The purpose of this work is to further develop experimental methodologies using flat punch nanoindentation to measure the constitutive behavior of viscoelastic solids in the frequency and time domain. The reference material used in this investigation is highly plasticized polyvinylchloride (PVC) with a glass transition temperature of −17 °C. The nanoindentation experiments were conducted using a 983-μm-diameter flat punch. For comparative purposes, the storage and loss modulus obtained by nanoindentation with a 103-μm-diameter flat punch and dynamic mechanical analysis are also presented. Over the frequency range of 0.01–50 Hz, the storage and loss modulus measured using nanoindentation and uniaxial compression is shown to be in excellent agreement. The creep compliance function measured using a constant stress test performed in uniaxial compression and flat punch nanoindentation is also shown to correlate well over nearly 4 decades in time. In addition, the creep compliance function predicted from nanoindentation data acquired in the frequency domain is shown to correlate strongly with the creep compliance function measured in the time domain. Time–temperature superposition of nanoindentation data taken at 5, 10, 15, and 22 °C shows the sample is not thermorheologically simple, and thus the technique cannot be used to expand the mechanical characterization of this material. Collectively, these results clearly demonstrate the ability of flat punch nanoindentation to accurately and precisely determine the constitutive behavior of viscoelastic solids in the time and frequency domain.

A polypropylene-matrix composite material functionalized by nanoporous particulates was produced. When the temperature is relatively low, the matrix dominates the system behavior. When the temperature is relatively high, with a sufficiently large external pressure the polymer phase can be intruded into the nanopores, providing an energy absorption mechanism.

The effects of ultraviolet (UV) radiation on ultra-low-k dielectric (ULK) thin film fracture toughness were studied. This work discusses both critical and subcritical crack growth behavior under different environments. The critical fracture toughness was measured as a function of applied phase angle by using the four-point bend flexure and mixed-mode double cantilever beam techniques. Results of critical fracture toughness obtained under different loading configurations and phase angles were found to increase with the UV treatment time. In contrast, mode I subcritical fracture toughness thresholds and the crack propagation velocity appeared to be insensitive to UV curing processes. This study revealed that subcritical fracture toughness values reduced with the moisture concentration in the environment.

Lamellar liquid crystal (Lα) was formed by room temperature ionic liquid [Bmim]PF6, nonionic surfactant Tween 85, and H2O. The microstructure of this lamellar liquid crystal was investigated by small angle x-ray diffraction (SAXD) and 2H NMR (nuclear magnetic resonance). Ag nanoparticles with relatively uniform dispersion were prepared successfully in this Lα phase. The rheological and lubrication properties of the Lα phase and the Lα/Ag nanoparticle mixed system were also investigated. The results showed that the structure strength, anti-wear capacity, and lubrication properties of the Lα phase were enhanced with an increasing amount of Tween 85, but were impaired with an increasing amount of H2O. Increasing the amount of [Bmim] PF6 could also make the structural strength weaker, but the lubrication properties of the system were improved because of the inherent lubrication properties of ionic liquid. The presence of the Ag nanoparticles in the lamellar phase could also enhance the structural strength, anti-wear capacity, and lubrication properties.

The α-, β-, and δ-MnO2 with various morphologies have been synthesized by a novel redox system of KMnO4 and CuCl with HCl added under a hydrothermal condition. The resultant MnO2 products have been characterized by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Upon control of reaction temperature and duration, it was observed that MnO2 polymorphs of different morphology (e.g., flowery δ-MnO2, β-MnO2 nanowires and octahedrons, α-MnO2 nanowires) can be prepared in an adjustable manner. The phenomenon is mainly attributed to the effect of cuprous ions controllably released from CuCl by the action of HCl at different experimental conditions. The corresponding formation mechanism for the MnO2 crystals will also be proposed and discussed.

In this work load–penetration curves obtained by nanoindentation were analyzed, using a spherical tip approximation and applying the stress/strain concept by Tabor. Nanoindentation experiments were done on sapphire, pure TiC, and a mixed ceramic with in situ formed TiCx layer, using a sharp cube-corner indenter at very low loads and penetration depths. With the implemented method it is possible to display the elastic to elastic–plastic transition of each investigated phase, and much more information can be extracted than by conventional analysis. Regarding the mixed ceramic, it was found that the present TiC phases exhibit slightly lower hardness than the alumina phase, but they can sustain much higher stresses during the transition from the elastic to the elastic–plastic regime. This is considered to be beneficial for the application as cutting material. No correlation was found between the nanomechanical behavior of the model materials sapphire and TiC and the corresponding phases of the mixed ceramic.

