Ce3+-activated lanthanide silicon oxynitride (La5Si3O12N, La4SiO7N2, LaSiO2N, and La3Si8O4N11) phosphors were prepared by firing the mixture of La2O3, Si3N4, SiO2, and CeO2 at 1500–1600 °C under a 0.5 MPa nitrogen atmosphere. Diffuse reflection spectrum, photoluminescence spectra, and temperature-dependent luminescence of these phosphors are presented in this work. A blue emission of Ce3+ in all lanthanide silicon oxynitrides was observed under ultraviolet irradiation, which is strongest in La3Si8O4N11:Ce3+. The concentration quenching and thermal quenching of the samples were discussed.

Optimization of the carrier concentration is a key to improve the power factor of thermoelectricity. The carrier concentration of sintered zinc oxides was primarily controlled by impurity doping of aluminum and secondarily adjusted by defect concentration by varying the oxygen partial pressure in the range of 101 to 104 Pa. The resultant carrier concentration measured at room temperature ranged from 1 to 1.8 × 1020 cm−3, which drastically modified the thermoelectricity. The Jonker plot of the measured Seebeck coefficient and conductivity revealed deviation of the slope from k/e (where k is the Boltzmann constant and e is the elemental electric charge), which was attributed to a mobility variation with respect to the carrier concentration. The approach to estimating the optimum conductivity taking into account mobility variation is discussed. Finally, the optimum conductivity is estimated to be 1800 to 2000 S/cm for high-temperature operation (500 to 800 °C).

A nanocrystalline surface layer of a Cu–Zn alloy was developed by electropulsing (ECP) surface treatment. The average grain size was about 20 nm on the top surface layer and was gradually augmented with the increase in depth from the top surface. Nanoindentation measurements showed that the hardness was significantly enhanced on the top surface layer compared with the as-annealed Cu–Zn sample. The mechanism for the evolution of this structure and property was related not only to a solid-state phase transformation, but also to the effect of the enhancement of the nucleation rate and the skin effect during the ECP treatment. Therefore, the ECP surface treatment provides a promising method for obtaining surface self-nanocrystallization materials.

Infrared (IR) luminescence covering 1.1 to ∼1.6 μm wavelength region was observed from bismuth-doped barium silicate glasses, excited by a laser diode at 808 nm wavelength region, at room temperature. The peak of the IR luminescence appears at 1325 nm. A full width half-maximum (FWHM) and the lifetime of the fluorescence is more than 200 nm and 400 μs, respectively. The fluorescence intensity increases with Al2O3 content, but decreases with BaO content. We suggest that the IR luminescence should be ascribed to the low valence state of bismuth Bi2+ or Bi+, and Al3+ ions play an indirect dispersing role for the infrared luminescent centers.

Polymer-derived ceramics have shown promise as a novel way to process low-dimensional ceramics such as environmental barrier coatings. Composite coatings have been developed as oxidation and carburization barriers on steel using poly(hydridomethylsiloxane) matrix and titanium disilicide as reactive fillers. A systematic study of the phase transformations and microstructural changes in the coatings and their components during pyrolysis in air is presented here. The system evolves from an amorphous polymer filled with a binary metal at room temperature to an inorganic amorphous network of oxidized silicon and titanium at the target temperature of 800 °C. Crystallization of the composite occurs at higher temperatures to reach cristobalite and rutile by 1600 °C. The polymer-to-ceramic conversion occurs between 200 and 600 °C. The oxidation of the expansion agent and the densification of the composite take place between 300 and 800 °C.

(Ni,Zn)Fe2O4 particle/organic hybrid was synthesized in situ from metalorganics below 100 °C. A mixture of nickel (II) acetylacetonate (NA), zinc acetylacetonate (ZA), and iron (III) 3-allylacetylacetonate (IAA) was hydrolyzed and polymerized yielding a spinel oxide particle/organic hybrid. X-ray diffraction analysis revealed that the crystallinity of spinel particles was dependent upon the hydrolysis conditions of NA-ZA-IAA. Nanocrystalline nickel zinc ferrite particles below 5 nm were uniformly dispersed in the organic matrix. The magnetization of hybrid increased with an increasing amount of water for hydrolysis. Nano-sized nickel zinc ferrite particle/organic hybrid showed a magnetization-applied field (BH) curve with no remanence above 40 K. The magnetization versus H/T curves from 40 to 100 K were superimposed on the same curve and satisfied the Langevin equation. The remanent magnetization and coercive field of the hybrid were 7.2 emu/g and 150 Oe, respectively, at 4.2 K. The absorption edge of the hybrid was blue-shifted compared with that of bulk ferrite.

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.

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.

