Biosensors based on lipid membranes promise an inexpensive and versatile platform for application in many fields of molecular sensing. An extensive review of the applications for tethered membranes was reported in the July 2006 MRS Bulletin [A.N. Parikh and J.T. Groves, Materials science of supported lipid membranes. MRS Bull.31(8), 507 (2006)]. The commercial use to which tethered lipid membranes have been applied has been limited by their stability under long-term storage. This report describes a novel membrane construct that is stable at room temperature for months, eliminates the mobile lipid phase present in lipid bilayers, and is robust against detergents under conditions that would destroy a lipid bilayer.

Poly-vinylpyrrolidones (PVP) with different molecular weights were used to modify the sol-gel solutions for preparing Pb0.91La0.09(Zr0.65,Ti0.35)0.9775O3 (PLZT, 9/65/35) thin films. The crystallization behavior and microstructural development of the PLZT films with and without PVP addition were investigated. It was found that the addition of PVP significantly improved perovskite phase formation of the PLZT films, but the films exhibited rosette-like morphology. Further study on the PLZT films and the gel particles showed that a premature nucleation of PbO grains in the PVP modified sol-gel solution induced the Pb-rich domains in the films, which accelerated the growth of the grains and thus led to the rosette-like structure. In addition, the electrical and optical properties of the PLZT films with rosette-like structure were also studied and discussed.

We investigated the photovoltaic response of nanocomposites made of colloidal, infrared-sensitive, PbSe nanocrystals (NCs) of various sizes and conjugated polymers of either regioregular poly (3-hexylthiophene) (RR-P3HT) or poly- (2-methoxy-5-(2-ethylhexoxy)-1,4-phenylene vinylene) (MEH-PPV). The conduction and valence energy levels of PbSe NCs were determined by cyclic voltammetry and revealed type II heterojunction alignment with respect to energy levels in RR-P3HT for smaller NC sizes. Devices composed of NCs and RR-P3HT show good diode characteristics and sizable photovoltaic response in a spectral range from the ultraviolet to the infrared. Using these materials, we have observed photovoltaic response at wavelengths as far to the infrared as 2 μm (0.6 eV), which is desirable due to potential benefits of carrier multiplication (or multi-exciton generation) from a single junction photovoltaic. Under reverse bias, the devices also exhibit good photodiode responses over the same spectral region.

This study elucidates the tunability of the magnetic properties of cobalt spinel ferrites embedded in a polyvinyl alcohol (PVA) hydrogel by changing the structure of the polymer network. We report on the preparation and characterization of sPS-CoFe2O4 ferrofluid and PVA/sulfonated polystyrene (sPS)-CoFe2O4 ferrogels obtained by submitting the samples to a different number of freezing–thawing (F–T) cycles. The magnetic properties were evaluated and interpreted as a function of the PVA/sPS-CoFe2O4 composition and final structure of the ferrogels.

In the present paper, Sr4Nd2Ti4Nb6O30 ceramics with filled tungsten bronze structure were prepared, and the dielectric characteristics over a broad temperature range (123 to 623 K) were investigated. Two dielectric abnormities were observed in the entire frequency range (100 Hz to 1 MHz). One is at higher temperature corresponding to a diffuse ferroelectric transition (P4/mbm → P4bm), and the other at lower temperature shows relaxor characteristics in both ϵ′ and tan δ curves. An activation energy and freezing temperature of 0.1659 eV and 148.05 K, respectively, were obtained by analyzing the frequency dependence of the dielectric maximum temperature using the Vogel–Fulcher relationship. The relaxor behavior is attributed to a polar-glassy system with thermally activated polarization fluctuations above the freezing temperature. In addition, the dielectric constant was almost stable with both temperature and frequency in the temperature range of 300 to 430 K (between the two dielectric abnormities).

