In this article, we present novel sample preparation methods using a helium ion microscope (HIM). We report the possibility of reshaping, at room temperature, thin metal lines on an electron-transparent membrane: A set of platinum bridges with standard geometry (300 × 200 × 15 nm) was modified at room temperature into different shapes using focused helium (He)-ion beam. Also the applicability of the HIM as a tool for precise modification of silicon (Si) and strontium titanate (SrTiO3) lamellae is shown and discussed. We demonstrated that in situ heating (e.g., at 600 °C) of the samples during He-beam illumination by use of a specially developed heating stage enables production of thin Si and SrTiO3 samples without significant artifacts. The quality of such cuts was inspected by transmission electron microscopy with high-resolution imaging, and the diffraction patterns were analyzed.

Red and near-infrared photons of longer wave lengths are poorly absorbed in thin film silicon cells and advanced light trapping methods are necessary. The physical mechanisms underlying the light trapping using periodic back reflectors are strong light diffraction, coupled with plasmonic light concentration. These are contrasted with the scattering mechanisms in randomly textured back reflectors. We describe a class of conformal solar cells with nanocone back reflectors with absorption at the Lambertian 4n2 limit, averaged over the “entire” wave length range for hydrogenated nanocrystalline silicon (nc-Si:H) thin-film solar cells. The absorption is theoretically found for 1-μm nc-Si:H cells, and is further enhanced for off-normal incidence. Predicted currents exceed 31 mA/cm2. Nc-Si:H solar cells with the same device architecture were conformally grown on periodic substrates and compared with randomly textured substrates. The periodic back reflector solar cells with nanopillars demonstrated higher quantum efficiency and photocurrents that were 1 mA/cm2 higher than those for the randomly textured back reflectors.

Lattice volume expansion or amorphization renders EuTiO3 ferromagnetic, although the stable phase of crystalline EuTiO3 is an antiferromagnet. The lattice volume expansion is induced into the crystalline EuTiO3 thin film by utilizing the lattice mismatch between the thin film and a substrate. The magnetization at low temperatures monotonically increases with an increase in lattice volume for the crystalline EuTiO3 thin film, coincident with the results of calculations based on the hybrid Hartree–Fock density functional approach. The ferromagnetic interaction between Eu2+ ions is enhanced by the amorphization as well; the amorphous EuTiO3 thin film becomes a ferromagnet, and the Curie temperature is higher for amorphous Eu2TiO4 than for its crystalline counterpart. The phenomenon, that is, the volume expansion- and amophization-induced ferromagnetism, is explained in terms of the competition between ferromagnetic and antiferromagnetic interactions among Eu2+ ions.

In this article, the effects of substrate temperature on the crystallographic structure and first-order magnetic phase transition in iron-rhodium (FeRh) thin films are investigated. It was found that for the as-deposited FeRh thin films, 350–400 °C is the optimal range of substrate temperature for obtaining B2 ordered FeRh thin films. After postannealing, it was shown that 400 °C is the optimized substrate deposition temperature for obtaining the best chemical/atomic ordering in postannealed FeRh thin films. Magnetization studies indicate that the as-deposited FeRh thin film with substrate temperature of 350 °C does not show a first-order antiferromagnetic (AFM)- to-ferromagnetic (FM) phase transition behavior during heating process and it gives a typical FM behavior whereas the as-deposited FeRh thin film deposited at 400 °C shows a broad first-order AFM-to-FM phase transition during heating and cooling processes. Both the postannealed FeRh thin films deposited at 350 and 400 °C give a clear first-order AFM-to-FM phase transition with a residual magnetization of about 50–100 emu/cc. The residual magnetization may possibly be caused by the disordered bcc (α) FM phase, B2 ordered (α′) FM phase or a near-surface/interfacial ferromagnetism in the ordered FeRh thin films.

Nanoindentation was performed on amorphous silicon nitride films of different thicknesses deposited on gallium arsenide (GaAs) (001) substrates using a conical indenter. Both “pop-in” and ‘pop-out’ were observed from the load-displacement curves when the indentation load exceeded a critical value. Pop-in occurring during loading is associated with plane-slip in the GaAs substrate, and pop-out during unloading is attributed to the interfacial delamination between the film and the substrate. Finite element modeling (FEM) was used to analyze the stress evolution during unloading. The FEM results showed that the stress at the interface evolved from compressive to tensile status during the withdrawal of indentation load, and the interfacial debonding was induced at a critical tensile stress, which is consistent with the pop-out observed. A deformation model for interpreting the pop-in and pop-out events is thereby proposed.

