To study the effect of nanotwins on thermal stability, a comprehensive characterization study was performed on two types of ultrafine grained (UFG) copper samples, with and without nanotwins. The two samples were sequentially heat-treated at elevated temperatures, and the grain size, grain boundary character, and texture were characterized after each heat treatment. The as-prepared nanotwinned (nt) copper foil had an average columnar grain size of ∼700 nm with a high density of coherent twin boundaries (CTBs) (twin thickness, ∼40 nm), which remained stable up to 300 °C. In contrast, the other UFG sample had few CTBs, and rapid grain growth was observed at 200 °C. The thermal stability of nt copper is discussed with respect to the presence of the low energy nanotwins, triple junctions between the twins and columnar grains, texture and grain growth.

The effect of crystallographic orientation and sample volume on incipient plasticity of commercially pure polycrystalline nickel 200 was investigated using electron back scatter diffraction (EBSD) and nanoindentation. A nickel sample was annealed, and grain orientations were determined using EBSD. Specifically oriented grains were indented using tips of nominal radii 100, 1000, and 1300 nm. The onset of plasticity in relatively defect-free small volumes is characterized by a sharp “pop-in” event during load-controlled nanoindentation. Grains in the (001) orientation yield at higher pressures; larger radii tips are more sensitive to orientation effects but yield at lower stresses. Subsurface defects may result in the dominance of tip radius over orientation, indicated by statistical analysis of yield points. An activation volume analysis, in conjunction with the yield pressure as a function of tip size, suggests that dislocation loops may play a critical role in causing these effects.

The indentation hardness of three different pure forms of silicon was investigated by two different methods. The hardness was probed by direct imaging of the residual impressions and by instrumented indentation using the Oliver–Pharr method. The forms of silicon used were a defective form of amorphous silicon, an amorphous form close to a continuous random network, and a crystalline silicon. The first form deforms via plastic flow and the latter two via phase transition. Two different unloading rates, fast and slow, were used to vary the phase transition behavior. This influenced the relative hardness as measured by instrumented indentation, which is not a reliable method to quantify hardness values in phase transforming materials. Thus, for our phase transforming silicon system, the relative hardness between samples can only be determined correctly by direct imaging, provided that the image accurately reveals the extent of the phase transformed volume.

With regard to the micromechanical characterization of particle–matrix composites like Li-ion electrode materials, we utilized nanoindentation technique as a method for quantifying the Young’s modulus of a single ceramic particle with a diameter of a few micrometers, which was embedded in a softer polymeric matrix. For the experiments, we used reference composites having high Young’s modulus and high hardness ratios of up to 100 (particle/matrix) and filler contents of 10 and 80 vol%. We further performed finite element simulations to understand the indentation process of single particles. It was found that depending on filler content, particle size, and particle/matrix properties, a significant error up to 75% may occur when characterizing single particles by nanoindentation. We finally propose a framework by using standard nanoindentation methods with conventional data analysis as well as an additional postprocess evaluation to determine the Young’s modulus of single particles and we discuss its limitations.

A sulfonated activated carbon fiber catalyst (SACF) was prepared through γ-irradiation-induced grafting of styrene onto the surface of activated carbon fiber (ACF) with an irradiation dose of 0.837 kGy/h for 48 h that was then sulfonated with chlorosulfonic acid under mild reaction conditions. Scanning electron microscopy observation showed that the ACF was wrapped by a thin layer of copolymer, and Fourier transfer infrared spectroscopy analysis indicated that sulfonic acid groups were successfully introduced onto the ACF. Pore structure analysis based on nitrogen adsorption isotherms at 77 K demonstrated that pore parameters of ACF were well maintained after the process of grafting and sulfonation modification. Proper conditions for the SACF preparation were sulfonated at 80 °C for 1.5 h in the 20% mass percentage of chlorosulfonic acid solution using ACF precursor, whose acid density could reach 1.47 mmol/g. The sulfonated ACF was used as catalyst for the esterification of acetic acid and ethanol. Evaluation of the catalytic activity of SACF showed evident advantages over other typical catalyst, with a turnover frequency value of 0.780 min−1, about five times higher than Nafion.

