A facile method to control the morphology of FeNi3 nanoparticles by solution reduction reaction is presented. The spherical to platelet FeNi3 particles were obtained by changing pH from 11.5 to12.5 with 0.16 mol/L of hydrazine under ultrasound irradiation, with the ratio of Fe2+ to Ni2+ as 1:3. The amount of hydrazine had little influence on the morphology of the particles. The saturation magnetization (Ms) and coercive force (Hc) of the platelet particles were 59 emu/g and 120 Oe, respectively. The real part μ′ of the permeability of the platelet particles was about 2.43–2.71 and was frequency-independent in the range of 0.1–1.0 GHz. The imaginary part (μ′′) of the particles showed increase from 0.04 to 2.14 within the same frequency range.

Dispersions of reduced tungsten oxide and tungsten bronze nanoparticles are known to show a remarkable absorption of near-infrared (NIR) light applicable to solar control filters for automotive and architectural windows. Origin of the NIR absorption has been investigated by analyzing dielectric constants of CsxWO3 (x = 0.15, 0.25, and 0.33) and WO2.72, and using Mie scattering theory. The optical analysis and Mie scattering theory analysis indicate that a localized surface plasmon resonance and polarons of localized electrons contribute alongside to the observed NIR absorption at different wavelengths.

Amorphous ribbons of Co69Fe7Si14B10-xZrx (x = 0, 2.5, 5, 7.5 and 10) alloys have been prepared and their structure, soft magnetic and magnetoimpedance (MI) properties have been investigated. Glass forming ability (GFA) of these alloys was calculated using GFA parameter (α = Tx/Tl) and verified by experimental results. Saturation magnetization of the amorphous ribbon decreases on replacement of B by Zr which reveals Zr has more pronounced effect in decreasing saturation magnetization. However, improvement of other soft magnetic properties (coercivity and permeability) leads to considerable increase in MI properties. Annealing leads to crystallization of Co2Si, Co2B, Co2Zr and CoSi phases causing deterioration of soft magnetic and MI properties due to the magnetic hardness of the secondary phase which arises due to the presence of magnetocrystalline anisotropy.

Positron annihilation lifetime measurements are performed for sol–gel-derived 70 mol% SiO2–30 mol% CaO bioactive glass. Strong positronium formation processes are shown to be an inherent feature for these kinds of materials. Observed orthopositronium (o-Ps) lifetimes show a three-modal distribution with lifetime values weighed at ∼2, ∼18, and ∼70 ns. The exposure of the investigated sol–gel-derived bioactive glasses to water vapor significantly modifies o-Ps lifetime distribution due to the penetration of water molecules into the nanopores, indicating high ratio of their interconnectivity. Classic Tao–Eldrup equation is used to relate the o-Ps lifetimes with the size of nanopores, whose distribution is verified by nitrogen adsorption porosimetry.

The conventional JKR theory was extended to the adhesive contact of a rigid sphere onto an elastic film perfectly bonded to a rigid substrate. An elasticity problem of axisymmetric indentation on an elastic film was revisited, in which the force–depth relations for both flat and spherical indentations were obtained in a simple form. With the obtained force–depth relations, the energy release rate at the debonding of a spherical tip from an elastic film was expressed in terms of pull-off force, elastic constants, and geometric parameters. The adhesion energy between a spherical tip and an elastic film can be measured as the critical energy release rate at the instability of debonding. This study suggests that when the critical radius of contact is larger than the thickness of an elastic film, the extended JKR theory should be used in place of the conventional JKR theory to correctly evaluate the adhesion energy between the spherical tip and the elastic film.

