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When a turbine is operated at a low partial admission rate, its performance can show wide deviation from the predicted results depending on the operating conditions and geometric parameters. In order to investigate the performance characteristics on a partially admitted turbine based on the geometric parameters, a turbine was tested with various tip clearances and nozzle flow angles. In addition, the effects of the partial admission rates were studied, and the turbine output power on each stage was measured to investigate the effects of the mainstream diffusion along the turbine stage by partial admission. The outer diameter of the turbine rotor was 108 mm, and its partial admission rate was 1.4–4.1 per cent. The tested turbine was designed as a radial-type turbine that had a circular plate disc for rotor rows. The rotor and the stator were designed as a typical axial-type blade, and the turbine consisted of three stages. The turbine performance was obtained in a wide rotational speed range in order to compare its performance according to various operating conditions. The net specific output torque was also measured to compare its overall performance. Computational analysis was conducted for predicting turbine performance. The computed results were in good agreement with the experimental results.

In this study, sidewalls of a turbine cascade experimental apparatus are designed to satisfy periodic flow conditions with two blades without any flow control or tailboards. Generally, the turbine cascade experimental apparatus needs removing fluid from the cascade walls or adjusting tailboards located downstream of the cascade to establish periodic flow conditions through the cascade blades. If a linear turbine cascade often consists of only a few blades within a passage, advantages to this experimental arrangement are increased from using larger turbine cascades, a lower mass flowrate and corresponding decrease in required power, and easier optical access within the cascade passage. However, fewer blades in the cascade make it difficult to establish periodic flow conditions between blades compared to infinite cascade flow conditions. In order to test a turbine cascade with a few blades without flow control devices, only two turbine blades are installed within a double-pitch passage. Sidewall shape is designed with 12 geometric design variables using a gradient-based optimization method, and surface isentropic Mach number distribution on the blades is chosen for the existence of periodic flow conditions. The computed result shows periodic flow conditions obtained by modifying only the sidewalls of the double-pitch passage as a cascade experimental apparatus.

A robust axial-type fan design technique is developed by using an optimization method based on the gradient method. A three-dimensional fan blade was initially designed by stacking several two-dimensional (2D) blade profiles along the spanwise direction. These 2D blade profiles were designed using the free-vortex method and profile parameters such as the incidence, deviation, camber, and so on. The initial fan blade adopts 13 design variables to improve the target value of the fan efficiency or the total pressure. These design variables are used to control the rotor and stator profile for obtaining a better target value. In this study, fan efficiency is chosen as a target objective variable to be maximized, and the total and static pressure on the design point are applied as constraints. These procedures are applied to the design of an axial-type fan that must operate at a mass flowrate of 8.37 kg/s with a minimum total pressure rise of 670 Pa. The optimized fan not only increases the efficiency by 2.9 per cent but also satisfies the required total and static pressure conditions compared with the initially designed fan performance. The optimized fan performance agrees with the experimental results; therefore, this fan design technique can be applied to improve the efficiency and the operating pressure of axial-type fans.

KITENIN was previously reported to promote metastasis in mouse colon tumour models; however, the signalling mechanism of KITENIN at the cellular level was unknown. Here the functional role of KITENIN with respect to colorectal cancer (CRC) cell invasion and its expression in CRC tissues were investigated.The effect of KITENIN on cell motility was analysed in a migration and invasion assay upon its overexpression and knockdown. Immunoprecipitation was used to elucidate binding partners, and immunohistochemistry was used to study expression levels.KITENIN overexpression enhanced the migration of rat intestinal epithelial cells, whereas a loss of invasiveness was observed in CRC cells after KITENIN knockdown. Mechanically, KITENIN served as a scaffolding molecule that simultaneously recruited both Dishevelled (Dvl) and protein kinase C delta (PKC delta) through the membrane-spanning C-terminal region to form a complex that stimulated extracellular signal-regulated kinase (ERK)/activating protein-1 (AP-1) via a PKC delta component but also organised the actin filament via a Dvl component. The KITENIN complex controlled the invasiveness of CRC cells aetiologically harbouring various mutations in APC, beta-catenin or K-ras, in which AP-1 activation is redundant but the organisation of the actin filament is indispensable for cell motility. Clinically, KITENIN expression was significantly higher in colon cancer tissues from advanced stage (III, IV) than that of stage I CRC and also in corresponding metastatic tissues.The functional KITENIN complex acts as an executor with regard to cell motility and thereby controls CRC cell invasion, which may contribute to promoting metastasis.

