Dense β-Si4Al2O2N6 and β-Si4Al2O2N6-0.5SiO2 ceramics were obtained from α-Si3N4, α-Al2O3, AlN, and Y2O3 upon sintering green bodies consolidated by aqueous gel casting. For comparison purposes, a β-Si4Al2O2N6 was also prepared by the conventional dry-powder processing route. In the case of gel-cast β-Si4Al2O2N6, the as-purchased AlN powder was treated with H3PO4 and Al(H2PO4)3 prior to use along with α-Si3N4, α-Al2O3, and Y2O3. The gel-cast β-Si4Al2O2N6 exhibited superior hardness (1423 ± 6 Hv), fracture toughness (3.95 ± 0.3 MPa⋅m1/2), and coefficient of thermal expansion (CTE) (3.798 × 10−6/°C between 30 and 1000 °C) in comparison to the ceramic consolidated by conventional dry pressing, which exhibited only 1317 ± 5 Hv, 3.30 ± 0.2 MPa⋅m1/2, and 3.532 × 10−6/°C between 30 and 700 °C. The in situ-generated ∼9 wt% SiO2 has considerably reduced the dielectric constant and CTE of β-Si4Al2O2N6 from 7.30 to 6.32 and from 3.798 × 10−6/°C to 3.519 × 10−6/°C, respectively. The loss tangent property of the investigated materials was little influenced by the variation of chemical composition and processing route.

Patterned magnetic recording media, in which data bits are stored in discrete single-domain magnetic particles, have been proposed for the next generation of recording media. To achieve high densities, features with periodicities on the order of 25 nm and below are required over large areas, which is a challenging task for any lithography process. Block copolymers (BCPs), which phase-separate into ordered periodic nanoscale structures, might provide a path to accomplish such patterning. In this article, we describe BCP lithography and show how the self-assembled patterns can be templated to make large-area arrays of nanoscale structures with long-range order.

The effects of ball milling on lithium (Li) insertion/extraction properties into/from single-walled carbon nanotubes (SWNTs) were investigated. The SWNTs were synthesized on supported catalysts by thermal chemical-vapor deposition method, purified, and mechanically ball-milled by high-energy ball milling. The purified SWNTs and the ball-milled SWNTs were electrochemically inserted/extracted with Li. The structural and chemical modifications in the ball-milled SWNTs change the insertion/extraction properties of Li ions into/from the ball-milled SWNTs. The reversible capacity (Crev) increases with increase in the ball milling time, from 616 mAh/g (Li1.7C6) for the purified SWNTs to 988 mAh/g (Li2.7C6) for the ball-milled SWNTs. The undesirable irreversible capacity (Cirr) decreases continuously with increase in the ball milling time, from 1573 mAh/g (Li4.2C6) for the purified SWNTs to 845 mAh/g (Li2.3C6) for the ball-milled SWNTs. The enhanced Crev of the ball-milled SWNTs is presumably due to a continuous decrease in the Cirr because the SWNTs develop a densely packed structure on the ball milling process. The insertion of Li ions into the ball-milled SWNTs is facilitated by various Li insertion sites formed during the ball milling process in spite of small surface area than the purified SWNTs. Lithium ions inserted into various insertion sites enhance the Crev in the ball-milled SWNTs with the large voltage hysteresis by hindrance of the extraction of Li ions from the ball-milled SWNTs. In addition, the ball-milled samples exhibit more stable cycle capacities than the purified samples during the charge/discharge cycling.

Zr60Ni21Al19 metallic glass rod, with a diameter of 8 mm, is manufactured by copper mold casting. The as-cast bulk metallic glass (BMG) exhibits nearly zero plastic strain, but a high strength of 1.88 GPa. The compression behavior of this new zirconium-base ternary BMG under high pressure at ambient temperature in a diamond-anvil cell instrument has been unraveled using energy dispersive x-ray diffraction with a synchrotron radiation source. The investigation shows that the amorphous structure of Zr60Ni21Al19 is stable under pressures up to 24.5 GPa at room temperature. According to the Bridgman equation of state, the bulk modulus B0 = 96 GPa has been obtained.

Imprint lithography has a remarkable patterning resolution of less than 5 nm, and it is simultaneously capable of patterning over large areas with long-range order. This combination enables a broad range of potential applications including terabit-density magnetic storage, CMOS integrated circuits, and nanowire molecular memory. This article provides a review of the status of imprint lithography for nanoscale manufacturing. First, representative nanoscale devices and their manufacturing requirements are reviewed, along with key patterning challenges that have to be overcome to enable these nanoscale applications. Two classes of top–down nanopatterning techniques, namely, photon-based lithography and proximity mechanical nanopatterning (including imprint lithography), are described, followed by the three primary building blocks of imprint lithography: imprint masks, tools, and materials. Theresults of the lithography process are detailed in terms of process data such as long-range order in the placement and size of the nanostructures, process throughput, and overall cost considerations.

The primary tool for mechanical characterization of surfaces and films is instrumented indentation using the Oliver-Pharr data analysis method. However, this method measures contact area between the indenter and sample indirectly, thus confounding instrumented indentation tests when characterizing dynamic properties, thin films, and materials that “pileup” around the indenter. Here, we demonstrate an electrical technique to continuously measure the in situ contact area by relating nonlinear electrical contact current–voltage (I–V) curves to the instantaneous contact area. Using this approach, we can obtain hardness as a continuous function of applied force.

