DE2361832C3 - Process for the production of a polycrystalline Mn-containing ferrite body - Google Patents

Description

nan ai

Magnetic heads that are even less prone to crumbling, in order to achieve even better operating properties of Tape recorders and video tape recorders.

From DT-AS 20 27 082 is a magnetic scanning head with a magnetic core from a pair of Ferrite monocrystals with a cubic crystal structure have become known.

The invention is therefore based on the object of a method for producing a dense polycrystalline To provide ferrite body available, which has a lower tendency to crumble, an improved Wear resistance and more suitable physical properties for e.g. B. has magnetic heads.

According to the invention the object is achieved in that a body consists of a manganese compound and Mixture containing ferrite components is formed in that the body of the mixture becomes a polycrystalline manganese-containing ferrite body with spinel structure is calcined, with the manganese compound in the form thin platelets are present which have substantially parallel main surfaces, these parallel main surfaces in the body of the mixture are oriented essentially in one direction and the polycrystalline manganese-containing Ferrite body consists essentially of crystallites, the crystallographic (III) planes of which in the are oriented essentially parallel to one another.

Preferred embodiments of the invention are set out in the subclaims.

The invention relates to a method for producing a polycrystalline Mn-containing ferrite body.

Spinel ferrite materials have heretofore been widely used for magnetic heads for audio equipment and video tape recorders has been used because the service life "". Maenet heads due to the mechanical hardness of the Ferrite materials is improved. When the front

Surface of magnetic heads a recording medium ^ nacnioigenu ra ^ r-icuurai ₆ ^ .. «..... _v - - .., ---

contacts having a rough and hard surface, consisting essentially of ₃₅ thin plates, the two hröckelt the front surface. Thus, the i _m substantially parallel main planes will have significantly impaired performance of the magnetic heads, and orients the major surfaces of the MCP-particles in the

was even then when the Magriet heads made of Spinellfer slurry essentially in one direction, rit materials have been produced, the mechanically annealing (sintering) the material so treated, so that one

l are, there is a need for a ferrite ₄₀ having oriented crystals obtained. '..,. < _An addition of other ferrite components, such as B.

Fe, Co, Zn, Ni, Mg, Li and Cu, as a manganese compound in the process stage in which the slurry is prepared from the starting material and / or after the process stage in which the major surfaces of the MCP particles are oriented, is required. When the ferrite components in the process step in which the slurry is made from the starting material will be admitted, will be in the disclosure mare get an oriented body. On the other hand, when the ferrite components are added after the orientation step only a temporarily oriented body is obtained in the orientation stage and it becomes a Green (unfired) oriented body only obtained after adding the ferrite components. The green one oriented body consists of a mixture of

MCP particles with ferrite components. A preferable amount of MCP particles in the obtained crystal-oriented Ferrite is above 5% by weight. Numerous types of

MCP particles are known and numerous methods of making them are known. Examples of types of MCP particles are y-MnOOH, 0-MnO ₂ , a-MnOOH, V-MnO ₂ , 0-MnOOH, and y-MnOOH and Mn (OH) ₂ . A method of making a

v-MnOOH powder is:

MnSO ₄ + NH ₃ -
Mn (OH) ₂ + H ₂ O ₂ -

Mn (0H) ₂ | _r MnOOH

A process for the production of j9-MnO ₂ powder consists in that one prepares a solution of MnCl ₂ , KMnO ₄ and KOH and this is subjected to a hydrothermal treatment in an autoclave at a temperature of e.g. B. 250 ⁰ C subjects.

The MCP particles have essentially thin platelet shapes, as shown in FIGS. 1A and IB The thin platelets are largely either hexagonal thin plates, ribbon-shaped or strip-shaped. The term "thin platelets" means that one dimension of the thickness of the platelets is much smaller than other dimensions of the platelets and that two are shown in FIGS IB specified main levels 1 are present. The in the F i g. Length L given in 1A or IB represents the grain size of the platelets.

Of the 7 types of MCP particles given above, y-MnOOH, 0-MnO ₂ , a-MnOOH and y-MnO ₂ can be grouped together (hereinafter referred to as group A) because ideally these have a shape such as it is shown in FIG. 1A, and the main planes of the particles of group A correspond to the (10O) planes of the corresponding crystal structure of the compounds, ie the two main surfaces are aligned parallel to the (100) planes of a particle of group A . JS-MnOOH, Ot-MnOOH and Mn (OH) ₂ can be grouped together (group B) because ideally they have a shape as shown in Fig. IB and the major surfaces of the particles in the group B correspond to the (001) planes of the corresponding crystal structure of the compounds, ie the two main surfaces with the (OOl) planes of a particle of group B are aligned parallel. Both crystallographic planes of these main surfaces, the (100) planes and the (OOl) planes, are formed in (III) planes of cubic MnO and cubic (X-Mn ₂ O ₃ by calcining the compounds (without ferrite components) at a temperature of, for example, about 700 ^° C. in a vacuum and at a temperature of, for example, about 600 ^° C. in air.

