Europium-doped organic–inorganic hybrid low-melting phosphite glass was prepared from SnCl2, Me2SiCl2, and H3PO3 (phosphonic acid) through the nonaqueous acid–base reaction process. The europium-doped glass melted at 250 °C showed fluorescence with a broad peak at 373 nm due to the 4f6 5d1 → 4f7 transition of Eu2+ ions, whereas no fluorescence from the Eu3+ ions was observed. Almost all of the Eu3+ ions incorporated into the glasses could be successfully reduced to Eu2+ ions at a temperature as low as 250 °C by the strong reducing power of H3PO3.

The reaction mechanism between electroless Ni–P and Sn was investigated to understand the effects of Sn on solder reaction-assisted crystallization at low temperatures as well as self-crystallization of Ni–P at high temperatures. Ni3Sn4 starts to form in a solid-state reaction well before Sn melts. Heat of reaction for Ni3Sn4 was measured during the Ni–P and Sn reaction (241.2 J/g). It was found that the solder reaction not only promotes crystallization at low temperatures by forming Ni3P in the P-rich layer but also facilitates self-crystallization of Ni–P by reducing the transformation temperature and heat of crystallization. The presence of Sn reduces the self-crystallization temperature of Ni–P by about 10 °C. The heat of crystallization also decreases with an increased Sn thickness.

In this paper, we report a simple method for preparing p-type ZnO thin films by thermal oxidization of Zn3N2 thin films. The Zn3N2 films were grown on fused silica substrates by using plasma-enhanced chemical vapor deposition from a Zn(C2H5)2 and NH3 gas mixture. The Zn3N2 film with a cubic antibixbyite structure transformed to ZnO:N with a hexagonal structure as the annealing temperature reached 500 °C. When the annealing temperature reached 700 °C, a high-quality p-type ZnO film with a carrier density of 4.16 × 1017 cm−3 was obtained, for which the film showed a strong near-band-edge emission at 3.30 eV without deep-level emission, and the full width at half-maximum of the photoluminescence spectrum was 120 meV at room temperature. The origin of the ultraviolet band was the overlap of free exciton and the bound exciton. The N concentration was as high as 1021 cm−3, which could be controlled by adjusting the parameters of the annealing processes.

CeO2 films are technologically important as buffer layers for the integration of superconducting YBa2Cu3O7−δ films on {100}-biaxially textured Ni substrates, yielding a Ni–CeO2–YBa2Cu3O7−δ layer sequence. The Ni–CeO2 interface is a metal–oxide interface, and the misfit between substrate and film is about 9%. An epitaxial growth model was suggested for this system in the literature. The investigated films were deposited by a reactive thermal evaporation process at substrate temperatures of 650–670 °C with a thickness of 100 nm after deposition. The CeO2 films were characterized by plan-view and cross-section transmission electron microscopy, atomic force microscopy, and scanning electron microscopy. The CeO2 films had a strong {100} biaxial texture with a roughness of approximately 90 nm. No intermediate layer could be found by cross-section transmission electron microscopy at the Ni–CeO2 interface. The films had columnar grains with diameters of 20–50 nm, much smaller than the grain size of the Ni substrate, which was larger than 1 μm. Small-angle grain boundaries and small amounts of 〈111〉-oriented grains were evidenced in plan-view samples by diffraction patterns. The Moiré fringes technique was applied and was ideally suited to image the small rotations (≤3°) of the small CeO2 grains with respect to the Ni substrate. These small rotations of small grains showed that the growth was nonepitaxial, however, biaxially textured. In the CeO2 film samples, nanovoids 5–10 nm in size were observed and were mostly located close to the film surface. A model for the growth of CeO2 thin films on nickel substrates can be proposed on the basis of our results.

This work reports on the processes involved in the wear of hydroxyapatite sliding against slip-cast, glass-infiltrated alumina. Synthetic hydroxyapatite was used as a model material representing tooth enamel, while the alumina used was designed for tooth restorations. The wear tests were conducted in distilled water using a pin-on-disk tribometer under contact conditions that mimic the oral environment. To investigate the wear process for this material system, the surfaces of the hydroxyapatite “pin” and the alumina “disk” were examined by scanning electron microscopy and atomic force microscopy. Transmission electron microscopy was used to examine wear debris fragments collected from the hydroxyapatite wear scar and, for comparison, the bulk structure of the pin and crushed fragments from an unworn pin. Wear tracks on glass-infiltrated alumina showed only minor damage consisting of removal of glass from intergranular pockets in this material. In contrast, the hydroxyapatite wear surfaces were covered by an adhered debris layer, which obscured the rough, underlying surface. When dried, this adhered layer was found to contain both single-crystal and polycrystalline hydroxyapatite fragments, together with porous amorphous particulates, containing Ca, P, and O as major elements and Al and La as minor constituents. The composition of this amorphous wear product suggests a tribochemical reaction of hydroxyapatite and infiltrated alumina with water. The wear process, therefore, consists of material removal by fracture and deformation of the hydroxyapatite, followed by mixing of the crystalline fragments with the reaction products and the glass-infiltrate to form a uniform debris layer on the hydroxyapatite wear surface. The effects of this surface layer on wear are considered to include moderation of the local contact stresses and control of the immediate environment under which wear occurs. Our wear data, represented in terms of the wear factor, are found to be consistent with published data on the wear of tooth enamel sliding against different types of ceramic restorations.

