JPS6272596A - Oxide garnet single crystal - Google Patents

Abstract

PURPOSE:To provide a substrate single crystal for epitaxial growth of a garnet structural body of which cations consist of 4 kinds of oxides of Y, Mg, Zr and Ga and which has good productivity. CONSTITUTION:The cations of this single crystal consist of 4 kinds of the oxides of Y, Mg, Zr and Ga and the crystal structure thereof is expressed by, for example, the formula Y3MgZrGa3O12. The crystal lattice constant thereof is 12.42-12.45Angstrom and the segregation coefft. is approximately 1. Since the singe crystal has the above-mentioned crystal lattice constant and segregation coefft., the single crystal is useful as the garnet substrate single crystal for epitaxial growth of the bismuth-substd. magnetic garnet film expressed by the formula (BiRe)3(FeM)5O12 and since the single crystal has excellent light transmittability, this crystal is useful as the substrate for an optical isolator as well. This single crystal is easily produced without twisting of the single crystal in the pulling-up stage by weighing respective raw materials to obtain the above-mentioned compsn., then housing the raw materials into a crucible and pulling up the crystal by a Czochralski process after heating and melting the crystal at 1,700-1,800 deg.C.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to a novel oxide garnet single crystal that has not been published in any literature,
In particular, the present invention relates to an oxide garnet single crystal that is useful for magnetic bubble elements and magneto-optical elements in which cations are made of four types of oxides: Y, Mg, Zr, and Ga.

A magnetic film with a garnet structure obtained by epitaxially growing a cold iron-based magnetic garnet fJj film is used as a magnetic bubble element and a magneto-optical element. Bi because it is necessary to increase the size, and for magneto-optical applications, it is necessary to increase the Faraday rotation speed.

R, Fe, M (here R is Ca, Y or a)
It is said that the use of a bismuth-substituted magnetic garnet film made of a cationic oxide of one or more of the following elements (M is a metal element that can be substituted with iron such as Ga or All) shows good results. Its use is attracting attention.

On the other hand, regarding the garnet substrate single crystal used to make the epitaxial growth layer having this garnet structure, l) the lattice constant of the crystal is about 0. 2) the segregation coefficient of the elements constituting the crystal is close to 1, and y) + is required. The lattice constant of conventional single crystal substrates of this type, such as gadolinium gallium garnet (GGG) and neodymium gallium garnet (NGO), is 12.42 to 12.45λ.
12.38 and 12.51λ, respectively, so it cannot be said that it is an optimal substrate for epitaxial growth of this bismuth-substituted magnetic garnet film, and its lattice constant is 12.43 among various conventionally known single crystal substrates. Only samarium gallium garnet (SGG) is used for this purpose and has been put into practical use. However, this SGG has the disadvantage that it is difficult to manufacture and has low productivity due to the phenomenon that the crystal is twisted during single crystal growth in the Czochralski method. Crystals are requested.

[Structure of the Invention] The present invention relates to a substrate single crystal for epitaxially growing a garnet structure, which does not have such disadvantages and has good productivity.
The present invention relates to an oxide garnet crystal consisting of four types: r, Ga.

That is, the present inventors determined the crystal lattice constant of the bismuth-substituted magnetic garnet film made of cationic oxides of f(F)Bi, R, Fe, M, (R, M are the same as above) as the epitaxial growth layer described above. 12.42-12.45
As a result of various studies on garnet structures with lattice constants similar to A, we found that the cations marked Y- are Y, Mg, Z
It was discovered that an oxide garnet single crystal consisting of four species, r, Ga, has a lattice constant of 12.43A, and that the segregation coefficient of this crystal is approximately l. The present invention was completed after confirming that the crystals do not sometimes become twisted and can be easily pulled up, resulting in excellent productivity.

The oxide garnet single crystal of the present invention consists of four elements as cations: yttrium (Y), magnesium (Mg), zirconium (Zr), and gallium (Ga). A wafer cut from the crystal was etched with hot phosphoric acid and its lattice constant was measured to be 12.429A.
R, Fe.

consisting of a cationic oxide of M, for example, the formula (Bi Re
) (FeM)sot2't' Lattice constant of bismuth-substituted magnetic garnet film 12.42-12.45
This is approximately the same as λ, and this segregation coefficient is Y and Mg based on the analytical value of this crystal.

t, oo ~ t, for both Zr and Ga.

2, it was confirmed that this is the optimum garnet substrate single crystal for epitaxially growing the bismuth-substituted magnetic garnet film described in b.

As mentioned above, the oxide garnet crystal of the present invention is made up of four types of cations: Y, Mg, Zr, and Ga, but this crystal has Y, [ Mg, Zr on al site.

Therefore, an example of this is one with the crystal structure shown as 2Y3MgZrGa30.2, but in this case, Y3MgZrGa30.2 is an example.
It is produced by charging a predetermined amount of 2O3, MgO, ZrO2, and Ga2O3 into a crucible, heating and melting it using high-frequency induction, and then pulling a single crystal from this melt using the Czochralski method.

