The effect of BaO addition on the crystallization of Li2O–Al2O3–ZnO–SiO2–TiO2– ZrO2 (LAZSTZ) glass was investigated and discussed. The crystallization temperature of BaO-added LAZSTZ precursor glass (LBAZSTZ) was decreased due to the increase in the number of broken ionic bonds, while the transparency of the glass–ceramic was maintained. The lowered activation energy for crystallization in LBAZSTZ glass strongly supports the increase in the number broken bonds. During heating LBAZSTZ glass, phase separation did not occur most probably due to the competition between metal cations having a certain degree of ionic field strength. The formation of β-spodumene as a major phase in LBAZSTZ glass–ceramic was identified using x-ray diffraction.

Superhard and elastic carbon nitride films with hardness and elastic recovery of 47 GPa and 87.5%, respectively, were synthesized by using a double-bend filtered cathodic vacuum arc combined with radio-frequency nitrogen ion beam source. The bombardment of energetic nitrogen atom onto the growing film surface results in the high atomic ratio of N/C (0.4), which contributes to the high sp2 content and the formation of a five-membered ring structure in the carbon nitride film at room temperature. The buckling of the five-membered ring basal planes may facilitate cross-linking between the planes through sp3 coordinated carbon atoms. A rigid three-dimensional network is formed, which contributes to the high hardness and elastic recovery of the deposited films.

We report the property studies of a MgB2 superconductor with high critical current density. The MgB2 superconductor was readily fabricated through a direct high-pressure synthesis of the respective elements. The obtained high-density MgB2 undergoes a sharp superconducting transition at 39 K. The bulk critical current density (Jc) of the sample was calculated on the basis of Bean's critical state model, and rather high critical current densities over a wide temperature range were obtained in comparison with the ambient prepared samples. The results highlight that high-pressure sintering would be a promising way to produce and search for this kind of intermetallic boride and the related superconductors.

In the equilibrium immiscible Y–Mo system, the total energies of the possible structures for YMo3 and Y3Mo metastable phases were calculated as a function of their lattice constants, by employing the Vienna ab initio simulation package, and the results suggested that the D019, L12, and L60 structures were three possible metastable states in the system. Experimentally, hcp and fcc YMo3 metastable phases were obtained in the Y–Mo multilayers driven far from equilibrium by ion irradiation. Moreover, the lattice constants determined by diffraction analysis were in agreement with the predicted values.

Strontium- and magnesium-doped lanthanum gallate (LSGM) was deliberately prepared to give A-site deficient nonstoichiometry with compositions (La0.9Sr0.1)z(Ga0.8Mg0.2)O3-δ (z = 1.0, 0.98, and 0.95). Creep tests in four-point bending for 950 °C < T < 1350 °C and 15 MPa < σ < 75 MPa in air demonstrated that all three compositions shared a common stress dependence, n= 1.49 ± 0.10, and a common apparent activation energy, Q = 426 ± 9 kJ/mol. Despite this agreement, the creep rates of the different compositions depended on grain size in different ways: p = 3.1 ± 0.2 for z = 0.98, and p = 1.9 ± 0.1 for z = 0.95. The measured apparent activation energy, Q, for creep is similar, though statistically significantly smaller, than that measured in another LSGM. Both are nearly twice as large as reported activation energies for cation impurity diffusion. The absolute magnitude of the creep rates, after correction for grain size, were 30 to 100 times slower than in another LSGM of similar composition.

A new process combining electric field activation and the imposition of pressure from mechanically activated powder mixtures is demonstrated as a means to simultaneously synthesize and densify nano-MoSi2 in one step. Nanophase reactants (Mo + 2Si) produced by mechanical activation are reacted by field activation with the simultaneous application of a uniaxial pressure. Mo + 2Si powders were comilled in a specially designed planetary mill to obtain nanometric reactants but to avoid formation of any product phases. These were then subjected to high alternating currents (1600 A) and pressures of 106 MPa. Under these conditions, a reaction is initiated and completed within a short period of time (3–6 min). The relative density of the product ranged from 82 to 93%. The crystallite size of the MoSi2 compound was determined by x-ray diffraction line-broadening analysis using the Langford method. The size ranged from 58 to 75 nm.

The crystallization behavior of amorphous TiOxNy (x ≫ y) thin films was investigated by in situ transmission electron microscopy. The Johnson–Mehl–Avrami–Kozolog (JMAK) theory was used to determine the Avrami exponent, activation energy, and the phase velocity pre-exponent. Addition of nitrogen inhibited diffusion, increasing the nucleation temperature, while decreasing the growth activation energy. Kinetic variables extracted from individual crystallites were compared to JMAK analysis of the fraction transformed, and a change of 6% in the activation energy led to agreement between the methods. From diffraction patterns and index of refraction the crystallized phase was found to be predominantly anatase.

