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Imaging strain fields at the nanoscale is crucial for understanding the physical properties as well as the performance of oxide heterostructures and electronic devices. Based on scanning transmission electron microscopy (STEM) techniques, we successfully imaged the random strain field at the interface of core-shell ZnO nanowires. Combining experimental observations and image simulations, we find that the strain contrast originates from dechanneling of electrons and increased diffuse scattering induced by static atomic displacements. For a thin sample with a random strain field, a positive strain contrast appears in the low-angle annular dark-field (LAADF) image and a negative contrast in the high-angle annular dark-field (HAADF) image, but for a thick sample (> 120 nm), the positive contrast always occurs in both the LAADF and HAADF images. Through the analysis of the relationship between strain contrast and various parameters, we also discuss the optimum experimental condition for imaging random strain fields.

The interface oxidation induced microstructural evolution of air plasma spayed (APS) thermal barrier coatings (TBCs) is investigated. As the oxidation progresses, the thermally grown oxide (TGO) formed at the YSZ/NiCrAlY interface develops from a bi-layered structure, to a three-layered structure, then to a four-layered structure of Al2O3, Y3Al5O12 (YAG), NiCr2O4 and NiO, respectively. An oxidation mechanism is proposed to account for the growth of the layered TGO. The YAG formation consumes the underlying alumina layer and facilitates the outward diffusion of Cr and Ni, leading to a detrimental effect on the TBC life.

Combining atomic-resolution scanning transmission electron microscopy (STEM) images and electron-energy-loss spectroscopy spectra in aberration-corrected STEM, first-principle calculations, and spectra simulations, we investigate the origin of the surface state in a $\mathrm{LaCo}{\mathrm{O}}_{3}$ nanoparticle. We show that a $\mathrm{LaCo}{\mathrm{O}}_{3}$ nanoparticle appears as the core-shell structure, where the core has the mixture of low- and high-spin states and the shell has increased concentration of the high-spin state. Based on experimental observations and theoretical calculations, we propose that it is neither the oxygen vacancy nor strain but the suppression of oxygen octahedral tilting due to surface reconstruction that plays a dominant role in the spin-state crossover to the higher-spin state at the surface. These results provide great insights into understanding the origin of ferromagnetism as well as the enhanced electrocatalytic activity in this compound.

A novel Cu-10Zn-1.5Ni-0.34Si alloy was designed to replace the expensive tin-phosphor bronze in this paper. The alloy had better comprehensive mechanical properties than traditional C5191 alloy. The aged Cu-10Zn-1.5Ni-0.34Si alloy had a hardness of 220 HV, electrical conductivity of 28.5% IACS, tensile strength of 650 MPa, yield strength of 575 MPa and elongation of 13%. Ni2Si precipitates formed during aging, and the crystal orientation relationship between matrix and precipitates was: (001)α//(001)δ, and [110]α//[100]δ. Ductile fracture surface with deep cavities was found in the alloy. Solid solution strengthening, deformation strengthening and precipitation strengthening were found to be core strengthening mechanisms in the alloy.

Homogeneous heat treatment serves the significant roles in eliminating the segregation and tuning the microstructure of alloy ingot. It usually cost tremendous power and time to achieve a homogeneous microstructure for aluminum alloys. In this article, the hot extrusion was directly introduced on the spray deposited aluminum alloy 7055 ingot before performing heat treatment to explore the newly feasible homogeneous routine. Equiaxed grains without dendrites or PPB were obtained in our current parameters of spray deposition, which allowed the as-deposited alloy to be deformed without being subjected to pre-homogeneous heat treatment. Significant amount of stored energy was produced during hot extrusion at 420 &deg, C with area reduction ratio of 6.25, which effectively promoted the homogeneity of microstructure and reduced significantly the heat treatment time. A newly feasible short routine, heat treatment at 450 &deg, C /6 h + 470 &deg, C/1 h following the hot extrusion, proved capable of obtaining a homogeneous microstructure for the spray deposited aluminum alloy 7055.

The effects of pre-aging treatments on subsequent artificial aging response were investigated by means of transmission electron microscopy observations and hardness test in age hardened Al-3.95Cu-(1.32Mg)-0.52Mn-0.11Zr alloys. In Al-3.95Cu-0.52Mn-0.11Zr alloy, when the pre-aging temperature is 25 °C, the pre-aging treatment has no evident effect on the peak hardness of subsequent artificial aging, while a positive effect (increase of peak hardness) appears when pre-aging temperature is 50 °C. However, in Al-3.95Cu-1.32Mg-0.52Mn-0.11Zr alloy, it is found that whether the pre-aging temperature is 25 °C or 50 °C, the peak artificial aging hardness is lower than that of T6 treated alloy, that is to say, pre-aging treatment has a negative effect on the peak hardness of subsequent artificial aging in the alloys.

