Epitaxial films of sodium potassium tantalate (Na0.5K0.5TaO3, NKT) and sodium potassium niobate (Na0.5K0.5NbO3, NKN) were grown on single-crystal lanthanum aluminate (LAO) (100) (indexed as a pseudo-cubic unit cell) substrates via an all-alkoxide solution (methoxyethoxide complexes in 2-methoxyethanol) deposition route for the first time. X-ray diffraction studies indicated that the onset of crystallization in powders formed from hydrolyzed gel samples was 550 °C. 13C nuclear magnetic resonance studies of solutions of methoxyethoxide complexes indicated that mixed-metal species were formed, consistent with the low crystallization temperatures observed. Thermal gravimetric analysis with simultaneous mass spectrometry showed the facile loss of the ligand (methoxyethoxide) at temperatures below 400 °C. Crystalline films were obtained at temperatures as low as 650 °C when annealed in air. θ-2θ x-ray diffraction patterns revealed that the films possessed c-axis alignment in that only (h00) reflections were observed. Pole-figures about the NKT or NKN (220) reflection indicated a single in-plane, cube-on-cube epitaxy. The quality of the films was estimated via ω (out-of-plane) and φ (in-plane) scans and full-widths at half-maximum (FWHMs) were found to be reasonably narrow (∼1°), considering the lattice mismatch between the films and the substrate.

Simplification of the ion-beam-assisted deposition (IBAD) buffer architecture is one of the key issues for reduced manufacturing cost of second-generation superconducting wire production. In this work, we studied various radio frequency magnetron sputter deposition conditions for epitaxial growth of LaMnO3 (LMO) layers, with varying thicknesses, directly on IBAD-MgO without homo-epitaxial MgO layers. Performance of the simplified LMO/IBAD-MgO samples was qualified by pulsed-laser-deposited 1-μm-thick YBa2Cu3O7−δ (YBCO) coatings. Detailed property characterizations revealed that though the growth temperature has a substantial effect on the texture of LMO layers, neither LMO thickness nor different sputter gas compositions had a significant effect on the performance of YBCO films. The superconducting properties of YBCO on LMO/IBAD-MgO are found to be similar to those obtained on templates having homo-epitaxial MgO layers. The present results underscore the strong potential of LMO as a single cap layer directly on IBAD-MgO for the development of a simplified IBAD architecture.

This paper presents a spin-coating layer-by-layer assembly process to prepare multilayered polyelectrolyte-clay nanocomposites. This method allows for the fast production of films with controlled layered structure. The preparation of a 100-bilayer film with a thickness of about 330 nm needs less than 1 h, which is 20 times faster than conventional dip-coating processes maintaining the same hardness and modulus values. For validation of this technique, nanocomposite films with thicknesses up to 0.5 μm have been created with the common dip self-assembly and with the spin coating layer-by-layer assembly technique from a poly(diallyldimethylammonium)chloride (PDDA) solution and a suspension of a smectite clay mineral (Laponite). Geometrical characteristics (thickness, roughness, and texture) as well as mechanical characteristics (hardness and modulus) of the clay-polyelectrolyte films have been studied. The spin-coated nanocomposite films exhibit clearly improved mechanical properties (hardness 0.4 GPa, elastic modulus 7 GPa) compared to the “pure” polymer film, namely a sixfold increase in hardness and a 17-fold increase in Young’s modulus.

Nanocrystalline (NC) Cu samples were synthesized by means of surface mechanical attrition treatment, from which a layer of NC structure was formed on a coarse-grained Cu plate. Low-amplitude oscillating wear/fretting behaviors of the NC Cu samples were investigated under oil lubrication in comparison with those of as-annealed coarse-grained Cu samples. It was found the NC Cu possesses a markedly enhanced wear resistance and a higher friction coefficient relative to the coarse-grained Cu. A continuous metal transfer layer is formed on the mating ball after fretting against the NC Cu, while no material transfer occurs for the as-annealed Cu. The effects of experimental parameters and the hardness of Cu samples on the formation of a transfer layer have been systematically investigated. The transfer layer is evidenced to play an important role in the enhanced wear resistance of the NC Cu, but it has a trivial effect on its high friction coefficient.

In nanoindentation, the occurrence of cracks, pileup, sink-in, or film delamination adds additional complexity to the analysis of the load–displacement curves. Many techniques and analysis methods have been used to extract both qualitative and quantitative information from the indentation test both during and after the test. Much of this information is obtained indirectly or may even be overlooked by current testing methods (e.g., cracks that open only during the loading cycle of the test may go unnoticed from a typical residual indentation analysis). Here we report on the development of a miniature depth-sensing nanoindentation instrument and its integration into a high-resolution scanning electron microscope. Real-time observation of the nanoindentation test via scanning electron microscopy allows for visualization and detection of certain events such as crack initiation, pileup, or sink-in, and other material deformation phenomena. Initial results from aluminum 〈100〉 and a thin gold film (∼225 nm) are presented.

