Short segments of YBa2Cu3O7-y (YBCO) coated conductors were fabricated on rolling-assisted biaxially textured substrates (RABiTS) with a layer sequence of CeO2/YSZ/Ni using an ex situ BaF2 precursor process. Pulsed laser deposition (PLD) was used to deposit both YSZ and CeO2 layers. The YBCO films were grown using e-beam coevaporated Y–BaF2–Cu precursors followed by postannealing. An overall engineering current density, JE, of 28,000 A/cm2 and critical current, Ic, of 147 A/cm width at 77 K were achieved for a 1.6-μm-thick YBCO film. This result demonstrates the possibility of using both the ex situ BaF2 precursor approach and the RABiTS process for producing long lengths of high-JE coated conductors.

The microstructural development of YBa2Cu3Oy (Y-123) coated conductors based on the ion-beam-assisted deposition (IBAD) of yttria-stabilized zirconia (YSZ) to produce a biaxially textured template is presented. The architecture of the conductors was Y-123/CeO2/IBAD YSZ/Inconel 625. A continuous and passivating Cr2O3 layer forms between the YSZ layer and the Inconel substrate. CeO2 and Y-123 are closely lattice-matched, and misfit strain is accommodated at the YSZ/CeO2 interface. Localized reactions between the Y-123 film and the CeO2 buffer layer result in the formation of BaCeO3, YCuO2, and CuO. The positive volume change that occurs from the interfacial reaction may act as a kinetic barrier that limits the extent of the reaction. Excess copper and yttrium generated by the interfacial reaction appear to diffuse along grain boundaries and intercalate into Y-123 grains as single layers of the Y-247, Y-248, or Y-224 phases. The interfacial reactions do not preclude the attainment of high critical currents (Ic) and current densities (Jc) in these films nor do they affect to any appreciable extent the nucleation and alignment of the Y-123 film.

Nanophase elemental Fe powders prepared by mechanical milling were sinter forged to full density with an average grain size in the nanophase range (below 100 nm). If Cu additions are introduced during milling to form supersaturated solid solutions (Fe85Cu15 and Fe60Cu40), grain sizes can be easily controlled to below 50 nm after consolidation. For Fe–Cu, it was observed that atomic level alloying between the two elements during milling was very helpful for obtaining a homogeneous microstructure and nanocrystalline grain/domain sizes in the consolidated product. The advantages of using sinter forging (upset die forging), as well as the role of the Cu addition, in the retention of nanocrystalline grain sizes are discussed. The consolidated Fe alloys exhibit very high strength under compression, further demonstrating that low populations of flaws and nanophase grain structures were attained in the consolidated products.

A titanium thin film was deposited on the flat (0001) face of a 6H–SiC by electron beam evaporation at room temperature in a vacuum of 5.1 × 10−8 Pa. The Ti film was epitaxially grown on the surface, and the interface between Ti and SiC was characterized by high-resolution electron microscopy. It was found that the structure of the deposited titanium is face-centered cubic (fcc), although bulk titanium metal usually has a hexagonal close-packed or body-centered cubic crystal structure. We believe that the unusual fcc structure of Ti thin film is due to the high adhesion of the film to the substrate and the high degree of coherency between them. The orientation relationship of the fcc-Ti/6H–SiC interface was (111)fcc-Ti//(0001)6H–SiC and [110]fcc-Ti//[1120]6H−SiC. Preliminary calculations indicate that this orientation relationship maximizes the lattice coherency across the interface.

The aim of the work described in the present paper was to investigate the microstructural stability during annealing treatments of a Fe–Al alloy obtained by melt spinning. To this purpose internal friction (IF) and dynamic modulus (Md) measurements were employed, and the results correlated with x-ray diffraction, optical microscopy, and scanning and transmission electron microscopy observations. In particular, the B2-ordered Fe–38A1–2Cr–0.015C–0.003B (in at.%) alloy was studied during repeated heating runs from room temperature to 823 K by IF and Md. The modulus exhibited a broad maximum (in the range of 600–800 K) only in the first run. On the basis of transmission electron microscopy and x-ray diffraction analysis, the irreversible transformation was explained by considering a two-stage process that occurs when vacancies in supersaturation move toward dislocations. The first stage is connected to dislocation locking; the second one is due to annihilation of some vacancies by dislocation climb.