The sintering behavior and the mechanical and oxidation properties of Sialon were investigated by varying the composition, amount, and cationic radii of sintering additives composed of AlN-Er2O3-M2O3 (M=Y or Sc). The optimum additive composition for the pressureless sintering of Sialon was determined to be (0.6 AlN:0.4 [0.3 Er2O3:0.7 M2O3]) and the optimum content was 10-15 mass%. The maximum relative densities of Sialon using AlN-Er2O3-Y2O3 and AlN-Er2O3-Sc2O3 additives (termed SAEY and SAES) were 94.4 and 97.9% at 0.1 MPa N2, respectively. The pressureless sintered SAES sample showed fairly high strength (506 MPa) using the optimized additive composition. In both systems, the oxidation resistance was improved by decreasing the total amount of sintering additives.

The partial quenching structure of diffusion flames, arising from the phenomenon of turbulent flame lift off, is investigated in a turbulent mixing layer by the method of flame hole dynamics. Modification of the flame hole dynamics by including the level-set method is specifically aimed to properly take into account the effect of slow flame-edge response near the crossover scalar dissipation rate at which the edge propagation speed vanishes. Simulating the flame hole dynamics with the level-set method results in two major improvements. The first improvement is observed in stabilizing lifted turbulent diffusion flames. The three necessary conditions for lifted stabilization are proposed and numerically tested to show that rapid variation of the edge propagation speed near the crossover scalar dissipation rate helps lifted stabilization. Secondly, an improvement in the statistical properties of the stationary turbulence reacting state is observed in that (1) the lift-off height is found to be higher because...

A systematic method as applied to an air circuit breaker (ACB) system is proposed to analyse the links of the spring-actuated linkage under repetitive impact loading. A fatigue life equation applicable to the links is presented on the basis of the fatigue test. The result obtained from the multi-body dynamic analysis is compared with that from the experiment. For the explicit finite element analysis of the links, the impact loading obtained from the dynamic analysis of the ACB system is used as the initial conditions. To enhance the fatigue life of a weak link, two modified designs are proposed and their maximum stresses are reduced very much compared with that of the original design. Considering a safety margin, one modified design satisfies the required specification of the fatigue life. The proposed approach in this work can be efficiently used in designing stable and reliable links of the ACB and in analysing a similar spring-actuated linkage system.

This study aims to analyze the effect of an evaporator in a fuel cell system which uses oxygen as a fuel. The oxygen from a liquid storage tank flows to the evaporator in order to supply gaseous oxygen fuel to the fuel cell stack. The design of the evaporator has an effect on the temperature and mass flow rate of the gaseous oxygen being supplied to the stack, which results in a change in the performance of the fuel cell system. In order to evaluate the characteristics, several components such as an oxygen storage tank, evaporator, stack, etc. were modeled and the parameters of the evaporator simulated. Increasing the heat exchange area in an evaporator enhances the effect of heat transfer, but its cost and overheated supplying oxygen gas may have a negative effect on the performance of the system. It is important to evaluate the optimization of the evaporator in a fuel cell system to ensure the better performance of the system.Copyright © 2010 by ASME

A PEMFC System of residential power generator (RPG) has different operating strategy from the PEMFC system of transportation application because of its environmental difference. In this study, a dynamic simulation model of PEMFC system is introduced which has model for a turbo blower, a membrane humidifier, two cooling circuits, and a PEMFC stack. The thermal efficiency of the PEMFC system for the RPG is very high because it supplies the electricity and hot water to the house. This study is designed to study the dynamic response of individual components during the dynamic change of current density. In particular, since the operation of turbo blower is very sensitive at low current density, the parasitic power consumption of blower is significant. Additionally, the system performance and the operating strategy are also presented.

Models for the growth and shrinkage of an interfacial oxide layer and for the stability of the interfacial oxide layer are formulated. Predictions of these models are compared to results obtained by high-resolution transmission electron microscopy. Wafers containing different concentrations of oxygen interstitials are bonded. Depending on the starting concentration of oxygen interstitials in the wafers, the interfacial oxide layer grows or shrinks during long-time annealing at high temperatures. For much shorter annealing times, local disintegration of the oxide layer may occur, which is less severely influenced by the concentration of oxygen interstitials. Rather, it depends on the thickness of the interfacial oxide layer. The influence of rotational misorientation is examined by rotating wafers around their common axes perpendicular to a wafer plane and subsequent bonding. Above a critical angle of about 1–3°, a continuous oxide layer is formed, whereas below this critical angle, sufficiently thin oxide layers disintegrate.