Non-stoichiometric Zr-based alloys were prepared, and the corresponding electrochemical properties were characterized as hydride electrode alloys. The microstructure and chemical composition of non-stoichiometric Zr–Ti–Mn–V–Ni hydride electrode alloys were systematically investigated by x-ray Rietveld refinement, transmission electron microscopy (TEM), and energy dispersive spectroscopy under TEM observation. C14, C15 Laves phases and non-Laves phases were identified in Zr1−xTix(MnVNi)2.2 (x = 0, 0.2, 0.3, 0.4) alloys. Non-Laves phases in Zr1-xTix(MnVNi)2.2 (x = 0, 0.2, 0.3, 0.4) alloys are Ti–Zr–Ni phases related to the TiNi phase with pseudo-body-centered-cubic structure of the CsCl type. The evolution of crystallography and phase constitution for Ti–Zr–Ni non-Laves phases with different alloy composition was systematically studied. The influence of the Ti–Zr–Ni phases on the electrochemical properties of non-stoichiometric Zr1−xTix(MnVNi)2.2 alloys is briefly discussed.

Time-dependent suspension behavior is reported for nonoxide ceramic powders (Si3N4, SiC, and MoSi2) in ethanol. The suspension pH (and therefore the stability) changed with time. X-ray photoelectron spectroscopy, inert gas fusion, inductively coupled plasma, and high-resolution transmission electron microscopy were used to track changes of surface chemistry. The adsorption of the base, tetramethyl ammonium hydroxide (TMAH), is examined. The pH drop on powder addition to pure EtOH was used to gain insight into the role of TMAH coverage of the powder surfaces.

Near-threshold ultraviolet-laser (355 nm) ablation of 125-μm thick Kapton films was investigated in detail using x-ray photoelectron spectroscopy. Different from the irradiation at higher fluences, the contents of the oxygen, amide group, and C–O group on the ablated surface increased with an increase in the pulse number, whereas the carbon contents decreased, although the contents of the nitrogen and the carbonyl group (C = O) decreased slightly. This implied that there was no carbon-rich residue on the ablated surface. Near the ablation threshold, only photolysis of the C–N bond in the imide rings and the diaryl ether group (C–O) took place due to a low surface temperature rise, and the amide structure and many unstable free radical groups were created. Sequentially, the oxidation reaction occurred to stabilize the free radical groups. The decomposition and oxidation mechanism could explain the intriguing changes of the chemical composition and characteristics of the ablated surface. In addition, the content of the C–O group depended on the opposite factors: the thermally induced decomposition of the ether groups and the pyrolysis of the Caryl–C bond. Upon further irradiation, the cumulative heating may induce the breakage of the Caryl–C bond and enhance the oxidation reaction, resulting in an increase of the content of the C–O group.

Hafnium oxide thin films for use in a gate dielectric were deposited at 300 °C on p-type Si(100) substrates using a Hf[OC(CH3)3]4 precursor in the absence of oxygen by plasma-enhanced chemical vapor deposition. A comparison of films deposited in the absence and presence of oxygen indicated that oxygen was an important determinant in the electrical properties of HfO2 films, which were subsequently annealed in N2 and O2 ambients. The capacitance equivalent oxide thickness of the as-deposited Pt/HfO2/Si capacitor was approximately 17 Å and abruptly increased at an annealing temperature of 800 °C in both N2 and O2 ambients. The hysteresis of the as-deposited gate dielectric was quite small, about 40 mV, and that of the gate dielectric annealed at 800 °C in an O2 ambient was reduced to a negligible level, about 20 mV. The interface trap density of the Pt/HfO2/Si capacitors was approximately 1012 eV−1 cm−2 near the silicon midgap. The leakage current densities of the as-deposited Pt/HfO2/Si capacitor and those annealed at 800 °C in N2 and O2 were approximately 8 × 10−4, 8 × 10−5, and 3 × 10−7 A/cm2 at –1 V, respectively.