Nanocrystalline transition alumina tape casts were used as interlayers to join conventional alumina ceramic pellets. The joining experiments were performed by hot pressing at 1200–1300 °C under uniaxial pressures of 55 and 80 MPa for 1- and 5-h durations, with and without a nanocrystalline interlayer. Successful joints were enabled only above 1250 °C in the presence of the interlayer. Generally, the joint 4-point bending strength increased with the increase in joining temperature, pressure, and duration. The average bending strength of the interface joined at 1250 °C was 245 ± 65 MPa compared to the pellet strength of 268 MPa. Postjoining heat treatments at 1400 °C for 3 h caused reduction in the joint strength. The interlayer at the joint exhibited homogeneous and crack-free microstructure. The changes in the joint strength were discussed with respect to the densification and grain growth behavior of the nanocrystalline interlayer.

Pb(Zr, Ti)O3 (PZT) thin films were deposited on Pt/SiO2/Si substrates by metalorganic chemical vapor deposition using solid delivery system. The effects of deposition parameters such as the substrate temperature, the concentration of Pb precursor in the precursor mixtures, and the reactor pressure on the structural and electrical properties of PZT thin films were investigated. To obtain single-phase PZT thin films, the optimal range of the substrate temperature should be between 600 and 650 °C. The PbO content in PZT thin films was proportional to the fraction of Pb in the precursor mixture below 550 °C, but it was independent of the fraction of Pb in the mixture above 600 °C. With the increment of the reactor pressure, Zr contents in PZT thin films were increased, and the Pb/(Zr + Ti) ratio became more stoichiometric so that the ferroelectric properties were improved.

NdBCO large-grain materials can improve the performance of engineering devices based on superconducting bulk materials if c-axis-oriented large grains can be produced in large quantities under simple processing conditions. This study concentrates on exploring the factors dictating the seeding behavior and the subsequent growth morphology of Ag-doped NdBCO grains under relatively high oxygen partial pressure using NdBCO seeds and a simple processing system. It was found that seeding temperature, aspect ratio of seed, and amount of Ag were all important factors affecting the success rate of inducing c-axis-oriented growths. With the optimized seeding conditions and in view of the simplicity of the processing system, the processing conditions derived from this study could lead to the up-scaling of NdBCO–Ag large-grain materials production.

Thermogravimetric analysis, x-ray photoelectron spectroscopy, and x-ray diffraction results and the humidity sensing properties of poly(vanadium–molybdenum acid) H2V9.5Mo2.5O32.0 · 8.8H2O xerogel thin films, which were fabricated by the sol-gel process, are described in this paper. The conductance and the capacitance of the thin films strongly depend on the relative humidity. Different electrodes have different influences on the humidity-sensing properties of the thin films.

La0.67Sr0.33MnO3 thin films were grown on LaAlO3 substrate in vacuum using pulsed laser deposition to investigate the effect of changing oxygen content. Transmission electron microscopy studies showed that the epitaxial (La0.67Sr0.33)2MnO4 phase with K2NiF4 structure formed unexpectedly as a matrix with a square-shaped nanometer-sized MnO phase distributed in a regular pattern throughout the whole film like self-assembled quantum dots. The MnO phase grew epitaxially from the LaAlO3 substrate to the top of the film with no outgrowth. High-resolution image simulation indicated that Sr ions take up only positions in every other La layer in the (La0.67Sr0.33)2MnO4 structure. Basing our theory on the composition and structure of the matrix phase, we propose that it is possibly electron-doped with a mixed valence of Mn2+/Mn3+ instead of the Mn3+/Mn4+ as in the hole-doped case.

