Substrate influence is a common problem when using instrumented indentation (also known as nano-indentation) to evaluate the elastic modulus of thin films. Many have proposed models to be able to extract the film modulus (Ef) from the measured substrate-affected modulus, assuming that the film thickness (t) and substrate modulus (Es) are known. Existing analytic models work well if the film is more compliant than the substrate. However, no analytic model accurately predicts response when the modulus of the film is more than double the modulus of the substrate. In this work, a new analytic model is proposed. This new model is shown by finite-element analysis to be able to accurately predict composite response over the domain 0.1 < Ef/Es < 10. Finally, the new model is used to analyze experimental data for compliant films on stiff substrates and stiff films on compliant substrates.

The possibility and suitability of micro-Raman spectroscopy as a noncontact, in-line measurement technique for boron (B) concentration in ultrathin (20~35 nm thick) Si1–xGex layers epitaxially grown on 300 mm diameter p−-Si(100) wafers, by ultrahigh vacuum chemical vapor deposition, was investigated. Raman spectra from Si1–xGex/Si(100) wafers were measured under 363.8, 457.9, 488.0, and 514.5 nm excitation. Strong correlation was found between B content and characteristics of the Si–Si Raman peak from the Si1–xGex films. As B concentration increased from undoped to 9.1 × 1020 atoms/cm3, the Si–Si Raman peak broadened and the peak height became smaller for a given Ge content. The B concentration in Si1–xGex film estimated from Raman measurement was in good agreement with secondary ion mass spectroscopy analysis results. Boron concentration as low as 8.7 × 1017 atoms/cm3 can be detected by Raman spectroscopy, which is ~30 times more sensitive than the detection limit (2.7 × 1019 atoms/cm3) of high-resolution x-ray diffraction.

Impedance spectroscopy studies were conducted on amorphous tantalum oxide thin films prepared using pulsed-DC reactive sputtering, which were post-annealed to crystallize the films. X-ray diffraction results showed that crystallization to Ta2O5 β phase occurs for samples annealed above 650 °C, with a crystallite size of ∼40 nm. The film microstructure was studied by electron microscopy, and remnants of the columnar amorphous microstructure were found in the polycrystalline films. Complex impedance analyses revealed significant differences in dielectric behavior between the amorphous and crystalline films. Lumped circuit models were conducted on the films using resistors, capacitors, and constant phase elements. Amorphous films exhibited a single relaxation with Arrhenius activation energy of 1.1–1.3 eV. Crystallized films exhibited two relaxations with activation energies equal to 1.1 ± 0.08 and 0.6 ± 0.03 eV. The relative permittivity of the bulk crystalline grain in tantalum oxide films is close to the established permittivity of the β phase (εr = 40) of Ta2O5.

The photoinduced formation of thin film structures from a Ti-alkoxide precursor (OPy)2Ti(TAP)2, where OPy = OC6H6N, TAP = OC6H2[CH2N(CH3)2]3-2,4,6, was demonstrated via direct deposition from a pyridine-based solution and by optical illumination of a solid-state spin-coated thin film of the compound. Photopatterned physical relief structures were produced using both of these deposition methods and feature sizes as small as ∼1 μm were readily achieved. Surface investigations of the material’s nanostructure revealed that films photo-deposited from solution exhibited nanometer-scale surface roughness with evenly distributed surface porosity (∼10 nm sized pores) while films produced through the illumination of spin-coated thin films exhibited, in comparison, a reduction in surface roughness. Vibrational spectra were compared with the results of quantum chemical computations (density-functional theory) of potential photoproducts in an attempt to identify and distinguish the dominant structural groups resulting from the optical processing of each precursor form (i.e., solution versus solid-state). It was determined that ultraviolet irradiation for both thin-film formation techniques resulted in a disruption of the ligand groups, facilitating the initiation of hydrolysis and condensation reactions in the films.