We hypothesize that Bacille Calmette-Guérin (BCG) may act through the regulation of various isoforms of nitric oxide synthase (NOS) [inducible (iNOS), endothelial (eNOS), and neuronal (nNOS)] genes and protein expression in rat bladder.Adult female Sprague-Dawley rats (200-250 g) were injected transurethrally with BCG (22 rats) and phosphate-buffered saline (22 control rats), and after 2, 4, 6, and 12 h, and 1, 2, 3, 5, 7, 10, and 14 days, the bladders were harvested. Normal and BCG-treated rat bladders were analyzed for mRNA expression for iNOS, eNOS, and nNOS by reverse-transcriptase polymerase chain reaction. Protein expression was determined by Western blotting and immunohistochemistry.mRNA expression for iNOS was induced after 2 h of BCG injection in the rat bladder. Gene expression for iNOS was highest at 6 h to 1 day followed by decreased expression, reaching its lowest level at 5 days. eNOS mRNA expression was detected in control bladders, but its level was higher in the BCG-treated animals. nNOS mRNA expression was present in all samples, but did not change after BCG treatment. Western blotting confirmed these findings. Immunohistochemistry analysis demonstrated that eNOS was present mainly in endothelium, while iNOS was detected in stroma and nNOS in epithelium and smooth muscle of the rat bladder.The present study demonstrates, for the first time, that BCG treatment up-regulates gene and protein expression of iNOS and eNOS in normal rat bladders, suggesting that BCG action may be mediated through NOS pathways.

Genes involving angiogenesis and metastasis play an important role in the progression and infiltration of cancer. We examined the expressions of various angiostatic and potential invasion/metastasis suppressor genes through RT-PCR analyses in 32 gastric cancer specimens with or without distant metastasis. The expressions of the invasion/metastasis suppressor, nm23 and E-cadherin increased much more in the cancer tissue (CT) and metastatic lymph node (MLN) than in the extraneoplastic mucosa (EM) and non-metastatic lymph node (NLN), respectively. The expressions of the angiostatic factor, angiopoietin 2 and thrombospondin 2 increased in the CT and MLN as compared with the EM and NLN, respectively. The newly cloned angiostatic factor, brain-specific angiogenesis inhibitor 1 (BAI1) decreased much more in the CT and MLN than the EM and NLN, respectively. However, BAI1 increased in the CT compared with the EM among the patients with poor prognosis and distant metastasis, such as liver or peritoneum. The expressions of the invasive factor, matrix metalloproteinase-2 and its suppressor, tissue inhibitor metalloproteinase-2 (TIMP-2) increased in the CM as compared with the EM, but the increased expression pattern of these genes in the CT became blunted among the patients with good prognosis. Our results indicate that BAI1 and TIMP-2 expressions in the extraneoplastic mucosa and non-metastatic lymph nodes were not suppressed in the patients with good prognosis, but increased expressions of angiopoietin 2, thrombospondin 2, TIMP-2, nm23 and E-cadherin in the tumor tissue did not lead to a long survival after operation. It is suggested that the extent of BAI1 and TIMP-2 expression in the gastric mucosa may be an important prognostic factor for predicting survival in gastric cancer.

We previously isolated a cDNA clone for a homeobox-containing gene with its expression restricted to the extraembryonic tissues. In this study, Psx gene expression was further examined using in situ hybridization to determine the cellular distribution of Psx transcripts during embryo development. Psx expression was first detected at embryonic day 8.5 only in trophoblast giant cells and chorionic ectoderm. At E 9.5 and E 13.5, the expression was restricted to the giant cells and the labyrinthine trophoblast layer. In addition, the gene expression was detected in differentiated Rcho-1 trophoblast cells in vitro, which is typical of trophoblast giant cells in vivo, but not in proliferating Rcho-1 cells and HRP-1 cells. Interestingly, rat Psx homologue mRNA is about 200 bp shorter than mouse Psx, suggesting that there is a high degree of sequence divergence between the mouse and rat Psx homologues. The sequence divergence, perhaps as a result of rapid evolution, is further supported by the zoo blot analysis because the Psx gene was detectable only in mouse and rat but not in other vertebrate species tested. Psx is localized to the murine X chromosome. Taken together, our results suggest that Psx gene plays a unique role in the function of differentiated trophoblast cells and also serves as a useful model for studying trophoblast cell lineages and the rapid evolution of homeobox genes.

Twenty-three cases of endoscopically assisted facial bone surgery were performed over the past 3 years. Our series is consistent with 16 cases of aesthetic contouring surgery and 12 treatments of facial bone fracture, including three cases for recontouring of frontal bone, three cases for recontouring of zygoma, endoscopically assisted correction of three zygomatic and blowout fractures, four cases for rhinoplasty and septoplasty for deviated nose, and three cases for mandible contouring surgery. To accomplish this technique, a rigid 4-mm, 30-degree down-angled endoscope was used. The frontal bone or zygomatic arch was approached endoscopically through two or three small incisions on the frontal or temporoparietal scalp. All endoscopic instruments were then manipulated through these incisions. The approach for endoscopically assisted rhinoplasty is the same as with standard rhinoplasty procedures. The approach for zygoma complex and maxillary sinus needs an intraoral incision. Recontouring of zygoma, mandible, and nasal dorsum by an air-driven burr and rasp was performed with endoscopic visual assistance. A plate and screw fixation for zygomatic arch fracture requires an additional small skin incision over the plate for the trocar method. The duration of follow-up ranged from 6 months to 30 months. The postoperative course was satisfactory with a few complications. The extra time needed for the endoscopic procedures was less than 1 hour. Endoscopically assisted facial bone surgery can be performed with adequate visualization and direct manipulation of all facial bones. Complications usually associated with extensive incisions in the bicoronal approach may be avoided. Poor visualization in the conventional approach for operation of orbit, nose, maxillae, and mandible may be avoided by use of the endoscope. This technique may prove to be ideal for aesthetic surgery for facial skeleton with smaller scar and less morbidity.