That is, the present inventors have, for example, the above formula Y MgZr
We investigated various industrial methods for manufacturing oxide garnet single crystals represented by Ga5O12, and determined that the single-crystal Czochralski method would be suitable for this purpose, and we conducted research on these conditions. I proceeded. Y O, MgO1Zr02. used here. Ga2O3 should be as pure as possible, and therefore all of these preferably have a purity of 99.9% or higher. Since the target single crystal is, for example, of the formula Y MgZrGa5O12, these compounding ratios are Y2O336-39 mol%, MgO11-14 mol%, Z r0211-14 mol%, Ga20316-3.
It is necessary to adjust the content to 9 mol%. After each of these is weighed, they are placed in a crucible and melted, but since the melting temperature of these crucibles is 1.700°C or higher, it is sufficient to use one made of iridium. Therefore, it is sufficient to perform this by high frequency induction, for example, by using a high frequency of 7 KHz, 10 KW, and heating these to 1,700 to 1,800 DEG C. to melt them.

[J-like? The i-crystal can be produced by pulling a single crystal from this melt using the Czochralski method, but the atmosphere in this case is 1 to 5% oxygen or 25% CO2 gas.
It is sufficient to use a nitrogen gas or argon gas atmosphere containing ~100%, and the seed crystal used for pulling the single crystal has the same formula as the target single crystal, for example, the formula Y3MgZrGa.
3012, but it may also be a single crystal of a garnet-type crystal such as gadolinium gallium garnet (GGG), and in this case, the pulling speed of the single crystal is 1 to 20 mm/hour. And it is sufficient.

In addition, in this pulling of the single crystal, unlike SGG, the single crystal does not twist during pulling, and this pulling can be performed extremely easily. By separating and cooling, a single crystal of type II can be obtained.

For example, the formula Y MgZ of the present invention thus obtained
rGa301. , t' is the single crystal shown.

As stated above, the crystal lattice constant is approximately 12.43λ and the segregation coefficient is approximately l, so the formula (Bi
Garnet for epitaxially growing the bismuth-substituted magnetic garnet film shown in Re) (FeM)50.2-t')^ It is said to be useful as a plate-type crystal, but it also has excellent optical transparency. Therefore, it is also useful as a substrate for optical isolators.

Next, I will discuss the ¥dense side of the present invention.

Example 1 In an iridium crucible with an outer diameter of 50 mm and a height of 50 mm,
Y2O3194.6g, (0.86 mol), Mg02
3-15g (0.57 mol) ZrO270.78g
(0,57 mol) and Ga203161.5g (0
, 86 mol) was weighed and charged, heated to 1,750°C by high frequency induction in an atmosphere of 98% nitrogen gas and 2% oxygen gas to melt it, and 5 mm square GGG seed crystals were added to the melt. 5 to 6 mm under rotation of 1 Orpm.
When the crystal was pulled at a speed of 7:00 to perform single crystal cutting, 86.3 g of transparent crystal was obtained.

Next, about 1 g of samples were cut out from the upper and lower parts of this crystal, and a 7-dimensional analysis was performed on each component total element using a high-frequency coupled induction plasma emission spectrometer. The results are shown in Table 1 below. As the following results were obtained, it was confirmed that this material had the crystal structure of the following formula % formula %: 8. Based on the results of this total analysis, the segregation coefficients of each of these metals were calculated. As a result, these are shown in Table 2, and IJ
It was confirmed that both of them were approximately 21.

Table 2 also shows the upper part of this crystal and the crystal IIr
181gJL-P, I+-(Je1++-/F-^〒-
1. Biting Toro Itl+j+lJJ■.

After etching with phosphoric acid, lattice constant precision measurement device/APL
2 (product name manufactured by Rigaku Denki Co., Ltd.) and its lattice constant is A! using the Pond method. As a result, both of these are 12.42
It showed a value of 9A.

Examples 2 to 4 Blend of metal oxides in Example 1 described in L? When treated in the same manner as in Example 1, except that the crystals were cleared as shown in Table 3 below, transparent single crystals were obtained (11), and from the analysis results, these had the formula Y MgZrGa5O12
It had the crystal structure shown below.

Table 3 Example 5 1. Except that the gas atmosphere in the melting of the metal oxide in the described Example 1 and the production of a single crystal from this melt was 50% nitrogen gas and 50% CO2 gas. Example 1
When treated in the same manner as in Example 1, the same results as in Example 1 were obtained in this case as well.

Claims (1)

[Claims] 1. An oxide garnet single crystal containing four types of cations: Y, Mg, Zr, and Ga. 2. The oxide garnet single crystal according to claim 1, which has a lattice constant in the range of 12.42 to 12.45 Å. 3. The oxide garnet single crystal according to claim 1, which has a crystal structure of Y_3MgZrGa_3O_1_2.