A new Ca–Mg–Zn alloys having significantly improved glass-forming ability (GFA) has been developed. The ternary Ca65Mg15Zn20 bulk metallic glass with diameter of at least 15 mm is successfully fabricated by conventional copper-mold casting method in air atmosphere. The critical cooling rate for glass formation in the cone-shaped copper mold is less than 20 K/s. When compared with the GFA of Ca–Mg–M (M: Cu, Ni, and Ag) alloys, the significantly improved GFA of the Ca–Mg–Zn alloy cannot be represented by ΔTx, Trg, K, and γ parameters.

Tin whiskers formed on sputter-deposited films on Muntz metal substrates have been examined following long-term aging at room temperature. It was found that while the initial annealing conditions determined the original nucleation and growth rates, whisker nucleation and growth was a continuous process and appeared to be occurring throughout the duration of the study. Whisker densities increased for all samples during aging, and samples that initially showed no whiskers during high-temperature annealing had a population density of 2.5 mm−2 after storage for 15 months.

Crystallization of amorphous Y- and La-doped HfO2 and ZrO2 nanophase powders was studied using thermal analysis and high-temperature x-ray diffraction. Substantial increase of crystallization temperature of amorphous hafnium and zirconium oxides could be achieved by alloying with La2O3. The crystallization temperature of Hf2La2O7 composition is higher than 900 °C, which makes it a candidate for advanced gate dielectrics. In contrast, Y-doping did not significantly raise the crystallization temperature.

Results are presented from a systematic investigation to design and optimize a low-pressure chemical vapor deposition (CVD) process for manganese-doped zinc sulfide (ZnS:Mn) thin films for electroluminescent (EL) device applications. The CVD process used diethylzinc (DEZ), di-π-cyclopentadienyl manganese (CPMn), and hydrogen sulfide (H2S) as co-reactants and hydrogen (H2) as carrier gas. A design of experiments approach was used to derive functionality curves for the dependence of ZnS:Mn film properties on substrate temperature and flow rates (partial pressures) of DEZ, CPMn, H2S, and H2. Film physical, chemical, structural, and optical properties were examined using Rutherford backscattering spectrometry, dynamic secondary ion mass spectroscopy, x-ray photoelectron spectroscopy, nuclear-reaction analysis, x-ray diffraction, transmission electron microscopy, atomic force microscopy, and scanning electron microscopy. EL measurements were carried out on ZnS:Mn-based dielectric–sulfur–dielectric stacks incorporated into alternating-current thin-film electroluminescent devices. An optimized process window was established for the formation of films with predominantly (0 0 2) orientation, grain size larger than 0.2 μm, and Mn dopant level approximately 0.5 at.%. A brightness of 407 cd/m2 (119 fL) and efficiency of 1.6 lm/W were obtained, as measured at 40 V above threshold voltage and 60 Hz frequency.

A series of Nb-rich Zr/Nb and Ti/Nb multilayers were sputter deposited. Upon a reduction in thickness, a pseudomorphic bcc phase was stabilized in the Zr and Ti layers. X-ray and electron diffraction techniques were used to confirm these phase transformations. The change in phase stability was modeled by the competition between volumetric and interfacial components of the total free energy of a unit bilayer representing the multilayer. An outcome of this model is the ability to plot phase stability diagrams for multilayers, referred to as biphase diagrams, as a function of bilayer thickness and volume fraction. A comparison of the phase stability boundary between hcp/bcc and bcc/bcc for these two systems has shown that the bcc Ti’s pseudomorphic phase stabilization is maintained for a much larger layer thickness as compared to Zr. Atom probe compositional profiles of the Ti/Nb multilayers have indicated that the Nb layers interdiffused into the Ti layers thus helping to facilitate the bcc Ti phase stability in the Ti/Nb multilayers.

The approach developed for the microindentation of layered elastic solids was adapted to analyze atomic force microscopy probing of ultrathin (1–100 nm-thick) polymer films on a solid substrate. The model for analyzing microindentation of layered solids was extended to construct two- and tri-step graded functions with the transition zones accounting for a variable gradient between layers. This “graded” approach offered a transparent consideration of the gradient of the mechanical properties between layers. Several examples of recent applications of this model to nanoscale polymer layers were presented. We considered polymer layers with elastic moduli ranging from 0.05 to 3000 MPa with different architecture in a dry state and in a solvated state. The most sophisticated case of a tri-layered polymer film with thickness of 20–50 nm was also successfully treated within this approach. In all cases, a complex shape of corresponding loading curves and elastic modulus depth profiles obtained from experimental data were fitted by the graded functions with nanomechanical parameters (elastic moduli and transition zone widths) close to independently determined microstructural parameters (thickness and composition of layers) of the layered materials.

