A phase change optical disk using a new quaternary system of Ag-In-Sb-Te as the active layer will be reported. With this disk, “complete erasure” of the recorded signal has been achieved. A carrier-to-noise ratio of 47 dB and an erase ratio of -47 dB were obtained in the two-pass writing-erasing mode with a linear velocity of 7 m/s and a writing power of 11 mW. In the one-pass overwriting mode, a carrier-to-noise ratio greater than 40 dB was obtained and this recorded signal was also completely erased. The peak power and the bias power for the overwriting were 10 mW and 5 mW, respectively. The facts that the widths of the written marks are narrow and that no large crystalline grains are observed in the periphery of the written marks are considered to be the major causes for the high erasability. We also found that the existence of fine crystalline particles in the initialized active layer can be considered to be of great advantage to high sensitivity.

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We describe a series of experiments and computer simulations on vibrated granular media in a geometry chosen to eliminate gravitationally induced settling. The system consists of a collection of identical spherical particles on a horizontal plate vibrating vertically, with or without a confining lid. Previously reported results are reviewed, including the observation of homogeneous, disordered liquid-like states, an instability to a 'collapse' of motionless spheres on a perfect hexagonal lattice, and a fluctuating, hexagonally ordered state. In the presence of a confining lid we see a variety of solid phases at high densities and relatively high vibration amplitudes, several of which are reported for the first time in this article. The phase behaviour of the system is closely related to that observed in confined hard-sphere colloidal suspensions in equilibrium, but with modifications due to the effects of the forcing and dissipation. We also review measurements of velocity distributions, which range from Maxwellian to strongly non-Maxwellian depending on the experimental parameter values. We describe measurements of spatial velocity correlations that show a clear dependence on the mechanism of energy injection. We also report new measurements of the velocity autocorrelation function in the granular layer and show that increased inelasticity leads to enhanced particle self-diffusion.

Crystals of Ba4+xNa2-xNb10-xTixO30 (x<0.8) were pulled from the melts and their optical and dielectric properties were examined. They were all biaxial, though the orthorhombic-to-tetragonal transition point was lowered with Ti substitution. The birefringence nb-na was so small that any detwinning procedure seemed unnecessary. The figure of merit for electrooptical performance was larger than that of Ba2NaNb5O15. An analysis of the observed results in birefringences and half-wave voltages was performed in comparison with a phenomenological calculation based on the spontaneous Kerr effect.