Analytical electron microscopy (AEM) was used to examine the initial interfacial reaction layers between a eutectic Sn–3.5Ag solder and an electroless nickel-immersion gold-plated (ENIG) Cu substrate during reflow at 255 °C for 1 s. AEM confirmed that a thick upper (Au,Ni)Sn2 layer and a thin Ni3Sn4 layer had formed through the reaction between the solder and ENIG. The amorphous electroless Ni(P) plated layer transformed into two P-rich Ni layers. One is a crystallized P-rich Ni layer, and the other is an intermediate state P-rich Ni layer before the crystallization. The crystallized P-rich layer consisted of Ni2P and Ni12P5. A thin Ni2P layer had formed underneath the Ni3Sn4 layer and is believed to be a predecessor of the Ni2SnP ternary phase. A Ni12P5 phase was observed beneath the Ni2P thin layer. In addition, nanocrystalline Ni was found to coexist with the amorphous Ni(P) phase in the intermediate state P-rich Ni layer.

Measuring Na in silicate glasses can be difficult in transmission electron microscopy due to modifications induced by electron irradiation. The modifications involve not only the loss of Na from the illuminated region, but also the formation of Na and Na2O. This work compares the electron energy loss spectroscopy (EELS) of plasmon and Na L23 edge in Na2O–SiO2 glass with those in Na and Na2O. The interpretations of the fine structures in Na L23 edge were also given with the aid of full multiplescattering calculations. It demonstrates that the formation of metallic Na can be easily identified by its bulk plasmon at about 5.8 eV, and the formation of Na2O can be better seen by Na L23-edge fine structure.

Scale-dependent microstructure and electronic transportation of Ni/Al-type nanomultilayers as a function of the bilayers number, the modulated ratio, and the periodicity were investigated. The deposited multilayers have anisotropic nanocrystalline structure and asymmetrical interfaces. This special interfacial feature is the result of asymmetrical diffusion of Ni to Al lattice near the Ni–Al interface. Anomalous resistivity enhancement increases with decreasing both the periodicity and the modulated ratio, but is insensitive to the number of bilayers. Accounting for the effects of grain boundary and interface boundary, the dominative mechanism at distinct length scales can be interpreted with the modified model of those of Fuchs–Sondheimer and Mayadas–Shatzkes. Especially for the thinnest film with smallest modulated ratio, the intermixing effect turns out to be the crucial mechanism in the electronic transportation of metallic nanomultilayers.

Metal-ferroelectric-insulator-Si (MFIS) structures using HfSiON as buffer layers were fabricated, and the impact of buffer layer thickness on the electrical properties of the MFIS devices was investigated. HfSiON films with thickness ranging from 1 to 4 nm were deposited by electron beam evaporation, which exhibited much reduced leakage current when compared to that of SiO2 with the same equivalent oxide thickness. From the viewpoint of polarization and charge injection, the flatband voltage and memory window width dependent on the sweeping voltages were discussed for the MFIS diodes with 1-, 2-, and 4-nm-thick HfSiON buffer layers. Small leakage current as well as excellent long-term data retention characteristics were found for all of these samples. It was also found that MFIS diodes with 2-nm-thick HfSiON buffer layer have the largest memory window width. Ferroelectric-gate transistors fabricated with a Pt/SBT(300nm)/HfSiON (2 nm)/Si gate structure showed a memory window of 0.8 V and a high drain current on/off ratio of 108 for the gate voltage sweep between +4 and −4 V. All of these excellent electrical properties proved that HfSiON acts as an excellent barrier for suppressing both leakage current and atomic interdiffusion.

Ni–P deposits of amorphous, nanocrystalline, and mixed structures were prepared by electroless deposition. The three deposits were hypoeutectic Ni–P alloys with different P concentrations. The overall transformation sequences of the deposits during post-deposition annealing were investigated using differential scanning calorimetry, x-ray diffraction, and transmission electron microscopy. It was found that there existed three heat-release peaks in a mixed-structure deposit during annealing. The first peak came from the precipitation of Ni nanocrystallites from an amorphous matrix, the second peak resulted from the decomposition of the retained amorphous matrix into Ni + Ni3P having a composition close to the eutectic point, and the third peak, newly found in hypoeutectic Ni–P alloys, was assumed to be caused by both grain growth and the precipitation of Ni3P from as-deposited supersaturated Ni(P) nanocrystals interspersed within the amorphous matrix. By comparing the transformation sequences of the amorphous deposit with that of the nanocrystalline deposits, it was concluded that the transformation sequence of the mixed-structure deposit was a superimposition of those of both the amorphous and nanocrystalline deposits.