Pyrolysis of MCP-particles are also manganese compounds, which are suitable for the invention, ie such pyrolysis are also when the pyrolysis at a relatively low temperature, preferably, is carried out at a temperature below 900 ⁰ C MCP materials. With such a pyrolysis there is no sintering of the MCP particles and the shape of the MCP parts is retained without major deformations. Examples of pyrolysis products of y-MnOOH are 0-MnO ₂ , ^ -Mn ₂ O ₃ , Mn ₃ O ₄ , Mn ₅ O ₈ , K-Mn ₂ O ₃ and MnO. Examples of pyrolysis products of 0-MnO ₂ are y-Mn ₂ O ₃ , Mn ₃ O *. MnsOe, (X-Mn ₂ O ₃ and MnO. Examples of pyrolysis products of a-MnOOH are O _{-MnO 2} , V-Mn _{2 O 3} , Mn ₃ O ₄ , Mn ₅ O ₈ , «-Mn ₂ O ₃ and MnO .

It has been found that the crystallographic planes of the two main surfaces of the MCP particles are converted into (111) planes of a cubic spin crystal material if, as shown in FIG. 2, an MCP particle I of group A or B and particles 2 composed of other ferrite components react with one another and transform into a spinel ferrule, which is based on a topotactic reaction. It has also been found that, as shown in Figure 3, the OricnticruPR; can be effected by e.g. B. Scdimcntiercn well dispersed MCP particles 1 and Fcrrilbcstnndtcilcn 2 in a liquid and / or by cold pressing of MCP particles 1 together with ferrite components 2 using a uniaxial pressure, a green (unfired) oriented body is obtained, and that this oriented body after sintering results in a crystal-oriented ferrite body which consists of crystallites whose (III) planes are oriented essentially parallel to one another. The conversion of the oriented body into the crystal-oriented ferrite body is essentially due to the above-mentioned topotactic reaction. The likely mechanism can be explained as follows: When the MCP particles are heated by the sintering step, they are decomposed and the metal ions of the ferrite components 2 diffuse into the oriented MCP particles t, so that an oriented ferrite body is obtained. To achieve a stronger orientation, it is advantageous if the MCP particles have an average grain size greater than 0.01 μπ \. The mean grain size is the mean of the largest dimension of the platelet in FIG. 1A or IB. For a stronger orientation, it is also advantageous to carry out the orientation step by means of a uniaxial pressure, preferably of more than 500 kg / cm ² , and / or sedimentation of MCP particles (which can contain ferrite components) in a liquid. The uniaxial pressure is preferably below 3000 kg / cm ² from a practical point of view, although it is better to use higher pressures. In one embodiment of the method of the invention, it is not necessary to first prepare the mixture of MCP particles and ferrite components. It is also possible to first orient the MCP particles alone and then, in a second process step, impregnate the MCP particles (the pre-oriented body) with ferrite components and then carry out the sintering process, the above-described oriented ferrite body also being obtained. The impregnation of a pre-oriented MCP body with ferrite components can be easily carried out, e.g. By immersing the pre-oriented MCP body in a saline solution of ferrite components, whereby a green oriented body is obtained. In order to obtain a crystalline-based ferrite having a very high degree of orientation, it is advantageous, a green-oriented body at a temperature of over 1000 ° C for ₁ preferably at a temperature of 1100 to 145 ° ⁰ C to carry out the sintering stage, so an oriented ferrite with a To obtain mean grain size of more than 10 μm, preferably between 20 μm and 150 μm, this mean grain size of a spinel ferrite body not only giving a very high degree of orientation, but also leading to good magnetic properties. It has been found that a tightly packed, well-oriented ferrite sintered body with good magnetic properties in a low () o oxygen partial pressure atmosphere such as e.g. B. in a vacuum and in an inert gas atmosphere. It has also been found that a close-packed, well-oriented ferrite body having an extremely low porosity and superior magnetic properties is obtained by hot-pressing the green oriented body with the application of a uniaxial pressure, the direction of which is coincident with one direction, clic perpendicular to the essentially

oriented main surfaces of the MCP particles is.

