In this study, we propose a Se-incorporated Ge10Sb90 as a phase-change material for phase-change memory (PCM) with high reliability and low operation power. We investigated the effect of the Se concentration on the thermal and electrical properties of Se-doped Ge10Sb90 films by varying the Se concentration from 0 to 20 at.%. The crystallization temperature, crystallization activation energy, and maximum ten-year data retention temperature increased with the increasing Se, thus demonstrating the improved thermal stability of Se-doped Ge10Sb90 films with higher Se contents. More Se also increased the rate factor, band gap, threshold voltage, and load resistance. In addition, the crystallization speed, programming window, and resistances of both the amorphous and crystalline states increased with the increasing Se concentration. In contrast, the reset current decreased with the increasing Se concentration. These results demonstrate that Se-doped Ge10Sb90 is a highly promising material for PCM applications.

The spectrally and temporally resolved luminescence of three-dimensional (3D) InGaN/GaN microrods and planar light emitting diode (LED) structures is studied for different energy densities of fs-laser excitation pulses and for different sample temperatures. We find an energy density threshold above which irreversible modifications of the structures take place, which leads to a decrease of the luminescence intensity and a change in the intensity ratio of the GaN to the InGaN luminescence. Due to the quantum confined Stark effect, a biexponential decay characteristic is found in the planar structure, while the 3D microrods with nonpolar InGaN quantum wells on their sidewalls show a monoexponential decay of the InGaN luminescence. For both structures, the decay of the luminescence becomes faster with increasing energy density per pulse. However, the luminescence of the planar LED decays faster with increasing temperature, while the opposite trend is found for the 3D sample.

We describe the main experimental challenges toward the metrological calibration of photodetectors based on single semiconductor nanowires, and we propose a method for the quantification of their photoresponse, focusing in particular on GaAs nanowires. Spatially resolved measurements of the device’s photocurrent were performed with a far-field scanning optical setup and a laser excitation at λ = 656 nm. The photoresponse was quantitatively described by fitting the two-dimensional mapping of the photocurrent at different positions along the main nanowire axis. Our results indicate that the device’s photoresponse strongly depends on the position along the nanowire, which is attributed to the inhomogeneous properties of the device’s contacts. Furthermore, we show that its spatial profile across the nanowire can be directly compared with the profile of the laser beam by taking into account the angle between the scanning direction and the main nanowire axis as a geometrical factor. Finally, we discuss the impacts of laser-induced heating effects on the calibration of such nanoscale devices.

0.62[0.75(Pb(Mg1/3Nb2/3)O3)–0.25(Pb(Yb1/2Nb1/2)O3)]–0.38(PbTiO3) ceramics were successfully textured in [001] via the template grain growth method using 1–7 vol% platelike BaTiO3 (BT) templated (the Lotgering factor of 0.91 at 5 vol% BT). Dielectric spectra indicated a normal ferroelectric behavior without any frequency dispersion and no low-temperature phase transition. The chemically stable BT phase within the matrix gave rise to a composite effect and its relatively inferior properties affected the dielectric and electromechanical properties. The lower T C of the BT decreased the Curie temperature from 226 to 213 °C (with a depolarization temperature of 204 °C). Significantly higher levels of strain (0.33%), narrower hysteresis level (7.7%), higher piezoelectric strain coefficient (660 pm/V), and low-field (<5 kV/cm) piezoelectric strain coefficient (1340 pm/V) at 50 kV/cm were achieved at 5 vol% BT addition. These results are very promising for the fabrication of high performance transducer and actuator applications without severe temperature limitations.

For the first time, valence electron energy-loss spectroscopy (VEELS) was applied to individual single-crystalline SnO2 nanowires to investigate the dielectric function, band gap, and optical absorption coefficient. The results are compared with data from optical techniques such as spectroscopic ellipsometry and UV-Vis, and theoretical calculations from variations of density functional theory. The data obtained agree well with the standard optical and theoretical techniques. The dielectric function and optical absorption coefficient are given up to 20 eV, which otherwise requires a synchrotron source and large single crystals via optical methods. The energy loss function is given up to 40 eV, which gives a useful comparison to previous theoretical studies in an energy range that cannot be achieved via optical measurements. The comparison gives confidence in the accuracy of this method for exploring spatially-resolved measurements in individual nanoparticles or more complex nanostructures that are otherwise difficult to measure accurately using optical techniques.

