JPS6065511A - Manufacture of single crystal of magnetic oxide - Google Patents

Abstract

PURPOSE:To obtain the single crystal of a thin film or a thin plate having a large area and an uniform composition of less detect easily at low cost by a method wherein after the crystalline magnetic oxide is made to be amorphous, it is recrystallized from the end in order under a partial temperature gradient. CONSTITUTION:The crystalline magnetic oxide is once fused in a platinum crucible to be made into an fused oxide substance 2 of uniform composition. When this is poured between metallic twin rolls 3 and is pressure-expanded and is rapidly cooled, the amorphous magnetic oxide 4 in a large-area thin plate form can be obtained. This amorphous oxide 4 is processed into a square paddle shape and parallel heater 5 and 5 are arranged on the upper and lower sides of it with being close. Then, it is heated from the grip part of a small area in order under a partial temperature gradient to be recrystallized to form the magnetic oxide signal crystal 6. In this method, compared with the slicing from a plate of a large area without a defect can be obtained. In addition, manufacture is easy and the properties for mass production is good and the low-cost manufacture is possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for producing a magnetic oxide single crystal used in element materials such as magnetic heads for magnetic recording, magnetic media, and microwave elements.

[Technical background of the invention and its problems]

Spinel-type manganese-zinc ferrite single crystals are widely used in magnetic helad cores for magnetic recording as magnetic oxide single crystals in the form of thin films or thin plates, and are widely used in microwave elements and magnetic bubble memories (-Rare earth iron garnet type ferrite single crystals are widely used. For magneto-optical recording, magnetic oxide single crystals such as perovskite-type rare earth iron orthoferrite, rare earth iron garnet ferrite, and hexagonal ferrite are being researched and are expected to be put to practical use.

Conventionally, such thin film or thin plate-shaped magnetic oxide single crystals, for example thin plate-shaped manganese zinc ferrite single crystals, have been produced by the Bridgman method (=thus, slicing and polishing a large single crystal grown by seeding from molten oxide). Through the following processing steps, it was formed into a plate shape and put into practical use (two times).

However, when producing a large-area thin film or thin plate-like single crystal, a large single crystal is required, but generally (
= It is difficult to obtain a large single crystal with a few cracks or defects and a uniform composition using the Bridgman method.Also, in manganese zinc ferrite single crystals produced by the Bridgman method, normally a single crystal is formed during single crystal growth. In the upper part, the amount of zinc is large, and in the lower part, when the zinc content decreases, compositional segregation tends to occur. Second,
The thinner the required single crystal, the greater the loss due to processing and the lower the yield.

Furthermore, for rare earth iron orn ferrite, rare earth iron garnet ferrite, and hexagonal ferrite, thin film-like single crystals have been produced using sputtering methods and liquid phase epitaxial methods (LEP methods); However, it requires expensive substrates such as gadolinium gallium garnet monocrystalline or antagonistic crystals, has poor mass productivity, and has the disadvantages that it is extremely difficult to produce multi-component single crystals.

[Purpose of the invention]

The present invention was devised in view of these points, and it is possible to obtain a thin film or thin plate single crystal with a large area, few defects, and a uniform composition, and it is easy to manufacture and has high mass productivity. The present invention provides a method for manufacturing a magnetic oxide single crystal at low cost.

[Summary of the invention]

In the present invention, a crystalline magnetic oxide consisting of a single phase or a solid solution is made amorphous, and then this amorphous magnetic oxide is sequentially recrystallized from the end side under a local temperature gradient. It is characterized by this. The present invention will be explained in detail below. The crystalline magnetic oxide of the present invention comprises iron group transition metal elements (Ti, V
, Cr, Mn, Fe, Co.

Ni, C*) and rare earth transition metal elements (La, Ce, Pr
, Nd.

Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, T
The main component is a magnetic oxide consisting of at least one of the following: alkali metals (Li, Na,
, K), alkaline earth metals (Mg, Ca, Sr, B
a) Sc, Y, B, Zr, Hf, Zn, Cd.

A magnetic oxide whose subcomponent is an oxide containing at least 11 of Si, Ge, Sn, Pb, A/, in, Bi, and sb.

Special (2) spinel type, garnet type, perovskite type and hexagonal ferrite.

