Yukihito Nagashima

Prediction of optical properties of commercial soda–lime-silicate glasses containing iron

Abstract We provide a new method to predict the optical absorption of soda–lime-silicate glasses containing low levels (≲1 wt%) of iron. We assumed that octahedral and tetrahedral ferric iron as well as octahedral ferrous iron contribute to the optical absorption of the glasses. The absorption coefficients were determined for the respective colorants, and the total transmission spectra were calculated in the wavelength range from 200 to 2100 nm. It has been shown that the calculated spectra agree well with the experimental ones in the entire range of wavelength. We have further calculated such optical properties as visible light transmittance, total solar energy transmittance, and total solar ultraviolet transmittance. It has been demonstrated that these optical properties are satisfactorily reproduced by the calculations.

Coherent interface structures and intergrain Josephson coupling in dense MgO/Mg2Si/MgB2 nanocomposites

Many efforts are under way to control the structure of heterointerfaces in nanostructured composite materials for designing functionality and engineering application. However, the fabrication of high-quality heterointerfaces is challenging because the crystal/crystal interface is usually the most defective part of the nanocomposite materials. In this work, we show that fully dense insulator (MgO)/semiconductor(Mg2Si)/superconductor(MgB2) nanocomposites with atomically smooth and continuous interfaces, including epitaxial-like MgO/Mg2Si interfaces, are obtained by solid phase reaction between metallic magnesium and a borosilicate glass. The resulting nanocomposites exhibit a semiconductor-superconducting transition at 36 K owing to the MgB2 nanograins surrounded by the MgO/Mg2Si matrix. This transition is followed by the intergrain phase-lock transition at ∼24 K due to the construction of Josephson-coupled network, eventually leading to a near-zero resistance state at 17 K. The method not only provides a s...