The effect of ion bombardment on alloy film stress was studied by coevaporating W and Si in the presence of 100 and 400 eV Ar+ ion bombardment at room temperature, 350 and 500 °C. In the absence of ion bombardment, internal stress increases and becomes more tensile as deposition temperature increases. At room temperature, increasing ion bombardment causes the stress to go from tensile to compressive. At 350 °C tensile stress increases as a function of ion flux and decreases slightly at higher flux value. At 500 °C, the effect on stress due to ion bombardment is less pronounced. The correlation between the effect of ion bombardment on stress, deposition temperature, and the structure of the material is discussed using the concept of enhanced surface diffusion and local atomic rearrangement as a mechanism responsible for ion beam stress modification. By using this mechanism, we explain the diminished effect of ion bombardment on stress in the WSi2 films that contain compound phases compared to the amorphous...

Rutherford backscattering analysis was used to evaluate TiSi2 films which were prepared by sputtering Ti on various substrates and nitrogen annealing. The resulting properties were then compared with that of films prepared by thermal evaporation. Ti films were deposited on single crystal Si, polycrystalline Si, thermally grown SiO2, and CVD Si3N4 by dc‐magnetron sputtering in an Ar plasma at a typical deposition rate of 20 A/s. Some films were passivated with a thin amorphous film of Si to compare the reaction kinetics with the samples without passivation. The temperature dependence of the electrical resistivity is basically the same as with the evaporated films [Ref. 1: C. Y. Ting et al., in Proceedings of the First International Symposium on VLSI Science and Technology (Electrochemical Society, New York, 1982), p. 224.], and the minimum value obtained after an 800 °C anneal is similar. Typical resistivity after taking into account the presence of TiN on the surface is approximately 13.9 μΩ‐cm. The prese...

Tungsten films reactively sputtered in nitrogen or oxygen were characterized by measurements of electrical resistivity and microstructure. The deposition rate of W–N films is slightly reduced with increasing nitrogen partial pressure accompanied by an increase in electrical resistivity. For example, the nominal resistivity of pure tungsten films increases from 11 to 16 μΩ cm as the nitrogen partial pressure increases to 17%. Transmission electron microscopy shows that films are polycrystalline tungsten with bcc structure and typical grain size range of 200 to 300 nm. Upon annealing at high temperature above 700 °C, the effects of nitrogen are gradually diminishing. For example, the high values of resistivity are annealed out and approach that of pure tungsten film after annealing at 1000 °C for 30 min. Annealing does not change the film thickness nor the grain size, although films prepared in nitrogen partial pressure of greater than 7% show precipitates with typical size of 20 nm. The effects of oxygen p...

Electrical resistivity and step coverage on thick oxide steps of various slopes were examined in tungsten silicide films sputter deposited by multilayering of W and Si utilizing magnetron targets. The desired composition was obtained by adjusting power levels to the targets and bias voltage. A broad minimum in electrical resistivity was obtained with bias voltage ranging from −40 to −80 V. Typical resistivity in films of 2500 A thickness after annealing at 1000 °C was 52–66 μΩ cm when deposited on poly‐Si substrates. The effect of bias was found to produce films with much lower levels of impurity such as N, O, C, and H and the sputtering gas Ar. Proper bias voltage (−50 V) was necessary to achieve good step coverage on thick oxide step with various slopes. Zero‐bias sputtering provided minimum step coverage, while too high bias (−100 V) led to poor step coverage and formation of rounded corners and faceting.

The crystallization behavior and electrical resistivity of WSix films (coevaporated on poly‐Si on SiO2) with x ranging from 1.0 to 2.4 were examined in a high‐resolution TEM before and after annealing at 1000 °C. The amorphous as‐deposited films with high resistivities (up to 650 μΩ cm) become crystalline WSi2 after annealing accompanied by a precipitous drop in resistivity to values below 30 μΩ cm. The as‐deposited Si‐rich films showed a reduction in thickness, up to −15% for x=2.4, while metal‐rich films showed an increased thickness, up to 13% for x=1.0. The minimum resistivity of 28 μΩ cm was found in a sample with as‐deposited composition of WSi1.4 which also had the largest thickness. The difficult problem of determining the thicknesses before and after the interaction of WSix with the CVD poly‐Si was solved by first measuring the thin SiO2 thickness (220 A) using the Si lattice fringes, and then comparing the thicknesses of poly‐Si and WSix with that of SiO2. Annealed WSix films with thickness rang...

