JPH0238558B2 - TANKETSUSHONOSEIZOHOHO - Google Patents

Description

[Detailed Description of the Invention] (1) Field of Application of the Invention The present invention relates to a method for producing a single crystal, and in particular to an improvement in the method for producing a single crystal in which a long, large-diameter crystal is obtained by sequentially supplying and melting crystalline materials. It is.

(2) Prior Art Conventionally, the Bridgeman method is generally known as a method for producing single crystals. in this way,
Large crystals such as magnetic materials can be produced relatively easily, but because the entire melt-solidification method is used, in multi-component crystals, large compositional segregation occurs in the upper and lower parts of the crystal after production, such as Mn-Zn-ferrite. In this case, the disadvantage was that the physical properties such as magnetic permeability varied greatly. In addition, in order to overcome this drawback, there is a method in which a long platinum group crucible is used to continuously supply the same amount of crystal material as the weight to be crystallized per unit time, thereby producing long, large-diameter crystals with less compositional segregation. is also known. However, in this method, since the crystal raw material is supplied as needed while growing the crystal, the platinum particles eluted from the crucible wall into the melt are transferred from the melt to the crystal via the solid-liquid interface during crystal growth. It has been difficult to obtain high quality single crystals.

(3) Problems to be solved by the invention The mechanism of platinum being mixed into the crystal is that platinum that dissolves into the melt from the inner wall of the platinum group crucible, which is the growth container, and becomes ionized, lowers the temperature of the melt by supplying solid raw materials. It is thought that platinum particles are precipitated in the form of particles due to rapid cooling due to crystal growth, and these platinum particles are mixed into the crystal at the same time as the crystal grows from the interface between the melt and the crystal, where crystal growth is progressing.To suppress this, it is necessary to lower the temperature of the melt. It is necessary to prevent crystal growth or stop crystal growth when the temperature drops. However, the former problem is unavoidable as long as crystalline materials are supplied. An object of the present invention is to obtain a high quality single crystal with less platinum particles mixed into the crystal.

(4) Means for Solving the Problems Therefore, the present invention provides a method for sequentially supplying and melting crystalline materials in a crucible in a heating device, and growing crystals from the tip of the crucible by changing the position of the crucible. In particular, it is characterized by not allowing the supply of crystal material and the growth of crystal to proceed at the same time.

(5) Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The single crystal manufacturing apparatus according to the present invention includes a platinum group crucible 1 in which a small amount of initial raw material (not shown) is preloaded into an electric furnace 3 shown in FIG. 1a having a temperature distribution shown in FIG. 1b. It is supported from below by a crucible support stand 6 and a crucible support pipe 7, and can be moved up and down and rotated by a crucible lifting device 5. In this configuration, the initial raw material is melted in the electric furnace 3, and the platinum group crucible 1 is lowered to obtain the single crystal b. After that, platinum group crucible 1
is stopped, and the granular raw material 8 is supplied by the raw material supply device 4.
is dropped from above through the raw material supply pipe 2 and supplied to the melt a to a depth of 20 to 40 mm, and after the supply is finished, the crucible 1 is lowered to 20 to 40 mm at a speed of 5 mm/hr to grow crystals. By repeating this process, long crystals are obtained. For example, when this method was applied to Mn-Zn-ferrite single crystals, the density of platinum particles, which was conventionally about 100 particles/ ^cm2 , was halved to less than 10 particles/ ^cm2 , resulting in a significant improvement in quality. I was able to measure it.

(6) Effects of the Invention As described above, according to the method for producing a single crystal according to the present invention, a high quality long single crystal with very little platinum particle contamination can be obtained.

[Brief explanation of drawings]

FIG. 1a is a schematic diagram of a manufacturing apparatus according to the present invention;
Figure b is a diagram showing the temperature distribution. 1 is a platinum crucible, 2 is a raw material supply platinum pipe, 3
is an electric furnace, 4 is a raw material supply device, 5 is a crucible lifting device, 6 is a crucible support stand, 7 is a crucible support pipe,
8 is a granular raw material, a is a melt, and b is a single crystal.

Claims (1)

[Claims] 1. Crystal raw materials are sequentially supplied and melted into a crucible placed in a heating device having an appropriate temperature distribution in the vertical direction, and by changing the relative position of the heating device and the crucible, crystals are sequentially formed from the tip of the crucible. 1. A method for producing a single crystal, characterized in that the supply of a crystal raw material and the growth of a crystal do not proceed at the same time.