Differentiation of the energy-based power function used to represent the nanoindentation unloading response at the peak indentation load generally overestimates the contact stiffness. This is mainly because of the larger curvature associated with this function and the proximity between the contact and maximum penetration depths. Using the nanoindentation data from ceramics and metals, we have shown that these two errors can be eliminated if the derivative is multiplied by the geometric and stiffness correction factors, respectively. The stiffness correction factor is found to be a function of the elastic energy constant and is independent of the peak indentation load. The contact stiffness evaluated by the proposed method is in excellent agreement with that obtained from the power law derivative for a wide range of elastoplastic materials and peak indentation loads. The relationship between the elastic recovery ratio and elastic energy constant developed in this study further simplifies the proposed procedure.

The paper established a model to investigate the interaction between the special rotational deformation and a semielliptical blunt crack in deformed nanocrystalline materials. By using the complex variable method, the effect of a disclination quadrupole produced by the special rotational deformation on the emission of lattice dislocation from a semielliptical blunt crack tip was explored theoretically. The complex form expression of the dislocation force was derived, and the critical stress intensity factors (SIFs) for the first edge dislocation emission were calculated. Then, the influence of the disclination strength, the disclination location and orientation, the special rotational deformation orientation, the grain size, and the curvature radius of blunt crack tip on the critical SIFs were discussed in detail, and a comparison with the sharp crack behavior was presented. The results show that the special rotational deformation and the curvature radius of blunt crack have great effects on the lattice dislocation emission form blunt crack tip. Some influence laws are also different with those of the edge dislocation emission from a sharp crack tip.

The indentation method of nonlinear viscoelastic materials is investigated through combined numerical and experimental efforts to reveal the correlation between the viscoelastic kernel function and the indentation responses. It is shown that the viscoelastic kernel function of a nonlinear viscoelastic solid with viscous response characterized by a linear rate constitutive equation scales with the normalized relaxation load in an indentation relaxation test. This scaling relation does not depend on the geometry of the indented solid and the profile of the indenter. Therefore, it may serve as a fundamental relation for characterizing the viscoelastic properties of some biological soft tissues and artificial soft materials with regular/irregular surface morphology.

Zinc oxide (ZnO) nanomaterial is a superior material for photoanode. However, the different reaction concentrations, growth time and reaction vessel have influences on the structure and morphology of ZnO, and and ultimately have a bearing on the performance of solar cells. In this article, we used the hydrothermal method for the preparation of ZnO nanostructure. For avoiding direct contact of electrolyte with fluorine-doped tin oxide conducting glass, and decrease the recombination probabilities, we used titanium tetrachloride pretreatment. For obtaining flower-like ZnO nanostructure that was composed of smaller diameter ZnO nanorods, we fabricated a smaller-particle seed layer prior to growing ZnO nanostructure. For the sake of getting the best performances of solar cells, we examined the various effects of different deposition cycles on the performance of the solar cells. We discovered that when the deposition cycles increased, short-circuit current density, open-circuit voltage, fill factor and conversion efficiency all increased. But when the deposition exceeded 9 cycles, the values of all the parameters decreased. When the deposition cycle is 9, the conversion efficiency is 1.156%.

Unique cocoon- and rod-shaped alpha-phase ferric oxide, hematite (α-Fe2O3) is prepared by a simple, scalable and surfactant-free chimie douce synthesis. The structure and morphology is confirmed by x-ray diffraction, field-emission scanning electron microscopy and high-resolution transmission electron microscopy. The electrochemical properties of α-Fe2O3 anodes are investigated using cyclic voltammetry, galvanostatic charge-discharge cycling and electrochemical impedance spectroscopy. The mesoporous α-Fe2O3 exhibited an initial discharge capacity >1741 mAh/g with excellent cycling performance and rate capabilities. The solvent used for the preparation of α-Fe2O3 plays a key role in determining the morphology of the materials, which greatly influenced its electrochemical properties.

