Preparing submicron particle of (Pb1-x, Lax) (Zry, Ti1-y) 1-x/4O3; (PLZT) for ceramic condensers or chemical sensors has been achieved by using the oxide-metal alkoxide method and/or fining of PLZT with monopotassium dihydrogen phosphate into PLZT. Particles of less than 1μm diameter have not been obtained by the conventional mechanical grinding of ferroelectric ceramics. The dielectric constant of ceramics prepared by fining PLZT (x=0.09, y=0.65) with monopotassium dihydrogen phosphate was lower than that of the transparent PLZT consisted of a larger particle, but the temperature dependency of the dielectric constant value was depressed. Crystal structures of PLZT (x<0.2, y>0.65) were hardly influenced by an adding of KH2PO4.
A new type of surface electromigration of metal covored semiconductors was recently found and investigated by the author's group. The experimental method and some typical results are described in comparison with the conventional electromigration. The specimens used for the observation of this phenomenon are In, Ag, Sb and Sn pads with a thickness of several monolayers evaporated on cleaned Si (111) substrates of 7×7. The following phenomena were observed by the scanning Auger electron spcctroscopy. Movement of the pad toward the cathode occurs with the application of dc current through Si substrate. A characteristic layer with a uniform thickness and structure proper to the transport grows on the cathode side of the pad during the supply of dc current.
Techniques for the characterization of semiconductor surface or interface electronic states were reviewed. Comparison was made between two limitting cases : free surfaces or pseudo-free surfaces with several monolayers and the interfaces between semiconductors and thick insulating layers. A novel technique that can be applied to the both cases is expected for better understanding of semiconductor interfaces.
The mechanism for the formation of ZrSiO4 from a system of Si(OC2H5)4-ZrOCl2·8H2O-C2H5OH solution was investigated in relation to the T-→M-transformation of ZrO2. The heat-treated powders were mixtures of metastable fine T-ZrO2 and amorphous SiO2. The T-ZrO2 aggregates were gradually transformed into M-ZrO2 with an increase in temperature. This is due to the decrease of surface energy. The solid state reaction between ZrO2 and SiO2 is crystallographically assumed to have a large activation energy, and, therefore, the T-→M-transformation is preferentially proceeded below ca. 1300°C without forming ZrSiO4. Beyond the temperature, the interface reaction between T-ZrO2 and SiO2 took place and resulted in the formation of ZrSiO4. With an increase in temperature, the formation reaction was accelerated due to the Hedvall effect, whence T-ZrO2 was responsible only for the reaction not for the transformation. With decreasing amount of T-ZrO2, the formation reaction terminated, but the addition of transition metal ions such as Ni2+ promoted the interface reaction between M-ZrO2 and SiO2. In order to increase the formation rate of ZrSiO4, it was important to maintain the T-ZrO2 powders metastable and fine by adding transition metal ions and by grinding the dried powders.
In the space station, maintaining the ecological life is essential. For this purpose the exhausted carbon dioxide gas must be converted into oxygen. The closed recycle system and the catalysts used are described.
A new technology for producing color patterns on stainless steel has been developed by utilizing YAG pulse laser irradiation. This technology is based on a new finding that an enrichment of chromium occurs in the surface layer of stainless steel immersed in an electrolyte solution when laser beams irradiate the surface through the solution. By combination of the change in surface composition due to laser irradiation and a subsequent coloring treatment (an oxidation process to provide an interference color), color patterns by computer aided design (CAD) can be produced on the sheet surfaces.