Transparent Pb(Zn1/3Nb2/3)O3–(Pb1-xLax)(Zr1-yTiy)O3 (PZN–PLZT) ferroelectric ceramics have successfully been prepared by hot-pressed sintering in oxygen atmosphere. Uniform cylindrical samples with diameter as large as Φ = 50 mm can readily be obtained. X-ray analysis and scanning electron microscopy experiments showed a pure perovskite phase, thin grain boundaries, and uniform dense microstructures. Very good transparency was reached for wavelength from near ultraviolet to infrared. The dielectric constant was also measured as a function of temperature and frequency. Some novel phenomena such as good piezoelectric and electro-optical properties have been observed.

A basic sulfate precursor [Sc(OH)SO4·2H2O] for well-sinterable Sc2O3 powders was precipitated from mixed solutions of scandium nitrate [Sc(NO3)3] and ammonium sulfate [(NH4)2SO4] at room temperature and which was subsequently converted to Sc2O3 via dehydroxylization and desulfurization at temperatures ≥900 °C. With the reactive powders synthesized in this work, polycrystalline Sc2O3 ceramics showing high inline transmittances of approximately 70% in the visible wavelength region (corresponding to ∼90% of the theoretical value of single crystals) have been fabricated via vacuum sintering at a relatively low temperature of 1700 °C.

Wet-chemical and electrochemical routes were used to synthesize zinc oxide nanoparticles showing peculiar luminescent properties. ZnO-I are the nanoparticles that show only band gap ultraviolet (UV) emission, whereas ZnO-II type nanoparticles show the defect green luminescence along with the UV emission. Photoluminescence excitation (PLE) spectra of ZnO-I nanocrystals exhibit a single feature located at about 368 nm whereas ZnO-II nanocrystals show two features in PLE: a prominent feature at about 368 nm which is size dependent and a hump at 325 nm. These results are discussed in detail in view of the luminescence behavior in ZnO quantum particles.

Comprehensive results are presented on the influence of interfaces on electronic structure and giant magnetoresistance (GMR). Two structures were calculated for Co5/Cu3/Co5 and Co3/Cu/Co/Cu3/Co/Cu/Co3, where numbers stand for monolayer numbers of atoms, by employing the discrete variational method in the framework of the local spin density approximation. It has been found that the electron spin-dependent scattering is very strong at the interfaces compared to the interiors of the ferromagnetic layers, independent of the moment alignment configuration. The calculation results of total energy for various magnetization configuration revealed that antiferromagnetic exchange coupling was present between any of the ferromagnetic layers separated by Cu layers at zero field in the Co3/Cu/Co/Cu3/Co/Cu/Co3. The evaluated GMR ratio for the Co3/Cu/Co/Cu3/Co/Cu/Co3 (about 35.1%) was much larger than that of the Co5/Cu3/Co5 (about 21.0%), indicating large GMR effect could be expected with more interfaces when the thicknesses were the same. The result also indicated that the negative polarization of 4s electrons could reduce the GMR effect.

Dense aluminum nitride ceramics were prepared by sintering green bodies at 1750 °C for 2 h. These green bodies were prepared by aqueous slip-casting from a powder that was surface-treated to prevent hydrolysis. The surface treatment of the aluminum nitride (AlN) powder consisted of dispersing the powder in warm-water solutions of aluminum dihydrogenphosphate Al(H2PO4)3. Different treatment temperatures in the range 30–80 °C were tested. For all the tested temperatures, the surface-treated AlN powder was found to be water-resistant, even after drying and/or redispersion. Various commercial dispersants were tested for their effectiveness, and the amount of dispersant was optimized in terms of a high solids loading of the suspension and an acceptable viscosity for slip casting. Based on these studies, a stable aqueous suspension of AlN powder, treated at 60 °C, with a total solids loading of 50 vol%, was prepared using CaF2 as a sintering additive. The well-dispersed powder made it possible to prepare green samples with close particle packing and relatively high sintered densities; that is, more than 96% of the theoretical density.

