Composite magnetoelectrics implemented as thin film heterostructures are discussed in view of their applicability as highly sensitive magnetic field sensors. Here, either PZT or AlN served as piezoelectric component. The magnetostrictive phase consisted of layer systems based on FeCo or (Fe90Co10)78Si12B10. All functional layers were deposited with thicknesses of a few micrometers on Si cantilever structures with typical lateral dimensions of 25 mm by 2.2 mm. Magnetoelectric coefficients as large as 6900 V/cm Oe and a limit of detection as low as 1 pT/(Hz)1/2 were measured. Currently, the best result demonstrates a detection limit of 500 fT/(Hz)1/2 at 958 Hz frequency using a set of two sensors for external noise suppression. A frequency conversion technique is proposed to broaden the applicability of resonant magnetoelectric sensors to a wider frequency range. Finally, the achieved sensor performance is evaluated with regard to typical magnetic field amplitudes in medical applications.

Using in situ transmission electron microscopy, we report the observation of the melting behavior of one-dimensional nanostructures of Sn with different length/width aspect ratios. The melting of small aspect-ratio nanowires (nanorods) results in the expansion of liquid Sn along both axial and radial directions with the tendency to form an isometric or spherical particle, thereby minimizing the total surface area. For nanowires with the length/width aspect ratio of ∼10.5, perturbation along the liquid stream causes an unstable necking phenomenon and the whole wire tends to shrink into a spherical particle. In contrast, Rayleigh instability sets in for the melting of the nanowires with the length/width aspect ratio as large as ∼21, which gives rise to necking and fragmentation of the wire into particles. The amorphous native surface oxide (SnOx ) layer serves as a confinement tube and plays an important role in the melting induced morphological evolution of Sn nanowires. A thin SnOx layer is flexible with the ability to shrink or expand upon the flow of molten Sn. The increased rigidity for a thick SnOx surface layer kinetically suppresses bulging and necking formation in molten Sn nanowires.

Atom probe tomography and transmission electron microscopy are used to analyze magnetron-sputtered MoS2 films containing Ti and Au/Sb2O3 as a model system for tribological coatings. Transmission electron microscopy characterization showed that the Ti–MoS2 film is dense and featureless whereas Sb2O3/Au–MoS2 film is less dense and have columnar morphology. Three-dimensional atom probe reconstructions revealed that the Ti–MoS2 films have a homogeneous composition and contain about 15 at.% Ti, which is uniformly distributed throughout the MoS2 matrix without any evidence of Ti precipitation. Sb2O3/Au–MoS2 films also showed homogeneous distribution of Sb2O3 throughout the MoS2 matrix and the presence of Au-rich precipitates. The complementary techniques of atom probe tomography and transmission electron microscopy indicate that Ti and Sb2O3 incorporation in the deposition of MoS2 produces amorphous microstructures, whereas the addition of Au forms nano-sized and well-dispersed precipitates.

An ultra-violet (UV) curable ink jet 3D printed material was characterized by an inverse finite element modeling (IFEM) technique employing a nonlinear viscoelastic–viscoplastic (NVEVP) material constitutive model; this methodology was compared directly with nanoindentation tests. The printed UV cured ink jet material properties were found to be z-depth dependent owing to the sequential layer-by-layer deposition approach. With further post-UV curing, the z-depth dependence was weakened but properties at all depths were influenced by the duration of UV exposure, indicating that none of the materials within the samples had reached full cure during the 3D printing process. Effects due to the proximity of an indentation to the 3D printed material material-sample fixing interface, and the different mounting material, in a test sample were examined by direct 3D finite element simulation and shown to be insignificant for experiments performed at a distance greater than 20 µm from the interface.

Tungstate based phosphors have efficient absorption in the UV region and can be used for UV-pumped light emitting. For novel and effective materials and synthesis methods in this system, a series of Eu3+ and Tb3+ co-doped NaY(WO4)2 phosphors have been synthesized via the molten salt method. The powder X-ray diffraction (PXRD) patterns, scanning electronic microscope (SEM), and photoluminescent spectra have been characterized for the prepared samples. The results show the flux (NaCl) not only decreases the reaction temperature (700–900 °C) than the normal solid state synthesis (∼1000 °C), but also controls the morphology of the products. The shape and size of products can be changed simply and effectively by the reaction conditions, such as temperature and heating time. It is also found that the emission colors of the samples can be tuned from red to green by simply adjusting the doping concentrations of Eu3+ and Tb3+ ions under the same wave length excitation, which has potential applications for multi-color display and illumination as a single-component phosphor.