Methods for making such a crystalline magnetic oxide amorphous include the liquid quenching method, in which the crystalline magnetic oxide is melted to a homogeneous composition, and then rapidly cooled, and the liquid quenching method, in which the substrate material (It is broadly divided into vapor deposition methods that involve vapor deposition and growth.

In the liquid quenching method, for example, as shown in Fig. 1, a crystalline magnetic oxide is once melted in a platinum crucible to form an oxide melt 2 with a homogeneous composition, which is then passed through a pair of rotating metal rolls. 3 (by pouring, rolling and quenching, a large-area thin plate-like amorphous magnetic oxide 4 is obtained. In this case, as the metal twin rolls 3, rolls such as steel, copper, stainless steel, etc. are used. Alternatively, it may be rapidly cooled using a single roll.

Further, as other liquid quenching methods, a method of pouring a high-speed moving metal belt C dioxide melt, or a dipping method in which a cooling medium is immersed in the oxide melt and pulled up can be used. In this liquid quenching method, the composition of the amorphous magnetic oxide obtained is very (bihomogeneous) because the composition of the melt can be maintained by stirring the melt well or by high-frequency heating.

The thin plate-like amorphous oxide 4 thus obtained is processed into a battledore shape, for example, as shown in FIG.

Parallel heaters 5.5 are placed close to each other on both sides of this upper and lower sides,
A magnetic oxide single crystal 6 is produced by sequentially heating and recrystallizing the magnetic oxide while applying a local temperature gradient due to the small area force of the handshake.

The heating means used in this recrystallization f: is not limited to the upper and lower parallel heaters 5, 5, but may be sequentially heated using a laser, infrared rays, an arc image furnace, or the like.

The maximum heat treatment temperature for recrystallization varies depending on the type of magnetic oxide. For example, when the magnetic oxide undergoes congruend (congruent melting), the heat treatment temperature is preferably higher than the melting point and lower than the melting point +300'O.

If the temperature is below the melting point, the growth rate of the single crystal will be slow and mass productivity will be reduced, and if the temperature exceeds the melting point +300'O, the oxide components will easily evaporate and cause compositional segregation, resulting in a homogeneous homomagnetic oxide single crystal. I can't get it.

In addition, when a magnetic oxide melts into an incongruent state, it decomposes into a magnetic oxide different from the original magnetic oxide.
Cannot be melted. In this case, by setting the heat treatment temperature to a temperature range above the crystallization temperature and below the melting point, it is possible to grow the amorphous magnetic oxide into a magnetic oxide single crystal through grain growth (particularly discontinuous grain growth). can. %
-2. Obtaining a magnetic oxide single crystal with excellent compositional uniformity (-
The heat treatment is preferably carried out at a temperature around 0.95 T'M (TM: melting point) below the melting point. This grain growth differs from grain growth in normal sintered bodies, and under temperature gradients, grains grow from amorphous or from extremely fine crystal grains, so the growth rate of single crystals is fast, and even below I mx. If it is in the form of a thin film or a thin plate, the growth will be even faster.

Methods for making crystalline magnetic oxides amorphous by vapor deposition include, for example, radio frequency sputtering, flow sputtering, magnetron sputtering, ion beam sputtering, ion brating, electron beam evaporation, and chemical vapor deposition. method (CVD method), etc.

For example, when using a sputtering method (2), a target 12 of crystalline magnetic oxide 11 connected to a high frequency power source 1o is placed in a vacuum vessel 9 equipped with a gas inlet valve 7 and an exhaust valve 8 as shown in FIG. At the same time, a substrate 13 is placed opposite to the substrate 13, and high frequency sputtering is performed to form a di-amorphous magnetic oxide 4 on the substrate 13 at a substrate temperature of 300" or less. Next, as shown in FIG. As shown in Figure 2, the entire sample (2,000 rows) is equipped with a heater 5°5 and heat-treated the amorphous oxide 4 on the surface of the substrate 13 from the end side under a local temperature gradient to form a magnetic oxide single crystal. 6. Particularly in the sputtering method, an amorphous magnetic oxide having a uniform composition can be easily created by rotating the substrate.

In this case, a sapphire substrate or a glass substrate is used as the substrate, but it is easier to single-crystallize the amorphous magnetic oxide deposited on it by using a single-crystal substrate like a sapphire substrate. be. In addition, recrystallization after one end (two seeds) of the amorphous magnetic oxide eliminates wasteful nucleation and makes single crystallization extremely easy.

