The possibility of localized doping by Er3+ diffusion at moderate (less than 500 °C) temperature was for the first time demonstrated for sapphire single crystal wafers. The doping was achieved by immersing the substrate wafers into reaction melt containing small amounts of erbium salt. The crucial point of the presented technology was a crystallographic orientation of the used wafers. The most suitable orientation of the cuts was the “X-cut” with orientation (11–20). The strong anisotropy of the moderate temperature Er3+ doping into lithium niobate and sapphire was explained on the basis of the crystal structure of particular cuts.

Blue photoluminescent emission was observed in pure nanometer-sized γ–Al2O3 powders prepared by the sol-gel process, with aluminum alkoxide as the precursor. The photoluminescent excitation spectrum detected at »em = 422 nm showed four peaks located at 238, 255, 278.5, and 348.5 nm, respectively, the first having the strongest intensity. The photoluminescent emission spectra were made up of a broad band with four peaks located at 404.5, 422, 447, and 484.5 nm. The emission band of 422 nm had the intensity. We suggest that the defect level in the nanometer alumina powder also is the main reason for the appearance of new luminescent emission bands.

Well-crystallized Ba2Zn2Fe12O22 (Zn2–Y) films with high c-axis oritentation were successfully formed on Ag substrates at low temperature by the polymeric precursor method. A precursor solution with stoichiometric Ba2+, Zn2+, and Fe3+ ions was deposited on the substrates by a dip-coating. The films were then heat-treated at temperatures ranging from 700 to 900 °C. The crystallization process of c-axis-oriented Zn2–Y films occurred at the considerably low temperature of 750 °C, though a small amount of spinel oxides contaminated them. The films had hexagonal grain structures which were developed by increasing the heat-treatment temperature. Magnetization curves of the Zn2–Y film heated at 900 °C clearly indicated that the film had large in-plane magnetic anisotropy and had small in-plane coercivity.

Hydrogen-free diamondlike carbon films were prepared on Si(100) with electron cyclotron wave-resonance plasma, which serves to sputter the graphite target and to simultaneously bombard the growing surface. Direct penetration of postionized carbon atoms (up to 140 eV) in addition to the momentum transfer from Ar plasma facilities the formation of the Ta–C structure. Surface morphology, mechanical, and optical properties of the deposits were examined with respect to the ion energy. Atomic force microscope images revealed island morphology in deposits with a typical root-mean-square roughness of 20 nm. A maximum content of about 70% for the fourfold-bonded structure was estimated from the Raman profiles, giving rise to a micro hardness of 60 ± 5 GPa.

Yttrium iron garnet (YIG) powder has been synthesized in just less than 10 min in a multimode microwave oven operating at 2.45 GHz. The simple solid-state synthesis involves an anisothermal reaction between a highly microwave absorbing Fe3O4 and a low microwave absorbing Y2O3 at temperatures of 1300 °C. The rapidity of the YIG formation suggests that the reaction rate is possibly enhanced by several times in a microwave field.

Effects of Ba filling fraction and Ni content on the thermoelectric properties of n-type BayNixCo4−xSb12 (x = 0−0.1, y = 0−0.4) were investigated at temperature range of 300 to 900 K. Thermal conductivity decreased with increasing Ba filling fraction and temperature. When y was fixed at 0.3, thermal conductivity decreased with increasing Ni content and reached a minimum value at about x = 0.05. Lattice thermal conductivity decreased with increasing Ni content, monotonously (y ≤ 0.1). Electron concentration and electrical conductivity increased with increasing Ba filling fraction and Ni content. Seebeck coefficient increased with increasing temperature and decreased with increasing Ba filling fraction and Ni content. The maximum ZT value of 1.25 was obtained at about 900 K for n-type Ba0.3Ni0.05Co3.95Sb12.

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.