We have studied grain-growth and texture development in polycrystalline lithium fluoride thin films using dark-field transmission electron microscopy. We demonstrate that we can isolate the size distribution of 〈111〉 surface normal grains from the overall size distribution, based on simple and plausible assumptions about the texture. The {111} texture formation and surface morphology were also observed by x-ray diffraction and atomic force microscopy, respectively. The grain-size distributions become clearly bimodal as the annealing time increases, and we deduce that the short-time size distributions are also a sum of two overlapping peaks. The smaller grain-size peak in the distribution corresponds to the {111}-oriented grains, which do not grow significantly, while all other grains increase in size with annealing time. A novel feature of the LiF films is that the {111} texture component strengthens with annealing, despite the absence of growth for these grains, through the continued nucleation of new grains.

The in vitro behaviors of the etched, electrochemically anodized, and hydroxyapatite (HA)-coated Ti6Al4V alloys were investigated through microstructural analysis, electrochemical measurements, and immersion tests in the Hank’s solution. A nanometer-scale, bonelike porous structure with a layer of TiO2 on top was formed during the anodization process. The surface of the coated substrate was composed of a thin TiO2 layer adjacent to the substrate, a thick monolithic HA on the outside, and a composite layer of TiO2 and HA in the middle. The anodization significantly improved the stability of the Ti6Al4V alloy in Hank’s solution due to a layer of TiO2 formed on the surface. The precoated HA further improved the stability of the Ti6Al4V alloy due to a composite layer of TiO2 and HA. The barrier layer of the composite of TiO2 and HA was suggested by the capacitive behavior of the HA-coated substrate in the electrochemical impedance spectroscopy. The electrochemical measurements implied a high tendency for the new formation of HA on the precoated HA and the anodized substrates, which was confirmed through the immersion tests. The newly formed HA on the anodized substrate was scattered over the entire surface. The newly formed HA on the HA-precoated surface mingled with the precoated HA, and gradually a new layer of HA was formed on top. These proved the favorable condition of the anodized surface as a prerequisite step for coating HA and the conductive promotion of new HA formation on the precoated surface. The new formation of HA during the immersion might suggest that artificial joints pretreated through anodization and HA coating could induce strong bonding to the bone due to the easy growth of new HA.

In this work, the oxide structures of three polycrystalline copper grades, unalloyed oxygen-free (OF) copper and alloyed CuAg and deoxidized high-phosphor (DHP) copper, were studied using cross-sectional analytical transmission electron microscopy (AEM) samples. The oxidation treatments were carried out in air at 200 and 350 °C for different exposure times. The detailed oxide layer structures were characterized by AEM. At 200 °C, a nano-sized Cu2O layer formed on the all copper grades. At 350 °C, a nano-sized Cu2O layer formed first on the all copper grades. After longer exposure time at 350 °C, a crystalline CuO layer grew on the Cu2O layer of the unalloyed OF-copper. In the case of the alloyed CuAg- and DHP-copper, a crystalline and columnar shaped layer, consisting of Cu2O and CuO grains, formed on the nanocrystalline Cu2O layer. At 350 °C, the unalloyed copper oxidized notably slower than the alloyed coppers, and its oxide structures were different than those of the alloyed coppers.

ZrO2 films deposited on silicon (100) substrates using pulsed-pressure metalorganic chemical vapor deposition (PP-MOCVD) with zirconium n-propoxide (ZnP) Zr(OC3H7)4 were dense and fully crystalline for substrate temperatures of 500 to 700 °C. Film thicknesses were 40 to 815 nm thick, measured after growth using ellipsometry and scanning electron microscopy (SEM). The growth rate was between 0.1 μm/h at 500 °C and 1 μm/h at 700 °C. Transmission electron microscopy (TEM) and x-ray diffraction (XRD) indicated an average grain size of 10 to 20 nm. There was a random orientation of cubic/tetragonal zirconia at the highest experimental temperature of 700 °C. SEM and atomic force microscopy (AFM) was used to characterize island height of discontinuous films in the initial stages of growth where defects in the substrate caused preferred nucleation of isolated particles. At later stages of growth, the average surface roughness of continuous films was 30 nm, which revealed a more uniform growth had developed. A growth model is proposed, and optimal growth conditions are suggested for targeted microstructures of ZrO2 films.