A multitarget sputtering method was applied to embed Au nanoparticles in TiO2 thin films (Au/TiO2 films) with a high concentration of Au particles (19–41 at%). The absolute values of imaginary part of the third-order nonlinear susceptibility, |Im [χ(3)]|, of the Au/TiO2 films, exhibited a peak around the localized surface plasmon resonance absorption peak (around 660 nm), and the maximum value was estimated to be 3.6 × 10−7 esu measured by the femtosecond Z-scan technique. The figure of merit, |Im [χ(3)]|/α, (α is the absorption coefficient of the film at the corresponding wavelength of the measurement) of the film was calculated to be 1.4 × 10−12 esu·cm, which was larger than that of the Au/SiO2 film. This is mainly due to the local field enhancement.

We grew epitaxial SrTiO3 (STO) thin films on (001) LaAlO3 substrates via a two-step procedure using pulsed laser deposition and studied them with transmission electron microscopy in plane-view and cross-sectional samples. We found that partial misfit dislocations are the main interfacial defects, whereas planar defects are the main defects in STO films. Our results suggest that a three-dimensional island mode dominates the growth of the STO film.

InN thin films were grown on GaN underlayer with sapphire substrate by metalorganic vapor phase epitaxy under different growth conditions, including growth temperature, reactor pressure, and V/III ratio. X-ray diffraction and Raman scattering measurements reveal that the samples grown at different temperatures are mixed with different phases, especially at higher temperature. The calculated phonon dispersion curves of wurtzite, zinc-blende, and rocksalt structures show that the samples mainly contain wurtzite structure and small amount of zinc-blende phase, while the samples grown at 600 °C and 650 °C include a new structural phase other than the three well-known ones. This analysis demonstrates that the InN epilayer grown at 550 °C has the highest phase purity and better crystalline quality. Besides the key role of growth temperature, a relatively higher reactor pressure and lower V/III ratio are found to be more conducive to the improvement of crystalline quality, though they have a modest effect on the InN microstructure.

We show that low-density nanoporous silica monoliths (aerogels), in contrast to the case of full-density silica, exhibit pronounced time-dependent deformation during indentation at room temperature. Logarithmic indentation creep and stress relaxation are revealed, with an exponential dependency of the creep constant on the applied stress. Such time-dependent deformation is attributed to stress corrosion fracture of nanoligaments that have a large surface-to-bulk atomic fraction.

This work uses a method based on indentation to characterize a polydimethylsiloxane (PDMS) elastomer submerged in an organic solvent (decane, heptane, pentane, or cyclohexane). An indenter is pressed into a disk of a swollen elastomer to a fixed depth, and the force on the indenter is recorded as a function of time. By examining how the relaxation time scales with the radius of contact, one can differentiate the poroelastic behavior from the viscoelastic behavior. By matching the relaxation curve measured experimentally to that derived from the theory of poroelasticity, one can identify elastic constants and permeability. The measured elastic constants are interpreted within the Flory–Huggins theory. The measured permeability indicates that the solvent migrates in PDMS by diffusion, rather than by convection. This work confirms that indentation is a reliable and convenient method to characterize swollen elastomers.

We have developed a new class of proton-conducting organic–inorganic hybrid silicophosphite membranes, produced by ethanol condensation of organically modified alkoxysilanes and anhydrous vinylphosphonic acid under solventless, catalyst-free, low-temperature, one-pot conditions. The membranes synthesized in this study are crack-free, large, and flexible, and they exhibit good thermal stability up to intermediate temperatures (~218 °C). Structural analyses using 29Si and 31P nuclear magnetic resonance spectroscopy and infrared measurements revealed that ethanol condensation produced an inorganic alternating copolymer structure, Si–O–P, with a phosphole group, and successive polymerization between vinyl and/or methacryl groups enabled these structures to connect with each other. In this way, it is possible to achieve structure manufacturing of inorganic–organic networks. The proton conductivities of the hybrids are as high as 5.2 × 10−3 S/cm at 85 °C under 80% relative humidity.

The decomposition mechanism of block copolymer templates inside as-synthesized mesostructured solids has been systematically studied using solid-state 1H magic angle spinning nuclear magnetic resonance spectroscopy, thermogravimetric analysis, and high-vacuum Fourier transform infrared spectrometry. It is shown that there exists hydrogen-bonding interaction between silanols and block copolymers at the inorganic–organic interface in the self-assembled as-synthesized mesostructured solids, which plays an important role in protecting the surfactants against decomposition during the high-temperature hydrothermal treatment process. Increasing silanol concentration can enhance the hydrogen-bonding interaction and thus shows better “protection” effect. Moreover, the thermal decomposition of the block copolymer in as-synthesized mesostructured solids in air commences at higher temperatures compared with that in acidic solution or in air, providing further evidence in support of the silanol protection mechanism.

