公开(公告)号：JP2000203988A

公开(公告)日：2000-07-25

申请号：JP936499

申请日：1999-01-18

Applicant: AGENCY IND SCIENCE TECHN

Inventor： IGA TAKEO ,  MURASE YOSHIO ,  FURUKAWA MASAMICHI ,  TABATA HIDEYO

IPC: C30B23/00 ,  C30B29/20 ,  C30B29/54

Abstract: PROBLEM TO BE SOLVED: To provide a method for producing an ultrapure material by sublimation refining. SOLUTION: In the method for refining a sublimable molecular compd. to obtain an ultrapure material by sublimation refining, a fiber not disturbing the formation of a free surface after the start of growth is used as a nucleation field, the compd. is sublimated on the fiber to form many single-crystal grains, the crystal surface is washed away, if necessary, with a solvent along with part of the crystals to remove the impurities close to the surface, and then the crystal grains are recovered by further sublimation. Since dry refining is used, a special installation such as a clean room is not needed, and the troublesome handling of an ultrapure material is considerably reduced. Provided that an easy-to-sublimate molecular compd. is obtained, this technique is effective regardless of the kinds of hosts and impurities, and the method is useful as a technique to make a material ultrapure.

公开(公告)号：JPS63147820A

公开(公告)日：1988-06-20

申请号：JP29446486

申请日：1986-12-10

Applicant: AGENCY IND SCIENCE TECHN

Inventor： MURASE YOSHIO ,  IGA TAKEO

IPC: C01F7/00 ,  C01F7/30

Abstract: PURPOSE:To obtain an acicular alumina particle with good reproducibility, the length of which is easily controlled, by previously adding acid or base into an aq. soln. of NH4HCO3 used in a ripening stage for crystallizing a reaction product of Al salt with NH4HCO3. CONSTITUTION:The reaction product, which is obtained by allowing a water-soluble Al salt such as ammonium alum or aluminium sulfate and NH4HCO3 to cause an aq. soln. reaction, is heated and applied with the ripening treatment in the aq. soln. of NH4HCO3. The ripening treatment is usually applied at 60-150 deg.C and is held at the temp. for 1-140hr. In this case, it is necessary that the acid or the base is previously added to the aq. soln. of NH4HCO3 used for the ripening treatment and then the ripening treatment is applied. In this case, the length of the generated alumina particle is controlled with the amt. of the added acid or base. Then, sulfuric acid or hydrochloric acid, etc., for example, is used as the acid, and KOH, NaOH, etc., for example, is used as the base, respectively.

公开(公告)号：JPH0543225A

公开(公告)日：1993-02-23

申请号：JP22524991

申请日：1991-08-09

Applicant: AGENCY IND SCIENCE TECHN

Inventor： MURASE YOSHIO ,  IGA TAKEO

IPC: C01F7/02 ,  C01F7/30 ,  C04B35/10

Abstract: PURPOSE:To increase production efficiency by heating an acicular precursor of Al2O3 after mixing with an Si compd. CONSTITUTION:An aq. soln. of (NH4)HCO3 is added to an aq. soln. of ammonium alum and a formed white precipitate is aged by heating to obtain an acicular precursor of Al2O3 such as Al(NH4)(CO3)(OH)2. A small amt. of an Si compd. forming Si oxide when heated in the air is added to the precursor and they are mixed and dried. The resulting powder is heated to a prescribed temp. in the air. Acicular alpha-Al2O3 signal crystal particles or Al2O3 type oxide single crystal particles are efficiently obtd. with high reproducibility.

公开(公告)号：JPH1121199A

公开(公告)日：1999-01-26

申请号：JP19184697

申请日：1997-07-01

Applicant: AGENCY IND SCIENCE TECHN

Inventor： MURASE YOSHIO ,  IGA TAKEO

IPC: C30B7/10 ,  C30B29/62 ,  C30B33/02

Abstract: PROBLEM TO BE SOLVED: To produce a fibrous aluminum compd. AACH and its fired body optimum for producing α-alumina single-crystalline particles having a fibrous form and alumina type oxide fibers. SOLUTION: An aq. soln. or suspension of a water-soluble or slightly water- soluble aluminum compd. such as aluminum sulfate, aluminum chloride, aluminum ammonium sulfate, aluminum hydroxide, aluminum ethoxide, aluminum isopropoxide or acetylacetonatoaluminum and, etc., is injected into an aq. NH4 HCO3 soln. having such a sufficiently high concn. of CO3 ions as >=0.01 mol/l or a basic aq. soln. having a sufficiently high concn. of CO3 ions and contg. NH4 ions and aging is carried out by heating at >=100 deg.C to produce the objective fibrous single-crystalline particles of AlNH4 CO3 (OH)2 having an aspect ratio of >=10, >=0.5 μm length and >=0.01 μm thickness. The objective fired body of the fibrous particles is produced by heating the fibrous particles to >=1,000 deg.C.

公开(公告)号：JPH05245369A

公开(公告)日：1993-09-24

申请号：JP8474092

申请日：1992-03-06

Applicant: AGENCY IND SCIENCE TECHN

Inventor： MORI TOSHIAKI ,  HORIUCHI TATSURO ,  MURASE YOSHIO

IPC: B01J21/12 ,  C01F7/02 ,  F23C13/00 ,  F23C11/00

Abstract: PURPOSE:To produce alumina keeping large surface area by calcining an acicular crystal of an alumina precursor coated with silica at a high temp. CONSTITUTION:An acicular crystal of carboxyaluminum ammonium hydroxide prepared by dropping an aq. solution of ammonium alum into an aq. solution of ammonium bicarbonate is coated by adding a small quantity of tetraethoxy silane on its surface and is calcined at 1300-1400 deg.C to obtain the alumina having 20-35m /g surface area.

公开(公告)号：JPS63147821A

公开(公告)日：1988-06-20

申请号：JP29446586

申请日：1986-12-10

Applicant: AGENCY IND SCIENCE TECHN

Inventor： MURASE YOSHIO ,  IGA TAKEO

IPC: C01F7/00 ,  C01F7/30

Abstract: PURPOSE:To easily obtain an extremely slender acicular Al particle by thermally decomposing a needle crystal of ammonium aluminium carbonate hydroxide generated by applying an aluminium hydroxide or its hydrate with the ripening treatment. CONSTITUTION:The needle crystal of ammonium aluminium carbonate hydroxide expressed with the formula of Al(NH4)CO3(OH)2 is allowed to generate by the above-mentioned process and furthermore with the ripening treatment at >=60 deg.C. And the concentration of the aq. soln. of NH4HCO3 used for the ageing treatment is usually in the range of 0.1-1.5mol NH4HCO3/l. Further, the aq. soln. added with the varieties of the water-soluble acid or base is usable as the above-mentioned aq. soln., at request. Then, the aimed extremely slender alumina particle, for example, the particle having more or less 0.01mum width and a few mum length, is easily obtained by calcining the above-mentioned AAC crystal usually in the temp. range of 400-1,100 deg.C.