The probability for amorphous silicon (a-Si) to phase transform under indentation testing is statistically determined as a function of annealing temperature from the probability of a pop-out event occurring on the unloading curve. Raman microspectroscopy is used to confirm that the presence of a pop-out event during indentation is a clear signature that a-Si undergoes phase transformation. The probability for such a phase transformation increases with annealing temperature and reaches 100% at a temperature of 340 °C, a temperature well before the temperature where the average bond-angle distortion is fully minimized. This suggests that multiple processes are occurring during full relaxation.

The organic light-emitting (OLE) materials have attracted great interest due to their potential applications in sensors, biodetectors and OLE devices. However, highly efficient emission from organic solids is still a great challenge because of the aggregation-caused quenching effect. In this article, a three-dimensional (3D) organic-inorganic hybrid nanoparticle, based on polyhedral oligomeric silsesquioxane (POSS), was precisely fabricated via click chemistry with high yield, and its structure was characterized by Fourier transform infrared spectroscopy, 1H, and 29Si nuclear magnetic resonance spectroscopies, and Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry, respectively. The resultant 3D organic-inorganic nanohybrid showed significantly enhanced emission in solid film (Φfilm 80%) with a slight red-shift as compared with its organic counterpart, (Φfilm 14%), which exhibits a large red-shift in solid film, due to the deaggregation effect of POSS. Simultaneously, the resultant nanohybrid also exhibited good film formability, excellent spectrum and thermal stability (>250 °C) due to the introduction of POSS.

Nanosized oxides of barium strontium zirconate of general formula Ba1-xSrxZrO3 (0 ≤ x ≤ 1) have been prepared over the entire range of x for the first time by polymeric precursor route using citric acid and ethylene glycol. These solid solutions were investigated by means of powder x-ray diffraction, transmission electron microscopy, scanning electron microscope and Brunauer, Emmett and Teller surface area studies. X-ray diffraction studies reveal the monophasic nature of the powders at 1000 °C. The grain size was found to be in the range of 17–52 nm for all the oxides at 1000 °C. Specific surface area of these solid solutions comes out to be in the range of 49.1–94.4 m2/g. Smallest particle size with highest surface area has been achieved for x = 0.25 and comes out to be 17 nm and 94.4 m2/g respectively. Dielectric constant (ε) and dissipation factor (D) were investigated as a function of frequency and temperature. The room temperature dielectric constant of Ba1-xSrxZrO3 was found to be maximum 105 for x = 0.20 at 1 MHz.

Resistance degradation of zirconium (Zr)-doped barium titanate (BaTiO3) was investigated. A series of Ba(Ti1−yZry)O3 powders and coarse-grained ceramics ranging y from 0 to 0.1 were prepared. The increase of Zr concentration systematically increased the time to as well as electric field to degradation. Such behaviors directly corresponded to those of ionic conduction contribution as evaluated by the Warburg impedance. The magnitude of Warburg impedance decreased with the increase of Zr concentration, which demonstrates that the Zr incorporation inhibits the ionic conduction caused by oxygen vacancies. The prototype multilayer ceramic capacitor (MLCC) samples were also prepared by applying these Ba(Ti1−yZry)O3 base powders and formulated X5R additives of commercial application. In this case, however, such distinct difference in degradation behavior with the variation of Zr concentration did not appear. It is supposed that the influence of additives far outweighs the effect of relative difference in the ionic conduction of Ba(Ti1−yZry)O3 under the MLCC test condition where the applied electric field strength is much higher than those for the coarse-grained bulk ceramics. Resistance degradation of MLCC under such high field might not be explained by only oxygen vacancy-related behavior alone.

We introduce a novel method for producing polystyrene (PS)-grafted multiwalled carbon nanotubes (MWCNTs), which provides a direct route to composites where carbon nanotubes (CNTs) are the major component. Infrared and Raman spectroscopies confirmed that the MWCNTs were functionalized with PS. Thermogravimetric analysis showed that CNTs increase thermal stability of the composite up to a critical loading (∼40 wt%) beyond which high nanotube loadings decrease the polymer degradation temperature, as a consequence of the thermal properties of CNTs and the composite morphology. Even at loadings as high as 80 wt% MWCNTs, the composite is an effective masterbatch material for both solution- and melt-processing. These results show that in situ polymerizations can be flexible and robust techniques for nanocomposite processing, overcoming limitations of conventional processing techniques to produce nanocomposites with very high nanotube loadings, not achieved hitherto.