We report the processing and immobilization of enzyme Ribonuclease A (RNase A) onto SiO2 glass collectors using the matrix assisted pulsed laser evaporation (MAPLE) technique. The experiments were performed inside a stainless steel irradiation chamber. A pulsed UV KrF* (λ = 248 nm, τFWHM ≈ 25 ns, ν = 10 Hz) excimer laser source was used for the irradiations. The laser fluence was varied in the range 0.4–0.7 J/cm2. The morphology of the obtained films was investigated by atomic force microscopy (AFM) and their structure and composition by Fourier transform infrared spectroscopy (FTIR). The FTIR spectra of the films obtained from composite MAPLE targets consisting of 1% (w/v) RNase A in Hepes-KOH 10 mM pH 7.5 buffer exhibit the same bands as the spectrum of the initial, nonirradiated material. The enzymatic activity of the obtained structures was analyzed using synthetic substrate polycytidylic acid (poly(C)). The poly (C) cleavage by the immobilized enzyme and the products of formation were analyzed by means of reverse phase high performance liquid chromatography (HPLC).

This work investigated the cell labeling of 12-nm meso-2,-3-dimercaptosuccinic acid (DMSA)-coated Fe3O4 magnetic nanoparticles with multiple mammalian cells. Six different cells, including RAW264.7, Hepa1-6, THP-1, HepG2, HeLa, and HL-7702, were treated with the nanoparticles at various concentrations (20~100 μg/mL) for different times (2~72 h), and the labeling effect was evaluated by observing the intracellular internalization of the nanoparticles with Prussian blue staining and measuring the corresponding cellular iron loading with colorimetric assay. The results demonstrated that the nanoparticles could label all cells studied. However, the labeling efficiency was not the same between different cells, which depended on the cell types, the nanoparticles’ concentration, and the time of treating cells with the nanoparticles. In comparison, RAW264.7 was labeled more effectively than other cells at any concentration of the nanoparticles. The iron loading of RAW264.7 significantly increased with the concentration of the nanoparticles and the treatment time. However, both human liver cells (HepG2 and HL-7720) were labeled with the lowest iron loading. The measurement of cell viability revealed that the growth of all cells was not affected by the nanoparticles at a common in vivo application dose of iron nanoparticles (30 μg/mL), demonstrating that the nanoparticles have better biocompatability.

A model is developed to analyze the microstructure evolution in a continuously solidified hypermonotectic alloy. The model takes into account the common actions of the nucleation and diffusional growth/shrinkage of the minority phase droplets, the spatial phase segregation, and the convections of the melt. The microstructure formation in a continuously solidified hypermonotectic alloy is calculated. The numerical results demonstrate that the convections have great effect on the microstructure formation. The convective flow against the solidification direction causes an increase in the nucleation rate while the convective flow along the solidification direction causes a decrease in the nucleation rate of the minority phase droplets. The convections lead to a more nonuniform distribution of the minority phase droplets in the melt. It causes an increase in the size of the largest minority phase droplets and is against the obtaining of the hypermonotectic alloys with a well-dispersed microstructure.

A facile, efficacious, and practical multifunctional paradigm has been developed for imparting corrosion resistance to low carbon steel based on the direct in situ growth of carbon nanofibers (CNF) onto steel substrates followed by infusion of a polymer matrix. The polymer layer locks into place between the nanofibers, simultaneously preventing coating delamination and imparting unprecedented surface passivation properties. The novel hybrid nanocomposite coatings maintain structural integrity even after 30 days of exposure to saline corrosive environments, indicating unprecedented corrosion protection derived from the redox-active nature of the CNF fillers and their excellent dispersion within the polymer matrix. These remarkable coating properties are further enhanced by the strong adhesion of the host polymer to the underlying steel substrate.