JPS6296387A - Production of single crystal - Google Patents

Abstract

PURPOSE:To prevent the contamination of a single crystal with platinum particles and to obtain a long single crystal having high quality, by supplying and melting a raw material of crystal in a platinum-group metal crucible held in a specific heating apparatus in stationary state, lowering the crucible to effect the growth of a single crystal and repeating the above process. CONSTITUTION:A platinum-group metal crucible 1 changed preparatorily with a small amount of initial raw material is placed on a crucible supporting table 6 attached to a crucible supporting pipe 7 which can be vertically moved and rotated with a crucible lifting apparatus 5. The crucible supporting table 6 is inserted in a electric furnace 3 having a proper temperature distribution shown in the figure. The initial raw material is melted in the electric furnace 3 and the crucible 1 is lowered to obtain a single crystal (b). The crucible 1 is stopped, a granular raw material 8 is supplied from a raw material feeder 4 through a raw material feeding pipe 2 to a melt (a) at a depth of 20-40mm. After feeding, the crucible 1 is lowered 20-40mm at a rate of about 5mm/hr to effect the growth of the crystal. The above procedures are repeated to obtain a long single crystal.

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 relates 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 1% crystal material. It is something.

(2) Prior Art Conventionally, the Pritznoman method is generally known as a method for producing single crystals. in this way.

Although large crystals such as magnetic materials can be produced relatively easily,
Because it is an entire melt-solidification method, in multi-component crystals, large compositional segregation occurs in the upper and lower parts of the crystal after 2nd production.
In the case of n-Zn-ferrite.

It also had the disadvantage that physical properties such as magnetic permeability varied widely. Also to cover this shortcoming.

A method is also known in which a long platinum group crucible is used to continuously supply a crystal material in an amount equal to the weight to be crystallized per unit time to produce a long, large-diameter crystal with less two-component segregation. 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 was difficult to obtain high quality single crystals.

(3) Problems to be Solved by the Invention The mechanism by which platinum is mixed into the crystal is that the ionized platinum is dissolved into the melt from the inner wall of the platinum group crucible, which is the growth container, and the temperature of the melt is lowered by the supply of solid raw materials. It is thought that these platinum particles are precipitated into two particles due to rapid cooling due to oxidation, 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. It is necessary to prevent the decrease in temperature or to stop crystal growth when the temperature decreases. However, the former problem is unavoidable as long as the crystal material is 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 in which crystal materials are sequentially supplied and melted in a crucible in a heating device, and crystal growth is performed from the tip of the crucible by changing the position of the crucible. supply of crystalline materials;
It is characterized by not allowing crystal growth to proceed at the same time.

(5) Examples Examples of the present invention will now be described in detail with reference to the drawings. A single crystal manufacturing apparatus according to the present invention is as follows.

A platinum group crucible 1 loaded with a small amount of initial raw material (not shown) in advance in the electric furnace 3 of FIG. 1(a) having the temperature distribution shown in FIG. Support/Nii 7'7. The crucible is supported from below by a crucible lifting device 5, and can be moved up and down one rotation. In this configuration, the initial raw material is melted in the electric furnace 3, and the platinum group metal is melted. 1 to obtain a single crystal. Thereafter, the platinum group crucible 1 is stopped, the raw material supply device 4 is activated, the granular raw material 8 is dropped from above through the raw material supply pipe 2, and is supplied to the melt a to a depth of 20 to 40+ seconds. Ge 1 at 20-40 rms * 5 WrIV/h
The crystal is grown by descending at a speed of r, and by repeating this process, a long crystal is obtained. For example, +Mn-Zn-
When this method was applied to a ferrite single crystal, the platinum particle density was 10 particles/-, whereas the conventional platinum particle density was about 100 particles/-.
We were able to significantly improve quality by reducing the amount by half.

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

[Brief explanation of drawings]

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

Claims (1)

[Claims] 1. Sequentially supplying and melting crystal raw materials into a crucible placed in a heating device having an appropriate temperature distribution in the vertical direction,
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 simultaneously in a method of growing a crystal sequentially from the tip of the crucible by changing the relative position of the heating device and the crucible.