A Mn3O4/graphene hybrid material is fabricated using a facile and simple in-situ reduction process and shown to be a promising anode for lithium rechargeable batteries. The hybrid material retains a high capacity with a good cycle life of up to 990 mAh g−1 after 30 cycles. The excellent electrochemical performance is attributable to the unique nanostructure of the hybrid material. Highly crystalline Mn3O4 particles (20–30 nm) are uniformly dispersed on graphene whose high electronic conductivity and high surface area provide a conductive percolating network throughout the electrode in the hybrid material. The conductive graphene networks enhance an electron transfer in the electrode and promote the electrochemical activity of the crystalline Mn3O4.

Sn/Ni–8.0 at.%V (Ni–7.0 wt%V) couples are prepared and the interfacial reactions at 210 and 250 °C are examined. In the early stage of reaction at 250 °C, a T phase is formed as a result of fast diffusion of Sn into the Ni–8.0 at.%V substrate. With a longer reaction, the outer region of the T phase transforms to a Ni-depletion layer, which has not been observed previously. Both the T phase and the Ni-depletion layer are analyzed using transmission electronic microscopy. This newly found Ni-depletion layer is composed of Sn and nanosize “VSn2(V2Sn3)” particulates. The solid/solid reaction paths in the Sn/Ni–8.0 at.%V couples evolve from Sn/T/Ni–V, Sn/Ni3Sn4/T/Ni–V to Sn/Ni3Sn4/VSn2(V2Sn3). During the liquid/solid reactions, the paths are liquid/T/Ni–V, liquid/liquid + Ni3Sn4/T/Ni–V, liquid/liquid + Ni3Sn4/liquid + VSn2(V2Sn3)/T/Ni–V, and liquid/liquid + Ni3Sn4/liquid + VSn2(V2Sn3).

A study is made of the rotation field in wedge indentation of metals using copper as the model material system. Wedges with apical angles of 60° and 120° are used to indent annealed copper, and the deformation is mapped using image correlation. The indentation of annealed and strain-hardened copper is simulated using finite element analysis. The rotation field, derived from the deformation measurements, provides a clear way of distinguishing between cutting and compressive modes of deformation. Largely unidirectional rotation on one side of the symmetry line with small spatial rotation gradients is characteristic of compression. Bidirectional rotation with neighboring regions of opposing rotations and locally high rotation gradients characterizes cutting. In addition, the rotation demarcates such characteristic regions as the pile-up zone in indentation of a strain-hardened metal. The residual rotation field obtained after unloading is essentially the same as that at full load, indicating that it is a scalar proxy for plastic deformation as a whole.

Nanofiber yarns with controlled twist levels were prepared by twisting a narrow fibrous strip cut directly from electrospun nanofiber mats. The effects of fiber morphology, diameter and orientation, as well as the yarn twist level on the yarn tensile properties were examined. For the yarns made from randomly oriented fine uniform nanofibers (e.g., diameter 359 nm) and beaded nanofibers, the tensile strength increased with increasing the yarn twist level. Higher fiber diameter (e.g., 634 nm) led to the tensile strength having an initial increase and then decrease trend. The modulus increased with the twist level for all the yarns studied. However, the elongation at break increased initially with the twist level and subsequently decreased. The orientation of aligned fibers within the fiber strip greatly influenced the yarn tensile properties. When the fibers were oriented along the fiber length direction, both tensile strength and modulus were the largest.

The (001) GaAs surfaces have been modified by thin elastically stressed InGaAs-buried layers and tested under Berkovich contact. The elastic–plastic transition determined from the pop-in event observed in the force control mode of the indentation machine appears at slightly lower loads (0.44–0.46 mN) when compared to bare GaAs surface (0.50 mN). Estimations indicate that for both studied sublayers, the stored elastic energy is about 20% of the elastic indentation energy reached at elastic–plastic transition when the sublayer is observed not to relax plastically.

We present a low-temperature, hydrothermal synthesis method for Ta-doped TiO2. Here, alkoxide-based precursors are mixed at low temperatures to suppress differential hydrolysis and phase separation. This method ensures homogeneous, molecular mixing of the Ta dopant with the native oxide up to a concentration of ∼2.5 at.%. X-ray diffraction and energy dispersive spectrometer analyses confirm a uniformly doped rutile TiO2. Scanning electron microscopy and transmission electron microscopy analyses reveal a highly branched structure. Optoelectronic properties of these structures were investigated using ultraviolet-visible spectroscopy and low-temperature photoluminescence.

In-situ tensile tests have been performed in a dual beam focused ion beam and scanning electron microscope on as-grown and prestrained single-crystal molybdenum-alloy (Mo-alloy) fibers. The fibers had approximately square cross sections with submicron edge lengths and gauge lengths in the range of 9–41 μm. In contrast to previously observed yield strengths near the theoretical strength of 10 GPa in compression tests of ∼1–3-μm long pillars made from similar Mo-alloy single crystals, a wide scatter of yield strengths between 1 and 10 GPa was observed in the as-grown fibers tested in tension. Deformation was dominated by inhomogeneous plastic events, sometimes including the formation of Lüders bands. In contrast, highly prestrained fibers exhibited stable plastic flow, significantly lower yield strengths of ∼1 GPa, and stress–strain behavior very similar to that in compression. A simple, statistical model incorporating the measured dislocation densities is developed to explain why the tension and compression results for the as-grown fibers are different.

