The nepheline-based transparent glass-ceramics are promising candidates for cover glass applications in electronic displays owing to their superior mechanical properties (than glasses) and ability to be chemically strengthened. However, our poor understanding about the kinetic and thermodynamic drivers controlling their crystallization processes usually results in their opacification and development of large internal stresses. The present work focuses on the development of nepheline-based nanocrystalline transparent glass-ceramic designed in the Na 2 O-Al 2 O 3 -SiO 2 ternary system nucleated with P 2 O 5 . The temporal evolution of the phosphate and nepheline nanocrystal formation has been followed using X-ray diffraction, scanning/transmission electron microscopy, and energy-dispersive spectroscopy. The incorporation of P 2 O 5 in the glass structure leads to the phase separation resulting in the crystallization of nanocrystalline Na 3 PO 4 as an intermediate phase; thus, acting as a nucleating site for volume crystallization of nepheline. The optimization of nucleation and growth profile in the designed composition results in the formation of a transparent glassceramic with high optical transmittance (91.5 ± 0.1%).

The rolling out of step-s with constant stretch (PV-E) is a new technology developed for rolling steel in recent years. We studied the B2F steel rolled by the new technology with the aid of the positron annihilation technique. The relationships of the average lifetime of positron annihilation with the rolling pressures, the ratio of rolIing speed and the mechanical properties are obtained. The value of the lifetime sliows that there are many dislocations and vacancy clusters in B,F steel after being rolled, and which are supported by observations with a transmission electronmicroscope.

The Bethe-Salpeter equation for bound states of a spinor straton-antistraton pair is discussed under the assumption that the interaction between the straton-antistraton pair is purely scalar and may be described by a relativistically covariant v-potential. The structure wave function of the meson is expanded according to the O(4) group, and solved numerically first by keeping the lowest partial waves, and then the in-fluence of the higher partial waves are considered. Numerical results of the wave functions are given both in the momentum space and configuration space, and the mean square radius of the meson is evaluated. It is shown that the low partial wave-large component approximation is valid for tightly bound systems. As a comparison, the loosely bound systems are also discussed.

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