The degree of orientation of the (111) planes is determined using X-ray diffraction methods measured in which the essentially oriented (III) planes with FeK «Radiation are irradiated, and determined according to the following equation:

where I _mmm = Ehl (hhh), l _to i _a i = Bki _m I (klm) and l (klm) - and l (hhh) integrated intensities of diffraction lines, coming from (kirn) - and (MiA / crystal planes, the There are diffraction lines at a diffraction angle below 20 = 85 °, and / _mmm and / _{(o (a} ; indicate corresponding amounts of a uniformly isotropic polycrystalline ferrite body.

An oriented ferrite body thus obtained has a degree of orientation of more than 20%, and that according to the The oriented ferrite body obtained in the preferred conditions described above has a degree of orientation of more than 40%. The tendency to crumble existing in the known ferrite heads is through Use of the polycrystalline ferrite produced according to the invention with oriented (III) planes eliminated as a magnetic head, as shown in FIG. 4 and, accordingly, the wear properties improved. In addition, the useful life of a magnetic head is greatly extended. Due to the (lli) orientation, the Initial permeability in the oriented (IU) planes improved, as the following examples show.

example 1

A slurry of a mixture of 0.352 kg of γ-MnOOH powder and 0.172 kg of α-MnOOH powder was prepared by grinding in a ball mill for 40 hours. The shape of the 5'-MnOOH corresponded to a thin strip shape with a grain size of about 10 μm (largest dimension of the strip) and a width (second largest dimension of the strip) of about 0.5 μm. The two main surfaces of a γ-MnOOH powder particle corresponded to the (100) planes. The shape of ö-MnOOH also corresponded to a thin strip shape with a grain size of about 10 μm and a width of about 0.05 μm. The slurry was then compressed into a solid body, which is a green oriented body, by applying a uniaxial pressure of 500 kg / cm ² so that the liquid wedge contained in the slurry was withdrawn. The oriented body was then dried and ^{sintered at a temperature of 1200 °} C. for one hour in a nitrogen atmosphere. The obtained manganese table 1

Ferrite had a degree of orientation of about 90% and an initial permeability of about 3300 when measured with respect to the oriented (111) planes and about 2400 when measured along the oriented (III) axis. For comparison, a manganese ferrite similar to the conventional ferrite was produced in essentially the same manner as described above, except that MnCO ₃ and Ot-Fe ₂ Os were used as raw materials for the production of the conventional ferrite. The conventional ferrite thus produced had the same stoichiometric composition as the above-described ferrite produced according to the invention. The conventional ferrite produced had a magnetic permeability of about 2,000.

Example 2

An (x-Fe ₂ O ₃ powder (0.640 kg) obtained by calcining Fe ₂ SO * was used in place of the in

20: «-FeOOH powder used in Example 1 is used. The mean grain size of the "-Fe" powder was about 0.5 μm. The ferrite obtained had a degree of orientation of about 60% and an initial permeability of 2600, measured with respect to the oriented (III) planes.

Example 3

Various manganese compounds were prepared and used as starting materials as shown in Table 1. The forms of y-MnOOH, j3-MnO ₂ , a-MnOOH and y-MnOj shown in Table 1 were each as shown in FIG. 1A, while the forms of O-MnOOH, ό-ΜηΟΟΗ and Mn (OH) _{2 were} SO as shown in Fig. IB.

Some of these manganese compounds were not pure and contained small amounts of other manganese compounds, ζ. B. a jJ-MnOOH powder contained Mn (OH) ₂ - and v-MnOOH particles. The particles of the (X-FeOOH powder had a stripe shape with a

40th mean grain size of 10μιη, and the particles of the (X-Fe ₂ O ₃ powder had a fairly spherical shape with the mean grain size given in Table 1).

These compounds were weighed so as to have a _{ratio equivalent to that of an MnFe 2} O 4 ferrite compound, and then milled in a ball mill for 40 hours. The resulting slurry was compressed using the specified pressure in Table 1 and at a temperature of 1200 ⁰ C.

so sintered in a nitrogen atmosphere for 2 hours. The orientations and grain sizes of the sintered bodies obtained are in the last two columns given in Table 1.