Thin films of Au, Si, Al, NiFe, Ta, and W have been prepared by ion beam sputtering, and physical properties have been compared with films deposited by rf sputtering, and electron beam evaporation. In general, films of a given material appeared to be comparable for the properties measured, independent of deposition method. In the ion beam sputtering system, the effects of deposition rates are studied as a function of the accelerating voltage of the ion beam, and of the angle created by the target tilt and the path of the ion beam. Deposition rates generally leveled off at an accelerating voltage of 750 V; and for several materials, a peak in deposition rate was observed at a target‐beam angle of 30°. The magnetic properties of ion‐beam‐sputtered NiFe films are compared before and after annealing in vacuum at 350°C for 30 minutes. Annealing produced a small drop in the resistivity of these films, with a corresponding increase in the magnetoresistive effect, Δρ/ρ. Electron microprobe measurements indicate n...

Oxygen contamination during rf sputter deposition of NiFe films is shown to cause adverse electrical and magnetic properties. This contamination is most pronounced in films deposited at low bias voltages. Although the bias voltage is not a direct cause of these changes, it is a factor which determines the amount of available oxygen in the sputtering gas which is incorporated into the interior of the films. In addition, a thin oxide layer is frequently found on both top and bottom surfaces of the films. It contains as much as 2 at. % oxygen, a concentration which is shown to mark the onset of deteriorating electrical and magnetic properties when occurring uniformly throughout NiFe in films.

The magnetic properties of vacuum-deposited multilayer films constructed in a closed-flux configuration in an integrated structure have been studied as a function of: a) film thickness; b) substrate temperature, and c) the character of the conductor metals. It is found the static magnetic properties of the magnetic layers depend on the material in the previous layers as well as the thickness and deposition temperature of those layers. Techniques of optimizing and controlling the magnetic properties are discussed.

The quasi-static magnetic properties of vacuum-deposited Permalloy films of zero-magnetostrictive composition are examined in situ in an evaporator equipped with a laser-operated Kerr magneto-optic hysteresigraph. The coercive force, whicho depends strongly upon the film thickness, is large (Hc > 20 Oe) when the hysteresis loop is first observable with a thickness of ∼ 50 A for low substrate temperatures (T 100°C). There are two peaks of coercivity, at ∼400 A and ∼1,000 A; the two are thought tob e related, respectively, to the transitions from the Neel to the cross-tie walls, and from the cross-tiet o the Bloch walls. Two distinct components of the uniaxial anisotropy field are identified, both of which are characteristic of fabrication parameters: K1, which is difficult to re-orient once the anisotropy is induced; and K2, which is readily re-oriented (with time constant lessth an 10 sec) along any angle between the easy and the hard axis. The net anisotropy field and the easy-axis orientation, both of which are affected by the K2 components, can be calculated for a given set of fabrication parameters. Experimental results agree well with the calculated values. The angular dispersion does not appear to be affected by the amplitude of the orienting field H or the nature of the field (ax. or d.c.) when H > Hc. There is a slight increase in angular dispersion as the K2 component of the anisotropy rotates from the easy to the hard axis.

The ferromagnetic Curie temperature of EuO films has been increased by selective doping with trivalent rare‐earth oxides. The electrical resistivity, which depends upon the temperature and has a broad peak at ≈100°K, decreases markedly to ≈10−1 Ω·cm with doping. A typical ferromagnetic Curie temperature, determined from magneto‐optic measurements in zero applied field, is ∼135°K. Maximum longitudinal Faraday rotation occurs at 0.65 μ with a specific rotation of +1×105 deg/cm for an incidence angle of 20 deg. At 0.84 μ the Faraday rotation reverses sign and reaches a negative maximum at 0.93 μ. The longitudinal Kerr rotation also has two maxima at 0.58 μ and 0.83 μ with double rotations of ≈4°. The transverse Kerr effect depends on the wavelength in the same manner and has maximum values of +0.4 and −0.3, respectively. There is a strong optical absorption band centered at 0.6 μ (at 300°K) with α≈1.2×105 cm−1 which shifts toward longer wavelengths at lower temperatures accompanied by a small decrease in α. ...

The coercivity of NiFe (80/20) films can be lowered by laminating several layers with nonmagnetic spacers. A reduction by a factor of 10 can be achieved with a simple bi‐layer, regardless of spacer material, provided the spacer thickness is below a critical value. No further reduction is found for multilayers. Two peaks of Hc near thicknesses of 250A and 1000A for single layer films, associated with changes in domain structure, are suppressed by lamination. After a minimum spacer thickness (S) of 10–15A, the domain walls in the separate layers no longer coincide but track closely, their separation depending on S. With S?100A the layers switch independently, giving rise to multiple values of Hc.