Instrumented nanoindentation technique is a powerful approach for accurately measuring mechanical properties of materials in micron or even nanoscale. In this article, the effect of tin (Sn) content upon mechanical properties of the α-phase in Cu–Sn alloys was studied by using an instrumented nanoindentation. The experimental results revealed that: (i) the hardness of the α-phase exhibited a linear relationship with Sn content (C) increasing, i.e., H = 0.0757C + 0.8916, when it was less than the maximum solid solubility (15.8 wt.%), which is in good agreement with the Friedel–Mott–Suzuki theory; (ii) the variation of Young’s modulus in a narrow range of 120–130 GPa is attributed to orientation variation of the α-phase in casting Cu–Sn dendrites.

The ultimate properties of a fibrous composite system depend highly on the transverse mechanical properties of the fibers. Here, we report the size dependency of transverse elastic modulus in cellulose nanocrystals (CNCs). In addition, the mechanical properties of CNCs prepared from wood and cotton resources were investigated. Nanoindentation in an atomic force microscope (AFM) was used in combination with analytical contact mechanics modeling (Hertz model) and finite element analysis (FEA) to estimate the transverse elastic moduli (Et) of CNCs. FEA modeling estimated the results more accurately than the Hertz model. Based on the AFM–FEA calculations, wood CNCs had higher transverse elastic moduli in comparison to the cotton CNCs. Additionally, Et was shown to increase with a reduction in the CNCs’ diameter. This size-scale effect was related to the Iα/Iβ ratio and crystalline structure of CNCs.

This study investigates spherical indentation of plastically graded materials (PGMs). The hardness of these materials decreases with depth due to microstructural or compositional changes. To predict the behavior of PGM, the knowledge of the plastic properties of the surface and the substrate is necessary. In this work, the spherical indentation technique is applied on carbonitrided steels to obtain their mechanical properties. First, spherical indentation was applied to characterize homogenous materials using inverse analysis. The comparison with tensile test’s results shows that the inverse analysis using spherical indentation data is a reliable method to determine the plastic properties of homogeneous materials. In the second part spherical indentation was used to characterize carbonitrided steels using inverse analysis to obtain plastic properties of the surface. The results show that spherical indentation using inverse analysis has a real potential for evaluating mechanical properties of PGM.

Nucleation doping strategy is an effective doping method; herein the synthesis of MnSe/CdSe nanocrystals using this strategy with different anion precursors was demonstrated. The resulted nanocrystals were characterized by various test technology to confirm the composition and structure. Wurtzite CdSe shell was achieved without using alkylphosphine, this is meaningful for the development of green chemistry. It is argued that the shell growth is more like a second nucleation process, rather than the epitaxial growth; this conclusion is believed to shed some light on the nucleation doping process.

Bulk production of iron nanowire inside carbon nanotubes (CNTs) from iron phthalocyanine (FePc) polymer under 800 °C is presented for the first time. The bis-phthalonitrile was firstly reacted with iron nanoparticles to produce iron phthalonitrile oligomer, and heat treatments made the formation of CNTs occurred during the carbonization process of FePc polymer at ambient pressure in nitro atmosphere under 800 °C. The iron nanowire inside carbon tubes from the metal Pc polymer possessed excellent electromagnetic loss and magnetic loss properties.

With 2 mol% Zn2+ codoping and 2 mol% K+ charge compensation, the red-emitting phosphor [K0.8Y0.63Eu3+0.08Zn0.02][Mo0.2W0.8O4] was synthesized by solid-state reaction. X-ray powder diffraction spectrum indicates that it owns single phase. Through its emission spectra, excitation spectra, and fluorescence decay curves measured, its emission mechanism was mentioned and it was calculated for its partial J-O parameters and quantum efficiency of Eu3+ 5D0 energy level under 395 nm excitation. The results indicate that Eu3+ 5D0 → 7F2 red luminescence in the host can be excited by 395 nm, but its quantum efficiency can be improved in space and it has potential applications for white light-emitting diode as the red luminescent materials.

We demonstrate the fabrication of shadow mask (SM) patterned as well as nanoimprint lithography (NIL) patterned organic transistors and integrated complementary organic inverters (ICOIs). As active layers pentacene (p-type) and either PTCDI-C13H27 or F16CuPc (n-type) were used. The SM-patterned ICOIs with a staggered bottom gate configuration, a nanocomposite dielectric and both active layer combinations (pentacene/PTCDI C13H27, pentacene/F16CuPc) exhibited high performance (3 V operation voltage; gain around 60; high level 3 V; low level 5 mV; noise margin 0.9 V). Flexible ICOIs with transistor channel lengths of 900 nm were successfully fabricated by NIL, using a benzocyclobutene derivative as dielectric. Because of the process inherent coplanar bottom gate configuration, F16CuPc was used. The ICOIs showed proper functionality (3 V operation voltage; gain around 5; high level 2.9 V; low level 25 mV). To our knowledge, this study demonstrates the first complementary submicron inverters based on fully R2R compatible imprint processes.

