The growth and characterization of high-Tc NbN films formed on room temperature substrates by pulsed laser deposition is described. The growth was performed at a high laser power density (>5 × 108 W/cm2), where the enhanced reactivity of species in the plume is proposed as the mechanism for increased nitrogen incorporation in films on unheated substrates. The Tcs were 16.2 K on MgO and 13 K on SiNx/Si substrates. In addition to electrical transport measurements, the films were characterized using RBS and x-ray diffraction. The particulate density on films grown at high power density was significantly reduced, which is correlated with the Nb target having a smoother morphology, characteristic of a quenched molten surface layer in the ablated area.

The thermodynamic stability of the solder channels at a scalloplike Cu6Sn5 layer formed between Sn-containing solders and Cu substrate was evaluated by studying the penetration behavior of the liquid solders into the grain boundaries of a Cu6Sn5 substrate. The orientational relationship between the grains of the Cu6Sn5 layer formed during reflow soldering was also analyzed using the electron backscattered diffraction technique. The results showed that liquid solders penetrate into the grain boundaries at an order of faster speed than the growth rate of the layer, which provided a direct evidence of thermodynamic stability of the channel.

Crystalline hydroxyapatite (HAp) powders were prepared at room temperature from heterogeneous reaction between Ca(OH)2powders and (NH4)2HPO4 solutions via the mechanochemical-hydrothermal route. X-ray diffraction, infrared spectroscopy, thermogravimetric characterization, and chemical analysis were performed, and it was determined that the room temperature products were phase-pure, thermally stable HAp with a nearly stoichiometric composition. Dynamic light scattering revealed that the dispersed particle size distribution of the room temperature HAp powders was in the range of 0.15–3.0 μm with a specific surface area of ≈90 m2/g. Both specific surface area measurements and scanning electron microscopy confirmed that the HAp powders consisted of agglomerates containing hundreds of ≈20 nm HAp crystals.

Three novel regioregular polymers substituted with electron-donating or -withdrawing groups, poly[1,4-bis(3-X-2,5-thienylene)phenylene-alt-2,5-dioctyl-1,4-phenylene] [PBT(X), X = OMe, H, CN], were synthesized and characterized. They are highly fluorescent, but the absorption wavelength of PBT(CN) and PBT(OMe) are shifted toward the blue and red regions, respectively, with reference to PBT(H). The onset reduction potential of PBT(CN) is –1.11 V versus SCE (saturated calomel electrode), which is higher than that of the cyano derivative of poly(phenylene vinylene), indicating it be a good candidate as electron transport layer. The onset oxidation and reduction potentials of PBT(OMe) (0.96 and –1.28 V versus SCE respectively) suggest it would perform well as emissive layer in light-emitting display applications.

It is well known that great difficulties are encountered in the cold compaction of ultrafine powders. Such difficulties have been qualitatively attributed to several origins (e.g., increasing relative contribution of oxidized layers to particle resistance as particle size decreases). The main densification stage during compaction is governed by plastic deformation at interparticle contacts under pressure. On account of the strength enhancement of plastic resistance in presence of plastic strain gradients (physically resolved by “geometrically necessary dislocations”) a contribution to the size effect on powder compaction efficiency is here predicted. Some quantitative experimental data available are in good agreement with this explanation.

Aging properties of porous GaAs were investigated nondestructively using variable angle of incidence infrared spectroscopic ellipsometry. In addition to the thickness and volume porosity, properties of the solid part of the porous material are investigated in terms of the long-wavelength dielectric function and chemical composition. The high sensitivity is employed to detect and identify infrared resonant absorptions related to different vibration modes of cubic and amorphous As2O3. Resonances centered at 333.3, 480, 785.8, 838, and 1045.5 cm−1 are from cubic As2O3, whereas resonances centered at 350, 490, and 808.5 cm−1 are from amorphous As2O3.

A close relationship between the photoluminescence emissions labeled Y and S, related to dislocations and extended structural defects, and the preparation of the surface state of ZnSe single crystals before PL (photoluminescence) measurements has been established. The samples were obtained by solid-phase recrystallization under different pressure conditions. An easy method for achieving good quality surfaces with a very significant reduction of such Y and S PL emissions is proposed.

Effects Cu and Ni additions on Au embrittlement of eutectic Sn–Pb solder interconnections during a solid-state aging treatment were evaluated using a ball shear testing method. The addition resulted in a formation of Au-containing ternary intermetallic compounds, either Au–Sn–Cu or Au–Sn–Ni phase, inside the solder matrix during aging treatment. The fracture energy of the solder interconnection containing 2.9 wt% Cu remained almost the same up to 200 h of aging treatment at 150 °C, demonstrating the possibility of suppressing the Au embrittlement by forming ternary intermetallic phases inside the solder matrix.