Although alterations in the gross mechanical properties of dynamic and compliant tissues have a major impact on human health and morbidity, there are no well-established techniques to characterize the micromechanical properties of tissues such as blood vessels and lungs. We have used nanoindentation to spatially map the micromechanical properties of 5-μm-thick sections of ferret aorta and vena cava and to relate these mechanical properties to the histological distribution of fluorescent elastic fibers. To decouple the effect of the glass substrate on our analysis of the nanoindentation data, we have used the extended Oliver and Pharr method. The elastic modulus of the aorta decreased progressively from 35 MPa in the adventitial (outermost) layer to 8 MPa at the intimal (innermost) layer. In contrast, the vena cava was relatively stiff, with an elastic modulus >30 MPa in both the extracellular matrix-rich adventitial and intimal regions of the vessel. The central, highly cellularized, medial layer of the vena cava, however, had an invariant elastic modulus of ∼20 MPa. In extracellular matrix-rich regions of the tissue, the elastic modulus, as determined by nanoindentation, was inversely correlated with elastic fiber density. Thus, we show it is possible to distinguish and spatially resolve differences in the micromechanical properties of large arteries and veins, which are related to the tissue microstructure.

A method is presented for recognition of nanograins in high-resolution transmission electron microscope (HRTEM) images of nanocrystalline materials. We suggest a numerical procedure, which is similar to the experimental dynamic hollow cone dark-field method in transmission electron microscopy and the annular dark-field method in scanning transmission electron microscopy. The numerical routine is based on moving a small mask along a circular path in the Fourier spectrum of a HRTEM image and performing at each angular step an inverse Fourier transform. The procedure extracts the amplitude from the Fourier reconstructions and generates a sum picture that is a real space map of the local amplitude. From this map, it is possible to determine both the size and shape of the nanograins that satisfy the selected Bragg conditions. The possibilities of the method are demonstrated by determining the grain size distribution in gadolinium with ultrafine nanocrystalline grains generated by spark plasma sintering.

Three-dimensional spherical assemblies of Ni-doped ZnO nanocrystals have been prepared by the solution phase synthesis process. It has been observed that transition metal ions (Zn, Ni) are uniformly distributed in the sample and exist in the +2 oxidation state. Detailed investigation of structural defects formed during the formation of spherical assemblies by oriented attachment of nanocrystals was carried out by high-resolution transmission electron microscope (HRTEM), Raman and photoluminescence (PL) spectroscopy. HRTEM analysis revealed the existence of various crystal defects, such as stacking faults, dislocations, etc. The incorporation of Ni2+ into ZnO structure strongly influences the vibrational and optical properties of the sample due to the increment of defect densities. Compared to the optical phonons of ZnO, additional mode observed at 538 cm−1 in Raman spectra of Ni-doped ZnO could be associated with the incorporation of Ni2+ in Zn2+ site. The increase in PL intensity of green emission with Ni2+ doping indicates the formation of a higher concentration of oxygen vacancy in doped nanostructures.

The growth mechanism for the out-of-plane orientation of Nd–Fe–B films has been interpreted by the adparticle mobility during film growth, from the point view of the extended structure zone model. The growth mode changes sequentially from zone II to zone Ic, with the lowered thermally induced adparticle mobility on the surface as the film grows. As such, the whole Nd–Fe–B film evolves from [00l] out-of-plane orientation to more randomly out-of-plane alignment. With the growth of the out-of-plane–oriented Nd–Fe–B film, the correlation between the magnetic properties and the alignment evolution has been studied. The coercivity variation with the film growth is understood by analyzing the nucleation-dominant reversal processes for the out-of-plane–oriented Nd–Fe–B films.

At 1100 °C, the diffusion properties of Ti4+ into congruent LiNbO3 crystals codoped with 0.5 mol% Er2O3 and different MgO concentrations of 0.5, 1.0, and 1.5 mol% have been studied by secondary ion mass spectrometry (SIMS). Three Y-cut and three Z-cut plates with different Mg doping levels were coated with a 60-nm-thick Ti film at first and then annealed at 1100 °C for 28 h in a wet O2 atmosphere. SIMS was used to analyze depth profile characteristics of diffused Ti ions and the constituent elements of the substrate as well. The results show that the diffusion reservoir was exhausted and the Ti metal film was completely diffused. All measured Ti profiles follow a Gaussian function. No Mg out-diffusion accompanied the Ti in-diffusion procedure for all crystals studied. The 1/e diffusion depth is similar to 8.3/10.2, 7.4/8.7, and 6.6/8.2 ± 0.2/0.2 μm/μm for the Y/Z-cut crystal with the Mg doping level of 0.5, 1.0, and 1.5 mol%, respectively, yielding a Ti4+ diffusivity of 0.62/0.93, 0.49/0.67, and 0.39/0.60 ± 0.03/0.03 (μm2/h)/(μm2/h), respectively. The diffusion shows definite anisotropy and a considerable MgO doping level effect. Under the same Mg doping level, the diffusion in a Z-cut crystal is faster. The diffusivity decreases with the increase of the Mg doping level. This effect is qualitatively explained from the viewpoint of the Mg doping effect on concentration of the intrinsic defects in LiNbO3 crystal.