Isothermal compression testing of Ti–5.8Al–3Sn–5Zr–0.5Mo–1.0Nb–1.0Ta–0.4Si–0.2Er titanium alloy is performed on a Gleeble-3500 thermal simulator, and the corresponding microstructures are analyzed to clarify the softening mechanism and participates evolution. A constitutive equation compensated by strain has been established to describe the hot deformation behavior of the alloy. The deformation activation energies are calculated to be 369760.93–699310.86 J/mol in α + β two-phase region and 268030.03–325800.41 J/mol in β single-phase region. At a temperature of 880 °C, the main softening mechanism is the continuous dynamic recrystallization of lamellar α colony, controlled by the mechanical rotation of the sub-grain followed by dislocation climbing and annihilation by diffusion. Meanwhile, the dominant softening mechanism is the discontinuous dynamic recrystallization of β phase during the deformation at temperatures of 920 °C–1080 °C. Silicide containing Er with an average diameter of 20 nm is formed during the water quenching.

Considered as a less hazardous piezoelectric material, potassium sodium niobate (KNN) has been in the fore of the search for replacement of lead (Pb) zirconate titanate for piezoelectrics applications. Here, we challenge the environmental credentials of KNN due to the presence of ~60 wt% Nb2O5, a substance much less toxic to humans than Pb oxide, but whose mining and extraction cause significant environmental damage.

Classical molecular dynamics (MD), along with a bond-order potential for GaAs, has been used to study threshold displacement energies (E d) of Ga and As recoils. Considering the crystallographic symmetry of GaAs, recoil events are confined in four unit stereographic triangles. To investigate the displacement energy’s dependence on crystallographic orientation, more than 3600 recoil events were simulated to uniformly sample values of E d. Various defect configurations produced at these low energy recoils and the separation distances of Frenkel pairs were quantified and outlined. For both Ga and As, the minimum, $E_{\rm{d}}^{{\rm{min}}}$ , is found to be 8 eV, but the maxima, $E_{\rm{d}}^{{\rm{max}}}$ , are 22 and 28 eV for Ga and As, respectively. The distribution of E d within unit stereographic triangles indicates that E d shows a weak dependence on the recoil directions, in contrast to other semiconductors. The average threshold displacement energy is 13 ± 1 eV, which is in excellent agreement with available experiments.

Effects of Mo addition on the microstructure, mechanical properties, and abrasive wear properties of an oriented bulk Fe2B crystal have been investigated systematically in the present paper. Five groups of pure Fe2B samples with different Mo contents have been examined by optical microscope, X-ray diffraction, scanning electron microscope integrated with energy disperse spectroscopy, microhardness tester, and three-point bending testing of fracture toughness. The results indicate that Mo tends to segregate on the grain boundaries after doping; with increasing Mo addition, interplanar spacing of the (002) crystal plane of Fe2B decreases firstly and then increases slightly while that of (200) increases gradually; microhardness on the transversal section changes little while that on the longitudinal section increases firstly and then decreases [possessing the opposite trend to interplanar spacing of (002)]; fracture toughness and wear resistance of both transversal and longitudinal samples can be improved to some extent with Mo addition less than 2.0 wt%. In conclusion, appropriate Mo addition plays a positive role in the improvement of mechanical properties of oriented bulk Fe2B.

One conceptually different approach has been developed to synthesize Ti3+ self-doped TiO2−x mesocrystals to narrow the band gap of TiO2. This simple and economical one-pot solvothermal method uses TiCl3 and tetrabutyltitanate (TBT) as a precursor and exhibits practical application. Different morphology including uniform spindle shape, tetragonal bipyramid, and capsule-like mesocrystals can be tailored easily by tuning the precursor ratio of TiCl3 to TBT. We have shown that our band gap engineered TiO2−x exhibits unique mesocrystal phase and owns substantial high visible light driven photocatalytic activities. Electron paramagnetic resonance (EPR) studies of this sample verified the presence of oxygen centered radicals, namely, hydroxyl (·OH) and superoxide radicals (O2 −·/·OOH). The catalysts have been characterized using transmission electron microscope, fluorescence spectra, Raman spectra, EPR, X-ray photoelectron spectroscopy, X-ray diffraction (XRD), Ultraviolet–visible absorption spectra, etc. It shows high catalytic stability. The findings of this work provide new insights for developing morphology tailored for visible light driven devices and other applications via controlled band gap engineering.

The amorphous carbon thin films were deposited by the ion beam sputtering deposition technique on Ni–Cu alloy substrates. The effect of sputtering ion beam energy on wettabillity, surface, and structural properties of thin films was examined. The sputtering ion beam energy was varied over a wide range from 2 to 5 keV. Raman spectra showed that the values of I D/I G ratio and the ‘G’ peak position have a reduction trend by increasing the argon ion beam energy while the surface roughness increased due to the resputtering effect. The wettability and surface energy of a-C carbon films were studied by contact angle measurements in relation to structure and topography. The deposited films showed a relatively high water contact angle (CA) that decreases from 87° to 75°. The X-ray photoelectron spectroscopy showed that the value of sp 3/sp 2 bond content of a-C thin films deposited with the highest argon ion beam energy of 5 keV was about 0.8. Furthermore, the optical band gap followed similar trends of the structural properties.

