Optical-standard surfaces of single-crystal silicon for calibrating ellipsometers and reflectometers

We show that hydrogen-terminated (111) Si wafers prepared with NH(4)F-based treatments can serve as a calibration standard for ellipsometers and reflectometers.     

Flexible high‐resolution full‐color top‐emitting active‐matrix organic light‐emitting diode display

We developed a high‐performance 3.4‐in. flexible active‐matrix organic light‐emitting diode (AMOLED) display with remarkably high resolution using an oxide semiconductor in a backplane, by applying our transfer technology that utilizes metal separation layers. Using this panel, we also fabricated a prototype of a side‐roll display for mobile uses. In these AMOLED displays, a white OLED combined with a color filter was used in order to achieve remarkably high resolution. For the white OLED, a tandem structure in which a phosphorescent emission unit and a fluorescent emission unit are serially connected with an intermediate layer sandwiched between the emission units was employed. Furthermore, revolutionary technologies that enable a reduction in power consumption in both the phosphorescent and fluorescent emission units were introduced to the white tandem OLED.     

A technique for precise depth representation in stereoscopic display

In observing a virtual 3D object displayed stereoscopically on a large screen, there is often a difference between the calculated depth and the perceived depth. This paper presents a method for reducing such differences of depth. To do this, we modify both the viewing position and the screen position in the stereoscopic calculation. The optimal amount of modification was determined from sample values of depth differences. The effectiveness of the proposed method is discussed on the merits of the experimental results. This technique decreased the average difference from 4.3 mm to 1.3 mm.     

Dynamic Recrystallization during the Sliding Wear of Alumina at Elevated Temperatures

In previous studies, a very fine grain size surface layer of several micrometer thickness has been consistently observed in the wear track of alumina couples after wear at elevated temperatures. Detailed microstructural observations have revealed that dynamic recrystallization is the most probable mechanism for the surface layer formation. In this study, grain size and thickness of the surface layer are reported for the samples tested under various wear conditions. Both the grain size and the thickness are dependent on the testing temperature, nominal contact pressure, and the sliding velocity. The strain rate and the local temperature of the wear surface are estimated taking frictional heat into account and the Zener-Hollomon parameter Z = exp( Q/RT ) is calculated. A logarithmic plot of the grain size and Z yields a good linear relationship. This linearity and the slope of –0.21, similar to that previously reported for metals, further substantiate that dynamic recrystallization occurring in the wear surface is responsible for the formation of the fine grain size surface layer     

Flame retardancy of poly(butylene terephthalate) blended with phosphorous compounds

The thermal degradation and flame retardancy of poly(butylene terephthalate) (PBT) were studied with a focus on the effect of phosphorous compounds. Thermogravimetric analysis, pyrolysis/gas chromatography/mass spectrometry (Py/GC/MS), and elemental analysis were used to analyze the flame retardancy, which were observed by an Underwriters Laboratory UL‐94 test and a cone calorimeter. The 50% degradation temperatures of PBT blends with phosphorous compounds were the same as that of neat PBT. Six scission products were assigned by Py/GC/MS. The burning times of the UL test of several PBT blends were much shorter than that of neat PBT. The relation between flame retardancy and thermal degradation was analyzed with respect to the results of the scission products and the char in burned polymers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2326–2333, 2004     

Analysis of gas transport properties of PPO/PS blends by Xe NMR spectroscopy

Relationships among variations of microvoids and gas transport properties for miscible poly(2,6-dimethyl-1,4-phenylene oxide) (PPO)/polystyrene (PS) blends in the glassy state have been investigated by Xe sorption, Xe permeation, and ¹²⁹Xe NMR measurements. Xe sorption isotherms of the blends can be interpreted successfully on the basis of the dual-mode sorption model. Decrease in the permeability of Xe is attributed to the decrease in the diffusivity of that in the Langmuir site. ¹²⁹Xe NMR spectra of ¹²⁹Xe in the blends show non-linear low-field shift with increasing sorption amount of Xe because of a fast exchange of Xe atoms between Henry and Langmuir sites. From the analysis of ¹²⁹Xe NMR chemical shifts, it is found that the mean volume of individual microvoids varies with a negative deviation against volume fraction of PPO in the blend. For PPO/PS blends, it has been clarified that the contraction of individual microvoids occurs by blending and highly affects gas transport properties.     

