ZnS:Mn2+ phosphors were synthesized by a modified solid-state reaction method. In the synthesis method, a sealed vessel is used, where heat and pressure are simultaneously utilized. The effects of various synthesis conditions such as temperature, Mn concentration, and pressure on the cathodoluminescence (CL) were investigated. Among them, pressure had an effect on CL property as much as others. It was observed that CL intensities of ZnS:Mn2+ phosphors increased with the increase of pressure and the best sample showed higher intensity than that of a commercial one by 180%. X-ray diffraction (XRD) and electron paramagnetic-resonance (EPR) were used to understand the enhancement. No change of XRD patterns was observed but the full width at half-maximum (FWHM) of the most intense cubic (111) peak of ZnS:Mn2+ decreased with the increase of pressure. EPR signal intensity of Mn2+ increased with the increase of pressure. The improved crystallinity and more substitution of Zn2+ with Mn metal were believed to be responsible for the enhancement.

Magnesium hydroxide nanoneedles and nanorods were synthesized by reverse precipitation in the presence of polyethylene glycol (MW 1000) at ambient temperature. The obtained magnesium hydroxide crystals were characterized in terms of morphology, particle size, crystal structure, and thermal stability by high-resolution transmission electron microscopy, x-ray diffraction, infrared spectroscopy, and thermogravimetric and differential thermal analysis. The experimental results show that the growth of magnesium hydroxide crystals and the dispersivity of the nanostructures were greatly influenced by polymer dispersant. The mechanism of the formation of magnesium hydroxide nanorods and nanoneedles was also proposed.

Taking Au as an example, we have investigated the epitaxial bain paths of 〈001〉 oriented face-centered-cubic metal nanowires. It demonstrates that there are one stable and one metastable phase, having the lattice constant ratio c/a of about 0.6 and 1.0, respectively. Even without any external stimuli, the surface-tension-induced intrinsic stress in the interior may drive the nanowires to phase transform spontaneously for surface-energy minimization. However, this structural transition depends on the feature sizes of the nanowires. Specifically, only when the cross-section areas are reduced to 4.147 nm2 or so can the surface energy and the intrinsic stress satisfy the thermodynamic and kinetic conditions simultaneously.

In this study, we investigated mechanical deformation-induced Sn whisker growth, which is frequently encountered in advanced flexible substrate packaging. Concentrated compressive stresses are introduced around the leads and solder surface finish joints connected by compression fixing. Six types of pure Sn thin films were electroplated on Ni-protected Cu substrates. These were 2- and 6-μm-thick Sn films electroplated with three different current densities: 2, 10, and 20 A/dm2. These films were compressed at room temperature and ambient humidity. The surface and cross-sectional grain morphologies of the films were examined by scanning electron microscopy and focused ion beam spectroscopy, respectively. The grain orientations of the electroplated Sn films were analyzed by x-ray diffraction and electron backscatter diffraction. After compression, nodule hillocks and whiskers were found around the indents. Beneath the indents, the original columnar Sn grains were deformed, and recovery and recrystallization processes occurred. Rapid whisker formation was observed. The whiskers induced by mechanical deformation are closely related to the grain microstructures, and the initial compression stresses are critical to the types and distribution of whiskers as well.

A transmission electron microscopy (TEM) study has been carried out to uncover how dislocations and twins accommodate large plastic strains and accumulate in very small nanocrystalline Ni grains during low-temperature deformation. We illustrate dislocation patterns that suggest preferential deformation and nonuniform defect storage inside the nanocrystalline grain. Dislocations are present in individual and dipole configurations. Most dislocations are of the 60° type and pile up on (111) slip planes. Various deformation responses, in the forms of dislocations and twinning, may simultaneously occur inside a nanocrystalline grain. Evidence for twin boundary migration has been obtained. The rearrangement and organization of dislocations, sometimes interacting with the twins, lead to the formation of subgrain boundaries, subdividing the nanograin into mosaic domain structures. The observation of strain (deformation)-induced refinement contrasts with the recently reported stress-assisted grain growth in nanocrystalline metals and has implications for understanding the stability and deformation behavior of these highly nonequilibrium materials.