The mechanical properties and microstructure of large-scale Al–Zn–Mg–Cu alloys fabricated by spray deposition/rapid solidification technology were investigated in detail. The as-extruded alloys under peak-aging temper exhibited ultimate tensile strength (UTS), yield strength (YS) and elongation of 690 MPa, 638 MPa and 17.2%, respectively. The simultaneous coexisting of high strength and large tensile ductility of the alloys were achieved in our experiment. It was considered that the high-density nano-precipitates distributed uniformly in the peak-aged alloys may be responsible for the high strength and improved ductility. Orientation relationship between η′ precipitates and α-Al matrix were verified by high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction patterns (SADPs) observations. The η′ phases in the alloy were fully coherent with the aluminum matrix, with the orientation relationship of ( 1 0 1 ¯ 0 ) η ′ / / { 1 1 0 } Al and [ 1 ¯ 2 1 ¯ 0 ] η ′ / / 1 ¯ 1 2 > Al . The relationship between the lattice parameters of η′ phase and the related plane-spacing of the aluminum were a η ′ = 3 d ( 1 1 2 ) Al and c η ′ = 6 d ( 1 1 1 ) Al . Based on obtained orientation relationship, the transition matrix of η′ phases were also calculated.

In this study, high-quality large billets of 7055 aluminum alloy were successfully fabricated by spray forming rapid solidification technology. Microstructure observation showed that there were equiaxed grains with the size of about 50 μm in diameter. The dendrite microstructure was suppressed and the undesirable macrosegregation did not exist in the as-deposited 7055 alloys, attributable to rapid solidification effects. The secondary phases were the main η -Mg(Zn,Cu,Al) 2 expansion phases and the very small amounts of Al x Fe 3 Cu Iron-bearing phase. As-deposited 7055 billet was subsequently processed by hot extrusion, solid solution treatment at 450 °C/24 h and aging at 120 °C for 12 h. The as-aged alloy was then subjected to tensile testing. The results revealed that yield strength, tensile strength and elongation rate of the alloy reached 608 MPa, 667 MPa and 10%, respectively. After extruding, the observation of the microscopic fracture morphology of as-extruded specimens manifested that fracture mode was the transgranular dimple fracture.

SnO{sub 2} nanorod bundles were synthesized by hydrothermal method. Field-emission scanning electron microscopy and transmission electron microscopy images showed that the as-prepared flowerlike SnO{sub 2} nanorod bundles consist of tetragonal nanorods with size readily tunable. Their electrochemical properties and application as anode for lithium-ion battery were evaluated by galvanostatic discharge–charge testing and cycle voltammetry. SnO{sub 2} nanorod flowers possess improved discharge capacity of 694 mA h g{sup −1} up to 40th cycle at 0.1 C. - Highlights: ► The flowerlike SnO{sub 2} nanorod bundles were synthesized by hydrothermal method. ► SnO{sub 2} nanorod bundles with tunable size by controlling concentration of SnCl{sub 4}. ► A probable formation mechanism of SnO{sub 2} nanorod bundles has been proposed.

The deformation structure of {0 0 1}〈1 1 0〉 grains in cold-rolled Ta–7.5 wt%W alloy foils has been investigated by transmission electron microscopy (TEM) and electron backscattering diffraction (EBSD). The results show that there are two kinds of {0 0 1}〈1 1 0〉 grains formed during the cold-rolled deformation process. Type A grains are surrounded by α-fiber, while type B grains are surrounded by γ-fiber. Dislocation analysis reveals a continuous evolution of dislocation substructures from dislocation arrays, to high dense dislocation walls, and to microbands in type A grains, while in type B grains from dislocation mesh to dislocation cells as a function of plastic strain. By both the analysis of EBSD and TEM, a new deformation mode in type A grains is developed.

The microstructure and properties of a hot rolled-quenched Cu-Cr-Zr-Mg-Si alloy were investigated by transmission electron microscopy observations, micro-hardness and tensile strength testing, and electrical conductivity measurement. The results show that the hot rolling-quenching (HR-Q) process and subsequent thermomechanical treatments are successfully developed to manufacture Cu-Cr-Zr-Mg-Si alloy strips. Solution treatment can be finished during the HR-Q process, and good combinations of strength, conductivity, and softening resistance are obtained for the thermomechanically treated strips. Ordered fcc structure precipitates which exhibit a cube-on-cube orientation relationship with the matrix are responsible for the improvements of properties. The properties of hot rolled-quenched Cu-Cr-Zr-Mg-Si alloy strips can be further improved by two-step rolling and aging process. The improvements of properties are attributed to the interactions of precipitation strengthening and strain hardening.