Transmission electron microscopy is used to characterize the hole‐formation process due to laser writing in evaporated and sputtered Te thin films and in a Se‐Te bilayer. Bilayers, with Se as the top layer, combine the effect of an antireflective coating with protection against oxidation and provide the advantage of alloy formation during spot writing. Solidification of the melt in the Se‐Te spot takes place as an amorphous alloy resulting in smooth‐rimmed, clean holes. In contrast, Te crystallizes from the melt, giving rise to uneven rims and debris inside the spot.

The coercivity of rf‐sputtered thick NiFe films (≳0.3 μm) on thick gold (≳0.3 μm) is generally lower than in films deposited by thermal evaportion. Especially low values of coercivity (Hc?0.7 Oe) are obtained in NiFe films on gold conductors which are deposited onto thin adhesive layers of refractory metals having lattice parameters around 3 A. For a given NiFe film thickness, the coercivity is found to decrease with increasing gold thickness up to 1 μm in sharp contrast to evaporated films.

We demonstrate here that bilayer films consisting of Si and transition metals with a layer thickness of 15–40 nm are promising materials for archival optical storage. They show a large optical reflectivity change before and after silicide formation, have a long lifetime at room temperature, and are nontoxic.

The stability of thin interfacial oxide layers between bonded silicon wafers is investigated experimentally and theoretically. For usual bonding temperatures around 1100 °C and typical times of a few hours, the oxygen diffusivity is not high enough to allow the oxide layer dissolution. For aligned wafers of the same orientation, the oxide layer instead tends to disintegrate in order to minimize the SiO2/Si interface energy. It is possible to stabilize a uniform interfacial oxide layer by rotationally misorienting the two wafers by an angle θ exceeding a critical angle, θ crit, estimated to be between 1° and 5°.

A large increase of ferromagnetic Curie temperature from 69.5 to ∼180°K has been discovered in EuO films by Fe doping. In films containing Fe up to 8% by weight, the structure is essentially the same as bulk EuO, the magnetic moment (at 4.2°K) is reduced slightly to 190 emu/g, the longitudinal Faraday rotation shows a similar wavelength dependence as that of pure EuO with a maximum positive rotation of 2.4×105 deg/cm at 6500 A at an incidence angle of 65°, square hysteresis loops extend to ∼160°K, and the optical absorption characteristics are modified by Fedoping with a peak absorption coefficient of 2.4×105/cm (at 300°K) at 5800 A.

EuO films with ∼8‐wt% Fe have saturation magnetic moments of about 180 emu/g at 4.2°K and Curie temperatures (Tc) as high as 200°K (for pure EuO, σ=232 emu/g, Tc=69.5°K). The temperature dependence of the magnetization does not scale relative to pure EuO but deviates from the normal magnetization curve in that it exhibits a long tail extending from about 100°K up to Tc. Optical absorption data at 6°K in the range 0.3–2.5 μ indicate a characteristic peak at λ=0.6 μ (due to the 4f‐5d transition) with α=2.2×105/cm, about 50% higher than pure EuO. The wavelength dependence of the normal Faraday rotation at 4.2°K is similar in shape to pure EuO; both peak at 0.7 μ but the peak rotation of the Fe‐doped film (6×105 deg/cm) is about 30% lower than pure EuO. Mossbauer measurements of 151Eu show mainly Eu+ + with an isomer shift of −12.25 mm/s as in bulk EuO. At 4.2°K the 151Eu hyperfine field is 280.8±5.6 kOe (pure EuO≈300 kOe). The isomer shift of the doublet observed on the 57Fe resonance at 300°K is characteris...

The preparation of EuO films by co‐evaporation of Eu and Eu2O3 has been studied. The two most important parameters to control are the ratio r=Eu/Eu2O3 and the background pressure. The latter should be in the 10−6‐Torr range, and only by starting with high density (>95%) Eu2O3 is it possible to maintain this. As r increases from 0.8 to 1.4 we observe the following: (1) A large increase in Tc is observed from 51° to 117°K; (2) the absorption a increases from 0.85×105/cm to 1.6×105/cm and the peak shifts toward the red (from 5900 to 6000 A); (3) the longitudinal Faraday rotation 2φ (with 25° incident angle at 6328 A) increases from 0.9×105 deg/cm to a maximum of 3.7×105 deg/cm, followed by a slight decrease; and (4) Hc (10°K) decreases sharply from 140 Oe to a minimum of 43 Oe for r=0.94, followed by a slight increase. The best films which were single‐phase stoichiometric EuO, with bulk‐like properties, are obtained with r=0.94. These have well‐defined x‐ray diffraction patterns with lattice constants a0=5.1...