Cu6Sn5 is a common intermetallic compound formed during electrical packaging. It has an allotropic transformation from the low-temperature monoclinic η’-Cu6Sn5 to high-temperature hexagonal η-Cu6Sn5 at equilibrium temperature 186 °C. In this research, the effects of this allotropic transformation and Ni addition on the thermal expansion of η’- and/or η-Cu6Sn5 were characterized using synchrotron x-ray diffraction and dilatometry. A volume expansion during the monoclinic to hexagonal transformation was found. The addition of Ni was found to decrease the undesirable thermal expansion by stabilizing the hexagonal Cu6Sn5 at temperatures below 186 °C and reducing the overall thermal expansion of Cu6Sn5.

Over the past two decades, nanoindentation has been the most versatile method for mechanical testing at small length scales. Because of large strain gradients, it does not allow for a straightforward identification of material parameters such as yield and tensile strength, though. This represents a major drawback and has led to the development of alternative microscale testing techniques with microcompression as one of the most popular ones today. In this research, the influence of the realistic sample configuration and unavoidable variations in the experimental conditions is studied systematically by combing in-situ microcompression experiments on ultrafine-grained nickel and finite element simulations. It will be demonstrated that neither qualitative let alone quantitative analyses are as straightforward as they may appear, which diminishes the apparent advantages of microcompression testing.

The elastic anisotropy of cementite (Fe3C) is still under discussion. Recent theoretical (ab initio) calculations predict a very high elastic anisotropy for this iron carbide, and a few published experiments suggest that prediction could be true. This work presents a first attempt of using nanoindentation for assessing the elastic anisotropy of such an important component of steels. Our nanoindentation results show that the elastic anisotropy of Fe3C is high but smaller than predicted by ab initio calculations. The elastic modulus is obtained from the load–penetration curves before the first pop-in indicative of plasticity nucleation is detected. The tests thus provide information on the plastic anisotropy of cementite. Surprisingly, the mean indentation pressure or the maximum shear stress under the indenter at the onset of plasticity has been observed to be nearly independent of the crystalline orientation of the indented surface.

The electromigration (EM) behavior of the Cu/Sn–In/Cu solder model strip was investigated under the conditions of high electrical current density (10 kA/cm2) at various temperatures. The composition of indium (In) was 0, 4, 8, and 16 in wt%. The interconnection of Sn–In solder alloys with a Cu substrate was prepared by reflow soldering at 250 °C. Microstructural analysis confirmed that primary intermetallic compound formed at the interface of the Cu/Sn–In strip was Cu6(In,Sn)5 regardless of In contents. Sn grain size became finer as In content increased. After current stressing, electrical failure was caused by the formation of voids and cracks at the cathode because of the migration of Cu atoms. Sn–16In alloy that has fine grain structure exhibits excellent EM resistance primarily due to the retardation of Cu migration.

Systematic nanoindentation experiments have been carried out to study the mechanical properties of a nanocrystalline Fe–51Ni coating exhibiting anelastic and creep characteristics. An analytical method based on the correspondence principle for linear viscoelasticity was developed. The holding displacement–time data obtained in indentation creep tests at a high loading rate of 20 mN/s were analyzed, and material parameters related to the elastic, anelastic, and creep characteristics were derived using a model containing one Maxwell unit and two Kelvin units. The anelastic deformation thus contains at least two relaxation processes having relaxation times of 0.37 and 6.8 s, respectively, and the creep deformation is described by a viscosity value of 4.2 × 104 GPa·s for the alloy in an as-deposited state. The anelastic and creep characteristics descend associated with increases of the elastic modulus and hardness values after the alloy was annealed at 673 K.

Surface and chemomechanical effects are very important in tribology, wear and friction, but are difficult to quantify due to being confined in the near-surface region. Nanoindentation techniques have been successfully used to investigate environmental effects on mechanical response. In this work, nanoindentation tests have been performed on various materials (silicon, fused silica, and gold nanofilms on a glass substrate) immersed in long-chain alcohols (i.e., 1-hexanol, 1-heptanol, 1-octanol, and 1-nonanol). The results consistently show an increase in mechanical properties for silicon and gold nanofilms immersed in the alcohols at shallow nanoindentation depths. The results for fused silica show little effect of immersion. The changes in the observed mechanical properties are attributed to the ability of the long-chain organic molecules to sustain elastic strains when they are in confined geometry. These long organic chains also distribute the normal stress of the indenter over a larger area on the sample surface thereby causing a decrease in the perceived contact area (Ac). As a result the long-chain alcohols modify both the Ac and the elastic compliance of the contact.