JPS62223097A - Production of single crystal ferrite - Google Patents

Abstract

PURPOSE:To obtain a large amount of stable single crystal ferrite inexpensively, by surrounding periphery of a bonded material of polycrystal ferritte having one end face to which seed of single crystal ferrite is attached with corner dummies consisting of polycrystal ferrite and making the polycrystal ferrite into single crystal ferrite under heating. CONSTITUTION:Seed 1 of single crystal ferrite is attached to one end face of polycrystal ferrite 2 to give a bonded material 3. periphery of the bonded material is surrounded by corner dummies (6-1, 6-2, 6-3 and 6-4) and the bonded material is heated to make the polycrystal ferrite into single crystal. The polycrystal ferrite used as the corner dummies has preferably <=100mum average particle diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing single crystal ferrite used for VTR magnetic heads etc. by solid phase reaction.

(Prior Art) Conventionally, in a method for manufacturing a ferrite single crystal, in which single crystal ferrite is grown in the direction of polycrystalline ferrite by heating polycrystalline ferrite and single crystal ferrite after contact, When polycrystalline ferrite and single-crystalline ferrite are brought into contact and heated, a means for suppressing discontinuous grain growth, such as a polycrystalline ferrite dummy, is provided on at least the back surface of the polycrystalline ferrite with respect to the joint surface of the polycrystalline ferrite that joins the single-crystalline ferrite. A method for preventing the generation of crystals with different crystal orientations is disclosed in JP-A-60-195097.

(Problems to be Solved by the Invention) However, in the method described above, although a single crystal ferrite with larger dimensions can be obtained compared to a method without means for suppressing discontinuous grain growth, polycrystalline ferrite to be made into a single crystal is Because discontinuous grain growth suppression means must be provided for each process, processes such as creating a polycrystalline ferrite dummy material and polishing and bonding the joint surfaces of the polycrystalline ferrite and the dummy material to be made into single crystals are required, which is time-consuming and time-consuming. It had some drawbacks that made it unsuitable for mass production.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing single-crystal ferrite that can eliminate the above-mentioned problems and produce stable single-crystal ferrite at low cost and in large quantities.

(Means for Solving the Problems) The method for manufacturing single crystal ferrite of the present invention is a single crystal ferrite in which a seed of single crystal ferrite is bonded to the end face of polycrystalline ferrite, and the polycrystalline ferrite is grown into a single crystal by heating. The method for producing crystalline ferrite is characterized in that a joined body of polycrystalline ferrite, in which a single-crystalline ferrite seed is joined to one end face thereof, is surrounded by a corner dummy made of polycrystalline ferrite and heated.

(Function) It is generally known that the equilibrium oxygen partial pressure of single crystal and polycrystalline ferrite increases as the temperature increases. For example, in Mn-Znn fusiite, it is almost Oat at room temperature.
m is known to be 1 to 2 atm at 1500°C. Ideally, heating under equilibrium oxygen partial pressure is desired as a heating state when polycrystalline ferrite is single-crystallized. However, since it is difficult to control the atmosphere to change the oxygen partial pressure according to temperature, conventional methods have been to seal polycrystalline ferrite in a heat-resistant container, such as an alumina container, and use the oxygen breathing effect of polycrystalline ferrite to produce a single crystal. Was.

The manufacturing method of the present invention takes this one step further by surrounding the polycrystalline ferrite with a corner dummy, and the self-breathing action of the corner dummy polycrystalline ferrite enables heating under equilibrium oxygen partial pressure in response to temperature changes. I made it so.

As a result, it has become possible to completely eliminate the process of joining dummy materials for each polycrystalline ferrite, and it has become possible to significantly reduce the number of processes. Furthermore, since the step of joining the dummy material and polycrystalline ferrite, which is performed after joining the seed single crystal, is not necessary, it is possible to prevent variations in crystal orientation due to joint deviation of the seed single crystal that occurs during joining.

The polycrystalline ferrite used as the corner dummy must be new, that has not been used as a dummy material even once, that is, one that has not experienced abnormal grain growth and has an average particle diameter of 100 IllI+ or less, preferably 15 μm or less, because its self-breathing action is active. It is preferable because it is.

(Example) The present invention will be described in detail below with reference to the drawings.

FIGS. 1(A) to 1(C) are perspective views for explaining one embodiment of the manufacturing method of the present invention, and show an example of a rectangular parallelepiped shape. First, as shown in FIG. 1(A), for example, Mn
- A polycrystalline ferrite 2 made of Zn and a seed single crystal ferrite 1 made of the same composition are prepared. As the polycrystalline ferrite 2, it is necessary to use polycrystalline ferrite manufactured using iron oxide having a spinel structure, iron oxide having a spinel structure history, or a mixture thereof as a raw material for iron oxide. Also, the difference in thermal expansion coefficient between polycrystalline ferrite and single crystal ferrite is ±10
10-' or less is desirable. Next, polycrystalline ferrite 2
The joint surface between the single-crystal ferrite 1 and the single-crystal ferrite 1 is mirror-polished using diamond abrasive grains so that the surface roughness is preferably 0.5 microns or less and the flatness is preferably 0.5 microns or less. The composition of the ferrite is P8zOi
: 45 to 60 mol%, preferably 52 to 57 mol%,
It is suitable to use a composition having a composition of Mn0 = 20 to 40 mol%, preferably 25 to 38 mol%, and ZnO: 5 to 30 mol%, preferably 9 to 22 mol%.