'robe no. Mn connection Grain size Other ferrite Grain size pressure Grain greetings des orientation 709 642/282 components sintered Body (lim) (μπι) (kg / cm ') (μηι) (%) 1 y-MnOOH IO (X-FcOOH IO 500 60 95 2 V-MnOOIl 10 (x-Fe? O3 0.5 500 50 60 3 ß-MnOi 15th (X-FcOOH 10 500 70 90 4th / J-MnO? 15th (x-FcjOj 0.6 500 30th 40 5 (V-MnOOlI IO (X-FcOOH 10 500 70 95 b (X-MnOOII Kl 1X-FC2O1 0.3 500 50 70 7th V-MnO? ^r i λ FcOOH 10 1000 40 60

continuation

ίο

Sample No. Mn compound grain size

(μηι)

Other ferrite components grain size pressure

(μηι)

(kg / cm *)

Grain size of the sintered body (μηι)

orientation

8th ) '- MnO2 5 «-Fe2Oi 0.3 1000 15th 30th 9 jS-MnOOH 5 «-FeOO H 10 1000 50 80 10 jS-MnOOH 5 «Fe2O3 0.3 1000 20th 40 11th (J-MnOOH 5 a-FeOOH 10 1000 50 50 12th 0-MnOOH 5 Ä-Fe2U3 0.3 1000 15th 30th 13th Mn (0H) 2 2 oil FeOO H 10 2000 60 60 14th Mn (OH) ₂ 2 «-Fe2O3 0.3 2000 10 20th

Example 4

A y-MnOOH powder, the particles of which had a thin strip shape with an average grain size of about 15μιτι, was heat-treated at the temperatures indicated in Table 2 and in the atmospheres indicated there. As in Example 3, an a-FeOOH powder was used as the ferrite constituent to achieve an MnFe2O4 ferrite. The

Table .2

The procedure used here was the same as in Example 3 except that in this case a pressure of 2000 kg / cm * was applied to all samples listed in Table 2. The last Both columns of Table 2 give the mean grain sizes and the orientation of the obtained oriented ferrite body again.

Sample No. pyrolysis products condition

Grain size
(μιη)

orientation

15th
16
17th
18th
19th

MnsOe

MnO

Example 5

150 ° C, air 450 ° C, air 600 ° C, air 600 ° C, N 800 ° C, vacuum 60
50
50
60
30th

80
60
70
50

A starting material containing 0.170 kg of a /? - MnO2 powder obtained by heating a) · -ΜηΟΟΗ powder at a temperature of 150 ° C in a normal atmosphere, 0.640 kg of a -Fe2O3 powder with an average grain size of about 0.8 μm and with spherical particles and 0.162 kg of ZnO powder with an average grain size of about 0.2 μm and with particles in the form of thin platelets was produced by mixing the components into a well-dispersed slurry. The original y-MnOOH particles had a thin strip shape and an average grain size of about 15 μm. The slurry thus obtained was press-molded into a green oriented body by applying a uniaxial pressure of 2000 kg / cm ^2. The oriented body was then sintered for one hour at 800 ⁰ C in a N ₂ atmosphere, and then, the sintered ferrite has been re-application of a uniaxial pressure of 2000 kg / cm ² in the same mold, which had been used for the previous compression molding , pressed. The pressing direction for the ferrite sintered body was the same as the pressing direction for the green oriented body. The sintered ferrite body thus treated was sintered again at a temperature of 1200 ° C. in a nitrogen atmosphere to give the finished, well-sintered ferrite body. The orientation of the resulting oriented ferrite body was about 70%.

.40

Example6

A well dispersed slurry made as in Example 1 and with additional water was allowed to stand for 48 hours. The water was drained off well and that sedimented Material was dried. The oriented body then became one at a temperature of 1200 ° C

For an hour in pinor W .. * im ^ -i, a: -. . v \ cr cn

—... "^," .mti 1 cmperaiur of \ i \ ßj ^ cm *. Sintered for hour in a ^ atmosphere. The manganese ferrite in this way had a degree of orientation -n 7no / n

received
of about 70%.

Example 7

It got a similar treatment as in that Example 6 was made with the exception, however, that before the sedimented material had been dried

ss, a uniaxial pressure of 500 kg / cm ^{2 was} additionally applied in a direction perpendicular to the upper surface of the sedimented material. The green oriented body thus obtained was at a temperature of 100 "C in a

Nj-Atmospharc sintered for one hour. the Manganese ferrite bodies obtained hold a degree of orientation of about 95%.

('S example 8

Kin material similar to that of Example 6 produced green oriented material was at a temperature of 1200 "C in one

Sintered vacuum for an hour. The ferrite body obtained had a degree of orientation of about 85%.