Bulk ceramics In2−xGexO3 have been synthesized in air by using citrate gel process. Nanoparticles of less than 20 nm have been synthesized through an accurate control of the processing parameters. X-ray diffraction and scanning electron microscopy studies confirmed that the solubility limit of Ge in In2O3 (xℓ) is very small and that additions of more than about 0.5 at.% Ge lead to the presence of In2Ge2O7 inclusions. Thanks to a high interdispersion of metal ions and homogeneity in elemental composition of the nanopowders obtained by citrate gel process, well-dispersed In2Ge2O7 secondary phases can be formed in the Ge-doped In2O3 matrix. An abrupt increase in the electrical conductivity and in the carrier concentration with x is observed in the monophasic region (x < xℓ), whereas in the biphasic region (x > xℓ), these values do not vary significantly. Similarly, the thermopower |S| value is correlated to this variation decreasing as x increases for x < xℓ. Above the solubility limit, the decrease in the lattice thermal conductivity is shown to be dependent on the presence of well-dispersed In2Ge207 secondary phases. The dimensionless figure of merit value is increased up to 0.3, thanks to electron doping and phonon scattering.

Optical emission spectroscopy (OES) was used to study plasmas generated by a novel plasma-enhanced linear antennas microwave chemical vapor deposition system for nanocrystalline diamond (NCD) growth in gas mixtures of H2 + CH4 + CO2. Atomic hydrogen intensities were investigated for pulsed plasmas and continuous wave (CW) mode plasmas. OES was used to study the effect of pressure (0.38–2 mbar), microwave pulse frequency (3.8–25 kHz), and total gas flow (125–1000 sccm). By using the Boltzmann plot for atomic hydrogen line intensities, plasma electron temperatures for pulsed and CW plasmas were calculated. During experiments, NCD films were deposited, which were investigated by secondary electron microscopy and Raman spectroscopy in terms of surface crystalline morphology and nondiamond carbon content. NCD films produced in high pulse frequency plasmas show low sp2 content (less than 5%) and homogenous crystalline structure with only a small amount of crystalline defects.

Silica-titania sub-close-packed single layers were deposited by spin coating titanium alkoxide sols containing inert 0.5 micrometer silica particles to study the process of reactive sintering more closely than has been done before. The sub-close-packed single layers were designed to achieve a coating density such that pairs or chains of silica particles were placed on the flat substrate and held together by the reactive titania thin films overlaid on the surface and in the neck regions of these essentially 2-D particle networks. Because of the low density of silica particles, all of the two-particle junctions and neck regions were aligned for geometrically direct viewing; as a result scanning electron microscopy was useful for observing the morphology of these neck regions. Image analysis was used to quantify the neck diameter for varying titania/silica precursor concentration ratios. Geometrical calculations that relate the change in neck volume to the neck radius are presented. Implications for design of reactive sintering systems are discussed.

The whiskers spontaneously grown in Cd–Mg–Yb alloy containing icosahedral quasicrystal as dominant phase have been investigated by electron microscopy. It is found that: (i) the whiskers are mainly composed of Cd with growth direction along . CdO particles are frequently observed on surfaces of whiskers and the alloy, indicating the importance of the oxidation process during the whisker growth; (ii) there exist four types of orientation relationship between Cd and CdO. The interfaces between them are shown to accommodate large lattice misfit, which is well explained by near coincidence site lattice model; (iii) nanosized Cd particles are observed to aggregate around the whisker root, providing a convincing experimental evidence for the long-range atomic diffusion. Our study offers a unique opportunity to unveil the relationship between unstability of quasicrystal structure and whisker formation and may have some implications for oxidation process of metals.

Nanohybrid shish kebab (NHSK) structure, in which fibrous carbon nanotubes (CNTs) act as shish, while polymer lamellae as kebab, is of particular interest both scientifically and technologically. In this work, two types of CNTs with the same diameter range and different topography structure, namely multiwalled carbon nanotubes (MWNTs) with a relatively smooth surface and double-walled carbon nanotubes (DWNTs) bundles with a groove structure, were used to induce polyethylene (PE) crystallization for the formation of NHSK. For PE/MWNTs system, NHSK was formed only at a relatively low crystallization temperature (Tc), and PE lamellae are not completely perpendicular to the long axis of MWNTs. However, for PE/DWNTs bundles system, NHSK could be obtained even at a much higher Tc, and almost all the PE lamellae are perpendicular to CNTs long axis, due to the unique “groove structure” formed by DWNTs bundles. The enhanced nucleation ability and the facilitated lamellae orientation by using DWNTs bundles are not only of great crystallography interest but also are very important for functional design in nanodevice applications.