Ordered nanostructure of single-crystalline GaN nanowires in a honeycomb structure of anodic alumina was synthesized through a gas reaction of Ga2O vapor with a constant ammonia atmosphere at 1273 K in the presence of nano-sized metallic indium catalysis. Atomic force microscopy, x-ray diffraction, Raman backscattering spectroscopy, scanning electron microscopy, and transmission electron microscopy indicate that the ordered nanostructure consists of single-crystalline hexagonal wurtzite GaN nanowires in the uniform pores of anodic alumina about 20 nm in diameter and 40–50 μm in length. The growth mechanism of the ordered nanostructure is discussed. The photoluminescence spectrum of this nanostructure is also reported.

The tribological behavior of a Zr–10Al–5Ti–17.9Cu–14.6Ni (at.%) bulk amorphous alloy, in both the as-cast and annealed states, was investigated using nano-scratch tests, including ramping load scratch and multiple sliding wear techniques. The crystallization sequence of the alloy was also characterized. Mechanical properties, such as Young's modulus, hardness, friction coefficient, and tribological wear were measured. These properties were found to vary with microstructure. In general, an increase in annealing temperature results in an increase in hardness, which in turn produces a decrease in friction coefficient but an increase in wear resistance. Samples having a structure consisting of supercooled liquid matrix with dispersed nanocrystalline particles exhibit the best wear performance.

A fully dense in situ Al3Ti–Al2O3 intermetallic matrix composite containing about 30 vol% Al2O3 particles was prepared by combining squeeze casting with combustion synthesis using the chemical reaction between TiO2 and Al. The microstructure of the in situ composite was examined using x-ray diffraction, scanning electron microscopy, and transmission electron microscopy techniques. Compressive behavior of the composite was investigated in the temperature range of 25–600 °C and compared with that of the as-cast Al3Ti alloy. The in situ formed spherical α–Al2O3 particles with a size of 0.2–1 μm were uniformly distributed in the Al3Ti matrix. The grain size of the Al3Ti matrix containing a small amount of Al2Ti precipitate was 2–10 μm. The compressive strength of the in situ composite was about 6–9 times that of the as-cast monolithic Al3Ti alloy and could be maintained at temperatures up to 600 °C. This was mainly attributed to the fine grain size of Al3Ti matrix and the rule of mixture strengthening of Al2O3 particles. The existence of Al2Ti phase and high dislocation density in the matrix also contributed positively to the composite strength.

Copper-doped LiNbO3 waveguides were prepared by Cu–Li ion-exchange process. Compositional, structural, and optical analyses were performed by secondary ion mass spectrometry, x-ray diffraction, and m-line spectroscopy, respectively. The chemical state of Cu2+ ions was studied by electron paramagnetic resonance, and the results were correlated with structural modification of the LiNbO3 matrix. Copper incorporation in the crystal took place under different regimes, and it induced a lattice rearrangement with the formation of new crystalline phases. Cu2+ ions were surrounded by tetragonally compressed octahedra with rhombic distortions. Cu:LiNbO3 optical waveguides were formed supporting two optical modes.

Nano-icosahedral phases were prepared by melt-spinning in the AlMnCe system (Al ≥ 89 at.%). Ce-induced structure alterations are reported by x-ray diffraction for the icosahedral (i) AlMnCe phase. They comprise apparition of superstructure diffraction lines, due to chemical ordering in the 6-dimensional icosahedral lattice, which gradually changes from a simple to a face-centered (FCI) type. Also, strong anomalies of diffracted intensities, with reference to model FCI phases, support Ce preferential location on a special set of sites. Microstructure investigations show a nanodispersion of i-AlMnCe in an Al-rich matrix, suggesting a low nucleation barrier of this metastable phase in the melt.

