Tosoh Corporation

Akio Kondo

Osamu Matsunaga

Toshiya Takahara

Satoshi Kurosawa

Yukio Ohnuki

Kentaro Utsumi

A sintered ITO compact is provided which is capable of retarding nodule formation, or particle generation. The sintered ITO compact is composed of In, Sn, and O, and has avelage length of void size of not larger than 0.7 .mu.m. This sintered ITO compact is produced by sintering, substantially in an oxygen atmosphere, a green compact formed from a mixed powder of indium oxide power and tin oxide powder, the mixed powder containing the tin oxide powder at a content ranging from 5% to 15%, and the tin oxide powder having particles of a particle size of not more than 1 .mu.m constituting not less than 90% portion thereof; or produced by sintering, in an oxygen atmosphere, a green compact formed from a mixed powder of indium oxide powder and tin oxide powder, the mixed powder having a tap density of not less than 1.8 g/cm.sup.3, and the tin oxide powder having a maximum particle size of not larger than 1 .mu.m and a median diameter of not larger than 0.4 .mu.m.

Process of preparing high-density sintered ITO compact and sputtering

A sintered ITO compact having an ultra-high density of at least 7.08 g/cm.sup.3 is produced by a process wherein an aqueous slurry comprised of indium oxide, tin oxide, a binder, a dispersant and an aqueous medium is cast in a mold, and the thus-obtained cast green body is sintered. The aqueous slurry used is prepared by the steps of: dispersing uniformly a tin oxide powder and a dispersant in an aqueous medium to give an aqueous slurry; allowing the aqueous slurry to stand whereby coarse particles of tin oxide are sedimented; separating by decantation an upper liquid layer of the aqueous slurry containing finely divided particles of tin oxide (preferably, the secondary particle sizes of which are not larger than 4 .mu.m) and the dispersant from a lower liquid layer containing the sedimented coarse particles; and then, incorporating an indium oxide powder and a binder in the separated upper liquid layer containing finely divided tin oxide particles and the dispersant to give an aqueous slurry.

Process for producing sintered ITO compact

An ITO sputtering target comprised of indium oxide and tin oxide and having a density of at least 6.4 g/cm.sup.3, wherein the center line average height (R.sub.a) of the surface to be sputtered is not larger than 0.8 .mu.m, and at least one property selected from the following (i), (ii) and (iii) is satisfied: (i) the maximum height (R.sub.max) is not larger than 7.0 .mu.m, (ii) the ten point average height (R.sub.z) is not larger than 6.0 .mu.m, and (iii) the maximum height (R.sub.t) of said surface as expressed by the distance between two lines which are parallel to the center line of a surface roughness curve drawn as measured at a sample length of 2.5 mm, and which sandwich said surface roughness curve, is not larger than 6.5 .mu.m. Preferably, R.sub.a and the or each property (R.sub.max, R.sub.z or R.sub.t) selected from (i), (ii) and (iii) satisfy the formula: R.sub.a .times.(R.sub.max, R.sub.z or R.sub.t).ltoreq.3.0 .mu.m.sup.2.

ITO sputtering target

A magnetic recording medium having coated thereon a lubricant of such a purity that no impurities and low molecular weight species are substantially detected by gel permeation chromatography.

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Konan, Japan

Akio Kondo