Polycrystalline aluminas sintered with 10 wt% additions of calcium oxide (CaO) and silica (SiO2) in varying molar ratios were fabricated via precipitation, calcination, and hot pressing. Alumina microstructures were analyzed by scanning electron microscopy in terms of their mean grain size, grain size distribution, and grain aspect ratios. High-resolution transmission electron microscopy (HRTEM) showed the presence of an amorphous intergranular glassy phase at two- and three-grain boundaries. The intergranular film width at two-grain boundaries, determined by HRTEM, appeared to vary with the [CaO]:[SiO2] ratio of the additive as did the chemical composition and local chemistry, determined by high-resolution analytical transmission electron microscopy and scanning transmission electron microscopy (using both energy dispersive x-ray and electron energy loss spectroscopy). The factors influencing the erosive wear rate are discussed including the chemistry and associated fracture energy of the intergranular glassy film. Wet erosive wear rates of the densified materials were determined and had a strong dependence on the [CaO]:[SiO2] ratio in the additive.

An Al–Cu–Fe partial phase diagram involving the icosahedral quasicrystal has been constructed along an Al62.5Cu37.5−xFex (x = 2.5 to 25 at.%) isopleth. The icosahedral quasicrystal forms at 850 °C via a peritectic reaction between a liquid and (Al,Cu) 13Fe4 phase and coexists with a liquid phase at temperature below the peritectic reaction. The icosahedral quasicrystal crystallizes as a primary phase in the temperature range of 760 to 850 °C from alloys surrounded by composition points of Al–Cu–Fe: 62.5–33–4.5, 62.5–34.5–3, 57.5–39.5–3 and 57.5–38.0–4.5 at.%. On the basis of the phase diagram, single grains of the Al–Cu–Fe icosahedral quasicrystal with a maximum size of 5 mm were successfully grown from Al–Cu–Fe melts.

Copper-doped LiNbO3 layers prepared by an Cu–Li ion-exchange process are characterized by electronic paramagnetic resonance. It is found that the majority of Cu2+ ions are coupled by strong exchange interactions which is characteristic of short distances between paramagnetic ions. Such ions are accumulated in a thin layer near the crystal surface and can enter in new crystalline phases formed as a result of the Cu–Li ion exchange. A small amount of Cu2+ ions is incorporated into weakly distorted LiNbO3 crystal lattice inside the diffusion layer.

Cross sections through nanoindents on Si, Ge, and GaAs {001} were examined through transmission electron microscopy. A focused ion beam workstation was used to machine electron transparent windows through the indents. In both Si and Ge there was a transformed zone immediately under the indent composed of amorphous material and a mixture of face-centered-cubic and body-centered cubic crystals. Cracking and dislocation generation were also observed around the transformed zone. In GaAs the dominant deformation mechanism was twinning on the {11} planes. The hardness of these materials is discussed in light of these observations and their macroscopic material properties such as phase transformation pressure.

Specimens of 1045 steel with quenched crack were treated under electropulsing. Scanning electron microscopy was employed to examine the change of specimens before and after the treatment. The results showed that the crack can be healed under electropulsing without melting, and the healing could be produced within a very short time. The original microstructure of specimens was not changed during the healing. It is thought that the temperature and the transient thermal compressive stress caused by high-rate heating are the main factors causing the healing of the crack.

Pt electrodes with a 6–8-μm thickness were produced on alumina substrates by a double-print Pt screen-printing process that included a sequential heat treatment at 600 °C and 1300 °C. This process improved the final sintered double-print film because the first printed layer acted as a sintering template for the second printed layer. The sintered Pt films have a 95% coverage of the alumina surface, 92% density, 0.73-μm average surface roughness, and 16.10−5 Ω cm resistivity. The sintering behavior of Pt films exhibited three stages of densification: Stage I (T °C < 700 °C), exhibiting neck growth, and Stage II (700 < T °C < 1300 °C), exhibiting grain growth, have activation energies of 64 kJ/mol and 125 kJ/mol, respectively. Stage III exhibits a decrease in shrinkage due to Pt coalescence and island formation. The transition temperature, 700 °C, between Stages I and II corresponds to an anomalous increase in surface roughness and resistivity. The thickness of Pt films was a critical parameter for achieving alumina surface coverage. Uniaxial pressing of dried Pt films increased densification and reduced the surface roughness of double-print Pt films.

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.