A theoretical model for an all-in-one thin film silicon solar cell (TFSSC) design with the anti-reflection (AR) coatings, the transparent electrodes, the silicon and the back reflective coatings all deposited on one piece of glass is proposed and the optical performance for the design is numerically simulated. The calculated average reflectance over the wavelength range of 0.4–1.0 μm and incident angles from 0° to 75° for the optimized dual-AR coatings as a whole is 3.67% – ranking among the lowest values for current AR coatings on silicon solar cells. Furthermore, the spectrum-averaged absorptance (SAA) in the 5-μm-thick cell in the 0.3–1.2 μm wavelength range decreases only by 2.58% when the incident angle varies from 0° to 75°, clearly showing the omnidirectional characteristics of the dual-AR coatings. With reasonable assumption of the internal quantum efficiency (near unity), the 5-μm cell produces a spectrum averaged external quantum efficiency (EQE) of 81.4% at 75° angle of incidence – 6.7% larger than the experiment result of the best planar bulk cell. Under equal sunshine conditions, TFSSCs generally give higher output voltages than their bulk counterpart if equal light absorption is assumed, so the 5-μm cell has the potential to reach the highest experimental conversion efficiency of the best planar bulk cell. By using a special mathematical technique, we are able to prove the angle-dependent absorption curves in the longer wavelength region tend to converge to a small neighborhood of the upper limit irrespective of significant differences between the transmission profiles. This indicates the AR requirement in the longer wavelength region can be significantly relaxed.

We have fabricated multilayer p–n hetero-junction structure La0.9Sr0.1MnO3/SrNb0.05Ti0.95O3 colossal magneto-resistivity thin films. The observations of transmission electron microscopy showed that the interfacial structure between La0.9Sr0.1MnO3 and SrNb0.05Ti0.95O3 was of great epitaxy and atomic level smooth. There was a superstructure within La0.9Sr0.1MnO3 thin films which was clarified in terms of the ordered partial substitution of La with Sr at center body of unit cell. Its chemical composition and distribution information investigated by electron energy loss spectrum and element mapping in the multilayer thin films were discussed.

Ammonia gas sensors were fabricated from polyaniline nanofibers, which were synthesized by a simple dilute polymerization method without external template. The films of polyaniline nanofibers were deposited on interdigitated array electrodes by drop casting method. The ammonia gas sensing mechanism arises from the deprotonation process of acid doped polyaniline. The sensors exhibited the sensitivity of 1.06 and response time of 10 s for 50 ppm of ammonia gas. Such high sensitivity and fast response are attributed to the large surface-to-volume ratio and interconnected network structures. These results suggest that polyaniline nanofibers are promising materials for ammonia gas sensors with high performance.

Single-crystalline SnO2 nanorods were successfully assembled on SnO2 nanowire backbones through a sequential gold-catalyzed thermal evaporation method. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies showed that uniform secondary nanorod branches were epitaxially grown from two side surfaces of the nanowire backbones. These branch rods are parallel to each other with 2-fold symmetry with respect to the backbones. The crystal structure of these as-prepared SnO2 centipede-like nanostructures was identified to coincide to the normal rutile structure. The photoluminescence (PL) properties of single centipede-like SnO2 structures were studied by confocal microscopy, which showed that these structures can act as good optical waveguides. Cathodoluminescence (CL) spectra of the SnO2 branched structures obtained in the SEM-CL system featured a blue emission band around 462 nm that is attributed to a defect-state-related emission.

ZnO nanoneedles were synthesized through a simple wet chemical route at room temperature. The diameters of the ZnO nanoneedles tips and roots are about 5 nm and 10 nm, respectively. The sensors fabricated by ZnO nanoneedles exhibited good sensing properties. The sensitivity is 173 against 100 ppm ethanol and the working temperature can be lowered to 150 °C. Additionally, a linear dependence of the sensitivity on the ethanol concentration was also observed. These excellent sensing properties can be ascribed to the small size effects, which can be further confirmed by the calculated results.