B is ρ ie 1 9 _s

A material corresponding to the green oriented material produced in Example 5 was hot-pressed at a temperature of 1200 ° C. and a pressure of 300 kg / cm ^{2 for 2 hours.} The oriented ferrite body obtained has a porosity of less than 0.1% and a degree of orientation of about 95%. To test the tendency to crumble or the brittleness of the ferrite produced by the method according to the invention and the ferrite produced by conventional methods, two magnetic heads were produced. One of the magnetic heads was manufactured using the ferrite manufactured by the method of the present invention in such a manner that a front surface of a magnetic head was substantially parallel to the oriented (III) planes. The other of the two magnetic heads was made using a conventional ferrite. These two magnetic heads were rubbed by a y-FejOa tape running at a relative speed of 12 m / s. After 200 hours of testing, the surfaces of the heads were photographed, see Fig. 4. It was found that the tendency to crumble or brittleness of ferrites according to the prior art by using a polycrystalline. Ferrite with oriented (Ul) planes is eliminated; wear properties have also been improved, and the useful life of magnetic heads has been greatly extended.

Example 10

Several green oriented bodies were applying various pressures, such as those in the Table 3, and using a

35 according to Example 1 obtained slurry. The bodies were sintered at a temperature of 1200 ° C. in an N2 atmosphere, and oriented manganese ferrites were obtained. It can be seen from Table 3 that the effect achieved by increasing a uniaxial pressure approaches a saturation value at high pressure, and that a pressure of about 500 to 3000 kg / cm ² is sufficient in practical use.

Table 3 orientation pressure (%) (kg / cm?) 70 100 80 300 90 500 90 1000 95 3000 98 5000

Example 11

A well dispersed slurry of γ-MnOOH powder having the shape described in Example 1 was left to stand for 48 hours. Almost all of the water was drawn off and the sedimented material was dried to obtain a pre-oriented material consisting of γ-MnOOH powder. The pre-oriented material was immersed in a FeCb solution so as to impregnate it with Fe and obtain a green oriented body. The green oriented body was ^{sintered at a temperature of 800 °} C. in a normal atmosphere for one hour and then ^{subjected to a sintering process at a temperature of 1200 °} C. in an N2 atmosphere. The manganese ferrite thus obtained had a degree of orientation of about 75%.

For this purpose 2 sheets of drawings

Claims (27)