Nanoparticles of barium europium zirconate, a complex perovskite oxide, were synthesized using a modified self-propagating combustion synthesis. The solid combustion products thus obtained were characterized by x-ray and electron diffraction, differential thermal analysis, thermogravimetric analysis, infrared spectroscopy, particle-size analysis, surface area determination, gas adsorption studies, and high-resolution transmission electron microscopy. According to the results of the x-ray and electron diffraction, as-prepared powder showed the single phase of barium europium zirconate (Ba2EuZrO5.5) without another phase and had a complex cubic perovskite (A2BB′O6) structure. The transmission electron microscopic investigation showed a mean grain size of 38 nm with a standard deviation of 12 nm. High-resolution lattice imaging of the nanoparticles indicated the possibility of finer crystallite in the particle having the same orientation. The nanoparticles of Ba2EuZrO5.5 obtained by the present method could be sintered to 97% theoretical density at a relatively low temperature of 1525 °C.

Thermal and ion-transport properties of the salt-in-polymer system poly(ethylene oxide)n–LiN(CF3SO2)2 [P(EO)nLiTFSI] were investigated for compositions ranging from n = 5 to n = 50. Particular attention was paid to the region n = 8 to 10 where a crystallinity gap previously had been reported. We concluded that the absence of distinct melting transitions for salt-rich compositions (n = 5 to 12) was attributable to the extremely slow kinetics of recrystallization of this system following a heat treatment. The results further indicated that it was primarily the nucleation process that was inhibited by the [(bis)trifluoromethanesulfonate imide] (TFSI) anion. As a corollary, the ionic conductivity was strongly dependent on the thermal history of samples, and an enhancement of up to 300% was observed in the ambient temperature ionic conductivity for pre-heated salt-rich samples.

Morphology and structure of ZnO films deposited on (0001) sapphire and glass substrates by off-axis sputtering were investigated at various temperatures and pressures. All films show highly textured structures on glass substrates and epitaxial growth on sapphire substrates. The full width at half-maximum of theta rocking curves for epitaxial films is less than 0.5°. In textured films, it rises to several degrees. The trend of surface textures in films grown at low pressures is similar to those grown at high temperatures. A morphology transition from large well-defined hexagonal grains to flat surface was observed at a pressure of 50 mtorr and temperature of 550 °C. The experiment results are explained by the transport behavior of depositing species.

A systematic study was carried out on the equilibrium phases after slow solidification of the Zr41Ti14Cu12.5Ni10Be22.5 alloy. The crystalline microstructure of the slowly cooled melt of the alloy shows “polygons” and “plates” embedded in a fine-grained two-component matrix. To analyze the crystal structure of the different components, microdiffraction technique combining convergent beam electron diffraction and conventional selected-area electron diffraction were used. The stoichiometry of these phases was confirmed by field ion microscopy with atom probe and energy-dispersive x-ray analysis in a transmission electron microscope. The polygons were determined to be cubic (a = 1.185 nm) with space group Fm3m (cF116). The plates were found to be tetragonal (a = 0.37 nm, c = 1.137 nm) with space group I4/mmm (tI6). Its composition is (Cu + Ni)(Zr + Ti)2. One phase of the fine-grained two-component matrix was rich in Ti and poor in Be; the other one was rich in Be and poor in Ti. The Ti-rich phase was determined to be hexagonal (a = 0.536 nm, c = 0.888 nm) with space group P63/mmc.

The effect of alloying additions of Ti and B on the process of micropyretic synthesis on NiAl and on the microstructure of the synthesized alloy was examined. It was observed that the combustibility of the quaternary alloy is good despite the presence of the alloying elements because of an additional combustion reaction between Ti and B. The microstructure of the quaternary alloy was found to consist primarily of the NiAl and Ti boride phases. The effect of preheating of the specimen prior to synthesis on the process of synthesis was also examined. It was observed that preheating not only can change the morphology of the phases but also influence the nature of the phases present in the alloy. The mechanism of the formation of the two phase microstructure during the synthesis from the elemental powders was established by stopping the combustion front and by carrying out a detailed microstructural characterization of regions around the stopped combustion front.