Hafnium silicon oxynitride (HfSiON) films were deposited on 200-mm silicon substrates by low-pressure chemical vapor deposition (LPCVD) from a combination of trisilylamine (TSA) and tetrakis(diethylamido)hafnium(IV) (TDEAH) in the temperature range 450 to 575 °C. A highly volatile and carbon-free silicon precursor TSA was used to deposit HfSiON films for the first time. HfSiON films were deposited in a single step with no need of a post-treatment process for nitrogen incorporation. The film composition was tuned in a wide compositional range, and high growth rates were achieved. NH3 was found to have profound effects on film growth rate, metal ratio (Si% or Hf%), nitrogen incorporation, and carbon residue in the films.

The effect of temperature on grinding-induced texture in tetragonal lead zirconate titanate (PZT) and lead titanate (PT) has been investigated using in situ x-ray diffraction (XRD) with an area detector. In contrast with previous results on electrical poling, mechanically-ground PT and soft PZT materials retain strong ferroelastic textures during thermal cycling, even after excursions to temperatures slightly above the Curie temperature. The relationship between the residual stresses in the surface region, caused by grinding, and those resulting from domain wall motion is elucidated by in situ texture measurements obtained during thermal cycling.

The goal of this work was to improve the strength of sintered zirconia (3 mol% yttria stabilized) by surface treatment, using a low expansion glass (Mg3Al2Si6O18) at high temperature. The room-temperature strength was increased by about 42% when the glass was penetrated for 30 min. There was a drastic increase in the Weibull modulus. However, the longer holding time led to grain coarsening and the excess glass deteriorated the strength. The magnitude of the strength increment was on the order of surface stress measured experimentally and thermo-elastic stress predicted theoretically. A significant contribution of phase transformation of zirconia from tetragonal to monoclinic phase on the residual stress was also found. Furthermore, compared to the as-sintered zirconia, the glass-treated sample (penetrated for 30 min) exhibited relatively higher strength at elevated temperature (750 °C) and also showed a significant improvement in the thermal shock resistance behavior.

Sputtered amorphous Ge4Sb1Te5, Ge1Sb2Te4, Ge2Sb2Te5, and Ag0.055In0.065Sb0.59Te0.29 thin films were studied by differential scanning calorimetry. Upon continuous heating, heat release due to structural relaxation of the amorphous phase between 0.5 and 1.0 kJ/mol was observed. This value depends on the thermal history of the sample. Preannealing of the amorphous phase revealed the glass transition temperature Tg within 10 K of the crystallization temperature upon continuous heating at 40 K/min.

The ultrafine titanium carbonitride particles (TiC0.5N0.5) with 100 nm in mean size was successfully synthesized by nitridation treatment at ordinary temperatures, 1373∼1473 K of the nanostructured half-stoichiometric titanium carbide (TiC0.5) particles, which were produced by the magnesium reduction of gaseous TiCl4+1/4C2Cl4. In addition, the nitrogen stability for the produced titanium carbonitride particles at various temperatures and vacuum conditions was investigated experimentally and compared with values calculated by an ideal solution model.

Similar to metals, the hardness of many polymers increases with decreasing indentation depths at depth ranges from several microns down to several nanometers. While for metals such phenomena are commonly attributed to geometrically necessary dislocation densities, such an explanation cannot be applied to polymers. To provide a micromechanically motivated model for the indentation size effect in polymers, here we propose an elasto-plastic extension of the higher order elasticity model recently developed by the authors. In this model, size effects in polymers (as well as in nematic liquid crystals) are related to Frank elasticity arising from bending distortions of the polymer chains and their interactions. On the basis of this theory, we derive a simple model for indentation size effects in polymers. Unlike other models, our model includes only elastic size effects due to rotational gradients. It is shown that the proposed model can explain the experimentally observed size effects in polymers. Together with the existing experimental data mentioned here, new experimental data for silicon rubber are also presented and discussed.

