprised several cycles of pre-coating and ball bombar...
The bismuth-tellurides have never ceased as the best candidates for thermoelectric (TE) coolers since the beginning of manufactures in the 1960s. As the years passed, the effort in boosting their performance continues abreast of breakthroughs in the conversion efficiencies with the occasional setbacks from the n-type alloys. Herein, a synergistic a...
In article number 2005612, Pai‐Chun Wei, Hsin‐Jay Wu, and co‐workers leverage the interplay between the spinodal decomposition and athermal phase transition in GeTe‐based thermoelectric materials. The exquisite microstructure, featured by strong composition fluctuations and the coexistence of rhombohedral‐ and cubic‐GeTe, yield high zT values of >2...
Phase transition in thermoelectric (TE) material is a double‐edged sword—it is undesired for device operation in applications, but the fluctuations near an electronic instability are favorable. Here, Sb doping is used to elicit a spontaneous composition fluctuation showing uphill diffusion in GeTe that is otherwise suspended by diffusionless atherm...
The orientation relationships and interfacial planes of the theta (θ)-Al2Cu/Cu and gamma2 (γ2)-Al4Cu9/Cu interfaces formed on the Cu (001) and (111) surfaces have been studied by transmission electron microscopy (TEM). Epitaxial thin Cu films are grown on the single-crystal NaCl surfaces and then Al is evaporated to form θ-Al2Cu and γ2-Al4Cu9. Resu...
PbTe‐based alloys have been widely used as mid‐temperature thermoelectric (TE) materials since the 1960s. Years of endeavor spurred the tremendous advances in their TE performance. The breakthroughs for n‐type PbTe have been somewhat less impressive, which limits the overall conversion efficiency of a PbTe‐based TE device. In light of this obstacle...
In recent years the emerge of high-entropy alloys (HEAs) imposes an evolution in metallic materials, which breaks the boundaries set by the traditional alloys. Alongside the development of HEAs, the medium-entropy alloys (MEAs), which comprise two to four majority elements, also reveal the outperforming properties with less compositional complexity...
The characterization of the FeAl intermetallic layer formed at the FeZn interface of a Zn-5 wt.% Al coating is presented in this paper. The interfacial layer was solely composed of Fe4Al13-xZnx crystals, but it exhibited different morphologies. The layer formed on α-Fe grains, having orientations of <100>//ND or <110>//ND, was smooth with a uniform...
Zn4Sb3-based compounds constitute a lead-free material family with its best thermoelectric figure of merit (zT) in the mid-temperature range. Unlike being a stoichiometric compound, the mutual solubility of Zn and Sb elicits rich microstructures and structural instability of Zn4Sb3. The solubility limit and neighbouring phase relations are crucial...
A superhydrophobic surface of titanium was fabricated by anodization in sodium chloride solution followed by immersion in perfluorodecyltriethoxysilane. The surface characteristics of the anodic film (morphology, composition, microstructure, and adhesion) were investigated by scanning electron microscopy, transmission electron microscopy, X‐ray pho...
The initial reaction between Pt and molten Sn has been studied by dipping tests of 1 and 2 s. It was found that both PtSn and PtSn4 formed in the first second of contact. PtSn formed 7 nm (1 s) and 20 nm (2 s) thick layers on top of the Pt substrate but PtSn4 formed scattered particles in the liquid Sn. No orientation relationship was found between...
The formation of Fe2Al5-xZnx inhibition layer at the Fe-Zn interface has been characterized by scanning electron microscopy/electron backscatter diffraction and transmission electron microscopy for interstitial-free steels galvanized in Zn baths containing 0.14–0.28 wt% Al. The inhibition layer formed in the 0.14 wt% Al bath is composed of fine, eq...
In this study, ultrasonic mechanical coating and armoring (UMCA) with subsequent annealing is applied to improve surface hardness of Al. The micro-scaled CuO powders are bombarded and inserted into Al by UMCA, leading to the increment in surface hardness by 6 times. The grain refinement, work hardening and dispersion hardening are contributed to su...
It has been demonstrated that the Al-Ni-Y based thin film metallic glass composites (TFMGCs) can provide high optical reflectivity, especially over the UV regime, suitable for various optical devices such as optical coating or as functional layer. When such optical devices are applied in humid environment which is sensitive to bacteria or fungus, t...
This paper describes the fabrication of superhydrophobic NiTi shape memory alloy (SMA) surfaces using an environmentally friendly method based on an economical anodizing process. Perfluorooctyltriethoxysilane was used to reduce the surface energy of the anodized surfaces. The wettability, morphology, composition, and microstructure of the surfaces...
A novel dry mechanical coating method producing by ultrasonic vibration is used to plate Sn on Cu. The Sn is plated on the Cu surface in ambient atmosphere at room temperature by high-velocity collision process between Sn powders and hard steel balls in a vibration chamber. The scanning electron microscopy (SEM), X-Ray Diffraction (XRD) and transmi...
This study presents a high-efficiency solar concentrator that can use full spectrum solar energy via reflecting ultraviolet (UV) to near-infrared (NIR) spectrum (300-996 nm) while transmitting NIR spectrum (>996 nm), making it ideal for cold and thermal condensing applications. The concentrator that comprises a primary parabolic reflector, a second...