In the present work, proton conducting nanocomposite electrolytes containing poly(vinylphosphonic acid) (PVPA) and TiO2 have been prepared and characterized. In the nanocomposite materials, the TiO2 content was varied from 5% to 20% (w/w) to improve mechanical strength and stability. The thermal stability, proton conductivity, as well as morphology of the electrolytes were investigated. The interaction existed between PVPA and TiO2 was confirmed by Fourier transform infrared spectroscopy. Thermogravimetric analysis showed that the samples are thermally stable up to approximately 200 °C. Differential scanning calorimetry results indicate that the Tg of the materials shift to higher temperatures as TiO2 content increases. Scanning electron microscopy results confirmed that the TiO2 nanoparticles were successfully incorporated and homogeneously distributed in the PVPA matrix. In the anhydrous state, the proton conductivity of PVPA(10)TiO2(in situ) has been found to be 0.004 S/cm at 120 °C. The proton conductivity of these membranes are also measured and compared with previous studies.

A Zn2SnO4/graphene (Zn2SnO4/G) hybrid was prepared by a facile one-pot hydrothermal route using SnCl4·5H2O, ZnSO4·7H2O, and graphite oxide as the precursors and NaOH as the mineralizer. Microsized Zn2SnO4 crystals with an octahedral shape are firmly confined by the graphene sheets, forming a unique hybrid structure. The confining effect of graphene leads to a more homogeneous size distribution of Zn2SnO4 crystals in Zn2SnO4/G than in bare Zn2SnO4. The introduction of graphene also brings an improved Li-storage performance for Zn2SnO4 due to the combined buffering, conducting, and confining effects of graphene. After being cycled at 200 mA/g for 50 times, Zn2SnO4/G can still keep a charge capacity of 326 mAh/g, while for bare Zn2SnO4, its charge capacity drops to only 100 mAh/g after the same cycles.

We have grown VO2/NiO epitaxial thin films by pulsed laser deposition where integration with Si(001) substrates was achieved by cubic yttria-stabilized zirconia (YSZ) buffer layer. The most interesting aspect of this work is that a complete relaxation along c-axis of VO2 is achieved in these large misfit systems through the domain matching epitaxy paradigm, which is critical for controlling the semiconductor to metal transition (SMT) characteristics. Regarding x-ray diffraction and cross-sectional transmission electron microscopy results, the epitaxial relationship across the YSZ/Si(001) interface was (001)[100]YSZ‖(001)[100]Si. In the case of YSZ/NiO interface, the epitaxial relationship was $(001)[010]_{{\rm{YSZ}}} \parallel (111)[00\overline 1 ]_{{\rm{NiO}}} $. The epitaxial relationship at the NiO/VO2 interface was determined to be $(010)[001]_{{\rm{VO2}}} \parallel (111)[00\overline 1 ]_{{\rm{NiO}}} $. The SMT characteristics of these fully relaxed films were determined, and a transition temperature of 341 K with amplitude over four orders of magnitude and the hysteresis of 3.4 K hysteresis were obtained, which are close to those of the bulk high quality single crystals.

Resistive memory devices have the potential to replace flash technology due to their increased scalability, low voltage of operation, and compatibility with silicon semiconductor manufacturing. We report a spin-on resistive switching material, hydrogen silsesquioxane (HSQ), which is a commonly used electron beam resist. We demonstrate device scalability from 100 μm to 48 nm and show that the switching properties do not depend on the device size. Set voltages were typically <3 V, while reset voltages were <1 V when analyzing the positive unipolar switching properties of these devices. The ratio of the high resistance to the low resistance was ranged from 101 to 102, creating a distinct memory window between the memory states. Composition–depth profiling revealed that copper from the bottom electrode migrated into the HSQ films as a result of annealing. It is therefore speculated that copper may play a role in the switching properties of devices based on this material.

Most CuIn(SexS1−x)2 (CISS) thin films are deposited via conventional two-stage process. However, a significant problem related to the conventional two-stage process is the separation of CuInSe2 and CuInS2 phases. In this article, single-phase CISS thin films have been successfully prepared by selenizing sulfides of copper and indium. The mixed sulfides of Cu–In precursors were synthesized by coprecipitation method and then partly reduced. The inks containing partly reduced powders and organic binders were deposited onto glass substrate using a spin-coating technique. After coating, the precursor films were selenized to get CISS. X-ray diffraction and energy dispersive x-ray spectroscopy data show that the single (112) peak position changed with the variation of Se/S ratio. The absorption energy Egchanges linearly with Se/(Se + S) calculated by ultraviolet–vis absorption spectra. Those results confirm the formation of single-phase CISS with homogenous composition.