Polyaniline (PANI) nanofibers were prepared electrochemically by a template-free method on different active substrates in aqueous solutions containing aniline and inorganic acid or organic acid. The influences of experimental parameters, such as polymerization potential, techniques of applied potential, electrolyte composition, and polymerization temperature, on the morphologies of the PANI nanofibers were systematically investigated. The PANI nanofibers obtained have promising applications in supercapacitors whose specific capacitance is as high as 1.21 × 103 F/g, which is the highest value possible using sulfuric acid (1.00 M H2SO4) as electrolyte. In addition, the formation mechanism of PANI nanofibers is discussed.

Geometrical self-similarity is a feature of mathematically sharp indenters such as conical and Berkovich indenters. However, self-similarity is considered inappropriate for practical use because of inevitable indenter tip blunting. In this study, we analyze the load–depth curves of conical indenters with various tip radii via finite element analyses. Based on the numerical data, we propose a method of restoring the Kick’s law coefficient C of finite tip-radius indenter to that of zero tip-radius indenter, thereby retaining the self-similarity of the sharp indenter. We then regress the unloading slope for the evaluation of elastic modulus in several ways. Finally, we establish a method to evaluate elastic modulus, which successfully provides the value of the elastic modulus with a maximum error of less than 5%, regardless of tip radius and material properties of both indenter and specimen.

A co-sputtering system was used to deposit silicon nanoclusters embedded in zinc oxide matrix (Si:ZnO) at low temperature without post-annealing. By adjusting the radio frequency power of the Si target during co-sputtering, Si:ZnO films with various crystallographic structures can be obtained. Silicon nanoclusters embedded in the zinc oxide matrix were examined using a high-resolution transmission electron microscope, x-ray diffractometer, and Fourier transformation infrared spectrometry. By comparing with photoluminescence spectra, we can clearly identify quantum confinement effect of silicon nanoclusters embedded in the ZnO matrix.

Nitrogen-doped titanium dioxide (TiO2) thin films were synthesized on glass substrates by reactive pulsed laser deposition technique (PLD). A frequency quadrupled Nd:YAG (λ = 266 nm, τFWHM ≅ 5 ns, ν = 10 Hz) laser source was used for the irradiations of TiO2 targets. The experiments were performed in controlled reactive atmosphere consisting of mixtures of oxygen and nitrogen gases. We demonstrated that there exists the possibility for the accurate control of the nitrogen incorporation through the growth parameters, i.e., the nitrogen partial pressure in the reaction enclosure. The substitutional nitrogen doping of the anatase phase TiO2 thin films allows for the continuous shift of the optical absorption edge towards the visible spectral range. When a threshold value of the nitrogen dopant level is surpassed the crystallization structure of the TiO2 anatase phase thin films changes, and the onset of a stable titanium-oxinitride phase formation takes place.

Advanced microelectronic interconnection structures will need dielectrics of low permittivity to reduce capacitive delays and crosstalk, but this reduction in permittivity typically necessitates an increase in the porosity of the material, which is frequently accompanied by reduced mechanical reliability. Failure by brittle fracture remains a typical manufacturing and reliability hurdle for this class of materials. Part I of this two-part work explores the instrumented indentation and indentation fracture responses of a variety of organosilicate low-dielectric constant (low-κ) films. Three different chemical varieties of low-κ material were tested. The influence of film thickness on the fracture response is also explored systematically. Correlations are made between instrumented indentation responses and differing modes of fracture. It is demonstrated that the elastic response of the composite film + substrate systems can be simply tied to the fraction of the total indentation strain energy in the film. These results are then used in the companion paper, Part II [D.J. Morris and R.F. Cook, J. Mater. Res.23, 2443 (2008)], to derive and use a fracture mechanics model to measure fracture properties of low-κ films.

The oxidation behavior of three types of plasma-enhanced chemical vapor deposition (PECVD) processed Ti–Si–C–N coatings with silicon content ranging from 4.3 to 11.6 at.% has been investigated at high temperatures. Systematic characterization was conducted to study the evolution of composition, phase constituents, hardness, surface morphologies, microstructures, and grain size during oxidation. A two-stage oxidation process was observed between 700 and 1000 °C for all three coatings. Experimental results indicate that a superhardness of 40 GPa can be maintained up to 700, 800, and 850 °C for 4.3, 7.4, and 11.6 at.% Si coatings, respectively; the dual-phased 7.4 and 11.6 at.% Si coatings show a better oxidation resistance than the single-phased 4.3 at.% Si coating. On the basis of the results, a mechanism is proposed to explain the relationship between the nanostructure and oxidation behavior.

Hydrothermal treatment has been applied successfully to convert amorphous titania films to crystalline anatase at 120 °C, a temperature compatible with most polymeric substrates. The amorphous films were deposited at 80 °C using atomic layer deposition (ALD). The crystallinity of the films was monitored by x-ray absorption near edge structure (XANES), and the film composition was determined by x-ray photoelectron spectroscopy (XPS). The effect of precursor chemistry and substrate material was investigated. It was found that titania films produced from Ti isopropoxide are easier to crystallize than those from Ti tetrachloride as the Ti precursor. The amorphous to crystalline transformation can be achieved more readily with films deposited on Si than polycarbonate substrates. The effect of a “seed” layer on the amorphous to crystalline transformation was also studied. Preformed anatase crystallites between the Si substrate and the amorphous film were shown to accelerate the crystallization process. The possible mechanisms responsible for the phase transformation are discussed.