The strategy to manipulate nanoscale building blocks into well-regulated hierarchical architectures is of great interest and valuable to both material synthesis and advanced nanodevices. Novel ZnO hierarchical structures with nanowire arrays connected on both faces of parallel ZnO hexagonal disks were produced in a facile temperature-dependent multi-step hydrothermal route within an open vessel, in which lamellar zinc hydroxide (LHS-Zn) disks were firstly formed as intermediate basic floor, whose surface may be roughened at elevated temperature; the resultant ZnO nanowires were then assembled into a highly ordered array on the top/bottom surfaces of disks in the presence of dense ammonia. Higher [Zn2+] at the beginning lead to multicell sandwiches or nanowire−disk−nanowire−disk−nanowire-like superlattice. Ammonia molecules in the vessel play a key role in controlling architecture evolution. Room-temperature Raman-scattering and photoluminescence measurements indicated the optical properties of single as-p...

A new cell line was established from 2-d-old embryonated eggs of Mythimna separata and has been designated as NEAU-Ms-927311. This cell line consists of a mixture of cell types, including spherical and spindle-shaped cells. The cell line has a population doubling time of 58. 8h. Chromosome analysis revealed its typical lepidopteran karyology. Isozyme characterization of esterase showed that the band pattern was different from that of other two cell lines (Xc-920730, and SF-21AE). Virus infectivity tests revealed this cell line can support replication of M. separata nuclear polyhedrosis virus.

The synthesis of TiO(2) nanostructures including nanowires and nanobelts has been demonstrated experimentally by anodization of Ti foil in an electrolyte, and by treatment in a PdCl(2) ethanol solution together with UV light irradiation and annealing at a temperature below 800 degrees C. The TiO(2) nanotube arrays resulting from the anodization were used as source precursor and transformed into nanowires and nanobelts respectively with high efficiency during the subsequent processes. The resulting TiO(2) nanowires and nanobelts, characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman and surface photovoltage (SPV) spectroscopy, are single rutile crystals of high quality. In addition to the synthesis of the nanostructure at low temperature, this method also shows great advantages for the selectable morphology of the final TiO(2) nanostructures via adjustment of the UV light irradiation time and annealing temperature.

Using the rigorous coupled-wave analysis method, we present a detailed study about the light transmission through periodic sub-wavelength textured surfaces. We investigate to what extent and under what conditions these textured surfaces are equivalent to a multilayer dielectric coating from the perspective of reversibility and azimuthal symmetry of the reflected and transmitted light. Our analyses show that this is completely determined by the relative size between the reciprocal lattice period of the textured surface structure and the wavevectors of the reflected and transmitted waves in the dielectric materials. It is found that these analyses can be used to determine the optimal surface texture which provides the best light trapping for solar cells in terms of the total internal reflection occurring in the high-index medium at incidence angles larger than the nominal critical angle. We also perform calculations for the antireflective characteristics of these sub-wavelength textured surfaces and find that an optimized surface texture can generally give quite small reflectance in a wide spectral and angle range, but for the current texture design its performance at higher incidence angles is usually poorer than an optimized multilayer AR coating with graded index along the thickness direction.

Rapid and ultrahigh sensing is realized from Au-coated ZnO rods with diameters down to 15 nm. Both the small diameters and the Au coating make the surface-depletion effect more pronounced for gas sensing. Such enhanced surface depletion increases the sensitivity, lowers the operation temperature and decreases the response time. A sensitivity of 89.5-100 ppm ethanol is obtained with response time shorter than 2 s at 300 °C, and the operation temperature can be as low as 150 °C. It is found that the Au coating improves the sensitivity by three times; this is much higher than that of noble metal-doped metal oxide sensors controlled by a grain-boundary barrier. Our results imply that the surface-depletion model is very helpful in fabricating high performance gas sensors.

Indium doping effects on the optical and electrical properties of ZnO nanowires are investigated. The abnormal Raman spectrum shows only a peak centred at 439 cm−1 related to high E2 mode, which is due to In doping. The acceptor binding energy is estimated to be 93 meV from the results of temperature-dependent photoluminescence spectra. The redshift of the bandgap edge is attributed to a merging of donor and conduction bands. The sensitivity of the sensors fabricated from In-doped ZnO nanowires is about 3–1 ppm ethanol, and increases nearly linearly up to 27 as the ethanol concentration is raised to 100 ppm. Our results indicate that the In-doped ZnO nanowires have potential applications in fabricating optoelectrical devices and gas sensors.

Fast humidity sensors are reported that are based on CeO2 nanowires synthesized by a hydrothermal method. Both the response and recovery time are about 3 s, and are independent of the humidity. The sensitivity increases gradually as the humidity increases, and is up to 85 at 97% RH. The resistance decreases exponentially with increasing humidity, implying ion-type conductivity as the humidity sensing mechanism. A model based on the morphology and surface energy of the nanowires is given to explain these results further. Our experimental results indicate a pathway to improving the performance of humidity sensors.