Differential speed rolling (DSR) has been carried out on AZ31 alloys with Mn additions of 0 to 0.6 wt% for investigating the effects of Mn on microstructure, texture, mechanical properties, and formability. The Al–Mn compounds were formed in the sample with a Mn addition of only 0.2 wt% because of its low solid-solubility limit. There were tiny differences among the DSR-processed AZ31 alloys with different Mn contents, while the AZ31 alloy without Mn addition exhibited a more homogeneous microstructure, a weaker basal texture intensity, and a much superior formability together with a larger likelihood of grain growth during annealing. The Mn dissolving in αMg matrix exerted a far stronger influence on the resulting properties compared with those existing in form of the Al–Mn compounds. The Mn solute atoms induced an increase in c/a ratio, which may suppress activity of nonbasal slips and in turn degrade the deformation capability.

Hollow carbon spheres encapsulating magnetite nanocrystals were obtained in high-pressure argon at 600 °C followed by hydrolysis of Fe(NH3)2Cl2 in the hollow interiors at room temperature and heat treatment in argon at 450 °C for 2 h. The structure, morphology, and properties of the products were characterized by x-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and vibrating sample magnetometry. The hollow carbon spheres have diameters of 1–10 μm and wall thicknesses of hundreds of nanometers; the wt% of magnetite nanocrystals in them is ∼13.2%. Equiaxed magnetite nanocrystals range in size from 15 to 90 nm, while acicular magnetite nanocrystals have diameters of ∼20 nm and lengths of 120–450 nm. The saturation magnetization value of the hollow carbon spheres encapsulating magnetite nanocrystals is 4.29 emu/g.

Highly aligned nanowire bundles were controllably fabricated through the reaction of Si with oxygen, using molten Ga and Au as catalysts. Scanning electron microscopy reveals that the bundles have the ability to self-assemble into various morphologies, a few of which, including one that strikingly resembles a sunflower, were not reported before. Examinations of the bundles by transmission electron microscopy show that they contain fine, amorphous SiOx nanowires, with x ranging from 1.2 to 1.5. In the sunflower-like morphology, highly packed bundles form the disc florets and loosely packed bundles around the rim of the disc form the ray florets. We have studied the conditions under which the sunflower-like morphology could be obtained and suggest a possible mechanism for its growth. Room-temperature cathodoluminescence spectra of the nanowire bundles show that they emit an intense broad-band light covering the entire visible range.

Rapidly solidified nanocrystalline RE–TM–B (RE = Nd, Pr, Dy, TM = Fe, Co) alloys with enhanced hard magnetic properties were synthesized by melt spinning. The composition- and microstructure-dependent elevated temperature magnetic properties were investigated. The temperature coefficients of remanence (α) and coercivity (β) were determined. The effects of Pr substituting Nd, Co substituting Fe, Dy substituting RE, and grain size on the Curie temperature and thermal stability were studied. Co or Dy substitutions were found to have a significant beneficial effect on the thermal stability. Reducing grain size could also improve elevated temperature behavior. Maximum energy product (BH)max > 100 kJ/m3 could be obtained in compositionally optimized nanophase alloys at temperature of 473 K. Extremely low coefficients of α and β were realized in exchange coupled nanocomposite alloys. Bonded nanocomposite magnets with α = −0.052%/K and β = −0.0365%/K for 300–400 K were also successfully fabricated.

Refractory materials such as carbon possess properties that make joining them difficult. In this work, bonding of a carbon–carbon composite is achieved by employing self-sustained, oxygen-free, high-temperature combustion reactions. The effects of several parameters, such as the composition of the reaction media, and the values of the applied current and pressure, on the mechanical strength of the joint were investigated. It was found that the C–C composite possesses a high activity with the reactive media layer, the level of electrical current used to initiate the reaction and the applied pressure do not need to be excessive to obtain a strong joint. Some aspects of the joining mechanism are discussed in detail.

Flowerlike manganese oxide microspheres and cryptomelane-type manganese oxide nanobelts were selectively synthesized by a simple decomposition of KMnO4 under mild hydrothermal conditions without using template or cross-linking reagents. The effect of varying the hydrothermal times and temperatures on the nanostructure, morphology, compositional, and electrochemical properties of the obtained manganese oxides was investigated. X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) studies showed that the flowerlike manganese oxide microspheres could be obtained at relatively low hydrothermal temperatures, while high hydrothermal temperatures were favorable for the formation of cryptomelane-type manganese oxide nanobelts. A morphology and crystalline evolution of the nanostructures was observed as the hydrothermal temperature was increased from 180 to 240 °C. On the basis of changing the temperatures and hydrothermal reaction times, the formation mechanism of cryptomelane-type manganese oxide nanobelts is discussed. Cyclic voltammetry (CV) was used to evaluate the electrochemical properties of the obtained manganese oxide nanostructures, and the results show that the electrochemical properties depend on their shape and crystalline structure. This easily controllable, template-free, and environmentally friendly method has the potential for being used in syntheses of manganese oxide nanomaterials with uniform morphologies and crystal structures.