Preparation of Mn2+-Cu+ co-doped P2O5–ZnO–Al2O3 glasses and their red fluorescence properties

To make a Mn²⁺-doped red glass phosphor that can be excited with ultraviolet (UV) light of light-emitting diodes (LEDs), 60P₂O₅-35ZnO-5Al₂O₃-8MnO-xCu₂O glasses (x = 0-1.00) were prepared by a melt-quenching method at 1200-1400°C for 30-180 minutes in atmospheric air, and the redox of Mn and Cu as well as fluorescence properties were investigated. The Mn²⁺ ion was not reduced and oxidized in the melting, quenching, and annealing processes. The valence of Cu in the glasses changed in the order of 0, 1+, and 2+ with the increase in the amount of Cu₂O and in the melting temperature and time. In this study, a 60P₂O₅-35ZnO-5Al₂O₃-8MnO-0.10Cu₂O glass melted at 1250°C for 90 minutes, having the highest Cu⁺ concentration, showed the strongest Mn²⁺ red fluorescence under the UV light at 275 nm. This strong Mn²⁺ red fluorescence has been caused by the energy transfer from excited Cu⁺ ions to Mn²⁺ ions.     

Unperturbed dimension of poly(4-acetoxystyrene) measured in good and theta solvents

In order to obtain the additional data concerning the unperturbed dimension of poly-4-substituted styrene, light scattering measurements are performed on the twenty-two fractions with molecular weight of (0.91–352)·10⁴ of poly(4-acetoxystyrene) in dioxan at 25°C, from which the molecular weight obtained was found easily to be evaluated with the gel permeation chromatography using THF. Phase separation experiments for this polymer indicate that the theta state is attained in isopropyl acetate at 19.7°C and butyl acetate at 26.8°C. By making viscosity measurements at that state, the value of K_Θ is directly evaluated as 5.4·10^?4 dl g^?1. The limiting viscosity number is also obtained in good solvents, THF and dioxan, at 25°C and constants of the Mark-Houwink-Sakurada equation in each solvent are determined. Further, approximately the same K_Θ as above is obtained from these data with the Stockmayer-Fixman plot. The calculated value of steric factor, 2.37, on this polymer may be plausible, compared with those of polyvinylaromatic derivatives.     

Preparation of Laminin-apatite-polymer Composites Using Metastable Calcium Phosphate Solutions

A synthetic polymer with a laminin-apatite composite layer on its surface would be useful as a percutaneous device. The preparation of such a composite was attempted in the present study using poly（ ethylene terephthalate ） （PET） and polyethylene （PE） as the synthetic polymer. PET and PE plates and those pretreated with an oxygen plasma were alternately dipped in calcium and phosphate ion solutions, and then immersed in a metastable calcium phosphate solution supplemented with laminin （ LCP solution ）. The PET and PE plates pretreated with an oxygen plasma formed a uniform and continuous layer of a laminin-apatite composite on their surfaces. In contrast, the PET and PE plates that had not been pretreated with an oxygen plasma did not form a continuous layer of a laminin-apatite composite on their surfaces. The hydrophilic functional groups on the PET and PE surfaces introduced by the plasma treatment were responsible for the successful laminin-apatite coruposite coating.     

A 0.1-μm delta-doped MOSFET fabricated with post-low-energyimplanting selective epitaxy

A simple fabrication technology for delta-doped MOSFETs, named post-low-energy implanting selective epitaxy (PLISE) is presented. The PLISE technology needs no additional photo-lithography mask, deposition step or etching step even for CMOS devices. The only additional step is growing undoped epitaxial channel layers by UHV-CVD after the channel implantation. With this technology, delta-doped NMOSFETs with 0.1-μm gate length were successfully fabricated. By optimizing the epi-layer thickness and the channel doping level, short-channel effects are suppressed enough to achieve 0.1-μm gate length. Moreover, the junction capacitance at zero bias is reduced by 50%     

The temperature dependence of luminescence from a long-lasting phosphor exposed to ionizing radiation

The temperature dependence of luminescence from a long-lasting phosphor (LLP), SrAl₂O₄ : Eu²⁺,Dy³⁺, exposed to ionizing radiation has been measured to understand the LLP luminescence mechanism. Evaluation of the decay constants of the LLP exposed to -, β- or γ-rays at temperatures from 200 to 390 K showed that the decay constant is divided into four components ranging from 10⁻⁴ to 10⁻¹ s⁻¹ with activation energies of 0.02–0.35 eV.

Total luminous intensity from the LLP with changing irradiation temperature has its maximum value around the room temperature. Irradiation at elevated temperature (390 K) has the total luminescence pattern with monotonous decrease as temperature rises. As a result of evaluating the temperature dependence of luminescence, the luminescence mechanism is considered as follows:

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Fiber-optic devices for local area network application

Recent developments on fiber-optic devices are reviewed from the local area network (LAN) application viewpoint. Future technical trends are also discussed, along with current research activities. In local area network systems, low device cost and easy maintenance or maintenance-free devices are especially required. Light sources and photodetectors suitable for the systems are described. InGaAsP/InP light emitting diodes can cover a broad application field, up to a gigabits per second super high-speed network region. Optical passive devices, which include branching couplers, switches and connectors, are mentioned as essential components. Compact transmitter/receiver module technology is a key factor in realizing optical-fiber local area network systems. An example of 200-Mbit/s transmitter/receiver module is reported.     

Effect of Forming Pressure on the Internal Structure of Alumina Green Bodies Examined with Immersion Liquid Technique

Green bodies prepared by compaction of alumina granules were made transparent by an immersion liquid technique, and the internal structure was characterized with an optical microscope to study the effect of forming pressure on the internal structure. Clear images obtained by the technique provide more detailed information than other existing methods for structures ranging from one to tens of micrometers. Intergranular pores were present between unfractured granules. Their sizes and concentration tended to decrease with increasing forming pressure. However, pores were clearly present even in the green body prepared at 600 MPa. A rod- and needlelike feature was also found and was concluded to correspond to a high-density region. The significance of large pores and high-density regions on processing as well as the details of the technique is discussed.