A series of Ti-B-C-N thin films were deposited on Si (100) at 500 °C by incorporation of different amounts of N into Ti-B-C using reactive unbalanced dc magnetron sputtering in an Ar-N2 gas mixture. The effect of N content on phase configuration, nanostructure evolution, and mechanical behaviors was studied by x-ray diffraction, x-ray photoelectron spectroscopy, Raman spectroscopy, high-resolution transmission electron microscopy, and microindentation. It was found that the pure Ti-B-C was two-phased quasi-amorphous thin films comprising TiCx and TiB2. Incorporation of a small amount of N not only dissolved into TiCx but also promoted growth of TiCx nano-grains. As a result, nanocomposite thin films of nanocrystalline (nc-) TiCx(Ny) (x + y < 1) embedded into amorphous (a-) TiB2 were observed until nitrogen fully filled all carbon vacancy lattice (at that time x + y = 1). Additional increase of N content promoted formation of a-BN at the cost of TiB2, which produced nanocomposite thin films of nc-Ti(Cx,N1-x) embedded into a-(TiB2, BN). Formation of BN also decreased nanocrystalline size. Both microhardness and elastic modulus values were increased with an increase of N content and got their maximums at nanocomposite thin films consisting of nc-Ti(Cx,N1-x) and a-TiB2. Both values were decreased after formation of BN. Residual compressive stress value was successively decreased with an increase of N content. Enhancement of hardness was attributed to formation of nanocomposite structure and solid solution hardening.

A poly(acrylic acid)/gelatin interpenetrating network hydrogel was synthesized by aqueous solution polymerization. The influences of preparation conditions including cross-linker, initiator, gelatin content, and neutralization degree on the swelling ratios of the hydrogels are investigated. The swelling, mechanical strength, biodegradability, and drug-release properties of poly(acrylic acid)/gelatin hydrogel are evaluated. The hydrogel has excellent mechanical properties; tensile strength is 1500 kPa, and elongation at break is 887%, respectively. The in vitro biodegradation shows that an interpenetrating network structure exists in the poly(acrylic acid)/gelatin hybrid hydrogel. A release study indicates that the theophylline release from the hydrogel depends on the cross-linking density of the hydrogel and pH of the medium, and the drug diffusion obeys an anomalous transport model.

Zinc oxide (ZnO)/carbon-nanotubular-structures (CNTS) nanohybrids were grown using a three-step laser process. First, an ultraviolet (UV) laser (KrF) was used to deposit Co/Ni catalyst nanoparticles (NP) directly onto SiO2/Si substrates. Second, a random network of CNTS was grown onto these Co/Ni-catalyzed substrates by using the UV-laser ablation method. Finally, ZnO nanostructures were grown onto the CNTS template by means of the CO2 laser-induced chemical liquid deposition technique. While the laterally grown CNTS mainly consist of nanotube bundles featuring a high aspect ratio (diameter of ∼20 nm and length of up to several microns), the ZnO nanostructures were found to consist of various morphologies including nanorods, polypods, and nanoparticles with a size as small as 2 nm. The ZnO/CNTS nanohybrids were found to exhibit a polychromatic photoluminescent (PL) emission, at room temperature, comprising a narrow near-UV band centered around 390 nm, a broad visible to near infrared band (500–900 nm), and a relatively weak emission band centered around 1000 nm. These PL results are compared to those of individual components (CNTS and ZnO) and discussed in terms of carbon defect density and possible charge transfer between the ZnO nanocrystals and the carbon nanotubes.

Synthetic Cd1–xZnxTe or “CZT” crystals are highly suitable for γ-spectrometers operating at room temperature. Secondary phases (SP) within CZT, presumed to be Te metal, have detrimental impacts on the charge collection efficiency of fabricated device. Using analytical techniques rather than arbitrary theoretical definitions, we identify two SP morphologies: (i) many void, 20-μm “negative” crystals with 65-nm nanoparticle residues of Si, Cd, Zn, and Te and (ii) 20-μm hexagonal-shaped bodies, which are composites of metallic Te layers with cores of amorphous and polycrystalline CZT material that surround the voids.

