We confirmed 64 mm-diameter magneto-optical disk systems of 4.7 Giga-byte have sufficiently wide system tolerance by domain-wall-displacement detection disks and land/groove substrates with one-side-wobbled grooves.
We developed a side-wall-annealing technique for land/groove substrates. By applying this technique to our Domain Wall Displacement Detection (DWDD) Magneto-Optical (MO) recording stack formed on a land/groove substrate, even with an NA of 0.6 and a wavelength of 660 nm, we realized a density of 15 Gbit/in<sup>2</sup> with a sufficiently wide recording tolerance. This density corresponds to a capacity of 4.7 GB mm disc like MiniDisc.
To realize high density magneto-optical recording, it is important to suppress the disk noise. As we have reported, UV irradiation before sputtering films on the substrate could suppress the disk noise. But UV irradiation changed the shape of land and groove. We found that it caused poor recording power tolerance, because cross-talk could not be canceled using the phase compensation method. We developed a substrate formed by using a RIE process. Using this RIE-formed substrate, we could suppress the disk noise without UV-irradiation and improve the recording power tolerance.
The electrochromic nickel oxide films were prepared onto transparent conducting film on glass substrate by the sol-gel method using an ethylene glycol solution of nickel nitrate hexahydrate. The films produced by the dip-coating method and calcined at 250, 300, and 350 degree(s)C. The formed films were characterized by their electrochromic behavior in cyclic voltammetry. The formed films showed electrochromic behavior in 1M KOH aqueous solution as electrolytic solution. The cyclic voltammograms were recorded up to 100 cycles for each film. The anodic peak of the coloration reaction appeared at approximately +400 mV, while the cathodic peak of the bleaching reaction occurred at about +200 mV versus Ag/AgCl. Both the anodic peak and the cathodic peak increased with an increase of the cyclic numbers in voltammograms, whereas these peaks at 100 cycles decreased with an increase of the calcination temperature of nickel oxide films. The calcination gave great influence on the other electrochromic behaviors of nickel oxide films.
To investigate the microstructure of nickel oxide electrochromic films, cross-sectional observation of sputtered nickel oxide film was performed using a high resolution electron microscope. Lattice and atomic image could be observed for an as-deposited sample and a bleached sample. These images showed that crystallized NiO exists in both samples. As- deposited film contained a small amount of Ni<SUB>2</SUB>O<SUB>3</SUB>. One of  axis shrank about 3% and the lattice was a little bit strained in the bleached state. The fact that no trace of Ni(OH)<SUB>2</SUB> or other species was observed implies that the boundary and surface of NiO microcrystallites played an important role in the electrochromic reaction.
Silicon-monoxide (SiO) film on aluminum (Al) substrate is known as one of the spectral selective radiating materials that utilizes selective infrared emission through the atmospheric window (8-13 micrometers ). Nevertheless, the radiative cooling power of them is rather low comparing to that of black body which is ranging from 60 to 100 W/m<SUP>2</SUP>, depending on the model of the atmosphere and the humidity. In other words, the sky radiator must have a considerably large are film with homogeneous thickness. This is the reason why it is difficult to put the radiative cooling idea to practical use. To attempt a solution of this problem, we have examined some silicon composite films and/or their multilayers on aluminum substrate by numerical calculation. The main results are following: (1) (SiO + Si)/SiO film with adequate thickness shows the best result to obtain the high power radiative cooling. The radiative cooling power at room temperature (300 K) is expected to be about 20% larger, and the obtainable temperature drop to be about 10% larger than that of SiO single film on Al. (2) The difficulty of deposition of the coating with large area and homogeneous thickness can be overcome by use of porous SiO stacked film whose optical properties are not so influenced by the film thickness. If we couple the above mentioned materials with cover films of high reflectance for solar radiation and high transmittance in atmospheric window region, the radiative cooling may be more realistic even under direct daylighting.
Thermochromic VO<sub>2</sub> films were prepared by reactive magnetron sputtering under various conditions of substrate temperature, total sputter pressure and oxygen flow ratio and characterized by XRD, RBS, AFM and spectrophotometry. Films with VO<SUB>2</SUB> single phase were formed from a fairly low substrate temperature of 300 degree(s)C by precisely controlling the oxygen flow ratio. The use of vanadium-nucleated substrates significantly improved the crystallinity of VO<SUB>2</SUB>. Tungsten doped V<SUB>1-x</SUB>W<SUB>x</SUB>O<SUB>2</SUB> films with x equals 0 approximately 0.26 were formed by dual-target sputtering and the thermochromism of films was evaluated. The tungsten doping linearly hysteresis loop width.