Observation of residual stress and defects in silicon induced by scribing

Residual stresses induced by three scribing methods, diamond point scriber, laser scriber and diamond blade saw, are studied quantitatively by infra-red photoelasticity. It is clear that diamond blade saw scribing is most desirable, for residual stress induced by it is several times smaller than the stress caused by the other methods. The stress gradient differs between the laser scribed sample and the others, probably because of the difference in stress generation mechanism. Removing the damaged layer by etching reduces residual stress. The three scribing methods are also studied by the observation of defects after annealing and the results are compared with those determined by photoelastic measurement.     

Fatty acid derivatives and glycolipids in high-protein bakery products

High-protein bakery foods, particularly breads, are ideal for alleviating protein malnutrition in poverty areas of the world. Fortifying wheat flour with a high level of protein-rich additives like soy flour can, however, induce adverse effects upon dough properties and bread quality. Several fatty acid derivatives, including sucroesters, fatty esters of polyalkoxylated polyoglycosides, sodium or calcium stearoyl-2 lactylate, and ethoxylated monoglycerides and glycolipids, recently have been shown to improve effectively the baking performance of wheat flour fortified with soy flour. The nutritional benefits of high-protein breads are reported with results from feeding studies using the breads in diets of experimental rats. The possible mechanisms concerning the improving action of fatty acid derivatives are proposed and discussed. One of 12 papers presented in the symposium “Novel Uses of Agricultural Oils” at the AOCS Spring Meeting, New Orleans, April 1973. Contribution 825 from the Department of Grain Science and Industry, Kansas State University.     

Fabrication and characterization of SiC-AIN alloys

SiC-AIN alloys were prepared by the carbothermal reduction of silica and alumina, derived from an intimate mixture of silica, aluminium chloride and starch. The resulting single-phase SiC-AIN powder was hot-pressed without additives to a high density. The dense bodies had a fine-grained uniform microstructure. The Young's elastic modulus, microhardness, fracture toughness, thermal expansion and thermal conductivity were measured as functions of composition. The creep behaviour of the SiC-AIN alloy was compared with that of silicon carbide.     

Hydrothermal crystal growth of perovskite-type fluorides

Single crystals of perovskite-type fluorides were grown from potassium fluoride and di-valent metal chloride solutions by a hydrothermal method under a temperature gradient, at maximum temperature 600° C and pressure 98 MPa. Single-crystal cubes of KMnF₃, KFeF₃, KCoF₃ and KZnF₃, of cube edge sizes ranging from 0.2 to 2.0 mm, were grown. Crystals of KNiF₃ grew in rectangular prisms and those of KCdF₃ in anhedral form. Single crystals of KCuF₃ were grown in pure water from co-precipitated KCuF₃ powder. KMgF₃ crystals were not grown by this method.     

Phase Formations and Electrical Properties of Various (Bi, La)4Ti3O12 Thin Films by Chemical Solution Deposition

The phase formation and electrical properties of (Bi, La)₄Ti₃O₁₂ (BLT) thin film and V-, Sm-doped BLT thin films prepared by the chemical solution deposition method on Pt/TiO₂/SiO₂/Si substrates have been investigated. It was observed that the microstructure and electrical properties of BLT thin films dramatically varied with V- and Sm-doping. The crystallinity and grain size of BLT thin films were definitely increased by V- and Sm-doping into BLT films, which resulted in the enhancement of remanent polarization in doped BLT films. The remanent polarization (Pr) of Sm-doped BLT films annealed for 3 min by an RTA system was about 9 C/cm². The V- and Sm-doped BLT films also exhibited good fatigue characteristics under bipolar stressing to 10¹⁰ cycles.     

