Preparation of finely divided ferrite powders

• US 4,664,831 A
• Filed: 08/16/1982
• Issued: 05/12/1987
• Est. Priority Date: 08/19/1981
• Status: Expired due to Fees

• Current Assignee: BASF AG (BASF SE)
• Original Assignee: BASF AG (BASF SE)
• Inventors: Hibst, Hartmut, Kullmann, Udo
• Primary Examiner(s): Cooper, Jack
• Application Number:
  US06/408,599
• Time in Patent Office: 1,730 Days
• Field of Search: 423/594, 423/632, 252/62.56, 252/62.59, 252/62.6, 252/62.61, 252/62.62, 252/62.63, 252/62.64
• US Class Current: 252/62.59
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01G 49/0036 containing one alkaline earth metal, magnesium or lead
• CPC Class Codes: C01G 49/0063 containing zinc
• CPC Class Codes: C01G 49/0072 containing manganese
• CPC Class Codes: C01G 49/009 Compounds containing, besides iron, two or more other elements, with the exception of oxygen or hydrogen
• CPC Class Codes: C01G 51/00 Compounds of cobalt
• CPC Class Codes: C01G 51/006 Compounds containing, besides cobalt, two or more other elements, with the exception of oxygen or hydrogen cobaltates C01G51/40
• CPC Class Codes: C01G 53/00 Compounds of nickel
• CPC Class Codes: C01G 53/006 Compounds containing, besides nickel, two or more other elements, with the exception of oxygen or hydrogen nickelates C01G53/40
• CPC Class Codes: C01P 2002/32 spinel-type (AB2O4)
• CPC Class Codes: C01P 2002/52 containing elements as dopants
• CPC Class Codes: C01P 2004/20 extending in two dimensions, e.g. plate-like
• CPC Class Codes: C01P 2004/41 octahedron-like
• CPC Class Codes: C01P 2004/61 Micrometer sized, i.e. from 1-100 micrometer
• CPC Class Codes: C01P 2004/62 Submicrometer sized, i.e. from 0.1-1 micrometer
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: C01P 2006/42 Magnetic properties
• CPC Class Codes: G11B 5/70678 Ferrites
• CPC Class Codes: H01F 1/36 in the form of particles H01F1/346, H01F1/348 and H01F1/38 take precedence

Abstract

A process for the preparation of finely divided ferrites of the general formula

MeFe.sub.2 O.sub.4                                         (I)

where Me=aMn+bNi+cZn+dCo+eFe(II), and the atomic weight ratios a, b, c, d and e are each from 0 to 1 and their sum is 1, or

M.sub.2.sup.1 Me.sub.2.sup.1 Fe.sub.12 O.sub.22            (II)

where M¹ is barium, strontium, calcium and/or lead, and Me¹ is divalent manganese, copper, iron, cobalt, nickel, zinc, magnesium and/or equimolar amounts of lithium and trivalent iron, or

M.sup.2 (Me.sup.2 Ti).sub.x Fe.sub.12-2x O.sub.19          (III)

where M² is barium or strontium, Me² is zinc, nickel and/or cobalt and x is from 0 to 1.5, wherein the aqueous solutions of the salts required for the particular composition are reacted with an aqueous solution of sodium carbonate and/or potassium carbonate, the water is removed, the dry salt mixture is heated at from 800° to 1200° C., and the resulting finely divided ferrite of the predetermined composition is isolated by leaching with water.

Claims

1. A process for the preparation of a finely divided ferrite of the formula

2. A process for the preparation of an isotropic ferrite powder having the spinel structure, of the formula MeFe₂ O₄ (I), where Me=a Mn+b Ni+c Zn+dCo +e Fe (II), and the atomic weight ratios a, b, c, d and e are each from 0 to 1 and their sum is 1, wherein an aqueous solution or suspension of one or more of the Me salts and an aqueous iron(III) chloride solution are reacted with an aqueous solution of sodium carbonate and/or potassium carbonate, the resulting mixture, consisting of sparingly soluble MeCO₃ and iron(III) carbonate in a solution of sodium chloride and/or potassium chloride, is dried without intervening filtering and washing steps, the dry salt mixture is then heated at above the melting point of sodium chloride and/or potassium chloride but not above 1200°

C., and the resulting ferrite of the composition MeFe₂ O₄, which has octahedral particules, is isolated by leaching with water.

3. A process for the preparation of a hexagonal Me₂ Y ferrite of the formula M¹₂ Me²₂ Fe₁₂ O₂₂ (II), where M¹ is barium, strontium, calcium and/or lead and Me¹ is divalent manganese, copper, iron, cobalt, nickel, zinc, magesium and/or equimolar amounts of lithium and trivalent iron, wherein an aqueous solution or suspension of an M¹ salt, an aqueous solution or suspension of an Me¹ salt and aqueous solution of an iron(III) salt are reacted with an aqueous sodium carbonate solution, the resulting mixture, consisting of sparingly solution M¹ salt, Me¹ salt and iron(III) carbonate in a sodium salt solution, is dried without intervening filtering and washing steps, the dry salt mixture is then heated at from 800°

to 1050°

C., and the resulting flaky Me¹₂ Y ferrite is then isolated from the Me¹₂ Y ferrite/sodium salt mixture by leaching with water.

4. A process for the preparation of a finely divided hexagonal ferrite of the formula M² (Me² Ti)_x Fe_12-2 xO₁₉ (III), where M² is barium or strontium, Me² is zinc, nickel, and/or cobalt and x is from 0 to 1.5, wherein an aqueous barium chloride or strontium chloride solution and an aqueous iron(III) chloride solution, with or without the addition of titanium tetrachloride, are reacted with an aqueous sodium carbonate solution, the resulting mixture, consisting of sparingly soluble precipitates in a sodium chloride solution, is dried without intervening filtering and washing steps, the dry salt mxiture is then heated to above the melting point of the sodium chloride but not above 950°

C., and the resulting finely divided flaky hexagonal ferrite of the above composition is then isolated by leaching with water.