In this work, a three-dimensional (3D) porous hybrid nickel/aluminum layered double hydroxide (Ni/Al-LDH)-carbon cloth (CC), the working electrode without binders or conductive additions for supercapacitor, was successfully synthesized via facile one-step hydrothermal method. The as-obtained Ni/Al-LDH/CC sample exhibited good charge storage performance (the specific capacitance was up to 359 F/g at a current density of 0.3 A/g), as well as superior cycling stability (5.9% capacitance increase after 3000 cycles at 1.0 A/g). Furthermore, an asymmetric supercapacitor, Ni/Al-LDH/CC as positive electrode and activated carbon (AC) as negative electrode (Ni/Al-LDH/CC//AC), achieved a high energy density (20.9 Wh/kg vs. the power density 262.5 W/kg) and good cycle lifetime (83.9% retention of the initial value after 3000 cycle tests at a current density of 0.5 A/g). The unique 3D porous structure and binder-free electrode display great potential in supercapacitors.

Calcium-based renal calculi demonstrated significant heterogeneity in the structure, density, mineral composition, and material hardness not elucidated by routine clinical testing. Mineral density distributions within calcium oxalate stones revealed differential areas of low (590±80 mg/cc), medium (840±140 mg/cc), and high (1100±200 mg/cc) densities. Apatite stones also contained regions of low (700±200 mg/cc), medium (1100±200 mg/cc), and high (1400±140 mg/cc) densities within layers extending from single or multiple nucleation sites. Despite having lower average mineral density, calcium oxalate (CaOx) stones demonstrated higher material hardness compared to apatite stones, suggesting other chemical components might be involved in determining stone hardness properties. Carbon concentrated sites were identified between morphologic layers in CaOx stones and in stratified layers of apatite stones. Elemental analyses revealed numerous additional trace elements in both stone types. Despite the widespread assumption that stone mineral density is an indicator of susceptibility to lithotripsy, calcium stone mineral density estimates do not directly correlate with actual ex vivo stone hardness. Underlying stone heterogeneity in both structure and mineral density could explain why historical approaches have failed in accurately predicting response of stones to lithotripsy.

A superelastic Ti–40Nb alloy enhanced with Cu element (0, 2.5, 5, 7.5, and 10 wt%) was synthesized by a spark plasma sintering method to obtain biomaterials with an antimicrobial effect. The microstructure results showed that β phase was the main phase in (Ti–40Nb)–Cu alloys while Ti2Cu was synthesized with the Cu addition above 5 wt%. (Ti–40Nb)–Cu alloys exhibited high compressive strength over 1693.08 MPa, high yield strength of 1140.26–1619.14 MPa, low elastic modulus in the range of 43.91–58.01 GPa, low elastic energy (14.81–24.73 MJ/m3), and together with large plastic strain over 18.5%. High concentration of Cu ion released steadily from alloys in early 7 days, then the released concentration of Cu ion showed long-lasting and moderate. Comparing with the Ti–40Nb alloy, high antimicrobial activity was pronounced on (Ti–40Nb)–Cu alloys, and (Ti–40Nb)–Cu alloys showed more inhibitory activity against bacteria (E. coli and S. aureus) than fungi (C. albicans). Cu contents in alloys influenced the Cu ion release, which in turn affected the antimicrobial activity. As a good combination of low elastic modulus, high mechanical properties, good elastic energy, and excellent antimicrobial performance, (Ti–40Nb)–Cu alloys offer potential advantages to prevent stress shielding and exhibit an excellent antimicrobial property for hard tissue replacements.

Cellular elasticity is frequently measured to investigate the biomechanical effects of drug treatment, diseases, and aging. In light of the cellular viscosity property exhibited by filament actin networks, this study investigates the viscoelasticity alterations of the human hepatocellular carcinoma (SMMC-7721) cell subjected to fullerenol treatment by means of creep tests realized by atomic force microscopy indentation. An SMMC-7721 cell was first modeled as a sphere and then as a flattened layer with finite thickness. Both Sneddon’s solutions and the Dimitriadis model have been modified to adapt to the viscoelastic situation, which are used to fit the same indentation depth–time curves obtained by creep tests. We find that the SMMC-7721 cell’s creep behavior is well described by the two modified models and the divergence of parameters determined by the two models is justified. By fullerenol treatment, the SMMC-7721 cell exhibits a significant decrease of elastic modulus and viscosity, which is presumably due to the disruption of actin filaments. This work represents a new attempt to understand the alternation of the viscoelastic properties of cancerous cells under the treatment of fullerenol, which has the significance of comprehensively elucidating the biomechanical effects of anticancer agents (such as fullerenol) on cancer cells.