Polyaniline/nano titanium dioxide/graphene nanoplatelet (PANI/TiO2/G) composite was synthesized by mechanochemical route. The structure and morphology of the composite were characterized by Fourier transform infrared spectra, ultraviolet-visible absorption spectra, x-ray diffraction and transmission electron microscopy. The electrochemical performances of the composite were investigated by galvanostatic charge-discharge, cyclic voltammetry, cycling stability and electrochemical impedance spectroscopy. The structure and properties of PANI/TiO2/G composite were compared with that of polyaniline/ graphene nanoplatelet (PANI/G) composite prepared under the same polymerization conditions. After comparative analysis with PANI/G, the effects of the nano titanium dioxide (TiO2) on the structural and physicochemical properties of the PANI/G have been discussed in depth. The comparison suggested that the PANI/TiO2/G composite has higher oxidation degree and lower crystallinity than PANI/G due to the addition of nano-TiO2. Morphology studies showed that PANI and nano-TiO2 particles were both observed on the bent and flat surfaces of graphene nanoplatelet in the PANI/TiO2/G composite. The electrochemical tests showed that the PANI/TiO2/G composite displayed a higher electrochemical activity with specific capacitance of 516 F/g (3 mA/cm2) and better cycle stability than PANI/G.

Polyaniline (PANI)–PbTiO3 composites were prepared by using different inorganic and organic acids by in situ polymerization technique using sodium dodecyl benzene sulfonic acid as a surfactant. The structural analysis was studied by using x-ray diffraction, and it was found that PANI is amorphous in nature. The scanning electron microscopy studies reveal that they are agglomerated and irregular, and size of these grains increase by increasing the amount of PANI with different organic and inorganic acids. The real part of complex permittivity (εʹ) and imaginary part of complex permittivity (εʹʹ) and the real part of the permeability (μ′) are studied at X-band frequency where (εʹ) and (εʹʹ) decreas with increase in frequencies, whereas μ′ increases with increase in X-band frequency and exhibits a maximum value of 0.87 at the resonance frequency of 9–11 GHz of 30 wt% PbTiO3 in PANI matrix. Reflection loss peak of 30 wt% of PANI–PbTiO3 composites is 28.6 dB at 10.8 GHz, which may be attributed to the maximum reflection of the microwave power for the particular doping concentration.

Uniform ytterbium ion and erbium ion codoped gadolinium oxyfluoride (GdOF: Yb3+, Er3+) hollow nanospheres of 100-nm diameter were synthesized via the nanoscale Kirkendall approach, using colloidal nanospheres of ytterbium ion and erbium ion codoped gadolinium hydroxide [Gd(OH)3: Yb3+, Er3+] as sacrificial templates and titanium tetrafluoride as fluorine source under hydrothermal condition. The shell thickness of the as-synthesized GdOF: Yb3+, Er3+ hollow nanospheres can be facilely tuned from 31 to 13 nm by controlling reaction temperature and reaction time. The upconversion emission color could be adjusted from red to yellow to green when the host lattices variedfrom gadolinium (III) oxide to gadolinium oxyfluoride to gadolinium fluoride. Furthermore, the formation mechanism of the hollow GdOF: Yb3+, Er3+ nanospheres was found to depend on the fluorine source.

Nanoerythrocyte-shaped ytterbium orthovanadate (YbVO4) with substantially uniform size have been successfully synthesized by a simple and facile trisodium citrate-assisted hydrothermal method. The erythrocyte-shaped YbVO4 nanocrystals with self-assembled spherical and biconcave structure have a diameter of ∼500 nm, which were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy and photoluminescence. The luminescent properties of erbium ion-doped ytterbium orthovanadate nanocrystals with different morphologies by different complexing agents were different in the relative intensity under identical measurement conditions, which exhibited the interesting morphology-dependent optical properties. The different energy transfer mechanisms and photoluminescence intensities might be the result of the greatly reduced defect centers.

