JPH04182383A - Noble metallic crucible and production of crystal - Google Patents

Abstract

PURPOSE:To use a crucible for a long period by partially thickening the thickness in the side wall part of the noble metallic crucible in comparison with the other side wall part. CONSTITUTION:For example, the part equal to the uppermost part of melt in a crucible is protruded in the shape of a pedestal. This part is regulated to thickness of about two times in comparison with the other side wall part. The crucible is used and melt is filled to the part regulated to this large thickness and crystal is grown by a liquid phase epitaxial method. Thereby, since this melt is held at high temp., noble metal constituting the crucible reacts with a metallic component contained in the melt. The side wall part of the crucible is gradually dissolved. However, since the side wall part regulated to large thickness is partially worn, the crucible is effectively used.

Description

[Detailed Description of the Invention] [Industrial Application Fields] The present invention is directed to the production of oxide garnet epitaxial thick films used in noble metal crucibles, particularly magneto-optical devices such as optical isolators and optical switches, and MSW (magnetostatic wave) devices. The present invention relates to a precious metal crucible that is useful in the field of manufacturing, and a crystal manufacturing method using this precious metal crucible.

[Prior art] Oxide garnet epitaxial films used in magneto-optical devices and MSW (magnetostatic wave) devices such as optical isolators and optical switches are made by the liquid phase epitaxial method in noble metal crucibles. The precious metal crucibles used in this process are, for example, 2.5 mm thick and finished with an accuracy of about 2 mm.

[Problems to be Solved by the Invention] However, if the melt used in this precious metal crucible contains precious metals that are the crucible material, such as bismuth element, which is an element that reacts with platinum, the inner surface of the crucible may deteriorate. The platinum crucible used to grow the bismuth-containing Carnet film had a wall thickness of 2.5 mm, as the melt significantly melted the platinum and reduced its thickness, eventually forming a hole and making it unusable as a crucible.
The disadvantage is that crystal production of 5 mm crystals has a hole in the crucible after about 1.5 months, forcing the production of crystals to be discontinued.

In addition, since the thickness of the side wall without holes in this crucible with holes is almost unchanged from before use, it can be repaired or recast and reused. Although attempts have been made to do so, they also have the disadvantage of being uneconomical.

[Means for Solving the Problems] The present invention relates to a precious metal crucible that solves these disadvantages, and a crystal manufacturing method using the same. A crystal manufacturing method, characterized in that crystals are manufactured by a liquid phase epitaxial method or a flux method using a noble metal crucible characterized by having a thickness larger than that of a metal and a melt composition containing a bismuth element. The gist is the method.

In other words, as a result of various studies by the present inventors on measures to prevent holes from forming due to reaction with the melt in the precious metal crucible, it was found that the thickness of the side wall of the precious metal crucible was not made uniform and there was a risk of holes forming. It was discovered that if the side wall of the part is thicker than the other side walls, the pitting is prevented, and if such a precious metal crucible is used, crystals can be grown using a melt that is reactive with precious metals. The present invention was completed after confirming that disadvantages such as operation stoppages due to holes can be avoided even when the holes are drilled.

This will be explained in further detail below.

[Function] The present invention provides a precious metal crucible that can prevent accidents such as drilling,
The present invention also relates to a crystal manufacturing method using this crucible.

The precious metal crucible of the present invention may be made of a precious metal such as platinum, platinum-rhodium alloy, zirconia, reinforced platinum added with ittria, etc. be taken as a thing.

This is because there is a hole in the side wall of the precious metal crucible because the precious metal that makes up the precious metal crucible is in the melt used here.
For example, if a metal element that reacts with platinum, such as bismuth element, is included, the side wall will gradually melt due to the reaction between platinum and bismuth, causing holes to form if used for a long period of time. However, when we examine crucibles with holes, we find that the perforated area is usually located at the highest end of the melt, and the reaction between the melt and the precious metal crucible is most likely to occur in this area. Since it is presumed that the damage is intense, the most effective way for the noble metal crucible of the present invention is to make the side wall near the highest part of the melt contained therein thicker than the other side wall parts.

To explain this with reference to the attached drawings, Fig. 8 shows the conventionally known one, which has a uniform thickness throughout, but the one of the present invention has the highest part of the melt as shown in Fig. 1. The portion corresponding to the side wall is raised into a platform shape, and this portion is approximately twice as thick as the other side wall portions. Therefore, if this precious metal crucible is used to fill the melt to the point where the thickness has increased and the crystal is grown by the liquid phase epitaxial method, this melt will be maintained at a high temperature. The side wall of the crucible gradually dissolves due to the reaction between the metal components contained in the liquid and the precious metals that make up the crucible. Upon inspection, it was confirmed that the thickened side wall as shown in Figure 2 was partially worn out, but this part was still thicker than the other side walls, and the overall It was found that the wear had not progressed up to the thickness of the side wall, so it could be used effectively again.

