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The phase stability, mechanical properties, and functional properties of Ti–5.5Al–11.8[Mo]eq alloys are focused on in this study by substituting 3d transition metal elements (V, Cr, Co, and Ni) for Mo as β-stabilizers to achieve similar β phase stability and room temperature (RT) superelasticity. The ternary alloy systems with the equivalent chemical compositions of Ti–5.5Al–17.7V, Ti–5.5Al–9.5Cr, Ti–5.5Al–7.0Co, and Ti–5.5Al–9.5Ni (mass%) alloys were selected as the target materials based on the Mo equivalent formula, which has been applied for the Ti–5.5Al–11.8Mo alloy in the literature. The fundamental mechanical properties and functionalities of the selected alloys were examined. The β phase was stabilized at RT in all alloys except for the Ti–Al–V alloy. Among all alloys, the Ti–Al–Ni alloy exhibited superelasticity in the cyclic loading–unloading tensile tests at RT. As a result, similar to the Ti–5.5Al–11.8Mo mother alloy, by utilizing the Mo equivalent formula to substitute 3d transition metal elements for Mo, a RT superelasticity was successfully imposed.

MEMS gas sensors could exert a significant impact on the automotive sector since future legislation is expected to stipulate the monitoring of NOx and unburned fuel gases in vehicle exhausts. Among the materials, zinc oxide and TiO2 are the most promising and extensively used materials for monitoring of NOx gas since zinc oxide and TiO2 show the high sensitivity, good stability, and fast response. Electrochemistry is a potential method to fabricate zinc oxide and TiO2 for the applications since it is carried out at relatively low temperature and can cooperate with photolithography, which is an important process in MEMS. This study integrated zinc oxide/gold-layered structure and TiO2/NiP hybrid structure on elastic fabrics, respectively, to realize an elastic gas sensor. Electroless plating (EP) and cathodic deposition were used to metallize and deposit metal oxides on elastic fabrics. Supercritical carbon dioxide (scCO2) was further introduced into the electrochemical process to enhance the composite reliability.

Capital market investors have limited information about the motives, exchange terms, and expected outcomes of corporate divestitures. Thus, when a firm announces a divestiture, capital markets may have difficulty distinguishing divestitures that are likely to be beneficial and investment worthy from those that signify hidden problems. Drawing on screening theory, we argue that one way investors might overcome their information disadvantages is to use screens to identify investment-worthy divesting firms. We test this logic using one such screen: change in blockholding equity stakes prior to a divestiture announcement. Data from 858 European Union divestitures occurring in 13 Western European Countries show that investors’ reaction to a divestiture announcement is positively associated with pre-divestiture changes in blockholdings in the divesting firm. Furthermore, investors’ valuations were more positive in higher performing divesting firms that had increases in blockholding equity stakes before the divestiture than those that had reductions in these owners’ equity stakes. The findings extend our understanding of how outsiders, such as investors, navigate incomplete information about divestitures. We describe how our study offers a range of implications for divestiture research.

In view of the urgent demands of shape memory alloys (SMAs) for biomedical applications due to the world population aging issue, the mechanical properties and functionalities of the biocompatible Ti-Au-Cr-based SMAs, which are tailored by Ta additions, have been developed in this study. The quaternary SMAs were successfully manufactured by physical metallurgy techniques and their mechanical properties and functionalities were examined. In the continuous tensile tests, it was found that the correlation between the yielding strength and phase stability followed a typical trend of mechanical behavior of SMAs, showing the lowest yielding strength at the metastable β-parent phase. Functional mappings between the alloy strength and elongation revealed that compared to the Ta-free specimen, the ductility was promoted 50% while the strength remained intact through the 4 at.% introduction of Ta. Slight shape recovery was observed in the cyclic loading-unloading tensile tests during the unloading process and the highest shape recovery was found in the Ti-4 at.% Au-5 at.% Cr-4 at.% Ta specimen. This indicates that the 4 at.% Ta tailored Ti-Au-Cr SMAs could be a promising material for biomedical applications.