The effect of additional elements on microstructure and mechanical properties of (TiCu)-based bulk metallic glasses (BMGs) has been systematically investigated. Based on the values of the heat of mixing between the additional elements and the major constituent elements Ti and Cu, small additions of elements having a positive heat of mixing with Cu and a negative heat of mixing with Ti are effective in forming nanoscale heterogeneities upon solidification and enhance the ductility. It is experimentally demonstrated that the selection of the minor elements in (TiCu)-based BMGs plays a crucial role to induce nanoscale heterogeneities and thus to control the deformation behavior of the bulk metallic glasses.

The ideal strengths of metals and alloys at finite temperatures have been studied using the statistical moment method. The tensile and shear strengths of the body-centered cubic (bcc) transition metals like Mo and W (refractory metals), and ordered FeAl (B2) and Fe3Al (DO3) alloys are calculated as a function of the temperature. The orthogonal tight-binding method is used for bcc transition elements, while the universal binding-energy relation (UBER)-type of pairwise potentials, derived from ab initio density-functional theory, is used for the FeAl and Fe3Al alloys. We discuss the temperature dependence of the tensile and shear strengths of the metals and alloys in conjunction with those of the second-order elastic constants.

A transmission electron microscopy (TEM) study has been carried out to uncover how dislocations and twins accommodate large plastic strains and accumulate in very small nanocrystalline Ni grains during low-temperature deformation. We illustrate dislocation patterns that suggest preferential deformation and nonuniform defect storage inside the nanocrystalline grain. Dislocations are present in individual and dipole configurations. Most dislocations are of the 60° type and pile up on (111) slip planes. Various deformation responses, in the forms of dislocations and twinning, may simultaneously occur inside a nanocrystalline grain. Evidence for twin boundary migration has been obtained. The rearrangement and organization of dislocations, sometimes interacting with the twins, lead to the formation of subgrain boundaries, subdividing the nanograin into mosaic domain structures. The observation of strain (deformation)-induced refinement contrasts with the recently reported stress-assisted grain growth in nanocrystalline metals and has implications for understanding the stability and deformation behavior of these highly nonequilibrium materials.

This study explored the effects of substrate surface pretreatments on the nucleation and growth of metal–organic chemical vapor deposited ruthenium. In situ plasma (dry), featuring O2, Ar, and H2/Ar chemistries, and ex situ (wet) treatments, consisting of a standard RCA bath, were examined in the nucleation and growth of up to 50-nm-thick metallic Ru films on SiO2 and Hf–silicate surfaces. The resulting surface morphology, grain size, and roughness of the metallic films were examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM), while Rutherford backscattering spectrometry (RBS) was used for compositional measurements. It was determined that an in situ plasma treatment using a H2/Ar yielded metallic Ru films with the highest nucleation density, smallest grain size, and lowest resistivity. Film buckling was also observed for the Ru films deposited on H2/Ar pretreated surfaces. The behavior was attributed to the presence of compressive strain. The films deposited on RCA-cleaned and Ar plasma treated surfaces exhibited very similar physical and electrical characteristics to the films grown on untreated substrates. Alternatively, the use of O2 plasma surface treatment adversely affected Ru nucleation on the SiO2 surface. Relevant mechanisms for Ru nucleation and growth on SiO2 and Hf–silicate nontreated surfaces are discussed in the context of the various predeposition dry and wet treatments.

Powders of the solid lead-free piezoelectric ceramic solution [Na0.5K0.5NbO3]1−x–[LiTaO3]x, x = 0.06, were produced using a mixed-oxide process. Phase analysis indicated the formation of an orthorhombic solid solution at 800 °C, which coexisted with intermediate binary niobate and tantalate phases. A tetragonal main-phase solid solution was formed at ⩾950 °C, along with minor quantities of a tungsten bronze phase. Addition of 3 wt% excess alkali carbonates to the starting powders allowed the orthorhombic solid solution to be retained to 1100 °C and prevented formation of the secondary tungsten bronze phase. Elemental chemical analysis confirmed changes in alkali oxide composition, consistent with volatilization losses, particularly of potassium and lithium oxides. Phase stability near the reported morphotropic phase boundary is shown to be sensitive to alkali oxide content.