Monodisperse ligand-capped cubic wüstite FexO nanocrystals were prepared by a novel thermal decomposition method of iron (II) acetate in the presence of oleic acid as the surfactant. Controlled size distributions of cubic nanoparticles possessing the rock salt crystal structure were isolated in the range 10–18 nm. The influence of molar ratio of surfactant to precursor was investigated to understand size control and monodispersity. Using inexpensive, nontoxic metal salts as reactants, we were able to synthesize gram-scale quantities of relatively monodisperse nanocrystals in a single reaction, without further size selection, characterized by x-ray diffraction and transmission electron microscopy. The procedure enables the collection of samples of uniform size as a function of time, thus permitting a preliminary solid-state kinetic analysis of the reaction as a function of increasing particle size. Following controlled evaporation from nonpolar solvents, self-assembly into two-dimensional arrays, three-dimensional single-component superlattices, and binary superlattices with gold nanoparticles were observed and characterized.

CeO2–ZrO2–γ-Al2O3 mixed oxides with different molar compositions have been synthesized by the sol-gel method using nitrate–alkoxide precursors. Some relationships between the molar composition of the ternary systems and their textural and structural properties are presented. CeO2–ZrO2–γ-Al2O3 mixed oxides have been studied and characterized using x-ray diffraction, transmission electron microscopy, and Raman spectroscopic analyses. By complete porosity analyses of all samples before and after hydrothermal (up to 75% steam) treatment at 500 °C, we have been able to optimize a highly hydrothermally stable CeO2–ZrO2–γ-Al2O3 system with a molar ratio of 10:10:80 mol%. γ-Al2O3 alone and CeO2-doped as well as ZrO2-doped γ-Al2O3 were also investigated by the hydrothermal treatment, and their steam-sensitive properties have been compared with those of the ternary CeO2–ZrO2–γ-Al2O3 system.

Static and dynamic Vickers indentations were performed on ZrHf-based bulk amorphous alloys. A decrease in indentation hardness was observed at higher strain rates compared with static indentation hardness. For equivalent loads, dynamic indentations produced more severe deformation features on the loading surface than static indentations. Using bonded interface technique, the induced shear band patterns beneath the indentations were studied. In static indentations, the majority of the deformation was primarily accommodated by closely spaced semicircular shear bands surrounding the indentation. In dynamic indentations two sets of widely spaced semicircular shear bands with two different curvatures were observed. The observed shear band patterns and softening in hardness were rationalized based on the variations in the confinement pressure, strain rate, and temperature within the indentation region during dynamic indentations. It is also proposed that free volume migration and formation of nano-voids leading to cracking are favored due to adiabatic heating and consequently cause the observed softening at high strain rates.

Suspension plasma spraying was used to synthesize Y2O3 nanoparticles. The Y2O3 starting material was first dispersed in a solvent to form a suspension and then injected axially into the plume of an inductive radio frequency plasma. It was found that the as-sprayed Y2O3 particles had a size distribution from nano to micron scale and various morphological features, which varied with processing conditions as well as solvent and plasma gas type. In comparison with water, organic solvents led to a higher productivity and smaller particle size, whereas water introduced impurities such as Y2O2C2, which is isotypic to La2O2C2. Introduction of oxygen as an auxiliary plasma gas was an effective way to eliminate this impurity. In addition, complete combustion of the organic solvent and recombination of oxygen atoms above 4000 K also elevated the heat treatment degree of Y2O3. As a result, application of O2 with an organic solvent resulted in an even smaller mean particle size and narrower size distribution.