Next, an organic acid or an inorganic acid is interposed on the joint surfaces of the mirror-polished polycrystalline ferrite 2 and single-crystal ferrite 1, and the polished surfaces are brought into close contact with each other as shown in FIG.
get. The obtained joined body 3 was placed in a firing container 7 consisting of two divided alumina containers 5-1 and 5-2 having the shape shown in FIG. 2, and corner dummies 6-1 and 6-2 made of new polycrystalline ferrite. , 6-3° and 6-4. In this state, the polycrystalline ferrite 2 is heated from a temperature below the temperature at which discontinuous crystal grain growth occurs, that is, about 1330 to 1350°C for the ferrite having the above-mentioned composition, to 1430°C at a temperature increase rate of 10°C/hour to form a single crystal. Develop. As a result, crystals of the single crystal ferrite 1 are grown in the direction of the polycrystalline ferrite 2, and a large-sized single crystal ferrite 4 as shown in FIG. be able to.

Examples will be described below.

Iron oxide (FezO+) produced via large coal magnetite (Fez04) with impurity 5iOz 0.005%,
Ti1t 0.005%, CaOO, 005%, Naz
o The raw materials are iron oxide containing 0.005%, manganese oxide and zinc oxide with a purity of 99.9%, and the composition is M
n027.7 mol%, Zn018.5 mol%, FezO
z 53.8 mol % of the mixture was calcined, pulverized, molded, and fired at 1320 ° C. for 4 hours under equilibrium oxygen partial pressure,
Mn-Zn polycrystalline ferrite was obtained.

This polycrystalline ferrite has an average particle size of about 10 μm,
The porosity was about 0.05%, and discontinuous grain growth occurred at around 1350°C. On the other hand, we prepared single-crystal ferrite manufactured by the high-pressure Bridgeman method and had almost the same composition as this polycrystalline ferrite.
A rectangular parallelepiped plate with 7x0.5 fins was cut out. Then, this polycrystalline ferrite is coated with diamond abrasive grains (2~
4 μm) to give the entire surface a surface roughness Rmax O,
05 pm and mirror polished to a flatness of 0.3.17 m.

Thereafter, a seed single crystal ferrite was joined to one end surface of the polycrystalline ferrite to obtain a joined body.

Next, a plurality of the obtained bonded bodies were loaded into the firing container shown in Fig. 2 without any gaps, and then heated at 1150°C for 30 minutes in an N2 gas atmosphere, followed by an O1 concentration of 5%.
Temperature increase rate 10℃/ from 1340℃ in N2 gas atmosphere
The mixture was heated to 1,430° C. for an hour to cause a solid phase reaction, and the single crystal ferrite was grown in the direction of the polycrystalline ferrite, thereby converting the entire polycrystalline ferrite into a single crystal.

By the method described above, each composition was mass-produced and the growth yield was determined. Incidentally, in Table 1, a passed product refers to a product in which no crystals in the true orientation occur and the entire polycrystalline ferrite becomes a single crystal. The results are shown in Table 1.

As is clear from the results shown in Table 1, by obtaining single crystal ferrite by the manufacturing method of the present invention without providing a dummy material, single crystal ferrite could be manufactured with a high yield.

(Effects of the Invention) As is clear from the above detailed explanation, according to the method for producing single crystal ferrite of the present invention, the periphery of a bonded body of polycrystalline ferrite in which a seed of single crystal ferrite is bonded to one end face Since the polycrystalline ferrite is surrounded by a corner dummy made of polycrystalline ferrite and heated to make the polycrystalline ferrite into a single crystal, compared to conventional methods, processes such as creating discontinuous grain growth suppressing means, polishing the bonding surface, and bonding are unnecessary. Therefore, single crystal ferrite can be obtained at low cost and in large quantities. Further, variations in crystal orientation caused by joining of the seed single crystal can also be effectively eliminated.

[Brief explanation of drawings]

FIGS. 1(A) to (C) are perspective views showing one embodiment of the manufacturing method of the present invention, and FIG. 2 is a sectional view showing one embodiment of the firing container used in the present invention. 1... Single crystal ferrite 2... Polycrystalline ferrite 3... Joined body 4... Single crystal ferrite 5-1.5-2... Alumina container 6-1.6-2.6-3 .6-4...Corner dummy Fig. 1 (A) Fig. 2 Dan #Body

Claims (1)

[Claims] 1. A method for producing single crystal ferrite in which a single crystal ferrite seed is bonded to an end face of polycrystalline ferrite and heated to grow the polycrystal ferrite into a single crystal. A method for producing single-crystal ferrite, which comprises heating a bonded body of polycrystalline ferrite bonded to one end surface of the ferrite while surrounding it with a corner dummy made of polycrystalline ferrite. 2. The method for producing single crystal ferrite according to claim 1, wherein the average particle diameter of the polycrystalline ferrite used as the corner dummy is 100 μm or less.