Molecular dynamics simulations of approximately 15 Å thick intergranular films (IGFs) containing SiO2 and CaO in contact with two surface terminations of the prism (10¯10) and basal planes (0001) of Si3N4 were performed using a multibody interatomic potential. Samples with the same composition (1.5 mol% CaO) and number of atoms but different crystal planes (i.e., the prism and basal planes of Si3N4) were studied. In both the prism and basal cases, the IGF in the final configuration is well-ordered in the interface region. A small number of N ions from the crystal moved into the IGF near the interface, and O ions moved into the N sites in the crystal, indicating the formation of a Si–O–N interface. In addition, Ca ions do not segregate to the IGF–crystal interface. The bonding characteristics of the O ions at the interface with neighbor Si ions are different in the prism and basal cases. Such difference may be explained by the difference in the two crystal Si3N4 surfaces. The Si–O bond length of the IGF has a range from 1.62 Å to 1.64 Å, consistent with recent experimental findings.

We report the synthesis of thin films of B–C–N and C–N deposited by N+ ion-beam-assisted pulsed laser deposition (IBPLD) technique on glass substrates at different temperatures. We compare these films with the thin films of boron carbide synthesized by pulsed laser deposition without the assistance of ion-beam. Electron diffraction experiments in the transmission electron microscope shows that the vapor quenched regions of all films deposited at room temperature are amorphous. In addition, shown for the first time is the evidence of laser melting and subsequent rapid solidification of B4C melt in the form of micrometer- and submicrometer-size round particulates on the respective films. It is possible to amorphize B4C melt droplets of submicrometer sizes. Solidification morphologies of micrometer-size droplets show dispersion of nanocrystallites of B4C in amorphous matrix within the droplets. We were unable to synthesize cubic carbon nitride using the current technique. However, the formation of nanocrystalline turbostratic carbo- and boron carbo-nitrides were possible by IBPLD on substrate at elevated temperature and not at room temperature. Turbostraticity relaxes the lattice spacings locally in the nanometric hexagonal graphite in C–N film deposited at 600 °C leading to large broadening of diffraction rings.

The hardnesses of electropolished, polycrystalline α-brass, and aluminum were measured as functions of load using Vickers microindentation, and Berkovich nanoindentation. Data were compared with literature data for silver, copper, and tungsten. In all cases, the hardness was observed to increase with decreasing size. Theories in the literature based on strain gradient plasticity and the addition of statistically stored and geometrically stored dislocation densities predict that the square of the hardness should increase linearly with inverse size of the indent. Our data and the literature data agree with this prediction over a limited range of indent diameters represented by microhardness and deep nanohardness data, whereas for the shallow nanohardness data, a second linear behavior is observed. The linear behavior of the microhardness and deep nanohardness data together with the second linear behavior generated by the shallow nanohardness data constituted what we designate a bilinear behavior. An algorithm is developed to calculate the induced shear stresses in a circular Volterra dislocation loop from a line integral of the Peach–Koehler equation using dislocation mechanics and isotropic elasticity. The computed induced shear stresses when plotted versus depth of indentation produced curves that exhibited a bilinear behavior identical to the bilinear behavior resulted from experiments, and the curves collapsed to a single curve for the different materials simulated.

Materials in nanocrystalline forms are well known to possess unusual and interesting properties when compared to the bulk conditions, and these open up an exciting range of novel applications. The key step involved in the systematic exploitation of nanocrystals for real applications lies in the development of reliable methods to synthesize nanocrystals of arbitrary chemical compositions in a range of crystal sizes. In particular, metallic alloy nanocrystals pose a special challenge. We demonstrate that nano-to-micro-sized crystals of intermetallic nickel–aluminide (Ni3Al) ranging from approximately 3 nm to over 100 nm in size can be synthesized by co-sputtering from elemental Ni and Al onto unheated, incompatible organic substrates, followed by controlled postdeposition heat treatment at mild temperatures. The crystal size of approximately 3 nm here is the smallest ever reported for monolithic ordered Ni3Al.