The infiltration behavior of compacts of SiC particles in two surface conditions, as-received and thermally oxidized, was investigated by using pure Al and Al-12wt%Si as infiltrating metals. Analysis of the threshold pressure for infiltration revealed that the process is governed by the same contact angle for all different systems, no matter the metal or particle condition. This leads to the conclusion that oxidation does not modify the wetting characteristics of the particles, most probably because they are already covered by a thin native oxide layer that remains unaltered in processing routes involving short contact times and low temperatures, such as actual conditions of pressure infiltration at 700 °C.

We have investigated the electrical resistivity of (0001)-oriented Tin+1ACn (A = Si, Ge, Sn, n = 1–3) thin films deposited by magnetron sputtering onto Al2O3(0001) substrates at temperatures ranging from 500 to 950 °C. Four-point-probe measurements show that all films are good conductors with resistivity values of ∼21–51 μΩ cm for Ti–Si–C films, ∼15–50 μΩ cm for Ti–Ge–C films, and ∼46 μΩ cm for Ti2SnC. We find a general trend of decreasing resistivity with decreasing n for the Ti–Si–C and Ti–Ge–C systems due to the increased metallicity obtained with increasing density of A-element layers. We also show that crystalline quality and competitive growth of impurity phases affect the measured resistivity values. The effect of a given impurity phase largely depends on its location in the sample. Specifically, a TiCx layer in the center of the film constricts the current flow and results in an increased measured resistivity value. However, TiCx transition or seed layers at the substrate–film interface as well as surface segregation of Ge and Ti5Ge3Cx (for Ti–Ge–C) have only little effect on the measured resistivity values. For the Ti–Sn–C system, the resistivity is mainly influenced by the segregation of metallic Sn, yielding a wide spread in the measured values ranging from 20–46 μΩ cm, in the order of increased film purity.

Nano-sized Eu3+-activated Gd1−xVO4 phosphors were prepared via hydrothermal reaction coupled with the coprecipitation method at a low temperature (230 °C). The coprecipitation provided chemical homogeneity. However, it resulted in a low crystallinity and reduced emission and excitation characteristics. Raman study showed that Gd–O bond lengths changed in powders, depending on the level of crystallinity. The particle morphology was controlled using ethylenediaminetetra-acetic acid during the hydrothermal reaction. Particle shapes in the nano-size range affected the vibration of atoms in the lattice, changing photoluminescence properties.

An iron-based amorphous metal, Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4 (SAM2X5), with very good corrosion resistance has been developed. This material was prepared as a melt-spun ribbon, as well as gas atomized powder and a thermal-spray coating. During electrochemical testing in several environments, including seawater at 90 °C, the passive film stability was found to be comparable to that of high-performance nickel-based alloys and superior to that of stainless steels, based on electrochemical measurements of the passive film breakdown potential and general corrosion rates. This material also performed very well in standard salt fog tests. Chromium (Cr), molybdenum (Mo), and tungsten (W) provided corrosion resistance, and boron (B) enabled glass formation. The high boron content of this particular amorphous metal made it an effective neutron absorber and suitable for criticality control applications. This material and its parent alloy maintained corrosion resistance up to the glass transition temperature and remained in the amorphous state during exposure to relatively high neutron doses.