In this paper, series crystals Nd:Gd0.8La0.2VO4, Nd:Gd0.6La0.4VO4, and Nd:Gd0.45La0.55VO4 were grown by the Czochralski method. The structure and lattice constants of the series crystals were measured. The morphology of Nd:Gd0.8La0.2VO4 is discussed, and it is composed of {100} and {101} simple forms. The thermal expansion and specific heat of the Nd:Gd0.8La0.2VO4 crystal were also measured. The absorption and emission spectra of the Nd:Gd0.8La0.2VO4 and Nd:Gd0.6La0.4VO4 crystals were measured at room temperature. The laser outputs at 1.06 and 1.34 μm were determined when a crystal sample of Nd:Gd0.8La0.2VO4 was pumped by a laser diode at 808 nm, and the visible green and red laser outputs of the intracavity frequency double at 0.53 and 0.67 μm were determined when nonlinear KTiOPO4 and LiB3O5 crystals were used.

The epitaxial growth of KTiOPO4 (KTP) films on different natural faces of KTi1-xGexOPO4 substrates was studied. The growth on faces (100) and (201) is generally of high quality, irrespective of the growth time or concentration of germanium in the substrates. On the other hand, the epitaxial growth on the face (101) is always of poor quality, and the defects are pyramids, even when the germanium content in the substrate is low and the growth time is short. The films on faces (011) and (110) generally have small hillocks as defects and for high concentrations of Ge in the crystals some cracks begin to appear. The film thickness, depending on the growth time and the face considered was measured by scanning electron microscopy (SEM) using backscattered electrons. The diffusion of germanium from the substrate to the film is very low, as demonstrated by electron probe microanalysis measurements and SEM observations. The difference in the refractive indices ny and nz of KTP and KTi0.92Ge0.08OPO4 are on the order of 0.01, which could be enough to produce wave guides. Finally, it was observed that the second harmonic generation response of KTP substituted with Ge decreases as the Ge content in the crystal increases.

Preferred-orientated 4H–SiC nanocrystalline films on silicon substrates were successfully prepared by the pyrolysis of the polyimide Langmuir–Blodgett films containing nanometer-sized amorphous silicon nitride powders. Fourier-transform infrared spectra revealed 4H–SiC nanoparticles with interfacial silicon oxide. Ultraviolet photoluminescence with energies above the band gap of bulk 4H–SiC was observed from the films in which the mean size of 4H–SiC particles was 10 nm, while no photoluminescence was observed from the films in which the mean size of particles was 17 nm. A quantum confinement/luminescence center model is suggested to explain the origin of the ultraviolet luminescence.

Dense BaTiO3 ceramics consisting of fine grains were prepared using fine powder (average grain size of 0.06 μm; BT006) as a starting material and the spark plasma sintering (SPS) method. The powder was densified to >95% of theoretical x-ray density by the SPS process, and the average grain size of the resulting ceramics was <0.5 μm; the particle size of the initial powder significantly affects the grain size of the resulting SPS pellets. Fixed-frequency (100 kHz), room-temperature permittivity measurements of the BT006-SPS ceramics showed relatively low values (3000–3500) compared with those (typically 5000) for SPS ceramics consisting of larger grains (approximately 1 μm). Lower permittivity was attributed to poor development of ferroelectric domains in the ceramics, which originated from incomplete development of the tetragonal structure as well as the presence of a local orthorhombic structure.

The widely observed secondary grain growth in electroplated Copper layers is shown to be incomplete after the sheet resistance and stress of the layer appear to have stabilized. Instead the layer is in an intermediate state with a grain size distribution that depends on the plating conditions. Further extensive annealing at high temperatures results in an additional considerable enlargement of the grain structure, accompanied by an additional decrease of the sheet resistance and desorption of impurities that were incorporated during plating.

γ–Fe2O3/SiO2 and Fe/SiO2 nanocomposites, with a Fe/Si molar ratio of 0.25, were prepared by the sol-gel method starting from ethanolic solutions of tetraethoxysilane and iron (III) nitrate. After gelation the xerogels were oxidated or reduced. Samples were investigated by transmission electron microscopy, x-ray diffraction, differential scanning calorimetry, and thermogravimetry. Magnetic properties of the samples were investigated at room temperature (RT) and at 77 K. Nanometric particles supported in the silica matrix were obtained in all cases. Bigger particles (10 nm) were obtained in the case of Fe/SiO2 nanocomposites with respect to the γ–Fe2O3/SiO2 samples (5–8 nm). A slight effect of sol dilution on particle size was observed only in the case of γ–Fe2O3/SiO2 nanocomposites. A superparamagnetic behavior was shown at RT only by γ–Fe2O3/SiO2 nanocomposites. Iron-based composites exhibited coercivity values higher than 700 Oe at RT.