Nano-structured graphene has recently attracted extraordinary attention due to its potential use as an electronic or spintronic material. We investigated the electrical conductivities of antidot and Ar-sputtered graphene samples under a magnetic field in terms of the carrier density. Antidot samples exhibit conductivity that is well explained by charged impurity scattering, which is associated with intravalley scattering. This suggestion is supported by the low intensity of the Raman D band, which is related to intervalley scattering induced by structural defects. In contrast, Ar-sputtered samples show a strong D band and conductivity that is affected by defect scattering. The difference in the main scattering mechanism between the two types of samples appears as Shubnikov-de Haas oscillations at high magnetic fields, which are observed in antidot samples but not in Ar-sputtered samples. Furthermore, an analysis of weak localization effects in both samples at low fields reveals that intra- and intervalley scatterings play significant roles in antidot and Ar-sputtered samples, respectively.

The liquid phase plasma reduction method has been applied to prepare silver nanoparticles from a solution of silver nitrate (AgNO3) using a bipolar pulsed electrical discharge system. The excited states of atomic silver, hydrogen and oxygen as well as the molecular bands of hydroxyl radicals were detected in the emission spectra. As the discharge duration increased up to 10 min, silver particle peaks produced by surface plasmon absorption were observed around 430 nm. Both the particle size and the particle numbers were observed to increase with the length of the plasma treatment time and with the initial AgNO3 concentration. Spherical nanoparticles of about 5–20 nm in size were obtained with the discharging time of 5 min, whereas aggregates of nanoparticles of about 10–50 nm in size were mainly produced with the discharging time of 20 min. The cationic surfactant of cetyltrimethylammonium bromide (CTAB) added with the CTAB/AgNO3 molar ratio of 30% was shown to inhibit nanoparticle aggregation.

This study presents a polymerization of L-lactide and poly(ethylene glycol) of various molecular weights to produce biodegradable poly(L-lactide)-poly(ethylene glycol) (L-PEG) block copolymers. The chemical structures, crystallization behavior and thermal properties of L-PEG copolymers were investigated using proton nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, gel permeation chromatography, thermogravimetric analysis and differential scanning calorimetry (DSC). The analysis of isothermal crystallization behavior of L-PEG copolymers using the Avrami equation revealed that the grain growth of L-PEG200 and 600 were unstable, jumping between one dimension and two dimensions. By contrast, the grain growth of L-PEG2000 was more stable, with a growth trend toward three dimensions. The results of L-PEG isothermal crystallization by DSC indicate that within a range of 123–127 °C, the crystallization rate was higher at lower temperatures. The values of the crystallization constants in the Avrami equation were also lower.

Films of 3-aminopropyltriethoxysilane films (APTES) deposited from nonpolar solvents show unusual hardness and tribological properties. The morphological origin of this behavior is determined using x-ray reflectivity. The deposited APTES films are smooth, evolving from a sparse structure when less than two-molecule-thick (<1 g/cm3) to a dense structure (1.26 g/cm3) when thicker. Previously reported improvements in wear resistance and hardness are due to the unusually dense nature of the APTES film. The density of multilayered APTES film has implications for its use as an interface-coupling agent because the film density limits the reactivity of embedded amine groups. A high-temperature cure (120 °C) does not affect film density but does significantly improve hydrolytic stability. Given their high density, predictable reactivity, stability and resistance to wear, multilayered APTES films are well suited for interfacial modification designed to improve mechanical properties, provided the films are properly cured.

The fast dissolution of certain calcium-containing compounds makes them attractive carriers for trace minerals in nutritional applications, e.g., iron and zinc to alleviate mineral deficiencies in affected people. Here, CaO-based nanostructured mixed oxides containing nutritionally relevant amounts of Fe, Zn, Cu, and Mn were produced by one-step flame spray pyrolysis. The compounds were characterized by nitrogen adsorption, x-ray diffraction, (scanning) transmission electron microscopy, and thermogravimetric analysis. Dissolution in dilute acid (i.d.a.) was measured as an indicator of their in vivo bioavailability. High contents of calcium resulted in matrix encapsulation of iron and zinc preventing formation of poorly soluble oxides. For 3.6 ≤ Ca:Fe ≤ 10.8, Ca2Fe2O5 coexisted with CaO. For Ca/Zn compounds, no mixed oxides were obtained, indicating that the Ca/Zn composition can be tuned without affecting their solubility i.d.a. Aging under ambient conditions up to 225 days transformed CaO to CaCO3 without affecting iron solubility i.d.a. Furthermore, Cu and Mn could be readily incorporated in the nanostructured CaO matrix. All such compounds dissolved rapidly and completely i.d.a., suggesting good in vivo bioavailability.