Thermoelectric properties of Fe0.98Co0.02Si2 with ZrO2 and rare-earth oxide dispersion by mechanical alloying

The n-type Co-doped β-FeSi₂ (Fe_0.98Co_0.02Si₂) with dispersion of several oxides, such as ZrO₂ or several rare-earth oxides (Y₂O₃, Nd₂O₃, Sm₂O₃ and Gd₂O₃), was synthesized by mechanical alloying and subsequent hot pressing. The effects of these oxide dispersions on the thermoelectric properties of Fe_0.98Co_0.02Si₂ were investigated. ZrO₂ was decomposed in the β phase, and the ZrSi and -FeSi phases, which are metallic phases, were formed in the samples with ZrO₂ addition. The Seebeck coefficient and the electrical resistivity were significantly decreased with increasing amount of ZrO₂, indicating that a part of the Zr atoms was substituted for Fe atoms in the β phase. In the case of the samples with rare-earth oxide addition, a decomposition of a large amount of these added oxides did not occur. However, the rare-earth oxide addition caused a slight increase in the amount of the phase. The Seebeck coefficient was significantly enhanced by the rare-earth oxide addition especially in the low temperature range. These facts indicated that a small amount of rare-earth oxides was decomposed in the β phase, and rare-earth elements were substituted for Fe atoms as a p-type dopant, resulting in the decrease in the carrier concentration. The rare-earth oxide addition was also effective in reducing the thermal conductivity.     

Assessment of protective function of steel rust layers by N2 adsorption

The specific surface area (SA) of the rusts formed by exposing various kinds of steels in different situations was determined by N₂ adsorption. The SA values of the rusts increased with the increase of corrosion rate, implying that the rust layers with large SA exhibit a high resistance to corrosion. The suppression of rusting by compact rust layers was interpreted by the blockage of pores in rust layers by the adsorption and capillary condensation of water. The SA values clearly reflect the corrosion levels estimated by the external observation. It was convinced that the SA measurement is a universal quantitative technique to appraisal the protective function of rust layers.     

ZL101合金半固态二次加热

采用半固态合金二次加热，对半固态坯料施加合理的二次加热路径，重新获得适于后续加工的具有近球状固相颗粒均匀分布的半固态组织。采用功率为20kW，频率为30kHz的高频感应加热装置，研究了采用再熔融加热法制备的ZL101半固态合金坯料的二次加热过程。结果表明：为了获得适于最终成形的半固态组织，有必要把半固态坯料二次加热过程分为几个加热速率不同的加热阶段，然后在半固态温度区间某一需要加工温度下进行适度保温。通过实验给出了ZL101合金半固态坯料二次加热条件，并讨论了二次加热条件对半固态组织演化的影响。     

Measuring the sizes of nanospheres on a rough surface by using atomic force microscopy and a curvature-reconstruction method

One of the advantages of atomic force microscopy (AFM) is that it can accurately measure the heights of targets on flat substrates. It is difficult, however, to determine the shape of nanoparticles on rough surfaces. We therefore propose a curvature-reconstruction method that estimates the sizes of particles by fitting sphere curvatures acquired from raw AFM data. We evaluated this fitting estimation using 15-, 30-, and 50-nm gold nanoparticles on mica and confirmed that particle sizes could be estimated within 5% from 20% of their curvature measured using a carbon nanotube (CNT) tip. We also estimated the sizes of nanoparticles on the rough surface of dried cells and found we also can estimate the size of those particles within 5%, which is difficult when we only used the height information. The results indicate the size of nanoparticles even on rough surfaces can be measured by using our method and a CNT tip.