Single crystals of 67Pb(Mg1/3Nb2/3)O3–33PbTiO3 (PMN-PT, PMNT) relaxor-based complex perovskite solid solution grown by Bridgman method have pseudo-cubic symmetry under ambient conditions. Examination by means of polarized light microscopy showed that the microstructure of the crystals was dominated by a large number of coarse twin domains. It was confirmed that the most common composition planes were {110} in addition, {112} planes were also observed. These twins may be associated with the transformation of PMNT complex perovskite from the cubic to tetragonal upon a decrease in temperatures. The morphology of the domain structure may be explained from the theory of martensitic transformation.

A low-power, atmospheric pressure, microwave plasma torch was used to make spherical alumina particles of controlled size from irregularly shaped precursor powders. Detailed studies of the impact of operating parameters, particularly gas identity (argon or air), gas flow rates, and applied power, showed that particle size changed in a predictable fashion. The most important factor in controlling particle size appears to be precursor particle density in the aerosol stream that enters the plasma hot zone. This and other facts suggest that particle collision rate is primarily responsible for determining ultimate particle size, although atomic addition also plays a role. Reproducible volume average particle sizes ranging from 97 to 1150 μm3 were formed from precursor particles of order 14 μm3. Moreover, for the first time we report the creation of an atmospheric pressure low-power air plasma (<1 kW).

The mechanochemical behavior of the Ti–Si system was investigated across the whole composition range at a constant milling intensity. At low Si content the mechanical alloying process leads progressively to an amorphous structure. In the central range of the equilibrium diagram, crystalline intermetallic compounds form with a combustion-like behavior. A nanostructured composite of TiSi2 gradually evolves above the Ti25Si75 stoichiometry. Transformation behaviors relate to the thermodynamic and thermochemical properties of the tested mixtures as well as with their mechanical features and structural refinement, which change drastically within the explored composition range.

Instrumented indentation testing (IIT) is a relatively new form of mechanical testing which significantly expands on the capabilities of traditional hardness testing. In an IIT experiment, an indenter of known mechanical properties is pressed into contact and then withdrawn from a test material. The fundamental measurements during an IIT experiment are the applied load and the resulting penetration of the indenter into the test surface. The Hertzian contact model, or a derivative thereof, is often employed to relate these measurements to interesting mechanical properties of the test material. This article argues for a small correction to the Hertzian contact model when applied to instrumented indentation data. The magnitude of the correction primarily depends on Poisson's ratio of the test material and the contact radius normalized by the radius of the indenter tip. Neglecting this correction can cause significant errors in the calculation of elastic modulus and hardness from instrumented indentation data.

Circular and hexagonal microholes, ranging in size from several nanometers to micrometers, were generated in a graphite surface by electron beam irradiation. The depth of the holes was always 0.34 nm, indicating that only the uppermost layer was modified. The shape of the holes was switched from circular to hexagonal when the size reached about 500 nm. Although the hexagons appeared at random on the surface, they were aligned in one direction, implying that the formation and growth of the holes were determined by the atomic structure of graphite. The results described in this study will be used to modify the surface structure of graphite for many applications.

The effect of compositions of host precursors on the afterglow and phosphorescent decay properties of Eu2+- and Dy3+-coactivated strontium aluminates (SAED) synthesized by a sol-gel process has been investigated. A variety of strontium aluminates such as Sr3Al2O6, SrAl2O4, and SrAl12O19 have been identified in the samples prepared from starting precursors with Al/Sr ratios ranging from 1 to 12, respectively. The initial afterglow intensity (I0) for SAED phases was found to vary with Al/Sr ratio of the sol-gel precursor, with a maximal I0 appearing in the sample with Al/Sr of 2 in which SrAl2O4 dominated. The afterglow decay rate was found to be fastest for sample with Al/Sr ratio of 1:1 in which Sr3Al2O6 phase dominated. Moreover, the afterglow decay rates for those with Al/Sr ratio of 2:1 to 12:1, in which SrAl2O4 and SrAl12O19 dominated, were found to be slow and similar.

Superlattices of TiC/VC have been deposited on MgO(001) substrates by simultaneous direct current metal magnetron sputtering and C60 evaporation in the temperature range 200–800 °C. Thin superlattices (approximately 1000 Å) deposited at 400 °C exhibited an epitaxial growth with abrupt interfaces while films deposited at 200 °C showed a partial loss of epitaxy. At 800 °C roughening by surface diffusion started to degrade the superlattices and introduced a columnar microstructure. A loss of epitaxy was observed for thicker (>7000 Å) superlattice films deposited at 400 °C. The results suggest that this observation is due to difficulties in depositing epitaxial VC.