Using a pure α–SiC starting powder and an oxynitride glass composition from the Y–Mg–Si–Al–O–N system as a sintering additive, a powder mixture was hot-pressed at 1850 °C for 1 h under a pressure of 20 MPa and further annealed at 2000 °C for 4 h in a nitrogen atmosphere of 0.1 MPa. High-resolution electron microscopy and x-ray diffraction studies confirmed that a small amount of β–SiC was observed in the liquid-phase-sintered α–SiC with this oxynitride glass, indicating stability of β–SiC even at high annealing temperature, due to the nitrogen-containing liquid phase.

The inelastic deformation of nacre that leads to its structural robustness has been characterized in a recent experimental study. This article develops a model for the inelastic behavior, measured in tension, along the axis of the aragonite plates. The model is based on observations for abalone nacre that the inelasticity is associated with periodic dilatation bands. These bands contain coordinated separations at the periphery of the plates. The separations open as the material strains. The response is attributed to nanoscale asperities on the surfaces of the plates. The model calculates the stresses needed to displace the plates, resisted by elastic contacts at the asperities. The results are compared with the measured stress/strain curves.

It is shown that to analyze the load versus displacement data obtained from a nanoindentation experiment on a flat surface, it is incorrect to use the so called “reduced modulus,” which includes the elastic properties of both the indenter and the test solid. It is suggested that, until correct analytical solutions become available, the indenter should always be of a much stiffer material than the test solid and it should be approximated to a rigid indenter in the analysis. Furthermore, when the indenter and the test surface are of comparable elastic moduli, the measured indenter displacement is the distance of mutual approach of the two contacting bodies rather than the penetration of the indenter below the original surface of the test solid.

A novel and fast microwave route is described for the synthesis of yttrium aluminum garnet (YAG) and for its sintering to translucent bodies. Precursor was made by microwave decomposition (20 min) of aluminum tri-sec-butoxide and yttrium nitrate dissolved in ethyl acetate. The precursor, conventionally calcined at 1000 °C (1 h), was sintered in microwave using SiC as secondary heater for just 35 min. Resulting translucent YAG has a microhardness (HV) of 18.1 GPa and fracture toughness (KIC) of 4.3 MPa m1/2. A 0.86-mm-thick sintered pellet exhibits approximately 45% transmission for 520-nm radiation. The entire microwave process requires less than 3 h.

A magnesium (Mg) solid solution with a long periodic hexagonal structure was found in a Mg97Zn1Y2 (at.%) alloy in a bulk form prepared by warm extrusion of atomized powders at 573 K. The novel structure has an ABACAB-type six layered packing with lattice parameters of a = 0.322 nm and c = 3 × 0.521 nm. The Mg solid solution has fine grain sizes of 100 to 150 nm and contains 0.78 at.% Zn and 1.82 at.% Y. In addition, cubic Mg24Y5 particles with a size of about 7 nm are dispersed at small volume fractions of less than 10% in the Mg matrix. The specific density (ρ) of the extruded bulk Mg–Zn–Y alloy was 1.84 Mg/m3. The tensile yield strength (σy) and elongation (δ) are 610 MPa and 5%, respectively, at room temperature, and the specific yield strength defined by the ratio of σy to ρ is as high as 3.3 × 105 Nm/kg. High σy values exceeding 400 MPa are also maintained at temperatures up to 473 K. It is noticed that the σy levels are 2.5 to 5 times higher than those for conventional high-strength type Mg-based alloys. The Mg-based alloy also exhibits a high-strain-rate superplasticity with large δ of 700 to 800% at high strain rates of 0.1 to 0.2 s−1 and 623 K. The excellent mechanical properties are due to the combination of the fine grain size, new long periodic hexagonal solid solution containing Y and Zn, and dispersion of fine Mg24Y5 particles. The new Mg-based alloy is expected to be used in many fields.

The thermodynamic stability of tetragonal (t-) ZrO2 nanocrystallites below the bulk stability temperature 1200 °C was studied through specially synthesized crystallites that exhibited an extremely slow coarsening rate. The nanocrystallites were mechanically transformed to the monoclinic (m-) structure, and, because the crystallite size was kept below approximately 20 nm, the t-structure was completely recovered solely by thermal treatments between 900 and 1100 °C. These results gave strong evidence to the notion that, for sufficiently small crystallite size, nanocrystalline t-ZrO2 is not just kinetically metastable but can be truly thermodynamically more stable than the mpolymorph in air below 1200 °C.