If the desired substrate material is a glass substrate, it is easier to form a single crystal by attaching an extremely thin single crystal budding or oriented polycrystalline film to the substrate surface in advance.

In this case, it is desirable that the attached single crystal and oriented polycrystalline film have a lattice constant close to that of the target oxide, and it is preferable to use a layered compound for the oriented polycrystalline film. In addition, when an amorphous magnetic oxide can be produced by the liquid quenching method or vapor deposition method in the present invention, the composition (in some cases, it becomes a polycrystal without becoming amorphous. In this case, the crystal grain size is 1 μm).
If it is below, the same as for an amorphous magnetic oxide (a magnetic oxide single crystal can be obtained by performing two heat treatments).

In the production method of the present invention, an amorphous magnetic oxide obtained by a liquid quenching method or a vapor deposition method is recrystallized under a local temperature gradient (-in order to avoid cracks that often occur, After being heat-treated at a temperature lower than the original recrystallization temperature to form a fine Hiko polycrystalline thin film or thin plate with a crystal grain size of 1 μm or less, the magnetic oxide single crystal is heat-treated sequentially from the edges under a local temperature gradient. In addition, the magnetic oxide single crystal in the production method of the present invention may be a polycrystal that is completely (bi-oriented) in a certain direction in a broad sense.For example, in a perpendicular magnetization recording material, the magnetic oxide single crystal It is preferable to use a fine polycrystalline thin film or thin plate that is perfectly oriented (-) in the direction of magnetization, which is easier than a single crystal.

[Embodiments of the invention]

The present invention will be specifically explained with reference to the following two examples.

Example 1 Composition consisting of Mn0.60 znO-34Fe2.0604 (D Mn Zn ferrite powder 12 f was first
As shown in the figure (dissolved in a two-platinum crucible, 50α
Steel twin rolls 3 rotating at a circumferential speed of /see (:
Poured, rolled and rapidly cooled, approximately 40mm wide and 3m long.
A thin plate having a thickness of approximately 1 μm was prepared. When a part of this thin plate was examined by X-ray diffraction, it was confirmed that it was amorphous. The crystallization temperature of this amorphous JR oxide 4 was measured using a differential thermal analyzer (2) and was found to be 650°C. , the upper and lower sides (22 platinum heaters 5 are arranged, and the maximum temperature is 13
Recrystallization was carried out from the edge side by passing the sample under the conditions of 20° C. and a temperature gradient of 00° C./cm at a rate of 2 g/min. X-ray diffraction and hydrochloric acid etching treatment (second analysis) confirmed that this oxide thin plate was a single crystal except for the edges of the thin plate.

Further, when an X-ray Laue photograph was taken of a part of this oxide single crystal thin plate, it was confirmed that the plate surface had a spinel type crystal structure with a (110) plane. Further, when the composition of elements Mn, Zn, and Fe was analyzed using an X-ray microanalyzer, it was found that there was no compositional variation at all.

Example 2 The same apparatus as in Example 1 was used except that the amount of Mn--Zn ferrite powder was 601, and the circumferential speed of the rotating twin rolls was 10 crtt/see. The obtained sample had a width of about 6C1+π, a length of about 200**, and a thickness of about 1 m. When a part of this thin plate was examined by X-ray diffraction, it was found to have a spinel-type crystal structure. When we examined the crystal grain size of this crystalline oxide thin plate using an optical microscope, it was found that the size of the crystal grains was 0.2.
It was confirmed that it consisted of crystal grains of μm or less. Next (two) one end of this fine polycrystalline oxide (two plate surface is (ioo
) single crystal 1fEt (D
Similarly, the maximum temperature was 1370°0. Temperature gradient 50”O/cIr
Under the condition of L, 0.4 tn x 1 minute was passed through the sample to sequentially recrystallize from the end. The oxide thin plate obtained from hydrochloric acid etching and X-ray Laue photography has a (100) plane,
It was confirmed that it was an oxide single crystal with a spinel type crystal structure.

Example 3゜ Figure 3 (Y3Fe using the high frequency sputtering device shown in Figure 2).