To enhance the mechanical properties (i.e. strength and elongation) of the face-centered cubic (fcc) α-phase in the Au-Cu-Al system, this study focused on the introduction of the martensite phase (doubled B19 (DB19) crystal structure of Au2CuAl) via the manipulation of alloy compositions. Fundamental evaluations, such as microstructure observations, phase identifications, thermal analysis, tensile behavior examinations, and reflectance analysis have been conducted. The presence of fcc annealing twins was both observed in the optical microscope (OM) and the scanning electron microscope (SEM) images. Both the strength and elongation of the alloys were greatly promoted while the DB19 martensite phase was introduced into the alloys. Amongst all the prepared specimens, the 47Au41Cu12Al and the 44Au44Cu12Al alloys performed the optimized mechanical properties. The enhancement of strength and ductility in these 2 alloys was achieved while the stress plateau was observed during the tensile deformation. A plot of the ultimate tensile strength (UTS) against fracture strain was constructed to illustrate the effects of the introduction of the DB19 martensite phase on the mechanical properties of the alloys. Regardless of the manipulation of the alloy compositions and the introduction of the DB19 martensite phase, the reflectance stayed almost identical to pure Au.

The requirements for biomedical materials have been raised greatly due to the rapidly aging global population. Shape memory alloys (SMAs) are indeed promising materials for biomedical applications due to their controllable shape deformation via the manipulation of temperature and/or stress. This study investigated the enhancement of the fundamental mechanical properties and the shape memory effect (SME) in the Ti–Cr–based alloys via the modification of Au and Cu. The quaternary Ti–Cr–Au–Cu alloys were successfully manufactured by physical metallurgy methods and their phase constitutions, mechanical properties, SME, and superelastic (SE) behaviors have been investigated in this study. Cold–workability, which was enhanced by the introduction of the Au element, was elaborated by the phase constitutions of the alloys. The β–parent phase was stabilized to around body temperature by the introduction of the β–stabilizers of Cr, Au, and Cu, and the functionalities of the specimens were revealed at the operating temperature. Perfect SME at the shape recovery rate of 100% was practiced by the substitution of Au by Cu and the mechanical properties, such as strength and ductility, were also enhanced. Functional mappings of the fundamental mechanical properties, which could be a helpful tool for the investigations of the quaternary Ti–Cr–Au–Cu alloys, were constructed in this work.

In view of the exponential rate of advancement in robotics technology, a composite material, which is promising for high-speed and large-strain actuation and sensing applications, has been developed in this study. Single-crystalline Ni49.9Mn28.5Ga21.6 (SC Ni-Mn-Ga) ferromagnetic shape memory alloy particles were fabricated from the polycrystalline Ni-Mn-Ga alloy by a well-controlled mechanical crushing. X-ray diffractions revealed a mixture of 5M- and 7M-martensitic phases in the SC Ni-Mn-Ga particles. A composite consisting of the silicone rubber and 20 vol.% of the crystallographically and spatially oriented SC Ni-Mn-Ga particles was fabricated by curing under a magnetic field and the chain-oriented structure was confirmed by a micro-computed tomography. This composite, which exhibited a magnetic field induced rubber-like behavior with a magnetostrain as high as 4.0% despite reduced filling factor, was attributed to the co-existence of the 5M- and 7M-martensitic phases.

The Au–Cu–Al biocompatible shape memory alloys (SMAs) have attracted much attention due to the requirements of biomedical applications. However, brittleness remains a critical issue in the intermetallics of Au–Cu–Al alloys. In this study, to solve the dilemma of embrittlement, Ag was introduced into the Au–Cu–Al alloy to realize the ductile phase toughening (DPT) since the ductile disordered–fcc phase was predicted to precipitate in the brittle parent β phase based on the Ag–Au–Cu phase diagram. Microstructure observations, chemical composition analysis, crystal structure identifications, and thermal analysis revealed that the Au–28Cu–16Al–28Ag (mol.%) alloy was mainly composed of the Ag–rich α1 primary solidification phase with disordered–fcc structure and the eutectic structure of the α1 phase and the β phase with L21 structure. The ductile phase was successfully inserted into the brittle Au–Cu–Al intermetallic while the martensitic transformation temperature and crystal structures remained almost uninterrupted. In the cyclic loading–unloading tensile tests, the alloy mainly composed of the β phase failed in the early elastic region due to its embrittlement; while the alloy mainly composed of the α1 phase performed 29% in the total strain deformation. The Au–28Cu–16Al–28Ag alloy, which is composed of the β phase and the α1 phase, solve the issue of embrittlement; in addition, shape recovery was also found in this alloy during unloading. According to the microstructure observations, cyclic tensile tests, and fracture surface observations, the aforementioned improvement of strengthening and enhancement of ductility were brought from the insertion of the ductile α1 phase into the brittle β/β grain boundaries.