Single and multilayer diamond films were grown on silicon by varying substrate distance in hot-filament chemical vapor deposition. The grown films were characterized by scanning electron microscope (SEM) and Raman spectroscopy. From SEM surface images, it was observed that the films grown at substrate distances of 8, 7, and 6 mm and temperatures of 740, 780, and 830 °C possessed cauliflower, pseudocubes, and finally well-faceted cubes morphology. SEM fracture cross-sectional investigations revealed that growth of pseudocubes initiated on the top of cauliflower structure. By using the parametric relations gathered from single layer diamond growth studies, first time, multilayer diamond coatings were grown in situ with tunable thickness by only varying the substrate distance from filament assembly during deposition.

Nanostructured tungsten trioxide films were prepared by reactive dc magnetron sputtering at different working pressures Ptot = 1–4 Pa. The films were characterized by scanning electron microscopy, x-ray diffraction, Rutherford backscattering spectroscopy, Raman spectroscopy, and ultraviolet–visible spectrophotometry. The films were found to exhibit predominantly monoclinic structures and have similar band gap, Eg ≈ 2.8 eV, with a pronounced Urbach tail extending down to 2.5 eV. At low Ptot, strained film structures formed, which were slightly reduced and showed polaron absorption in the near-infrared region. The photodegradation rate of stearic acid was found to correlate with the stoichiometry and polaron absorption. This is explained by a recombination mechanism, whereby photoexcited electron–hole pairs recombine with polaron states in the band gap. The quantum yield decreased by 50% for photon energies close to Eg due to photoexcitations to band gap states lying below the O2affinity level.

Ag nanoparticles dispersed SiO2 composite films were successfully prepared by a sol–gel method. The structural transition, formation, and optical property along with relevant band gap of Ag/SiO2 thin films during the annealing process were studied by Fourier transform infrared spectroscopy, thermogravimetry–differential thermal analysis, x-ray diffraction, and ultraviolet–visible spectroscopy, while the microstructure of thin films was revealed by transmission electron microscopy. The results indicate that the Ag spherical particles with the diameter of 10–20 nm were formed by breaking Si–O–Ag bonds above 200 °C and dispersed in the SiO2 matrix. The optical absorption property of Ag/SiO2 nanofilm in the visible range is enhanced, and the band gap (Eg) is widened with raising annealing temperatures, which is promising for the potential applications in nonlinear optical and related fields.

The ability of silver (Ag)-containing borate bioactive glass (BG) coatings to improve the biocompatibility and antibacterial properties of titanium (Ti) implants was investigated in vitro and in vivo in a rabbit tibial fracture model. Dense coatings of borate BG (thickness ≈ 20 μm) containing 0, 0.75, and 1.0 wt% Ag2O were prepared by depositing a layer of particles on Ti plates, followed by sintering at 900 °C. The as-prepared coatings had an adhesive strength of 10 ± 1 MPa, and when immersed in an aqueous phosphate (K2HPO4) solution, the coatings converted to hydroxyapatite, releasing Ag+ ions continuously for over 4 wk. After implantation of BG-coated Ti constructs in a rabbit tibial fracture model and of methicillin-resistant Staphylococcus aureus-induced osteomyelitis, the BG coating doped with 1.0 wt% Ag2O was most effective for the simultaneous eradication of the infection and fracture fixation. Implants coated with Ag-containing BG coatings could provide an approach for reducing implant-related bone infection.

The composite nature of mineralized natural materials is achieved through both the microstructural inclusion of an organic component and an overall microstructure that is controlled by templating onto organic macromolecules. A modification of an existing laboratory technique is developed for the codeposition of a CaCO3–gelatin composite with a controllable organic content. First, calibration curves are developed to determine the organic content of a CaCO3–gelatin composite from infrared spectra. Second, a CaCO3–gelatin composite is deposited on either glass coverslips or demineralized eggshell membranes using an automated alternating soaking process. Electron microscopy images and use of the infrared spectra calibration curves show that by altering the amount of gelatin in the ionic growth solutions, the final organic component of the mineral can be regulated over the range of 1–10%, similar to that of natural eggshell.