[Sm–Co (3x nm) /Co (x nm)]10 (x = 10, 7, 4) multilayered films have been prepared by magnetron rf-sputtering. It is found that the thickness of both hard and soft layers has important effects on phase transformation and magnetic interaction of films. With a fixed ratio of hard- to soft-layer thickness, decreasing simultaneously the thickness of these layers results in increasing coercivity. The effects of the external magnetic field during annealing depend on the Co-layer thickness (x value), mainly because of the formation of different main phases for different thickness of Co layer. For the films with x = 10 and 7, the main phase is Sm2Co17 after annealed. Applying a magnetic field during annealing promotes the crystallization of films, and therefore, it increases the coercivity of the films with x = 10 and 7. Magnetic interaction has been investigated by measuring δm and remanence magnetization. All the films show that although the exchange coupling favorable for magnetization is significant, the increase of the coercivity mainly originates from improving the pinning effects. Temperature dependence of the coercivity supports that the pinning of domain-walls constitutes a control mechanism of the coercivity. This behavior can be well understood in terms of the Gaunt’s approach of the coercivity.

Particulate composites of magnetostrictive Terfenol-D were prepared with polyamine and anhydride cured epoxy polymer matrices with the presence or the absence of a strong magnetic field. These composites were studied to investigate (i) the influence of magnetic field that is applied during specimen preparation in strain output levels, (ii) performance loss at high temperatures, and (iii) the influence of matrix material in magnetostrictive strain performance. A six-way comparison is made of materials processed under magnetic field with materials processed under no magnetic field, and magnetostrictive strain performance at glass transition finish temperature with magnetostrictive strain performance at glass transition start temperature, and magnetostrictive strain performance in low modulus matrix systems with magnetostrictive strain performance in high modulus matrix systems. A four-way comparison is also made between the micrographs for strain-cycled and non-strain-cycled samples and relative damage incurred by samples prepared using high and low modulus matrix systems.

Secondary mullite has been formed in 60 wt% kaolin–40 wt% Al2O3 ceramics by solution-precipitation in the glassy phase in contact with Al2O3 particle, showing a plate-like morphology, at temperatures above 1673 K. The lattice constant modification of secondary mullite has been determined: the lattice parameters of orthorhombic structure of a, b, and c axes decrease from 8.653, 8.770, and 3.167 Å to 7.958, 8.064, and 2.926 Å, respectively. The Al2O3 content in the secondary mullite crystals increases from 59.69 to 70.41 wt% when the grain width increases from 15 to 40 nm. Both the formation of secondary mullite and its grain growth are intimately related to the presence of the glassy phase originated from impurity (K2O) in the kaolin. Their locations as well as their chemical composition of mullite grains, Al2O3 grains, and glassy phase are provided by the meticulous experiments using high-resolution transmission electron microscopy, selected-area electron diffraction, and energy dispersive spectroscopy techniques.

The reduction mechanism of particle surface oxide films on Al–Mg alloy specimens sintered by the pulse electric current sintering (PECS) process was investigated via transmission electron microscopy, energy dispersive x-ray spectroscopy, and thermodynamic calculation. The reduction products were either MgAl2O4 or MgO or both, which is dependent on the sintering temperature and Mg content in Al–Mg alloy. Comparing the experimental temperature of the reduction products with that from thermodynamic calculation, it was suggested that the temperature at interfaces between particles was higher than that inside particles. This difference of temperature enhanced reduction of surface oxide films of Al–Mg alloy powders and hence accelerated the sintering in the PECS process.

Aluminum nitride thin films were deposited by multipulse KrF* (λ = 248 nm, τ∼450 fs) excimer laser ablation of AlN targets in low-pressure nitrogen. We investigated the morphology of the deposited films by scanning as well as transmission electron microscopy, as a function of laser fluence and ambient nitrogen pressure. The AlN films entirely consist of grains (clusters) with average diameters of a few tens of nanometers. In addition, particulates several hundreds of nanometers in diameter (spherical droplets) were observed on the surfaces of the deposited films. Besides these particulates, we noticed the presence of micrometer-size whiskers, or dendritic- and wave-like structures, consisting of agglomerates of nanoparticles. The particulates density decreases with the decrease of the laser fluence, or with the increase of the ambient nitrogen pressure, while their average size increases. This indicates that clustering is the dominant particulates formation mechanism, as a result of the enhanced number of collisions in the fs laser generated ablation plasma.