A sintered body having a composition consisting of
Target 1 was discharged in an atmosphere with a mixing ratio of 5:5.
A thin film 4 was sputter-deposited on an alumina substrate 13 placed opposite to 2. In this case, the alumina substrate 13 was kept at room temperature. Also, the obtained thin film has a length of 80 ** and a width of 8
It was 6 m1 in thickness and approximately 100 μm thick, and when examined by X-ray diffraction, it was confirmed that it was amorphous. Furthermore, when this amorphous oxide thin film was examined by differential thermal analysis, the crystallization temperature was 740.
It was ℃.

In this way, the amorphous oxide thin film 4 formed on the alumina substrate 3 is heated to a maximum temperature of 1350°C with a temperature gradient of 30° by two platinum heaters 5, as shown in Figure 4).
Let it pass at a speed of 0.247 min under the condition of O/(m,
Recrystallization was performed sequentially from the end side.

When a part of the oxide single crystal 6 thus obtained was taken by an X-ray Laue photograph, it was confirmed that it was a garnet type single crystal with a (111) film surface.

As described above, the method for producing a magnetic oxide single crystal according to the present invention can yield a thin film or thin plate single crystal with a large area and no defects (1g++z or less), compared to conventional slicing from a large single crystal. It is easy to manufacture, mass-producible (one size), low cost (can be manufactured twice), and has remarkable effects.

In particular, the MnZn ferrite single crystal obtained by the production method of the present invention is low cost, has excellent properties, and has high reliability and reproducibility of properties. It is highly effective.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of the present invention in which an amorphous magnetic oxide is produced by the liquid quenching method, and FIG. Fig. 3 is a schematic view of the apparatus showing the state in which an amorphous oxide is sputter-deposited using a high-frequency sputtering apparatus, and Fig. 4 is a perspective view showing the state in which a highly magnetic oxide is recrystallized. It is a perspective view showing a state in which an amorphous magnetic oxide deposited on a substrate (varnish batter vapor deposited) is recrystallized. l... Crucible, 2... Oxide melt, 3... Twin roll, 4 ...Amorphous oxide, 5...Heater,
6...Magnetic oxide single crystal, 9゛°° vacuum container, 10
...High frequency power supply, 12...Target, 13...
·radix. Representative Patent Attorney Kensuke Norichika (1 other person) Figure 1 Figure 3 Figure 4

Claims (6)

[Claims] (1) After amorphizing a crystalline magnetic oxide consisting of a 1-phase or solid solution, the amorphous magnetic oxide is sequentially recrystallized from the edges under a local surface temperature gradient. A method for producing a characteristic magnetic oxide single crystal. (2) A method for producing a magnetic oxide single crystal according to claim 1, characterized in that the crystalline magnetic oxide is made amorphous by a liquid quenching method. (3) A method for manufacturing a magnetic oxide single crystal according to claim 1, characterized in that the crystalline magnetic oxide is made amorphous by being attached to a substrate material by a vapor deposition method. (4) The magnetic oxide according to claim 1, wherein the recrystallization is performed at a maximum temperature higher than the crystallization temperature of the amorphous magnetic oxide and lower than the melting point +300"O. Method for producing single crystals. (5) The method for producing a magnetic oxide single crystal according to claim 1, characterized in that the recrystallization is performed at one end (two types) of the amorphous magnetic oxide. (6) As a crystalline magnetic oxide, an iron group transition metal element (T
i, v, Cr, Mn, Fe, Co, Ni, Cu) and rare earth transition metal elements (La, Ce, Pr, Nd, Pm,
Sm, Eu, Gd, Tb, Dy, Ho. The main component is a magnetic oxide consisting of at least one of the following: Er, Tu, Yb, Lu) and an alkali metal (Li).
. 41i metals on alkali (Mg, Ca,
Sr, Ba), Sc. Y, B, Zr, Hf, Zn, Cd, Si, Ge, Sn,
The magnetic oxide according to claim 1, characterized in that it contains a magnetic oxide whose subcomponent is an oxide containing at least one of Pb, A/, In, Bi, and Sb. Method for producing single crystals. (Force crystalline magnetic oxides are spinel type, garnet type,
7. The method for producing a magnetic oxide single crystal according to claim 6, wherein the magnetic oxide is a perovskite type and hexagonal ferrite magnetic oxide.