A systematic evaluation of the electrical conductivity of Sr-substituted YAlO3 system has been performed. A comparison between the Ca- and Sr-doped YAlO3 systems is reported. The samples have been synthesized by citrate gel route, and the electrical conductivity measurements have been conducted in air in the 300–800 °C temperature range. The influence of phase development of the compositions on the total conductivity has been investigated using the x-ray diffraction technique. Also, the effect of microstructure and composition of the phases evolved on the electrical conductivity has been analyzed using scanning electron microscopy and energy dispersive spectrum techniques.

A method is presented for the identification of plastic material properties, i.e., yield strength and work hardening rate, using the residual imprint geometry formed by a spheroconical indentation. A corresponding finite element simulation with the same tip geometry and maximum as applied in the indentation experiment yields a numerical imprint profile. Then, the imprint profiles resulting from simulation and experiment are compared, and the material parameters of the simulation are varied by an optimization procedure until a satisfying agreement between simulation and experiment is established. At this stage, the material parameters used for the simulation represent the true material properties. It is shown that this procedure yields unique results that are furthermore verified by independent uniaxial straining experiments. Finally, the reliability of this method with special emphasis on its sensitivity with respect to measurement errors of the imprint geometry is demonstrated. Hence, it is concluded that the residual imprint can be regarded as the fingerprint of a material that contains sufficient information on plastic material behavior to uniquely extract values for yield strength and work hardening rate.

The aim of this study was the development of biocomposite scaffolds (membranes and matrices) based on natural polymers used for bone tissue engineering. The novelty featured in this paper is the use of phosphorylated dextran (PDex) as natural component in collagen-based biocomposites. The PDex both in acid form and as mixed salts of Mg–Na, Zn–Na, Ca-Na was characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) spectroscopy, potentiometric and conductometric titration and energy dispersive x-ray spectroscopy (EDX) analysis. The biocomposite scaffolds were obtained by freeze-drying as matrices and by free-drying as membranes with specific microporous morphological structures that depended on drying process of collagen gels with PDex. The biocomposites were physical–chemical characterized by differential scanning calorimetry (DSC) and, water and water vapor absorption. The biocompatibility was evaluated in vitro with human osteosarcoma MG 63 cell lines. The results showed that biocompatibility was improved by the use of PDex as mixed salts of Mg–Na, Zn–Na, Ca-Na in collagen biocomposites.

When thin nanomaterials spontaneously deform into nonflat geometries (e.g., nanorods into nanohelices, thin sheets into ruffled forms), their properties may change by orders of magnitude. We discuss this phenomenon in terms of a formal mathematical concept: codimension c = D − d, the difference between the dimensionality of space D, and that of the object d. We use several independent examples such as the edge stress of graphene nanoribbons, the elastic moduli of nanowires, and the thermal expansion of a modified bead-chain model to demonstrate how this framework can be used to generically understand some nanomaterial properties and how these properties can be engineered by using mechanical constraints to manipulate the codimension of the corresponding structure.

Backscattered electron microscopy provides gray-level contrast resulting from variations in atomic composition. Through the use of reference materials, quantitative backscattered electron (qBSE) imaging can be used to measure the mineral content of mineralized tissues at submicron resolution. We have developed novel tunable reference materials that can be adjusted for analysis of an individual tissue or a wide range of tissues with variable atomic density. As an alternative to conventional metallic reference materials, these amorphous materials maintain long-term stability and possess no long-range order that may induce channeling contrast. Using these reference materials, we characterized the mineral content of a broad range of mineralized tissues from immature mouse femur to whale bulla. Mineral volume fraction correlated to more traditional measurements of mineral content with microcomputed tomography and ashing techniques. Further, we demonstrate the advantage of location-matched measurements of nanomechanical properties and qBSE mineral content.