Note that the thickness of this side wall portion may be increased by any method, but for example, a concave portion is provided in a part of a mold for forming a crucible, the precious metal is cast, and a third layer is placed in this crucible. A square section as shown in the figure, a trapezoid section as shown in FIG. 4, or a circular trapezoid section as shown in FIG. 5 may be provided. As shown in Figure 2, another noble metal such as platinum-rhodium alloy, zirconia, or reinforced platinum added with ittria may be welded onto the side wall of a ready-made platinum crucible.

[Example] Next, examples of the present invention and comparative examples will be given.

Examples and Comparative Examples A platinum crucible with an inner diameter of 150 mm, a height of 200 mm, and a side wall thickness of 2.5 mm was prepared.
A crucible was prepared by heating a platinum material with a width of 15 mm and a thickness of 2 mm at a position 30 mm above the crucible using a burner until the platinum material melted at the side wall of the crucible, and the thickness of the side wall at this portion was 4.5 mm.

Next, Bi2039,77 was added as a metal oxide to form an oxide garnet epitaxial film in this crucible.
3.8g, Eu2O,, t<, aqg, Tb4o
.

139.29g, Fe2031.228.6g and Ga20352.73g as flux components
When 09.363.6 g of Pb and 8203417.2 g of Pb were charged and heated to 1.100°C to melt them, a melt with a height of 130 mm was obtained, which was heated to the growth temperature of 750°C. Lower the temperature and add NO to this melt.
A G-wafer was immersed 20 mm below the surface and rotated for 50 hours to form a film with a thickness of 55 mm on both sides of the substrate crystal.
A 0 μm oxide garnet epitaxial thick film was grown, and then a Carnet crystal component corresponding to the composition precipitated on the substrate crystal was added to this melt, heated to 100°C to melt it, and then grown at the growth temperature. The temperature was lowered to a certain 750° C., and a thick oxide garnet epitaxial film with a thickness of 5504 m was grown from this melt on both sides of this substrate crystal using the same method as described in 142.

By repeating such crystal growth and addition of precipitated crystal components, the growth of bismuth-containing garnet crystals is continued.
After two months, the melt was taken out and the thickness of the platinum on the side wall of the crucible was measured, and it was found that the part where the thickness was 4.5 mm in the above was considerably eroded due to the reaction between platinum and bismuth, and the other side walls were The thickness of the crucible was about the same (2.5mm) as that of the crucible, or the hole could not be drilled, so for this crucible, a width of 1.
A platinum plate with a diameter of 5 mm and a thickness of 2 mm was heated with a burner until it was fused to the platinum material or the crucible, and the side wall of this part was made 4.5 mm thick. I have been able to use it.

However, for comparison, the above-mentioned oxide garnet epitaxial thick film was grown using a platinum crucible in which the entire side wall was 2.5 mm thick, with no part of the side wall being thick. However, after 15 months, this platinum crucible became unusable due to a hole with a diameter of 5 mm in the area that contacted the upper part of the liquid level.

[Effects of the Invention] The present invention relates to a precious metal crucible and a method for producing crystals, and this invention relates to a noble metal crucible in which the side wall portion is partially thicker than other side wall portions as described above, and a method for manufacturing a crystal using this crucible. The gist is a crystal growth method for producing crystals using liquid phase epitaxial method or flux method.
According to this, since the side wall part that is at risk of being pre-drilled is thicker than other side wall parts, even if this crucible is used to grow crystals by liquid phase epitaxial method or flux method, Even if the side wall part melts due to the reaction between the metal elements contained in this melt and the precious metal elements constituting the precious metal crucible, this is considered to be the thickened part, so it is not necessary to use this crucible for a long period of time. It gives you the advantage of being able to do it.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of the precious metal crucible of the present invention, Fig. 2 is a longitudinal cross-sectional view after using this for two months, and Figs. 3 to 7 are the increased thickness of the side wall portion of the precious metal crucible of the present invention. FIG. 8 is a longitudinal sectional view of a conventionally known precious metal crucible. Patent applicant: Shin-Etsu Chemical Co., Ltd. r-. Agent/patent attorney Ryo Yamaki = 〃 〃 Kane Tsukasa Arai-1, E-4, □・
・＼ Figure 3 Figure 4 Figure 6 Figure 8 Figure 5 Figure 7

Claims (1)

[Scope of Claims] 1. A noble metal crucible characterized in that a side wall of the crucible is partially thicker than other side walls. 2. The noble metal crucible according to claim 1, wherein the noble metal is mainly composed of platinum element. 3. A crystal manufacturing method, which comprises manufacturing a crystal from a melt composition containing bismuth element by a liquid phase epitaxial method or a flux method using the noble metal crucible according to claim 1.