Junichi Mohri

A compositional fluctuation and properties of Pb(Zr, Ti)O3

Abstract Structure and properties of piezoelectric materials of composition Pb(ZrxTi1−x)O3 near the morphotropic phase boundary between tetragonal and rhombohedral phases are studied. When these materials were prepared by a new “wet-dry combination technique”, no coexistence of these two phases was found in any range of compositions. This fact is in contrast with the case of Pb(ZrxTi1−x)O3 prepared by an ordinary dry method. The coexistence behavior is interpreted in terms of compositional fluctuation, on the basis of which various properties of the materials are explained.

Synthesis of Telechelic Olefin Polymers via Catalyzed Chain Growth on Multinuclear Alkylene Zinc Compounds

Multinuclear alkylene zinc (MAZ) compounds of the type EtZn-(R″-Zn)n-Et (R″ = ethyl and propyl branched alkylene groups) were synthesized by a simple one-step procedure in nonpolar hydrocarbon solvents from α,ω-dienes (e.g., 1,7-octadiene or 1,9-decadiene) and diethylzinc using a bis(salicylaldiminato)Zr(IV) complex, [(2-methylcyclohexyl)N═CH(2-O-C6H3-3,5-di-tert-butyl)]2ZrMe2, as a catalyst. The MAZ serves as a divalent reversible chain-transfer agent for olefin polymerization, resulting in telechelic Zn-metalated polyolefins whose molecular weights are controllable over a wide range. The Zn-terminated telechelics serve as a polymer precursor for further reactions and can be converted into a variety of telechelic functionalized polyolefins in high yield.

Sintering of Synthetic Mica by a Hydrothermal Equipment

Mica is known to be chemically and thermally stable and also to have a good electrical insulation and mechanical strength. Moreover mica is a famous machinable ceramic material which can be machined to precision tolerances using conventional tools. The machinability results from the fact that fracture propagation is very difficult across the vassal planes of mica. For this reason individual plate-like mica crystals are preferred to array randomly for machinable mica ceramics.

Sintering of titanium metal

AbstractStoichiometric TiH2 powder, which is stable in air, was used as a starting material in the sintering of titanium metal. Powder compacts of stoichiometric TiH2 , finely ground in air, were fired in vacuum to remove the hydrogen, and then sintered. Using this method the Ti particles did not experience surface oxidation, which would otherwise usually occur, and the powder showed good sinterability, giving a sintered density above 98% of theoretical at the relatively low temperature of 1000°C

Sintering of Synthetic Mica by a Hydrothermal Hot Isostatic Process

Mica is well known as one of machinable ceramics.1,2) Mica ceramics which are made of synthetic mica, generally fluorphlogopite, can be fabricated by a sintering of its powder compact or melting-nucleation-crystallization such as glass-ceramics.