Owing to the world population aging, biomedical materials, such as shape memory alloys (SMAs) have attracted much attention. The biocompatible Ti–Au–Ta SMAs, which also possess high X–ray contrast for the applications like guidewire utilized in surgery, were studied in this work. The alloys were successfully prepared by physical metallurgy techniques and the phase constituents, microstructures, chemical compositions, shape memory effect (SME), and superelasticity (SE) of the Ti–Au–Ta SMAs were also examined. The functionalities, such as SME, were revealed by the introduction of the third element Ta, in addition, obvious improvements of the alloy performances of the ternary Ti–Au–Ta alloys were confirmed while compared with that of the binary Ti–Au alloy. The Ti3Au intermetallic compound was both found crystallographically and metallographically in the Ti–4 at.% Au–30 at.% Ta alloy. The strength of the alloy was promoted by the precipitates of the Ti3Au intermetallic compound. The effects of the Ti3Au precipitates on the mechanical properties, SME, and SE were also investigated in this work. Slight shape recovery was found in the Ti–4 at.% Au–20 at.% Ta alloy during unloading of an externally applied stress.

The effects of the Cr and Sn addition concentrations on the cold–workability, phase constituents, mechanical properties, shape memory effect (SME), and superelasticity were investigated. A systematic screening of the β–Ti alloy, which was slight–alloyed by Cr and Sn, was executed in this work. Cold–workability of the Ti–Cr–Sn alloys was greatly promoted along with the increasing concentration of Cr and Sn. The parent β–phase was successfully stabilized at room temperature merely by the slight introduction of Cr and Sn β–stabilizers. Perfect SME of 100% recovery rate was realized in the Ti–5.5Cr–3Sn alloy and the shape recovery rate performed a good inclination with the overall Cr + Sn addition concentration in the bending tests. Obvious two–stage yielding, which inferred the stress–induced martensitic transformation (SIMT) and/or martensite variant reorientation (MVR) before yielding, was observed in the tensile tests. The two–stage yielding also explained the SME well. The excellent elongation of 40% and 45%, which were found in the Ti–6.0Cr–3Sn and the Ti–6.0Cr–2Sn alloys, was explained by the {332} mechanical twinning. Slight pseudoelasticity was also found in most of the specimens. Functional mappings of the Ti–Cr–Sn alloys, which could be powerful tools for future investigations, have been constructed in this study. The Ti–6.0Cr–3Sn alloy, which possessed high ultimate tensile strength, excellent ductility of 40%, outstanding SME of 91.0%, and good shape recovery after removing the external stress, could be a promising material for the applications in biomedical materials.

Functional materials for biomedical and biomaterial applications, such as shape memory alloys (SMA), are important topics among the critical population aging issues. The Ti–Au–Mo alloys, which possess biocompatibility, good X–ray contrast, and excellent functionalities, were conducted in this study towards biomedical applications. The near–eutectoid Ti–4 at.% Au–5 at.% Mo specimens were prepared by the physical metallurgy methods, and the effects of the aging temperature on the phase constitutions, microstructures, mechanical properties, thermal properties, and shape memory effect (SME) were analyzed. The hardness and strength of the aging–treated specimens were clearly enhanced due to the formation of the precipitates. Elevating the aging temperature could be a strategy for the elimination of the undesired brittle ω–phase and the elongation was enhanced accordingly. Excellent shape recovery was found at 89% upon heating. The phase transformation between the β–phase and the α′′–martensite phase under stress and thermal treatments was conducted and explained. This study systematically screened the fundamental properties at various aging temperatures of the near–eutectoid Ti–4 at.% Au–5 at.% Mo SMA, which could be a guideline for further researches of the promising Ti–Au–Mo specimens.

Sn-Ag-Zn alloys are promising Pb-free solders. In this study, the Sn-Ag-Zn liquidus projection was determined, and the Sn-Ag-Zn thermodynamic modeling was developed. Various Sn-Ag-Zn alloys were prepared. Their as-cast microstructures and primary solidification phases were examined. The invariant reaction temperatures of the ternary Sn-Ag-Zn system were determined. The liquidus projection of the Sn-Ag-Zn ternary system was constructed. It was found that the Sn-Ag-Zn ternary system has eight primary solidification phases: e2-AgZn3, γ-Ag5Zn8, β-AgZn, ζ-Ag4Sn, (Ag), e1-Ag3Sn, β-(Sn) and (Zn) phases. There are eight ternary invariant reactions, and the liquid + (Ag) = β-AgZn + ζ-Ag4Sn reaction is of the highest temperature at 935.5 K. Thermodynamic modeling of the ternary Sn-Ag-Zn system was also carried out in this study based on the thermodynamic models of the three constituent binary systems and the experimentally determined liquidus projection. The liquidus projection and the isothermal sections are calculated. The calculated and experimentally determined liquidus projections are in good agreement.