The effect of TiB2 on the densification behavior and properties of microwave-sintered AlN/TiB2 ceramic was investigated. The densification of the composite was significantly retarded in nitrogen atmosphere due to strong nitridation of TiB2 compared to sintering in argon atmosphere. The densities of the AlN/TiB2 composites containing different amounts of TiB2 all reached 99% of the theoretical density during 2 h of sintering at 1850 and 1900 °C. Microstructure analysis revealed that the TiB2 particles were dispersed in the AlN matrix while AlN grains retained its contiguity. This microstructure led to a composite with superior properties; thermal conductivity as high as 149 W/(m K) was achieved. The microwave sintered composites are harder and tougher than pure AlN. Microwave-sintered AlN/TiB2 composite is a promising material for structural applications in which high thermal conductivity and controlled dielectric loss are important.

A fatigue damage accumulation model based on the Paris law is proposed for strain-rate-sensitive polymer composite materials. A pre-exponent factor c2/f and strain-rate-sensitive exponent n are introduced. Numerical analysis of the model was performed using experimental data obtained in the literature. Both factors were found to enhance fatigue damage accumulation. The analysis also revealed that the extent of damage increases with decreasing frequency and that the damage rate is more sensitive to the applied maximum stress than to the stiffness of the material.

The effects of the precursor pH and sintering temperature on the synthesizing behavior and morphology of mullite were studied using a stoichiometric mullite (3Al2O3 · 2SiO2) precursor sol. The mullite precursor sol was prepared by the dissolution of aluminum nitrate enneahydrate [Al(NO3)3 · 9H2O] into the mixture of silica sol. The precursor pH of the sols was controlled to the acidic (pH ≈ 1.5 to 2), intermediate (pH ≈ 4.5 to 5) and basic (pH ≈ 8.5 to 9) conditions. The gels dried from the synthesized aluminosilicate sols were formed into a disk shape under 20 MPa pressure; then the green bodies were sintered for 3 h in the temperature range of 1100–1600 °C. The synthesizing temperature of mullite phase was found to be above 1200 °C for pH ≈ 1.5 to 2, and above 1300 °C for pH ≈ 4.5 to 5 and pH ≈ 8.5 to 9. The grain morphology of the synthesized mullite was changed to a rod shape for pH ≈ 1.5 to 2, and granulate shape for pH ≈ 4.5 to 5 and pH ≈ 8.5 to 9 with increasing sintering temperature. It was found that the morphology of mullite particle was predominantly governed by precursor pH and sintering temperature. However, at higher pH, the precursor pH and sintering temperature did not affect the synthesis behavior and grain morphology.

A series of coarse-grained BaTiO3 specimens with different dopant (Nb) concentrations were prepared by adjusting the oxygen partial pressure during sintering. They were again heat-treated in air, and the behavior of the grain boundary electrical properties with the increase of Nb concentration was investigated under the conditions of the same microstructure and heat treatment. The interface states of the grain boundaries were estimated using the grain boundary R (resistance) and C (capacitance) values at each temperature that were obtained from impedance analysis. An increase in the interface state density at certain energy levels with increasing Nb concentration was verified experimentally. One type of interface state was observed for specimens with low Nb concentrations and another for specimens with high Nb concentrations. It is proposed that the changes in the interface state with increasing Nb concentration are related to the transition of the compensating defect mode and differences in the extent of oxygen adsorption at the grain boundaries.

The corrosion behavior of the bulk glass-forming Mg65Y10Cu15Ag10 alloy was studied in neutral and weakly acidic media. Potentiodynamic polarization studies in cyclic and linear modes were carried out in electrolytes with a pH = 7, containing different anions. The alloy corroded freely in electrolytes with sulfate and pthalate ions, whereas passivity was observed in the electrolyte with borate ions. Further tests were performed in boric-acid-added borate buffer solution with pH = 7, 6, and 5. From Tafel characteristics, corrosion potentials and corrosion current densities were estimated. The data were compared with those of the ternary Mg65Y10Cu15 metallic glass. Potentiostatic anodic polarization tests were conducted on the Mg65Y10Cu15Ag10 alloy in boric-acid-added borate buffer solution with pH = 7 at two different potentials, 800 and 300 mV, saturated calomel electrode, which revealed different current transient characteristics. Auger electron spectroscopy was employed to characterize the anodically generated passive layers. The depth distributions of the elements as well as their chemical states were detected to be different for layers formed in electrolytes (i) with different pH values (8.4 and 7) of the same anion, (ii) with the same pH value but containing different anions (borate, sulfate, and pthalate), and (iii) with the same pH value and anion (borate) but at two different anodic potentials.