Nanocrystalline strontium titanate (SrTiO3) particle/polymer hybrid was synthesized from metal–organics and 2-(methacryloyloxy)ethyl maleate (MMEM). SrTiO3 precursor was prepared from strontium isopropoxide and titanium isopropoxide in 2-methoxyethanol. Nanocrystalline SrTiO3 particle/poly-MMEM hybrid was formed by hydrolysis followed by reaction with MMEM. The crystallinity of SrTiO3 particles depended on the amount of water for hydrolysis. The nanocrystalline particles were identified to be strontium titanate by x-ray diffraction. Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy showed the presence of the chemical bond between SrTiO3 particles and the organic matrix. The fluid consisting of SrTiO3 particle/poly-MMEM and silicone oil revealed a yield stress dependent on various conditions, such as hydrolysis conditions and applied field. The hybridization was found to have a pronounced effect on the electrorheological properties of the nanoparticle/polymer-based system.

Ca0.5Th0.5VO4 was prepared by a solid-state reaction of component oxides and characterized by powder x-ray diffraction (XRD) at ambient and higher temperatures and impedance spectroscopy. Crystal structure was refined by Rietveld refinements from powder XRD data. At room temperature, Ca0.5Th0.5VO4 has a zircon-type tetragonal (I41/amd) lattice with unit cell parameters: a = 7.2650(1) and c = 6.4460(1) Å. Despite the large charge difference, Ca2+ and Th4+ are statistically distributed over a single site. The crystal structure of Ca0.5Th0.5VO4 is built from the (Ca/Th)O8 (bisdisphenoid) and VO4 tetrahedra. The in situ high-temperature XRD studies on Ca0.5Th0.5VO4 revealed anisotropic thermal expansion behavior with coefficients of thermal expansion αc = 10.96 × 10−6/°C and αa = 5.32 × 10−6/°C. The impedance measurements carried out in the temperature range from ambient to 800 °C indicate semiconducting behavior with appreciable ionic conductivity above 400 °C. The activation energy obtained from the temperature-dependent AC conductivity data is ∼1.37 eV. In wider range of frequencies and temperatures, the relative permittivity of approximately 50 to 60 is observed for Ca0.5Th0.5VO4.

The enthalpies of oxidative drop solution (ΔHds) for a series of CdSxSe1–x samples were obtained by calorimetry in molten 3Na2O·4MoO3 at 975 K. They become more exothermic linearly with increasing S content. The enthalpies of formation from the elements (ΔHf,el) depend linearly on molar ratio of S/(S + Se). This is the first report of thermodynamic properties of CdSxSe1–x solid solutions measured by any direct calorimetric method. The enthalpies of formation at 298 K from the binary chalcogenide end-members (ΔHf,CdM) (M = S, Se) for wurtzite CdSxSe1–x are found to be zero within experimental errors. These results strongly suggest that wurtzite CdS and CdSe form an ideal solid solution, despite a substantial difference in molar volume and anion radius. This implies that size difference affects thermodynamics less strongly when larger and more polarizable anions are mixed in chalcogenides than when cations are mixed in oxides.

The electronic transport and magnetic properties of nanocomposites, in which nanoparticles of superconducting (SC) molybdenum carbides are embedded in a ferromagnetic (FM) carbon matrix to form a three-dimensional SC-FM network, are studied. The high-resolution transmission electron microscope observation shows that the carbon in the nanocomposites is in both ordered and disordered forms. The magnetic properties of the nanocomposites are ruled by the ferromagnetic carbon matrix. The temperature dependence of electrical resistivity of the nanocomposites is dominated by the carbon matrix, showing the semi-conductivity. The special I-V curves near the zero voltage bias of the nanocomposites are observed at low temperatures, due to the influence of contact barriers between molybdenum carbides and the carbon matrix.

Phase transformations in (111) Si after spherical indentation have been investigated by cross-sectional transmission electron microscopy. Even at an indentation load of 20 mN, a phase transformation zone including the high-pressure crystalline Si phases was observed within the residual imprints. The volume of the transformation zone, as well as that of the crystalline phases increased with the indentation load. Below the transformation zone, slip was found to occur on {311} planes rather than on {111} planes, usually observed on indentation of (100) Si. The distribution of defects was asymmetric, and for indentation loads up to 80 mN, their density was significantly lower than that reported for (100) Si. The experimental observations correlated well with modeling of the applied stress through ELASTICA.