Patent claims: 1. A method for producing a polycrystalline Mn-containing ferrite body, characterized in that that a body made of a containing a manganese compound and ferrite components Mixture is formed that the body from the mixture to a polycrystalline manganese-containing Ferrite body with spinel structure is calcined, whereby the manganese compound is thinner in the form There are platelets which have essentially parallel main surfaces, these parallel main surfaces are oriented essentially in one direction in the body of the mixture and the polycrystalline manganese-containing ferrite body consists essentially of crystallites, their crystallographic (Hl) planes are oriented essentially parallel to one another. 2. The method according to claim 1, characterized in that the manganese compound consists of one y-MnOOH powder consists of two particles Have major surfaces parallel to crystallographic (100) planes of a crystallographic Aligned structure of y-MnOOH, and / or obtained by pyrolysis of y-MnOOH powder Manganese compounds exist. 3. The method according to claim 1, characterized in that the manganese compound consists of one Beta-MnOr powder is made up of whose particles have two main surfaces that are parallel with crystallographic (100) planes of a crystalline structure of Beta-MnÜ2 are aligned, and / or made by Pyrolysis of manganese compounds obtained from beta-MnCV powder consists. 4. The method according to claim 1, characterized in that the Manga nvev connection from one «-MnOOH powder is composed, the particles of which have two major faces, parallel with crystallographic (100) planes of a crystalline structure of a-MnOOH are aligned, and / or made by Pyrolysis of manganese compounds obtained from «-MnOOH powder consists. 5. The method according to claim 1, characterized in that the manganese compound consists of one y-MnCV powder consists of two particles Have major surfaces parallel to crystallographic (100) planes of a crystalline structure of y-MnC> 2 are aligned, and / or from manganese compounds obtained by pyrolysis of y-MnO2 powder consists. 6. The method according to claim 1, characterized in that that the manganese compound consists of a beta-MnOOH powder, the particles of which are two Have major faces parallel to crystallographic (OOl) planes of a crystalline structure of Beta-MnOOH aligned, and / or obtained from pyrolysis of Beta-MnOOH powder Manganese compounds exist. 7. The method according to claim 1, characterized in that the manganese compound consists of one ö-MnOOH powder consists of two particles Have major faces parallel with crystallographic (OOl) planes of a crystalline structure of OMnOOH are aligned, and / or from manganese compounds obtained by pyrolysis of o-MnOOH powder consists. 8. The method according to claim 1, characterized in that the manganese compound consists of a Mn (0H) 2 powder, the particles of which have two main surfaces which are aligned parallel with crystallographic (OOl) planes of a crystalline structure of Mn (0H) 2 , and / or consists of manganese compounds obtained by pyrolysis of Mn (OH) _{2 powder.} 9. The method according to claim 1, characterized in that the thin platelets have a medium one Have a grain size of more than 0.01 μm. 10. The method according to claim 2, characterized in that the obtained by pyrolysis Manganese compounds by heating the y-MnOOH powder at a temperature below 900 ° C can be obtained. 11. The method according to claim 3, characterized in that the manganese compounds obtained by pyrolysis are obtained by heating the Ji-MnO ₂ powder at a temperature below 900 ° C. 12. The method according to claim 4, characterized in that the manganese compounds obtained by pyrolysis are obtained by heating the Λ-MnOOH powder at a temperature below 900 ^0C. 13. The method according to claim 10, characterized in that the manganese-containing constituents obtained by pyrolysis are a beta-MnO2 powder, a γ-Mn ^ powder, an Mn ₃ O ₄ powder, a MnsOe powder Contains Mn2O3 powder and a MnO powder. 14. The method according to claim 11, characterized in that the manganese-containing constituents obtained by pyrolysis are another}> - Mn ₂ O3 powder, another Mn ₃ O ₄ -PuIvCr, another MnsOe powder, another Ot-Mn ₂ O ₃ powder and another MnO powder included. 15. The method according to claim 12, characterized in that the manganese-containing constituents obtained by pyrolysis are another /? MnO ₂ powder, yet another y-Mn2O ₃ powder, yet another Mn ₃ O ₄ powder, yet another Mn5Og powder, yet another <% - Mn ₂ O ₃ powder and yet another MnO- Powder included. 16. The method according to claim 1, characterized in that the main surfaces of the thin platelets be oriented by sedimenting the manganese compound in a liquid. 17. The method according to claim 1, characterized in that that the main surfaces of the thin platelets by cold pressing the manganese compound under Can be oriented using a uniaxial print. 18. The method according to claim 17, characterized in that the uniaxial pressure is 500 to 3000 kp / cm ² . 19. The method according to claim 1, characterized in that that the thin platelets by sedimenting the manganese compound in a liquid and also by cold pressing the manganese compound using uniaxial pressure be oriented. 20. The method according to claim 1, characterized in that the mixture is formed before the Main surfaces of the thin platelets are oriented. 21. The method according to claim 1, characterized in that the mixture is formed after the main surfaces of the thin platelets have been oriented into a previously oriented body. 22, method according to claim 21, characterized Indicates that the mixture is made by impregnating the previously oriented body with the perrit constituents is formed. 23 The method according to claim 1, characterized in that the calcining at a temperature is carried out above 1000 ° C. 24. The method according to claim 1, characterized in that the calcination is carried out at a temperature of HOO to 1450 ⁰ C. 25. The method according to claim 1, characterized in that that Jas calcination is carried out in a vacuum. 26. The method according to claim 1, characterized in that the calcining in an inert gas is performed. 27. The method according to claim 1, characterized by that the calcined body is also hot-pressed. The invention achieves that a ferrite material for magnetic heads can be produced with the permeabilities of about 3300 can be achieved. Preferred embodiments are based on the drawings the invention explained in more detail F i g. IA and 1B are schematic representations of FIG ideal platelet shapes, Fig. 2 is an illustration of an idealized conversion and a reaction of a thin platelet particle of a manganese compound and others Ferrite components, F i g. 3 is an idealized representation of how thin platelet particles orient themselves and in a converting crystal-oriented polycrystalline ferrite bodies after calcining, and F i g. 4 is a photographic view of the front surface of magnetic heads made by the method of the invention and the front surface of a magnetic head made from conventional ferrite material after 200 hours of normal operation of the magnetic heads using magnetic tape with y- Fe ₂ O ₃ particles. The ferite body produced by the process according to the invention is made up of crystallites, whose (111) crystallographic planes essentially parallel are oriented towards each other. According to the invention, a superior crystal-oriented ferrite body having improved properties be prepared by the following process steps: Make a slurry of one Starting material which is at least a powder of crystalline particles of a manganese compound (hereinafter referred to as MCP particles), which in the