When supported by suitable metal oxides such as ceria, platinum often displays increased catalytic activity and selectivity. A chemical vapor infiltration technique was used to impregnate Pt nanoparticles into an ordered mesoporous gadolinium-doped ceria (OMG), which was templated from KIT-6 silica. High Pt loading, up to 38 vol% of OMG, was achieved. This synthesis method is highly scalable and offers easy control over catalyst–support geometry. A detailed study of the OMG structure was conducted by controlling the synthesis parameters of the KIT-6 silica template. Formation mechanism and thermal stability of the OMG/Pt–OMG composite were also studied. The mesostructure composites were found to sustain until 750 and 650 °C, respectively. The highly structural composite holds the promise of increased activity, selectivity, and stability for applications in heterogeneous catalysis.

A mixture of pure Ni powder and pure W powder with a nominal composition Ni–15 at.% W was subjected to ball milling in a planetary mill and in a shaker mill. The microstructural evolution upon milling and upon subsequent annealing in the temperature range from 25 to 800 °C was investigated using ex situ and in situ x-ray diffraction integral breadth (single-line and Williamson–Hall) methods and whole powder pattern modeling as well as scanning electron microscopy, transmission electron microscopy, and differential scanning calorimetry. A nanocrystalline Ni(W) solid solution phase develops upon ball milling, with a higher W content by milling in the shaker mill as compared to the planetary mill. Grain coarsening studies indicated a very high stability of the nanocrystalline state, up to almost about 500 °C. Results of annealing at higher temperatures showed that, while the dissolved W content increased in the Ni matrix, a high stability against grain coarsening occurs, which can be ascribed to the presence of (segregated) W atoms at the grain boundaries.

Ce0.35Zr0.65−xRExO2 (RE = Y and La; x = 0 and 0.10) and Ce0.35Zr0.50Y0.075La0.075O2 were prepared by a coprecipitation method. The textures, structures, oxygen storage capacity (OSC), and redox properties of all samples were investigated using Brunauer–Emmett–Teller surface area characterization, x-ray diffraction (XRD), Raman spectra, temperature-programmed technique, and oxygen pulse reaction. The results showed that the fresh Ce0.35Zr0.65O2 has cubic phase, 434 μmol/g of OSC, 82 m2/g of surface area, and good redox properties; after aging at 1000 °C, Ce0.35Zr0.65O2 still has cubic phase, 418 μmol/g of OSC, and 50 m2/g of surface area; when Y3+ or La3+ is added to CeO2–ZrO2, the aged Ce0.35Zr0.65−xRExO2 (RE = Y and La; x = 0 and 0.10) still remains cubic phase, high OSC, and large surface area (47 m2/g); when Y3+ and La3+ are simultaneously added into CeO2–ZrO2, a stable solid solution with cubic phase is formed and has 459 μmol/g of OSC; and the aged Ce0.35Zr0.50Y0.075La0.075O2 reaches to 60 m2/g of surface area and has 390 μmol/g of OSC.

In this article, ZnO microtube was prepared using mixed powder of Zn, ZnO, and carbon as source via chemical vapor deposition method. The growth process was discussed in detail, and the high Zn vapor pressure and high growth temperature were considered as two crucial factors determining the formation of tubular structure. A two-step growth model was proposed, namely initial deficient-oxidation and followed by second-volatilization. Four another experiments were further conducted to analyze the growth behavior of reagent species under different Zn vapor pressure and growth temperature, respectively. These experimental results indicated that the formation of Zn-rich structure under enough high Zn vapor pressure and second-volatilization of these abundant interstitial Zn under high growth temperature were important to form tubular structure. Our experimental method provided a feasible route to prepare other hollow structures, such as oxide, sulfide, etc. Furthermore, these synthesized ZnO microtube might have potential application as functional blocks in nanodevices.