The intercolumnar fracture strength of a columnar TiN film was deconvoluted by nanoindentation load-displacement curves. The columnar boundary strength of such films strongly depends on the amount of residual stress present in the film. The residual stress of the coating was modified by plastically stretching the substrate. Indentation studies on the columnar TiN coating as a function of residual stress reveals that the column sliding stress diminishes with residual stress, suggesting that the presence of a high compressive stress substantially improves the fracture strength of a columnar TiN film. True film hardness on the other hand does not change.

This study explored the effects of substrate surface pretreatments on the nucleation and growth of metal–organic chemical vapor deposited ruthenium. In situ plasma (dry), featuring O2, Ar, and H2/Ar chemistries, and ex situ (wet) treatments, consisting of a standard RCA bath, were examined in the nucleation and growth of up to 50-nm-thick metallic Ru films on SiO2 and Hf–silicate surfaces. The resulting surface morphology, grain size, and roughness of the metallic films were examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM), while Rutherford backscattering spectrometry (RBS) was used for compositional measurements. It was determined that an in situ plasma treatment using a H2/Ar yielded metallic Ru films with the highest nucleation density, smallest grain size, and lowest resistivity. Film buckling was also observed for the Ru films deposited on H2/Ar pretreated surfaces. The behavior was attributed to the presence of compressive strain. The films deposited on RCA-cleaned and Ar plasma treated surfaces exhibited very similar physical and electrical characteristics to the films grown on untreated substrates. Alternatively, the use of O2 plasma surface treatment adversely affected Ru nucleation on the SiO2 surface. Relevant mechanisms for Ru nucleation and growth on SiO2 and Hf–silicate nontreated surfaces are discussed in the context of the various predeposition dry and wet treatments.

Biomorphic SiO2 fibers were synthesized with cotton tissue as the template and with cetyltrimethylammonium bromide (CTAB) as surfactant through a surface sol-gel process. The as-prepared samples retain well the original morphology of cotton and show a uniform and large amount of nanopores. Sliver nanoparticles were successfully incorporated into the nanopores through impregnation and chemical reduction to form SiO2/Ag composite fibers. Ag nanoparticles with mean diameter approximately 3 nm have a size distribution in accordance with the nanoporosity of SiO2 matrix. Such composite fibers show prominent surface plasma resonance (SPR) effect, and during heat treatment under increasing temperatures, the SPR intensity is enhanced because of the size effect, and the SPR position undergoes a redshift first and then a blueshift.

The structure of a region of a highly Al-rich mullite (Al4+2xSi2–2xO10–x with x ∼ 0.82; 47Al2O3-6SiO2; Al/Si ∼16) in a chemically vapor-deposited, functionally graded mullite coating was studied by high-resolution transmission electron microscopy. The region consisted of a fully ordered and twinned multidomain structure. Within each domain, well-ordered oxygen vacancies resulted in antiphase boundaries (APBs) characterized by a shift vector of [001]. The APBs were oriented parallel to (601) and (601). Along [001], the structure consisted of alternating layers of (601)- and (601)-domains with a spacing of 17d601, separated by (001) twinning planes. The (001) twinning did not generate any additional spots in the [010] mullite diffraction pattern. The lattice parameters of this ultrahigh Al-rich mullite phase were calculated from selected-area electron-diffraction patterns to be: a = 0.762 nm; b = 0.754 nm; and c = 0.291 nm.

We synthesized bulk amorphous alloy systems of Cu43Zr43Al7X7 (X = Be, Ag; numbers indicate at.%), with the objective of simultaneously enhancing the glass-forming ability (GFA) and the plasticity. The alloys not only exhibit high plasticity (∼7%, ∼8%), but also possess enhanced GFA (alloys with 12 and 8 mm diameter). The possible mechanisms underlying this enhanced GFA and plasticity exhibited by these alloys are discussed based on the atomic-packing state and atomistic-scale compositional separation associated with the mixing enthalpy difference. A strategy for designing bulk amorphous alloys with simultaneous improvement in the GFA and the plasticity is proposed from the viewpoint of atomic-packing state and atomistic-scale phase separation.