Monolithic TiN and multilayered structures of TiN films that alternate with thin Ti interlayers were coated by filtered arc deposition onto a stainless steel substrate. Microscratch tests with a diamond indenter of 5-μm radius were carried out in combination with focused ion beam (FIB) sectioning and scanning and transmission electron microscopy to explore the controlling deformation mechanisms of these TiN coatings in relation to their microstructural design. It was found that for the monolithic TiN coating, columnar TiN grains slid against each other under normal forces and, at the same time, tilted under tangential forces. For the TiN multilayers, however, intercolumnar shear sliding was suppressed considerably by the multilayered structure and the interlayers, and grain tilting occurred largely within the upper TiN layer, presumably due to the shear effect of the soft Ti interlayers. With further increases in tangential force, rupture of TiN grains was observed within both types of coatings; for the TiN multilayers, rupture of TiN grains occurred predominantly within the layers close to the steel substrates. It can be concluded that the application of TiN multilayers provides better resistance to contact damage than the traditional monolithic TiN coatings did.

The paper correlates the growth and structure formation with the properties of indium-tin-oxide (ITO) films fabricated by pulsed reactive magnetron deposition onto amorphous substrates held at elevated temperatures ranging from room temperature to 510 °C. The evolution of the microstructure is consistent with the well-known structure zone model. The temperature dependence of the film texture is described with consideration of the interplay between the shadowing and surface-diffusion processes. It is shown that deposition at elevated temperatures lowers the crystallization threshold and is more effective in reducing resistivity than the postdeposition vacuum annealing at comparable temperatures. The films grown at a substrate temperature of 400 and 510 °C have the lowest resistivity of 1.2 × 10−4 Ω cm, the highest free electron density of 1.2 to 1.0 × 1021 cm−3, and mobility of 35–42 cm2 V−1 s−1 and exhibit the strongest (222) texture with the largest grain size.

We show that the thickness of yttrium–barium–copper–oxide (YBCO) superconducting films grown from trifluoroacetate precursors can be strongly modified using polymeric additives, while deposition conditions by spin or dip coating remain unchanged. A screening of different families of organic additives has been performed, and the best results have been achieved using polymers having an oxygen functionalized backbone. Two different polymeric additives, polyvinyl pyrrolidone (PVP) and poly(ethylene glycol) (PEG), have been more thoroughly investigated, and thermal analysis suggests that PEG is the most promising alternative because the pyrolysis step of the new complex precursors remains sharp and narrow and hence the final homogeneity of the film is preserved. The combination of anhydrous trifluoroacetic acid (TFA) solutions and poly(ethylene-glycol) (PEG8000) as additive can produce an increase of the YBCO film thickness up to 300%, while keeping a fast pyrolysis process and high critical current densities.

Epitaxial ZnO thin films doped uniformly with nitrogen at 1020 atoms/cm3 were fabricated by pulsed laser ablation of a Zn-rich Zn3N2 target. The films grown at 300 °C and annealed at 600 °C in O2 showed p-type conductivity. Two acceptor levels at 105 and 224 meV were determined by temperature-dependent Hall and photoluminescence measurements of the p-type samples. Transmission electron microscopy studies revealed that the p-type ZnO films consist of 10–20 nm columnar grains with a high density of defects and grain boundaries that may facilitate the annihilation of native donors and the activation of acceptors during postdeposition annealing.

Mechanical properties of high-purity nano-polycrystalline diamonds synthesized by direct conversion from graphite and various non-graphitic carbons under static high pressures and high temperatures were investigated by microindentation testing with a Knoop indenter and observation of microstructures around the indentations. Results of indentation hardness tests using a superhard synthetic diamond Knoop indenter showed that the polycrystalline diamond synthesized from graphite at ⩾15 GPa and 2300–2500 °C (consisting of fine grains 10–30 nm in size and layered crystals) has very high Knoop hardness (Hk ⩾ 110 GPa), whereas the hardness of polycrystalline diamonds synthesized from non-graphitic carbons at ⩾15 GPa and below 2000 °C (consisting only of single-nano grains 5–10 nm in size) are significantly lower (Hk = 70 to 90 GPa). Microstructure observations beneath the indentations of these nano-polycrystalline diamonds suggest that the existence of a lamellar structure and the bonding strength of the grain boundary play important roles in controlling the hardness of the polycrystalline diamond.