In this study, chitin was deposited on AZ91 magnesium alloy at room temperature for 180 min, and then HA coating was applied as second layer for 180, 240, 300, 360, and 420 min by dipping method. The layers were analyzed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and field emission-scanning electron microscopy (FE-SEM), as well as adhesion, nanohardness, and potentiodynamic polarization tests. XRD results analyzed by Williamson–Hall method revealed residual tensile and compressive strains in the chitin and HA coatings, respectively and with prolonged deposition time to 420 min, coating adhesion decreased. FTIR results indicated the presence of the chemical factors affecting the chitin and HA coatings. FE-SEM results indicated that prolonged deposition time resulted in increased coating density and formation of a porous structure of HA coating. Overall, the optimum corrosion resistance was observed for the sample with 300 min deposition time.

Nanoscale metallic material composites consisting of bilayer and trilayer systems of two and three different metallic alternating layers show significant gains in hardness over monolithic single phase films. One of the main applications of these composites can be as protective coatings to technical components to increase their lifespan acting as a mechanical barrier to the carriers of permanent deformation. In this work, we study the strength of bilayer structures made of alternating layers of niobium (Nb) and copper–nickel (Cu–Ni) alloys. The effect of the layer size and composition on strength and hardening as well as the effect of the metal–alloy interface on the dislocation motion is investigated. The simulations reveal a close relationship between the atomic composition of the alloy and the hardening of the film. The results are also compared with experimental findings on nanopillars made of similar structures, and strong similarities are revealed and discussed.

The element Re is known to be a very potent strengthener concerning the creep properties of Ni-base superalloys. In this paper the influence of Re on the properties of new γ′-strengthened Co-base superalloys is addressed. Atom probe tomography reveals that Re partitions preferentially to the γ phase, but not as pronounced as in ni-base superalloys. Nanoindentation and micro-pillar compression tests of the γ′ phase indicate an increase of the hardness and the critical resolved shear stress caused by a considerable concentration of Re in the γ′ phase. Creep investigations show that the positive effect of Re is by far not as pronounced as in Ni-base superalloys. Several effects, which can contribute to this behavior, such as the lower Re concentration in γ and hence a slightly reduced effective diffusion coefficient, a smaller diffusion barrier of Re in Co compared to Ni, a slightly lower lattice misfit and γ′ volume fraction of the Re-containing alloy, are discussed.

The shear-band propagation in bulk metallic glasses (BMGs) during deformation plays a key role in determining their macroscopic ductility. In this work, the shear band propagation during plastic deformation was investigated in the Cu46Zr46Al8 BMG and its in situ or ex situ prepared BMG composites. Compared with the brittle BMG, both types of ductile BMG composites show a more stable shear banding behavior as revealed by a larger power-law scaling exponent obtained from statistical analysis of serrations recorded in compressive curves. A higher cut-off elastic energy density (δc) linked with the multiplication of shear bands is observed for the in situ prepared BMG composites. However, the ex situ fabricated BMG composites show an almost equivalent or slightly larger δc since the dominant shear band but not multiple shear bands mainly governs their deformation. Such observations imply that the shear banding stability of BMGs during deformation is enhanced not only by inducing multiple shear bands but also by obstructing the movement of the dominant shear band at its driven path.

Zr–Co–Al alloys possess prospects of wide applications in the field of nuclear reactor cladding materials and biomedical materials. (Zr0.5Co0.5)100−x Al x (x = 1, 2, 3 at.%) alloys were prepared by the water-cooling copper mold suction casting technique, and the microstructure and compression mechanical properties of the alloys were investigated. The results showed that the as-cast Zr–Co–Al alloys mainly consisted of the B2 ZrCo phase with columnar or equiaxed grains and a small quantity of intermetallic compounds, i.e., Co2Zr and Zr2Co. The yield strength of Zr–Co–Al alloys increased with increasing Al content, but the plasticity decreased at the same time. The as-cast Zr49.5Co49.5Al1 alloy attained the highest ultimate compression strength up to 2.57 ± 0.02 GPa and the largest compression strain up to ∼54.7%. The B2 to B33 martensitic transformation that occurred during the deformation process was investigated using high resolution transmission electron microscopy. It was concluded that the enhanced plasticity of Zr49.5Co49.5Al1 alloy can be attributed to the transformation induced plasticity associated with the deformation-induced martensitic transformation.

The addition of Co to CuZr-based shape memory bulk metallic glass composites stabilizes the high temperature B2-CuZr and decreases its stacking faulty energy, which promotes an increase in ductility caused by an easier twinning formation. A similar effect is expected for TiCu-based alloys. The present work aims to investigate the effect of Co additions on the phase formation, mechanical properties, and thermal stability of rapidly solidified Ti–Cu-based alloys. Rods of six Ti–Cu-based compositions with different amounts of Co were prepared by Cu-mold suction casting and investigated by X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, dilatometry, and compression tests. The results show that the addition of Co decreases the glass-forming ability of Ti–Cu-based alloys and stabilizes B2 Ti(Cu,Ni,Co) at room temperature. The Co-added alloys exhibit an almost identical phase formation and microstructure, but their mechanical behavior is completely different nonetheless, which is mainly connected with the different composition of the B2 phase. The addition of Co makes the stress-induced martensitic transformation of this phase more difficult, which is one of the main reasons for the increase of the yield strength when a higher amount of Co is added.