This study reports preparation and characterization of biocompatible, conductive, and flexible silk–Pt composite materials for applications in wearable and medical devices. The distinct Pt and silk materials were integrated via supercritical carbon dioxide (sc-CO2) promoted electroless plating. Sc-CO2 was introduced into the catalyzation step, which is a critical step in electroless plating, to overcome the common difficulty of inlaying the catalyst into the textile substrate. High surface coverage and thick Pt layer were constructed as the metallization time extended. Metal ions released in a simulated body fluid in an immersion test were negligible when compared to the daily metal input and output of the human body. The composites showed high corrosion resistances in both 3.5 wt % NaCl and simulated body fluid solutions. The electrical conductivity and corrosion resistance persisted after the adhesion tests. The assessments revealed the applicability of this silk–Pt material to wearable and medical devices.

Along with the rise of diabetes mellitus issue, glucose sensor has become an imperative tool for healthcare. Studies have been widely conducted on electrode materials for glucose sensors; metal nanoparticles and/or oxide particles in its nano-size are reported to exhibit remarkable electrocatalytic activities in the non-enzymatic glucose sensors. However, the decoration processes of metal nanoparticles or nano-sized oxides are known to be tedious and time-consuming. In addition, the processes usually result in great amount of waste solution emission. In this study, therefore, an Au nanoparticles (NPs)-TiO

Sensors for precise detection of alcohols are needed in various applications. One challenge of such sensors is to obtain high selectivity. By modifying a conducting polymer with metal catalyst, reaction kinetics can be improved. Previous research shows detection only in the liquid phase. In this paper, gas phase detection of propanol using atomic gold decorated polyaniline sensor is reported. Difference is seen from the cyclic voltammogram obtained with and without catalyst.

Since the invention of triboelectric nanogenerators (TENGs), many approaches have been proposed to enhance their performances by modifying the triboelectric materials, mostly attributed to the increase in work function differences or effective contact area. In the work, we firstly demonstrate the output performance enhancement distinctly by the effect of surface dipoles rather than the common approaches. By bonding copper ions onto the oxygen-containing functional groups of graphene oxides, the orientations of surface molecular dipoles are inverted, leading to the output enhancement of the TENG. Interestingly, the variations of the output performances of the TENGs with surface modifications are just opposite to the predictions from the differences in work functions, measured by Kelvin probe force microscopy. The work implies that other important factors dominating the performances of TENGs than work functions. A self-bias-enhancement model by surface dipoles is proposed and testified by further polling processes. The mechanisms should be universal to other materials for enhancing the performances of TENGs and self-powered devices.

The recently developed dipole-based surface-enhanced Raman scattering (SERS) technique has opened a new opportunity to fabricate high-performance sensing platforms with advantages including molecular identification abilities, decreased costs, and high sensitivity. Although extensive efforts have been devoted to increasing the area density of molecular dipoles on graphene to improve sensing sensitivity, limited dipole moments hinder them from further enhancement and applications. Here, we propose a versatile approach to significantly increase the dipole moments of oxygen-containing functional groups (OFGs) on graphene using cation bonding. Taking Cu2+ as a model, dozens of enhancements in dipole moments are demonstrated using theoretical calculations as confirmed by SERS measurements, and a comparison is made with general OFGs and graphene oxide-based SERS platforms. The outstanding contribution of Cu OFG bonds to SERS is proven using IR, XPS, and EFM, where electromagnetic and typical chemical mechanisms are excluded by the TEM and UPS results. The as-prepared Cu-OFG SERS platforms not only show a high sensitivity to Rhodamine 6 G (10−10 M), but also demonstrate their further applications in detecting trace nitrate (10−10 M), a harmful substance in drinking water, and thiabendazole (0.01 ppm), a parasiticide for fruits. The cation bonding strategy applies to various cations to fabricate excellent versatile SERS platforms for use in various fields, such as trace poison detection and biomedical sensing.