In this work, the high-performance silicon carbide particle SiCp[carbon nanotube (CNT)] hybrid reinforcement is currently explored to develop the advanced metal matrix composites. 17 wt% SiCp(CNT)/Al composites were fabricated by a powder metallurgy technique, in which SiCp(CNT) hybrid reinforcement with various CNT contents (e.g., 3, 6 and 9 wt%) were applied. Effects of CNT content on the morphology of SiCp(CNT) hybrid reinforcement, the microstructural characteristics, and the tensile mechanical behavior of SiCp(CNT)/Al composites were studied as well. Especially, the SiCp(CNT)/Al composites with 6 wt% CNT in SiCp(CNT) hybrid reinforcement exhibited the most significant enhancing effects in the elastic modulus and tensile strength. Meanwhile, the SiCp(CNT)/Al composites produced a synergistic strengthening effect of SiCp and CNT compared to SiCp/Al composites, while the SiCp(CNT)/Al composites with high CNT content in SiCp(CNT) hybrid reinforcement provided weak improvement in the tensile strength and ductility due to the forming agglomeration of CNT in the matrix.

Elastic strain is an effective and thus widely used parameter to control and modify the electrical, optical, and magnetic properties of crystalline solid-state materials. It has a large impact on device performance and enables adjusting the materials functionality. Here, we promote a micromechanical strain enhancement technology to achieve ultra-high strain in semiconductors. The here presented suspended membranes enable the accurate control of the strain on a wafer-scale by standard top-down fabrication methods making it attractive for both device applications and also, thanks to the simplicity of the method, for fundamental research. This review aims at discussing the process of strain enhancement and its usage as an investigation platform for strain-related physical properties. Furthermore, we present design rules and a detailed analysis of fracture effects limiting the strain enhancement.

Thermoelectric properties of oxygen-deficient filled strontium barium niobates (SBN, Srx Ba6−x Nb10O30−δ) in the composition range from the barium end member to a Sr:Ba ratio of 80:20 were investigated. The electrical conductivity, Seebeck coefficients, and power factors for ceramic samples annealed at 1300–1310 °C for 30 h under forming gas (∼10−16 pO2 atm) were evaluated from ∼350 to 970 K. The conduction mechanism in the filled SBNs was found to be similar to that of the heavily-reduced unfilled SBNs reported in literature. However, relative to the unfilled counterparts heat-treated at 10−16 atm pO2, larger power factors were observed in the filled SBNs. The thermoelectric performance of these filled SBNs was composition-sensitive; lower Sr contents showed higher electrical conductivities, and power factors. Electron diffraction and Hall experiments suggest that both mobility and carrier concentration are enhanced with decreasing Sr. For ceramic samples, the highest power factors achievable were found for low Sr, heavily-reduced filled compositions.

The effect of Cr fibers on the deformation of directionally solidified NiAl–Cr eutectics, prepared at three different solidification speeds affecting the fiber diameter and fiber spacing, was studied at varying length scales using different micromechanical testing techniques. In situ tensile tests in a scanning electron microscope of individual Cr fibers showed high strength accompanied by ductile behavior. Comparative microcompression tests on single-phase NiAl pillars and NiAl pillars containing a single fiber showed that the pillars with the single fiber were marginally weaker than the single-phase pillars for similar pillar diameters. Composite pillars with multiple fibers exhibited an increase of 0.2% offset strength values with increasing solidification speed. Transmission electron microscopy of the composite pillars containing a single fiber after deformation revealed significant dislocation activity both in the fiber and the matrix. It is argued that the interface between the fiber and matrix acts as dislocation source promoting plastic deformation of the brittle NiAl matrix.

Probing the distribution of donor and acceptor molecules in the active layer of polymer solar cells requires high-resolution methods that provide chemical contrast. A combination of the synchrotron-based soft X-ray technique near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and scanning transmission X-ray microscopy (STXM) can map surface composition and local composition in lateral phase-separated domains, as well as identify molecular signatures of degradation. Here we illustrate, by way of selected results, the relevance of these complementary techniques to the field of organic photovoltaics. We demonstrate firstly that the determination of local composition from X-ray absorption spectra requires cautious use of fitting techniques. Furthermore, we show that drop-like clusters of PC70BM formed during the transfer of spin-coated polymer:PC70BM blend films onto Cu-grids lead to an underestimation of PC70BM/polymer concentration ratios. Finally, we show that the selective degradation of one of the components can impair the accurate determination of local blend composition.