In the present work, various Mn amounts (up to 2 wt%) have been added into Al–Mn–Mg 3004 alloy to study their effect on the evolution of microstructure and elevated-temperature properties. Results showed that the dominant intermetallics are interdendritical Al6(MnFe) until to 1.5 wt% Mn. With further addition of Mn to 2 wt%, the blocky primary Al6Mn/Al6(MnFe) and high volume of fine Al6(MnFe) intermetallics form in the matrix, leading to the rapid increase on the volume fraction of intermetallics. After the precipitation heat treatment (375 °C/48 h), the precipitation of dispersoids increased with increasing Mn contents and reached the peak condition in the alloy with 1.5 wt% Mn, resulting in the highest yield strength and creep resistance at 300 °C. However, the elevated-temperature properties became worse in the alloy with 2 wt% Mn due to the lowest volume fraction of dispersoids and highest volume of dispersoid free zone.

Metal working tools are generally exposed to hard conditions, and the control of their excessive wear is of a crucial importance for the metal working process. Indeed, tribo-layers as mechanically mixed layers and wear debris are completely involved in the wear behavior. This paper undertakes the study of the frictional behavior and wear of X40CrMoV5 (AISI H13) tool steel as a function of speed rotation at room temperature. The utmost objective of this research work is to assess some wear mechanisms of this tool steel used at room temperature. The tribological experiments were accomplished on high temperature pin-on-disc tribometer with an open sliding contact. The pin material was X40CrMoV5 steel and the disc material was Fe360B steel. The investigations were accomplished for different rotatory speeds of the disc ranging from 25 rpm to 100 rpm, and different nominal pressure. SEM and EDS explored the development surface damage and oxides tribo-layers. It was concluded that the increase of the rotation speed of the disc and the nominal pressure reduce the friction coefficient by the creation of a wear protective layer.

In a hot forming process, the study of the interface tool/product proves important. This study focuses on the influence of the third body in the case of pin-on-disc in an open contact. The objective of this work was to identify the third body-particle circulation mechanisms at high temperatures. The “wear and friction” tests were conducted with an open sliding contact on pairs of X40CrMoV5/Fe360B steels under a normal force of 70 N at 600 °C and with a speed of rotation of the disc of 50 rev/min. The pin material was X40CrMoV5 (AISI H13) steel and the disc material was Fe360B steel. Scanning electronic microscope, energy-dispersive spectroscopy (EDS), and X-ray diffractometer explored the development surface damage and oxides tribo-oxides. It was concluded that various types of the third body particles were present in the contact. The wear mechanism on the X40CrMoV5 pin in a high temperature contact is proposed.

SiC nanoparticles reinforced magnesium matrix composite was fabricated by ultrasonic vibration assisted squeeze casting. Since ultrasonic device could meet the use requirements according to theoretic calculation, uniform dispersion of SiC nanoparticles was expected to achieve. The grains of the composite were refined compared with the AZ91 alloy, which was related to the increase of nucleation sites during solidification and Zenner pinning effect caused by SiC nanoparticles. With increasing the ultrasonic power, grain size of the composite changed no obviously while the morphology of β-Mg17Al12 phase was significantly affected. The ultimate tensile strength, yield strength, and elongation to fracture of the composites fabricated under different ultrasonic powers were simultaneously improved compared with the AZ91 alloy. The increase of yield strength could be attributed to Hall–Petch strengthening and Orowan strengthening for the present composites. Theoretical value of the yield strength obtained by the square root method was close to the experimental value.

The effects of retrogression and re-aging (RRA) treatment on intergranular corrosion (IGC), exfoliation corrosion (EXCO), stress corrosion cracking (SCC) behavior and microstructure of spray formed Al-7075 were investigated by a scanning electron microscope, a transmission electron microscope, slow strain rate test, and EXCO and IGC test. The results show that the precipitates are redissolved in the matrix of the alloy after retrogression at 200 °C for a suitable time (8 min), and the grain boundary precipitates are discrete and the obvious precipitate free zones are left at the grain boundaries. After RRA with suitable retrogressed time, thin homogeneous dispersive precipitates are separated out again in the matrix. After retrogression at 200 °C for 8 min and re-aging, the ultimate tensile strength, elongation, IGC depth, EXCO rating, and SCC index of spray formed Al-7075 are 791 MPa, 8.5%, 29.8 μm, EA, and 0.155, respectively.