(Na2O,BaO)–Nb2O5–SiO2 and (K2O,SrO)–Nb2O5–SiO2 glass ribbons with varying proportions of alkali and alkaline earth were formed using roller quenching. (Na2O,BaO)–Nb2O5–SiO2 glasses of compositions devitrified to form Ba2NaNb5O15 (in the form of ∼80 nm crystallites in an amorphous matrix) yielded frequency-stable dielectric constants of ∼250 and losses of ∼0.05. Such low losses and frequency stabilities were also observed from (K2O,SrO)–Nb2O5–SiO2 glasses of compositions forming predominantly KSr2Nb5O6 (∼30 nm crystals), yielding dielectric constants of ∼400. Both optimized compositions showed moderate decreases in dielectric constant with increasing temperature.

Fast degradation rates in the physiological environment constitute the main limitation for magnesium alloys used in biodegradable hard tissue implants. In this work, the corrosion behavior of AZ91 magnesium alloy in simulated body fluids (SBF) was systematically investigated to determine its performance in a physiological environment. The influence of the main constituent phases on the corrosion behavior was studied by in situ visual observation and scanning electron microscopy. Energy dispersive x-ray spectrometry and Fourier transfer infrared spectroscopy revealed that both calcium and magnesium phosphates are present in the corroded products besides magnesium oxide. Electrochemical methods including open circuit potential evolution and electrochemical impedance spectroscopy were used to investigate the mechanism. The corresponding electrode controlled processes and evolution of the corrosion products layer were discussed. The degradation rate after immersion in SBF for seven days was calculated from both the weight loss and hydrogen evolution methods.

We have measured the porosity in thin films of lithium fluoride (LiF), magnesium fluoride (MgF2), barium fluoride (BaF2), and calcium fluoride (CaF2) as a function of the substrate temperature for films deposited by thermal evaporation onto glass substrates. The amount of porosity in the thin films was measured using an atomic force microscope and a quartz crystal thickness monitor. The porosity was very sensitive to the substrate temperature and decreased as the substrate temperature increased. Consistent behavior was observed among all of the materials in this study.

A monodisperse spherical Y2O3:Eu3+ phosphor was prepared by a homogeneous precipitation method. The mean size of the phosphor particles (MSPP) was successfully controlled by changing the volume ratio of normal alcohol (RA) (propanol) in the solvents mixed between deionized water and normal propanol. When the RA was increased from 0 to 0.7, the MSPP decreased while maintaining a high yield of >95%. Although the prepared phosphor samples were fired at the same temperature, the thermal energy was delivered more efficiently into the inner side of the phosphor particles with the decrease of the MSPP. Therefore, the crystallinity and also the photoluminescence (PL) intensity of the phosphor increased with the decrease in the MSPP. In addition, because the numbers of Eu3+ ions located near the particle surfaces increased with the decrease of particle size, the ratio of PL intensity caused by the 5D0–7F2 transition to that caused by 5D0–7F1 transition increased from 10.8 to 12.7 with the decrease in MSPP.

In situ measurements of stresses due to the phase transformation in Sn and Ni(P) films were analyzed relating to the formation of layered intermetallic compounds such as Ni3Sn4, Ni3Sn2, Ni3P, and the crystallization of Ni(P) films. When Sn/Ni(11.7P) films were heated up to 480 °C, the first tensile stress developed due to formation of Ni3Sn4 and Ni3P around 220 °C, and the second one appeared at 335 °C due to formation of Ni3Sn2 as well as the self-crystallization of Ni(11.7P). For Sn/Ni(3P), a tensile stress developed mildly with the temperature between 300 and 410 °C due to formation of Ni3Sn2 and precipitation of Ni3P. The onset temperatures of self-crystallization of Ni(P) and Ni3P precipitation decreased due to the Ni–Sn reaction.

By injecting additional argon gas, we were able to grow one-dimensional ZnO nanorod arrays with a uniform distribution on a large scale at a low temperature of less than 330 °C by metalorganic chemical vapor deposition. All of the nanorods grown on the sapphire substrate had a 30° in-plane rotation with respect to the substrate and showed the epitaxial characteristics of [10¯10]ZnO//[11¯20]sapphire, despite the low-temperature growth. These ZnO nanorods with high crystalline quality exhibited a high enhancement factor and low turn-on field value, thus having good potential to be used as a field emitter.

An experimental study of the elastic and plastic properties of sucrose single crystals, which can be considered to be a model material for both pharmaceutical excipients and explosives, has been carried out using nanoindentation. Instrumented indentation was used to characterize the properties of both habit and cleavage planes on the (100) and (001) orientations; the elastic modulus on the (100) is 38 GPa, while the modulus on the (001) is 33 GPa. The hardness of sucrose is approximately 1.5 GPa. Nanoindentation enables assessment of the onset of plastic deformation on cleaved surfaces, and a maximum shear stress of 1 GPa can be supported prior to plastic deformation. The deformation in this material is crystallographically dependent, with pileup around residual indentation impressions showing evidence of preferential slip system activity.