The effects of a dielectric overlayer on Kerr magneto‐optic properties in thick EuO films were examined. The dielectric film serves not only as a passivation layer, but also to increase the Kerr effects. A series of thin Eu2O3 films were vacuum deposited on a thick EuO film, followed by in situ measurements of the reflectivity and the transverse Kerr effects using a polarized light (with the electric field vector in the plane of incidence) at 45° angle of incidence in the wavelength region from 0.4 to 0.8 μ. As the dielectric (Eu2O3) thickness increases the characteristic reflectance minimum of EuO shifts toward longer wavelengths, accompanied by decreasing reflectivity. This shift agrees well with calculated reflectances using optical constants of Eu2O3 film and EuO. The minimum reflectance of ∼0.04% occurs at 0.675 μ for a dielectric thickness of ∼500 A. The transverse Kerr effects also depend strongly upon the dielectric thickness. The maximum Kerr effects occur at the wavelength of minimum reflectance...

Kerr rotation in Gd‐Co‐Mo alloys is due mostly to the cobalt atoms. We investigate Polar Kerr loops vs composition and temperature, and determine total magnetization (from initial loop susceptibility and domain size) and the cobalt sublattice magnetization (from the saturation Kerr rotation angle). Deviations from the characteristics Kooy and Enz loop behavior due to thin ∠100A surface layer anomalies are first identified and removed in order to analyse the bulk film behavior.

We investigated the interaction of extremely thin (less than 10 nm) crystalline gold and rhodium films with amorphous silicon by transmission electron microscope in situ annealing. In thin Au/Si bilayers an amorphous phase with a diffraction peak at d ≂ 0.226 nm is formed by thermal annealing between 150 and 200 °C. Depending on the thickness and composition, silicon sputtered onto thin gold films leads to the formation of a layer of amorphous silicon and a partially amorphous Au-Si layer during deposition. The silicon layer crystallizes by itself at temperatures as low as 150 °C, and at 300 °C the amorphous Au–Si layer crystallizes into a metastable gold silicide (for silicon-rich compositions). In Rh/Si bilayers an amorphous Rh–Si phase is formed by annealing to 300 °C and can be detected by electron diffraction for a rhodium thickness of less than 5 nm and compositions with more than 50% Si if completely reacted. Above 300 °C the amorphous Rh-Si crystallizes preferentially in the cubic form of RhSi for intermediate silicon compositions and in the orthorhombic form of RhSi for high silicon compositions. Excess amorphous silicon is not found to have a lowered crystallization temperature when in contact with the amorphous Rh-Si alloy, and crystalline silicon is only observed above 730 °C together with the cubic and/or orthorhombic RhSi. In Rh/Si bilayers with a thicker rhodium layer, no formation of an amorphous phase was observed on annealing; instead crystalline Rh2Si forms during annealing above 300 °C.

Auger Electron Spectroscopy in conjunction with ion sputtering technique has been used to measure the composition profile in Au/NiFe and NiFe/SiO2 films. Interfacial mixing was found to exist as a result of biased sputtering and its extent was affected by bias voltage and substrate materials. Changing the bias voltage from 0 to 60 volts in sputtering NiFe films of 600 A thickness on SiO2 can reduce the resistivity by 40% and Hc by about 80% but increase the magneto‐resistive effect from 1% to 2.5%. Also as a result of mixing at the Au/NiFe interface, the magnetic moment has been observed to be diluted by about 80% in a 500 A NiFe film deposited on a glass substrate at 0 to 60 volts. The degree of dilution was significantly reduced if deposition was made on a SiO2 substrate or at higher voltages. An intermediate layer of 100 A SiO2 was found to be effective in eliminating the mixing between Au and NiFe.

We have investigated reactively sputter',d ZrN, the most thermally stable of the refractory metal nitrides, for its applicability as a submicron gate electrode. One would require for such gate electrode in addition to the lowest possible resistivity, a metal work function that will tailor the threshold voltage of metal/oxide/semiconductor (MOS) field effect transistor in such a way as to minimize the channel implant. Having these requirements in mind, we have measured the temperature dependence of resistivity, its dependence on the annealing temperature and work function of ZrN films. Our best films have resistivity, p of 20 A2-cm, comparable to TiSi. We find that p of as-deposited films being nearly stoichiometric, decreases about 20% after 1000°C anneal. Such anneal does not significantly alter the average grain size, which remains about 300 A even at this temperature. The temperature dependence of p at low temperatures indicates phonon scattering mechanism and we suggest that small amounts of oxygen are re- sponsible for residual resistance. The films undergo superconducting transition at 7.5-8 K and this transition provides an additional check on the compositonal homogeneity of the films. The work function, determined from the capacitance-voltage (C-V) characteristics of ZrN capacitors with various thicknesses of Si02, has value 0. = 4.6 Volts, at the midgap between n+ and p+ polysilicon and thus is applicable to 0.5 1m N-MOS and submicron C-MOS.