Aging and Annealing Effects of ZnO Thin Films on GaAs Substrates Deposited by Pulsed Laser Deposition

Zinc oxide (ZnO) thin films were deposited on GaAs (100) substrates at different temperatures in the pulsed laser deposition (PLD) system. From the measurements of X-ray diffraction (XRD) at room temperature, 300–500°C were found to be good condition for the crystallization of the thin films. From the photoluminescence (PL) measurements, 500°C was found to be the optimized temperature for its optical property. Samples grown at 100, 200, 300, and 400°C showed near band-edge (NBE) emissions and deep-level emissions. The intensity of deep-level emissions decreased as time goes on, which is believed to originate from oxygen vacancies or zinc interstitials in thin films. While for the sample grown at 500°C, bright NBE emissions were observed at room temperature, and no deep-level emissions observed. This means that the high-optical-quality thin film was grown at 500°C. At the same time, annealing process of ZnO thin films grown at room temperature was carried out in PLD chamber. It was found that the annealing temperature of 600°C has strong effects on its PL. Aging and annealing effects in ZnO thin films grown on GaAs substrates by PLD were observed for the first time.     

Synthesis and characterization of poly(terphenylenevinylene) derivatives containing alkoxy substituents and (or) phenyl pendant group

The blue electroluminescent polymers, poly(terphenylenevinylene) derivatives that have advantages of PPP and PPV, were prepared by Suzuki coupling reaction. The structure and properties of the polymers were analyzed by various spectroscopic methods. Poly(MHTPPV) and poly(TPPV) with phenyl pendant group in a vinyl bridge showed blue shifted absorption spectra, large band gap and enhanced thermal stability as compared with that of poly(MHTPV). The PL spectra of the films of the polymers showed maximum peaks at 450-460 nm, which are pure blue emissions. The blue electroluminescence was obtained with the turn on voltage of 8-10 V, when the simple light-emitting diodes of ITO/polymer/Al were fabricated. The excimer emission due to interchain interaction was reduced by the introduction of substituents into the vinyl bridge and (or) the main chain.     

Hazardous waste destruction and nitric oxide reduction with externally forced oscillation

The research described here focuses on the enhancement of hazardous waste destruction and the reduction in nitric oxide and unburned emissions in a cavity incinerator, which has externally forced acoustic oscillation. The specific configuration of the incinerator was manufactured to consist of two opposing jets and a rearward facing step [Chun, 1999]. The cavity-type incinerator warrants a sufficient residence time and effective turbulent mixing by the formation of a strong recirculation region in a combustion cavity. The experiments were carried out about combustion characteristics in a 3.2 kW laboratory scale, transportable, cavity incinerator without external oscillation. These showed that hazardous waste was destructed effectively, but unfortunately NO was increased by high gas temperature. To solve this problem, we developed an externally oscillated auxiliary burner embedded on the incinerator furnace. The external oscillation was effective to reduce NO which is produced at high temperature incineration and to destruct hazardous waste, simultaneously. Emissions of NO are seen to be decreased by nearly 60%, and DRE (destruction and removal efficiency) is above 99.99%, all with external forcing at a specific optimum conditions.     

Effect of heat transfer on the transient dynamics of temperature swing adsorption process

The effect of radial heat transfer on temperature swing adsorption (TSA) was studied by using an air-drying TSA experiment. The experimental dynamics of water adsorption and thermal regeneration in a fixed bed packed with zeolite 13X were used to evaluate the predicted results from the developed models. One-and two-dimensional models for energy balance with various equations describing internal velocity were compared in terms of the prediction of transient dynamics of TSA. Since the heat effect in adsorption step depended on the isosteric heat of adsorption, a dynamic simulation was performed under adiabatic, near-adiabatic, and constant wall temperature conditions. A comparison between one-and two-dimensional models was also made under near-adiabatic condition, which reflected on the experimental condition. There was little difference between adsorption breakthrough curves predicted by the one- and two-dimensional models because the radial distribution of temperature was negligible at the adsorption step. In the case of the regeneration step, a small difference between two models was expected just at the early period of time because the radial effect disappeared with time. One-dimensional model could provide an adequate prediction of the transient dynamics in this system when the wall energy balance was included.