Crystallization behavior of amorphous Zr65Cu17.5−xAl7.5Ni10Agx (x = 0, 5) alloys prepared by melt spinning and injection casting techniques has been studied using differential scanning calorimetry, x-ray diffractometry, and transmission electron microscopy. Ag addition changes crystallization sequence of the amorphous phase. The amorphous Zr65Cu17.5Al7.5Ni10 alloy crystallizes via simultaneous precipitation of icosahedral phase and NiZr2 phase in the first crystallization step whereas that in Zr65Cu12.5Al7.5Ni10Ag5 alloy crystallizes via precipitation of only icosahedral the phase. Partial replacement of Cu by Ag in Zr65Cu17.5Al7.5Ni10 alloy stabilized the icosahedral phase relative to competing intermetallic phases resulting in suppression of the precipitation of the NiZr2 phase, enhancement of the precipitation of icosahedral phase, and reduction of undercooled liquid range. Crystallization behavior of the amorphous Zr65Cu12.5Al7.5Ni10Ag5 alloy is not affected by cooling rate during solidification. Johnson–Mehl–Avrami analysis of isothermal transformation data suggests that the formation of the quasicrystalline phase is not entirely polymorphic in nature and may involve partitioning of the solute at later state.

Alkali halides such as KBr, KI, CsBr, and CsI were added to Dy3+-doped Ge–Ga–S glasses, and their effects on the 1.31-μm emission property were investigated. The intensities of the 1.31-μm emission (6F11/2 · 6H9/2 → 6H15/2) increased at the expense of the 1.75-μm emission intensity (6H11/2 → 6H15/2) with the alkali halide addition. The lifetimes of the 1.31-μm emission level also increased as much as 35 times from 38 μs for Ge–Ga–S glass to 1320 μs for the glass containing 10 mol% CsBr. These enhancements occurred only when the ratio of MX (M = K, Cs; X = Br, I)/Ga was equal to or larger than unity. Raman spectra of Ge–Ga–S–CsBr glasses indicated the formation of [GaS3/2Br]− complexes, which provide the preferred sites for Dy3+. Due to this new local environment of Dy3+, the multiphonon relaxation rates from the Dy3+:6F11/2 · 6H9/2 level decreased by approximately four orders of magnitude. The enhancement in the 1.31-μm emission properties with alkali halide addition supports the potentials of these glasses as hosts for the Dy3+-doped fiber-optic amplifiers.

Thin films of lanthanum substituted bismuth titanate, Bi4−xLaxTi3O12 (BLTx), were prepared by chemical solution deposition. Crystallized BLTx films were obtained by rapid thermal annealing at a temperature as low as 650 °C. Structural and electrical characteristics of crystalline BLTx films were studied as functions of La composition. Structure characterization was conducted by x-ray diffraction and Raman spectroscopy. The lowest lattice vibration mode around 116 cm−1 showed softening with increasing lanthanum composition. Surface morphology of BLTx films were recorded by scanning electron microscopy. BLTx films have saturated hysteresis loops with remnant polarization of 9.7, 12.3, and 4.5 μC/cm2, respectively, for x = 0.50, 0.75, and 1.00 films. BLT0.75 films showed fatigue-free behavior over 250 kV/cm, 50 kHz cycling, which could be compared with that of SrBi2Ta2O9 thin films. Fatigue resistance decrease at lower cycling field. The field dependence of fatigue property was discussed briefly in terms of competition between domain pinning and field-assisted unpinning.

NiAl–AlN + Cr composites were produced by blending cryomilled NiAl powder with approximately 10 vol% Cr flakes. In comparison to the as-consolidated matrices, hot isostatically pressed Cr-modified materials did not demonstrate any significant improvement in toughness. Hot extruded NiAl–AlN + 10.5Cr, however, possessed a toughness twice that determined for the base NiAl–AlN alloy. Measurement of the 1200 to 1400 K plastic flow properties revealed that the strength of the composites was completely controlled by the properties of the NiAl–AlN matrices. This behavior could be successfully modeled by the Rule-of-Mixtures, where load is shed from the weak Cr to the strong matrix.

Five glasses in the system SiO2 · CaO · P2O5 have been synthesised via sol-gel method. The textural properties of the calcined glasses have been studied using mercury intrusion and N2 adsorption porosimetries. The glasses with higher SiO2 content showed lower pore volume, smaller diameters in the meso- and macropore regions, and higher surface areas. The pore morphology in the mesopore range was influenced by the SiO2 content, where there was a transition from ink bottle to cylinder shaped pores.