Aluminum alloys, applied as heat sink, are often inherent with high thermal conductivity but poor infrared radiation emissivity. Thus high emissivity coating is often added on the Al substrate in decreasing surface temperature by radiation. In this study, efforts were made in using the ultrasonic mechanical coating and armoring (UMCA) technique to...
The Fe-Al intermetallic compounds formed at Fe-Zn interface during galvanizing the interstitial-free (IF) steels in Zn-Al-Mg baths have been analyzed by scanning electron microscopy/electron backscatter diffraction and transmission electron microscopy. The interfacial compounds formed on the IF steel hot-dipped in a 0.28wt% Al-0.28wt% Mg bath was t...
Galvannealing the Mn-Si transformation induced plasticity (TRIP) steels is a challenging task because the Fe-Zn reactions are interfered by the oxides formed during intercritical annealing. In this study, the coatings of Mn-Si TRIP steels after galvannealing were characterized mainly by cross-section transmission electron microscopy. Two TRIP steel...
TiO2 anatase has been routinely prepared by a sol–gel method. The purpose of this research is to study if TiO nanocrystals are present which can lead to the formation of anatase. Amorphous powders were first prepared and subsequent thermal annealing in air was used to form anatase. X-ray diffraction and transmission electron microscopy (TEM) were u...
This study investigated the interaction between the Al in the Zn bath
and the surface oxides formed by selective oxidation on a
1.2Si-1.5Mn TRIP steel during hot-dip galvanizing. XPS and TEM
were employed for characterization. The results indicated that the
amorphous xMnO·SiO2 oxide could react with Al to form
a Si-Mn-Al-containing oxide. The cryst...
The present study aims at clarifying the oxides that form on the surface of a 1.2Si-1.5Mn (in wt%) transformation-induced plasticity (TRIP) steel during intercritical annealing. X-ray photoelectron spectroscopy and transmission electron microscopy were employed as complementary tools for analyzing the oxides. The results indicate that both the dew...
Anodic oxidation followed by hydrothermal treatment has been widely applied for surface modification of titanium alloys to precipitate a crystalline hydroxyapatite (HA) layer in order to achieve improved osteoconduction. A majority of the studies in the literature imposed relatively high powers to enhance Ca and P in the anodic oxide film (AOF). Ho...
The formation of the Fe-Al inhibition layer in hot-dip galvanizing is a confusing issue for a long time. This study presents a characterization result on the inhibition layer formed on C-Mn-Cr and C-Mn-Si dual-phase steels after a short time galvanizing. The samples were annealed at 800^{\circ}C for 60 s in N_{2}-10% H_{2} atmosphere with a dew poi...
A very thin η-Cu6Sn5 layer has been formed by dipping thin Cu foil into molten Sn at 240°C for 1s and quenching in ice water. After removing electrolytically the Sn on the surface, the η-Cu6Sn5 grains on the Sn side are shown to have a worm-type shape 0.3–0.5μm wide and up to 2μm long. Transmission electron microscopy (TEM) analysis shows that the...
The orientation relationships and interfaces of δ-AuSn with the Au (001), (110) and (111) surfaces have been studied with transmission electron microscopy. Au was evaporated onto the NaCl (001), (011) and (111) surfaces to form epitaxial Au thin films and Sn was evaporated onto the Au films to form δ-AuSn. Two types of orientation relationships hav...
This work presents characterization results on inhibition layers formed on a TiNb-stabilized interstitial-free steel after short time galvanizing. The Fe-Al and steel interface was free from oxide, so that the Fe-Al intermetallic compound could directly nucleate on ferrite grains. Electron diffraction performed in a transmission electron microscope...
The microstructure of η′-Cu6Sn5 during the early stage of growth was studied. Sn was electroplated onto thin Cu foil at room temperature and the specimen was annealed at 150 °C for 30 s. The Cu and Sn on the η′-Cu6Sn5 surfaces were removed electrolytically and the specimens were analyzed by scanning and transmission electron microscopy. The η′-Cu6S...
Questions
Questions (7)
Now, I am trying to deposit pure Al film onto PMMA(acrylic) surface by e-beam system. however,I found out that it had poor adhesion between pure Al and PMMA.
Dose anyone/expert can provide any information or suggestion relating to how to increase the adhesion between pure Al and PMMA for me. Example, what cleaning process, buffer layer or anything I can use it. Thank you for help in advance.
I am planning to deposit metal film by E-beam on PMMA and BK7 glass with mirror face. In order to increase reflective of UV(365~405nm in wavelength) light, we must search applicable coating/thin film for optical reflective lens under exposure process. Does anyone can provide relevant information/suggestion to me? Thank you in advance.
I try to prepare the Ni-Ti alloy by vacuum melting method and then perform press forging and rotary swaging in sequence. However, I observed a external crack with ~5 mm in length on the surface of Ni-Ti bar in the swaging step. It is sometime occurrence. Can anyone help me to explain the phenomenon? Thank you for your help in advance.
Can anyone suggest or provide about chemical etching or electrolytic polishing method or relevant information for pure copper.
I have surveyed some materials such metal matrix composites(MMCs), ceramic and foamed metal with good damping capacity to absorb noise and wave propagation. i.e. with high shock absorption property. However, I would like to realize whether the microstructure of metal (such as grain shape, grain size, grain boundary, dislocation, and subgrain .etc.) is relative to damping capacity. Consequently, can anyone give me relevant information/advice? Thanks you in advance.
