Hydrothermal process for producing magnetoplumbitic ferrite

A process for producing a magnetoplumbitic ferrite of the formula:

• MO.n(Fe.sub.2-x M'.sub.x O.sub.3) (1)
• wherein M is one or more metals selected from the group consisting of Ba, Sr, Ca and Pb;
• n is a number of 3 to 6;
• M' is at least one component selected from the group consisting of Si, Ta, Sb, Nb, Zr and Ti, or a combination of that component with at least one other component selected from the group consisting of Ni, Co, Cu, Mg, Mn and Zn;
• x is a number from 0.01 to 0.7;
• having a saturation magnetization of not less than 50 emu/g and a coercivity in the range of 200-2000 Oe;
• by a hydrothermal reaction, comprising the steps of:
• preparing a uniform mixture of the metallic components that provide the ferrite of the formula (1), said mixture being in the form of an aqueous solution containing metal ions, an aqueous slurry containing metal hydroxide or an aqueous slurry containing both metal ions and metal hydroxides, from the salt of the metallic components that is selected from the group consisting of halides, nitrates and hydroxides;
• bringing said mixture into contact with an alkali in the form of an aqueous solution containing an alkali substance and form thereform an alkaline slurry containing precipitated solid particles, wherein the alkali is used in such an amount that the ratio of the equivalent weight of alkali to that of an acid residue contained in the slurry is greater than 1.0 or when an acid residue is absent in the slurry, the alkali is used in such an amount that the alkaline slurry has a pH of 11.0 or more;
• placing the resulting slurry in an autoclave and reacting the slurry components to form a ferrite composition, at a temperature higher than 100.degree. C. but not exceeding 400.degree. C., in the presence of 1-70 weight percent, based on the amount of the ferrite composition produced, of at least one organic compound selected from the group consisting of sodium lignosulfonate, sodium dodecylbenzenesulfonate, sodium dodecylsulfonate, laurylamine acetate, oleic acid, sorbitan monooleate, tallowdiamine, formalin sodium bethanaphthalene sulfonate, steary trimethylammonium chloride, sodium tricarballylate, and ligninsulfonic acid;
• and 0.01 to 10 weight percent, based on the amount of the ferrite composition produced, of at least one additional compound selected from the group consisting of dextrin, diethyleneglycol, diose, betha-methyl alcohol, ascorbic acid, and sodium citrate;
• removing the resulting reaction mixture from the autoclave;
• washing the ferrite composition to remove any impurities;
• and subsequently,
• drying and disintegrating to produce the magnetoplumbitic ferrite of the formula (1).

A process for producing a magnetoplumbitic ferrite of the formula:

• MO.n(Fe.sub.2-x M'.sub.x O.sub.3) (1)
• wherein M is one or more metals selected from the group consisting of Ba, Sr, Ca and Pb;
• n is a number of 3 to 6;
• M' is at least one component selected from the group consisting of Si, Ta, Sb, Nb, Zr and Ti, or a combination of that component with at least one other component selected from the group consisting of Ni, Co, Cu, Mg, Mn and Zn;
• x is a number from 0.01 to 0.7;
• having a saturation magnetization of not less than 50 emu/g and a coercivity soercivity in the range of 200-2000 Oe;
• by a hydrothermal reaction, comprising the steps of:
• preparing a uniform mixture of the metallic components that provide the ferrite of the formula (1), said mixture being in the form of an aqueous solution containing metal ions, an aqueous slurry containing metal hydroxide or an aqueous slurry containing both metal ions and metal hydroxides, from the salt of the metallic components that is selected from the group consisting of halides, nitrates and hydroxides;
• bringing said mixture into contact with an alkali in the form of an aqueous solution containing an alkali substance and form therefrom an alkaline slurry containing precipitated solid particles, wherein the alkali is used in such an amount that the ratio of the equivalent weight of alkali to that of an acid residue contained in the slurry is greater than 1.0 or when an acid residue is absent in the slurry, the alkali is used in such an amount that the alkaline slurry has a pH of 11.0 or more;
• placing the resulting slurry in an autoclave and reacting the slury components to form a ferrite composition, at a temperature higher than 100.degree. C. but not exceeding 400.degree. C., in the presence of 1-70 weight percent, based on the amount of the ferrite composition produced, of at least one organic compound selected from the group consisting of sodium lignosulfonate, sodium dodecylbenzenesulfonate, sodium dodecylsulfonate, laurylamine acetate, oleic acid, sorbitan monooleate, tallowdiamine, formalin sodium bethanaphthalene sulfonate, steary trimethylammonium chloride, sodium tricarballylate, and ligninsulfonic acid;
• and 0.01-5 weight percent, based on the amount of the ferrite composition produced, of at least one additional compound selected from the group consisting of sodium hexamethaphosphate, colloidal silica and sodium aluminate;
• removing the resulting reaction mixture from the autoclave;
• washing the ferrite composition to remove any impurities;
• and subsequently,
• drying and disintegrating to produce the magnetoplumbitic ferrite of the formula (1).