The phase stability of epitaxial KTaxNb1−xO3 (0 ≤ x ≤ 1) thin films, with compositions over the entire solid solution range, was investigated. KTaxNb1−xO3 thin films were deposited on (100) MgAl2O4 substrates by metalorganic chemical vapor deposition. Films with compositions x ≤ 0.30 were orthorhombic, as determined by x-ray diffraction. Dielectric measurements at room temperature indicated the presence of morphotropic phase boundaries at x = 0.30 and at x = 0.74. Temperature-dependent measurements of the dielectric constant for KNbO3 from 80 to 800 K indicated three structural phase transitions at 710, 520, and 240 K. For intermediate compositions, a decrease in the Curie and tetragonal–orthorhombic transition temperatures was observed with increasing Ta atomic percent, similar to the bulk phase equilibrium. In contrast to bulk materials, an increase in the orthorhombic–rhombohedral transition temperature with increasing x was observed for the films, resulting in the stabilization of a rhombohedral phase at room temperature for compositions 0.45 ≤ x ≤ 0.73. Differences between the phase stability for the thin films and bulk were attributed to lattice misfit strain.

Epitaxial thin films of PbZr0.52Ti0.48O3 (PZT) were synthesized successfully on SrRuO3/SrTiO3/MgO/TiN/Si heterostructures by pulsed laser deposition. The films were single phase and had (001) orientation. The deposition parameters were varied to obtain the best epitaxial layer for each of the compounds. Transmission electron microscopy indicated good epitaxy for the entire heterostructure and sharp interfaces between the epilayers. Dielectric and P–E hysteresis loop measurements were carried out with evaporated Ag electrodes. The dielectric constant for the films was found to be between 400–450. The value of saturation polarization Ps was between 55–60 μC/cm2, and the coercive field Ec varied from 60–70 kV/cm. Integration of PZT films with silicon will be useful for future memory and micromechanical devices.

Nanostructured gold/titania and gold/silica particles with up to 4 wt% Au were made by a single-step process in a spray flame reactor. Gold(III)-chloride hydrate and titania- or silica-based metalorganic precursors were mixed in a liquid fuel solution, keeping concentrations in the flame and overall combustion enthalpy constant. The powders were characterized by x-ray diffraction, transmission electron microscopy, Brunauer–Emmett–Teller, and ultraviolet–visible analysis. The titania or silica specific surface area and the crystalline structure of titania were not affected by the presence of gold in the flame. Furthermore the size of the gold deposits was independent of the metal oxide support (TiO2 or SiO2) and its specific surface area (100 and 320 m2/g, respectively). The gold nanoparticles were nonagglomerated, spherical, mostly single crystalline, and well dispersed on the metal oxide support. Depending on the Au weight fraction (1, 2, and 4 wt%) the Au nanoparticles' mass mean diameter was 3, 7, and 15 nm, respectively, on both titania and silica. The particles showed surface plasmon absorption bands in the ultraviolet–visible region, which is typical for nano-sized gold. This absorption band was red shifted in the case of the titania support, while no shift occurred with the silica support.

Combustion of the thermite system is a promising approach for synthesis of alloys (e.g., Co-based) that are widely used in orthopedic applications. This process typically involves formation of two liquids (oxide and metal alloy), followed by their phase separation. The latter is generally believed to be controlled solely by gravity-driven buoyancy. To verify this hypothesis, a fundamental study of phase separation during alloy synthesis was conducted in both normal gravity and microgravity conditions. It was shown that a non-gravity-driven mechanism primarily controls the segregation process. Quenching experiments identified the reaction and phase separation mechanisms in the investigated systems.

Physical properties of a-Si:C:H films, including composition, optical constants, microhardness, and surface energy, were investigated. A factorial experimental design was employed to establish the effects of plasma-assisted chemical vapor deposition parameters on the physical properties of the films. The dynamics of the plasma deposition process are discussed in relation to the interactions observed among the process variables and the effects of the variables on the physical properties of the films.

A model is developed that describes the sharp indentation behavior of time-dependent materials. The model constitutive equation is constructed from a series of quadratic mechanical elements, with independent viscous (dashpot), elastic (spring), and plastic (slider) responses. Solutions to this equation describe features observed under load-controlled indentation of polymers, including creep, negative unloading tangents, and loading-rate dependence. The model describes a full range of viscous–elastic–plastic responses and includes as bounding behaviors time-independent elastic–plastic indentation (appropriate to metals and ceramics) and time-dependent viscous–elastic indentation (appropriate to elastomers). Experimental indentation traces for a range of olymers with different material properties (elastic modulus, hardness, viscosity) are econvoluted and ranked by calculated time constant. Material properties for these polymers, deconvoluted from single load–unload cycles, are used to predict the indentation load–displacement behavior at loading rates three times slower and faster, as well as the steady-state creep rate under fixed load.