Magnetic and structural properties of vacuum‐evaporated MnAlGe films are presented and magneto‐optical data storage with this material is discussed. X‐ray analyses of films prepared by simultaneous evaporation and sequential layering show polycrystalline MnAlGe with bulk lattice constants. The optical absorption is featureless in the visible and near infrared regions with a typical absorption coefficient of 4.7 × 105/cm at 0.6328 μm. The Faraday rotation in the visible spectrum is also flat and is ∼ 1 × 105 deg/cm. Hc is typically 9 kOe in 1000A thick films. Thermo‐magnetic Curie‐point writing was achieved at 25°C with a 2 μmx20 μm GaAs laser beam, and the written bits were read out with the same laser at a reduced intensity.

The effects of preferred orientation on the magnetic properties of Co‐Ni thin films, prepared in a ultra‐high‐vacuum vapor deposition system, have been investigated. A variety of single‐crystal substrates were used with a 2000 A intermediate Au layer in order to obtain Co‐Ni films with different structures and orientations. Large variations in the coercivity, Hc, of 500 A thick Co‐Ni (80%−20%) films with the amounts of different phases and degree of preferred orientation were observed. In contrast, similar Co‐Ni films deposited directly on the above substrates contained mostly the f.c.c. phase, and their coercivity ranged between 50 and 90 Oe. The importance of the magnitude and the anisotropy of the magneto‐crystalline energy in thin films is illustrated by the structure and orientation dependence of Hc observed in this investigation.

Ternary alloy films were produced by variable‐ratio sequential and simultaneous two‐source evaporation under conditions comparable to those of technical Permalloy film evaporation. Intrinsic film properties measured at Mo concentrations up to 6%–8% indicated reductions of M, Hc, Hk, and dispersion. At high Mo concentrations, oblique incidence produced strong anisotropies. Crystallite dimensions were substantially less than in normal Permalloy films, and increased resistance to annealing was observed.

Measurements of quasistatic and dynamic switching properties of EuO have been made. EuO was pressed in the form of toroidal cores, and fired at different temperatures to obtain a variety of grain sizes. The quasistatic switching properties measured at 4°K with a 105 cps drive field (H

Large compositional variations reported in thin evaporated nickel‐iron films by Chu, Wolfe, and Wagner have not been observed in three new independent microprobe studies. Apparent compositional variations in the vicinity of isolated lumps of material are explained via thickness dependence of the nickel‐iron count ratio.

EuO films doped with Fe and Gd+++ raise the Curie temperature to ≳200 °K (from 70°K for EuO). The magnetic moment is slightly reduced to 200 emu/g (vs 232 emu/g for EuO). The characteristic optical absorption band, which is due to an electronic transition from 4f to 5d levels of Eu++ ions, remains unchanged with the peak absorption of 2.4×105/cm at 5800 A. The longitudinal Faraday rotation at 6328 A with an incident angle of 65° is 1.9×105 and 1.4×105 deg/cm at 7.0 and 77°K, respectively. Films deposited on several types of glasses possess square hysteresis loops with higher values of Hc (86 ∼ 100 Oe at T

The magneto‐optic Faraday effect was used to study films of permalloy (435 A) and EuO (350–1400 A) in intimate contact. The two films exhibit negative (antiparallel) coupling, that is, more external field is required to align the two magnetizations parallel than antiparallel. This causes the minor loop of permalloy to shift by as much as 35 Oe at 10°K. The shift is independent of EuO thickness, indicating an interfacial effect. The coupling energy is 0.13 erg/cm2, about half the value for coupled films of Fe and EuO (0.22–0.25 erg/cm2), but since the magnetization of permalloy is also half that of Fe, interface conditions for the two sets of coupled films appear to be quite similar. To establish the nature of the coupling, thin dielectric layers (Eu2O3, 11–44 A) were introduced between the EuO and the permalloy. A 22‐A intermediate layer reduced the coupling energy tenfold. This indicates that the negative coupling between the films is due to exchange interaction. Negative exchange coupling can predict th...

Localized stress fields which are present at the edges of evaporated layers pin domain walls. In the experiments Cr layers on epitaxial EuGaYIG films were primarily used to study these effects. Since the domain walls are pinned at the layer edges, magnetic bubbles can be pinned with their centers either inside or outside the layer. To pull off the bubbles a pulsed field gradient established by parallel conductor lines was applied. In total, five different interaction forces can be distinguished. The pinning forces are proportional to the stress in the film, i.e. the layer thickness, and independent of the layer width as long as the width exceeds the bubble diameter. For edges with a normal parallel to 〈110〉 the pinning is symmetric for both edges whereas for 〈211〉 there is an asymmetry. Most of these effects agree qualitatively with theoretical predictions by Dishman et al., which are based on perturbations of the domain wall energy through inverse magnetostriction.