A process for producing a magnetoplumbitic ferrite of the formula:

• MO.n(Fe.sub.2-x M'.sub.x O.sub.3) (1)
• wherein M is one or more metals selected from the group consisting of Ba, Sr, Ca and Pb;
• n is a number of 3 to 6;
• M' is at least one component selected from the group consisting of Si, Ta, Sb, Nb, Zr and Ti, or a combination of that component with at least one other component selected from the group consisting of Ni, Co, Cu, Mg, Mg, Mn and Zn;
• x is a number from 0.01 to 0.7;
• having a saturation magnetization of not less than 50 emu/g and a coercivity in the range of 200-2000 Oe;
• by a hydrothermal reaction, comprising the steps of:
• preparing a uniform mixture of the metallic components that provide the ferrite of the formula (1), said mixture being in the form of an aqueous solution containing metal ions, an aqueous slurry containing metal hydroxides or an aqueous slurry containing both metal ions and metal hydroxides, from the salt of the metallic components that is selected from the group consisting of halides, nitrates and hydroxides;
• bringing said mixture into contact with an alkali in the form of an aqueous solution containing an alkali substance and form therefrom an alkaline slurry containing precipitate solid particles, wherein the alkali is used in such an amount that the ratio of the equivalent weight of alkali to that of an acid residue contained in the slurry is greater than 1.0 or when an acid residue is absent in the slurry, the alkali is used in such an amount that the alkaline slurry has a pH of 11.0 or more;
• placing the resulting slurry in an autoclave and reacting the slurry components to form a ferrite composition, at a temperature higher than 100.degree. C. but not exceeding 400.degree. C., in the presence of 1-70 weight percent, based on the amount of the ferrite composition produced, of at least one organic compound selected from the group consisting of sodium lignosulfonate, sodium dodecylbenzenesulfonate, sodium dodecylsulfonate, laurylamine acetate, oleic acid, sorbitan monooleate, tallowdiamine, formalin sodium bethanaphthalene sulfonate, steary trimethylammonium chloride, sodium tricarballylate, and ligninsulfonic acid;
• 0. 01-10 weight percent, based on the amount of the ferrite composition produced, of at least one compound (agent B) selected from the group consisting of dextrin, diethyleneglycol, diose, betha-methyl alcohol, ascorbic acid, and sodium citrate;
• and 0.01-5 weight percent, based on the amount of the ferrite composition produced, of at least one compound selected from the group consisting of sodium hexamethaphosphate, colloidal silica and sodium aluminate;
• removing the resulting reaction mixture from the autoclave;
• washing the ferrite composition to remove any impurities;
• and subsequently,
• drying and disintegrating to produce the magnetoplumbitic ferrite of the formula (1).