The grain morphology of the intermetallic compound (IMC) that forms at the interface between liquid solders and solid-metal substrates was observed at solder joints. Cu6Sn5 grains on Cu substrates were rough or rounded, and Ni3Sn4 grains on Ni substrates were faceted. Through the energy-based calculations, the relationship between the IMC grain morphology and Jackson's parameter α was explained. The Jackson's parameter of the IMC grain with a rough surface is smaller than 2 while it is larger than 2 for faceted grains.

Multilayer oxides of SrNb0.1Ti0.9O3/La0.8Sr0.2MnO3/SrTiO3 have been grown by computer-controlled laser molecular beam epitaxy and characterized by transmission electron microscopy. Electron microdiffractions and high-resolution imaging reveal that the as-prepared thin film of La0.8Sr0.2MnO3 with thickness of 200 nm is epitaxially grown on the SrTiO3(001) substrate and the SrNb0.1Ti0.9O3 with thickness of 250 nm epitaxially on the as-received La0.8Sr0.2MnO3 film. The microstructures in the La0.8Sr0.2MnO3 film are clarified in terms of the oriented microdomains. In contrast, microstructures in SNTO are featured by the formation of superstructures due to charge ordering. Crystallographic relationships of these domains are discussed on the basis of an orthorhombic cell and rationalized by theoretical calculations based on a geometrical model.

Nanocrystalline TaC was synthesized by the field-activated combustion method. The crystallite size ranged from about 30 to 55 nm, depending on the applied field. At low fields (8.54 ≤ E < 16.39 V cm−1) the average crystallite size was relatively unaffected by the field, but it showed a significant increase at fields higher than 16.39 V cm−1. From temperature measurements, this field was found to coincide with the melting of Ta. The combustion wave velocity likewise showed a significant increase when the temperature was at the melting point. The composition of the product showed a dependence on the magnitude of the applied field. At low field values (above a threshold) the product contained Ta2C. When synthesized at high fields, the product showed the presence of TaC phase only. The lattice parameter and the C/Ta ratio showed a slight dependence on the field, both increasing with an increase in the magnitude of the field.

The development and evolution of texture in a Mg–10.6%wt Zr deposit obtained by physical vapor deposition was studied. The deposit exhibits a microstructure characterized by elongated grains with the [0001] direction parallel to the deposit growth direction. The volume fraction of the basal plane component increases throughout the thickness from 45% at the collector side up to around 70%. The minimization of interfacial energy of (0001) planes induces the initial texture at the earliest stage of the deposit formation. Furthermore, the increase in the volume fraction of the (0001) component during deposit growth is provoked by texture competition, which results in the development of grains with the [0001] direction parallel to the deposit growth direction.

PbMg1/3Nb2/3O3 (PMN) powder was prepared by citrate organic solution, and barium titanate (BT) seed particles were added to encourage the perovskite phase formation. Sintering was followed using the constant heating rate mode of a dilatometer, and it was observed that the seed concentration affected the PMN shrinkage rate and crystal structure. The study of the lattice parameters of the samples after the sintering process indicates that the diffusion of the titanium and of the barium inside perovskite and pyrochlore PMN phases occurs. Moreover, this substitution provoked a decrease of the lattice parameters as showed by the Rietveld refinement.

Cellular metal foams are of interest because of the ability to tailor their mechanical, thermal, acoustic, and electrical properties by varying the relative density and cell morphology. Here, a tetrakaidecahedral unit-cell approach is used to represent an open-cell aluminum foam and a simplified electrical resistor network derived to model low frequency current flow through the foam. The analysis indicates that for the range of relative densities studied (4–12%), the conductivity of tetrakaidecahedral foams has a linear dependence upon relative density. The distribution of metal in the cell ligaments was found to significantly affect the conductivity. Increasing the fraction of metal at the ends of the ligaments resulted in a decrease in electrical conductivity at a fixed relative density. Low frequency electrical conductivity measurements of an open-cell aluminum foam (ERG Duocel) confirmed the linear dependence upon density, but the slope was smaller than that predicted by the unit-cell model. The difference between the model and experiment was found to be the result of the presence of a distribution of cell sizes and types in real samples. This effect is due to the varying number of ligaments, ligament lengths, and the cross-sectional areas available for current conduction across the cellular structure.

The mechanism and kinetic parameters for the thermal decomposition of four functionalized addition-polymerized polynorbornenes were studied by dynamic and isothermal thermogravimetric analyses and by mass spectrometry. The dynamic and isothermal thermogravimetric analyses showed a first-order degradation reaction mechanism with an activation energy of 229.6 ± 12.5 kJ/mol. Based on the polymer structure, reference mass spectra for related molecules, and a cross-comparison of the mass spectra, the backbone, free-radical scission mechanism was found to occur by cleavage of the linkages between bicyclic rings and the production of volatile monomer and oligomers. The degradation of polynorbornene occurred via a depropagation and transfer reaction process. Initially, the depropagation pathway was preferred, but with increasing conversion, intra- and intermolecular hydrogen transfer reactions dominated.