The effects of Cr and Sn additives on the phase constitution, lattice deformation strain, transformation temperature, and deformation behavior of Ti-Cr-Sn alloys were systematically investigated to inform the development of a superelastic alloy with high lattice deformation strain. The addition of Cr and Sn changes the reverse martensitic transformation temperature by −190 K/mol% Cr and −141 K/mol% Sn, respectively. The lattice deformation strains (η1, η2, and η3) were evaluated in terms of the lattice parameters of the parent β phase to the martensite α″ phases. In addition, the composition range of the alloys that are expected to exhibit superelasticity and high deformation strain near the human body temperature was established based on the composition dependence of lattice deformation strain and transformation temperature. The deformation behavior of Ti-Cr-Sn alloys at room temperature changes from the shape memory effect to superelasticity with increasing Cr and Sn contents. In particular, Ti-2.5Cr-8.5Sn, Ti-3.0Cr-7.5Sn, Ti-3.0Cr-8.0Sn, Ti-3.5Cr-7.0Sn, and Ti-4.0Cr-6.5Sn alloys exhibit superelasticity at room temperature and a high lattice deformation strain (η2) that exceeds 6.32%. It is concluded that Cr and Sn are more effective than other β-stabilizing elements at lowering the martensitic transformation temperature of β-Ti shape memory alloys without reducing the lattice deformation strain.

A series study of the ternary near–eutectoid Ti–Au–Cr shape memory alloys (SMA) at the Ti–rich corner was explored in this work towards the applications of biomedical materials. Fundamental analysis, such as microstructures, phase constitutions, lattice parameters, and mechanical properties of the specimens, were examined along with their functional properties, such as shape memory effect (SME) and superelasticity (SE). Most of the alloys possess good cold–workability except for those with great amounts of precipitates of the brittle Ti3Au at the high Au addition specimens. The Ti–4Au–8Cr alloy excelled in strength while the Ti–2Au–8Cr alloy surpassed other alloys in ductility. Most of the specimens possess SME as well as pseudoelasticity and/or superelasticity indicating the functionality of the Ti–Au–Cr alloys towards biomedical applications. The discrimination between the α′–martensite phase and the α′′–martensite phase was conducted by the TEM observation. The α′–martensite phase, which unexpectedly performed SME in this study was determined to locate exactly at the boundary of the α′–martensite regime and the α′′–martensite regime. The SME of the alloys, which were composed of the α′–martensite phase, were thus deduced to originate from the similarity of the α′–martensite and the α′′–martensite.

Influences of the Fe addition in various concentrations on the near–eutectoid Ti–4Au alloys were systematically investigated in this study in consideration of the great number of requirements for the biomedical materials. The Ti–4Au–xFe (x = 1, 3, 4, 5, 6, and 7 at.%) alloys were synthesized by physical metallurgy and their microstructures, crystal structures, lattice parameters, phases, and mechanical properties were analyzed. In addition, the investigations for the shape memory effect (SME) and superelasticity (SE) were also conducted to examine their performances of functionality. The β–phase was stabilized at room temperature by the 3 at.% addition of Fe into the binary Ti–4Au alloy. The specimen with optimized mechanical properties by trading–off its strength and ductility was found in the Ti–4Au–4Fe alloy. SME was revealed clearly in the Ti–4Au–3Fe alloy and slightly in the Ti–4Au–4Fe alloy; while SE was observed in the Ti–4Au–4Fe alloy. It was observed that there was a growing trend of the Ti3Au precipitate amount with the raised concentration of Fe addition. The precipitates of the Ti3Au were fine–tuned by the Fe addition for tailoring the various mechanical properties of the ternary Ti–4Au–xFe alloys, and the balanced performance was achieved by the 4 at.% Fe addition.

Ge doped Cu 3 SbSe 4 semiconductors with Cu deficiencies were synthesized by melting and spark plasma sintering for the investigation of their thermoelectric transport properties. Ge atoms can successfully substitute Sb lattice sites, and result in lattice shrinkage with increasing Ge content. Doping with Ge not only improves the electrical conductivity but also optimizes the power factor of Cu 2.95 (Sb 1−x Ge x )Se 4 . Ge doped specimens also reveal a competition between alloying effects and increased carrier thermal conductivity. The zT enhancement of Ge doped alloys is mainly ascribed to the enhanced power factor and the reduced lattice thermal conductivity. As a result, Cu 2.95 (Sb 0.96 Ge 0.04 )Se 4 reaches a maximum zT of 0.7 at 640 K, showing an approximately 35% enhancement over the pristine Cu 2.95 SbSe 4 .