JPH03228891A - Method and apparatus for producing single crystal fiber - Google Patents

Abstract

PURPOSE:To easily obtain the single crystal fiber having a desired compsn. even from a nonstoichiometric melt with which the conventional method is heretofore difficult by adopting specific constitution in the method for forming a starting raw material soln. in the projecting part of a heating element, bringing a seed crystal into contact with the molten part thereof, pulling down and growing the single crystal fiber. CONSTITUTION:The raw material soln. 4 having such a compsn., from which the desired single crystal fiber 8 is obtainable is pooled in the projecting part 2 of the heating element 1 (e.g. platinum heater) having a microhole 3 and is extended from the microhole 3. The single crystal fiber 8 is then grown while a raw material (raw material rod 5) of substantially the same compsn. as the compsn. of the single crystal fiber 8 and of the same amt. as the amt. of the single crystal fiber 8 to be grown is supplied to the above-mentioned pool.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a single crystal fiber manufacturing method and manufacturing apparatus, and more specifically, to a single crystal fiber manufacturing method and a manufacturing device that enable the growth of single crystal fibers of solid solution compounds, decomposed molten compounds, and phase change compounds. related to manufacturing technology.

[Prior Art] Laser pedestal method (LHPG) is a method conventionally considered as a single crystal fiber manufacturing technology. In this method, a finely focused CO2 laser is used to melt a minute area at the tip of a raw material rod, and from the melted area, crystals are pulled up into fibers using minute crystals as seed crystals.

According to this method, unlike the conventional Czochralski method, there is no contamination by impurities caused by the crucible, there is no restriction on the melting temperature, and crystal growth is possible without paying special attention to the surrounding environment.

Fiberization of nonlinear optical crystals is described by Fejer et al. (Rev, Sei.) for LiNbO3 single crystals.

Instrument, 55.1791 (1982),
Regarding the fiberization of B a T i O, single crystal, 5aifi et al. (J, Mater Res,, l.
452.19813).

Another major reason is that with normal single crystal pulling technology, there is a limit to the ability to reduce the diameter due to problems such as temperature fluctuations depending on location due to thermal convection and time delays in temperature control.

The amount of melt is limited to a minute amount, a minute convex part is provided on the surface of the platinum heat generating material, the raw material is melted in contact with this, the surface is wetted with the melt, and crystal seeding is carried out with this convex part. proposed a method for crystal pulling (Omen, 34th Spring Proceedings of the Japan Society of Applied Physics, 31a-Z-5゜31a-Z-[i, p. 193 (1987)).

The melt layer formed in this way is thin, so the temperature difference in the thickness direction is small, suppressing thermal convection, and the melt adheres closely to the heating element, improving temperature controllability. 1 Continuous pulling of small-diameter fiber single crystals is possible by concentrating the melt due to surface tension, fixing the crystallization position, and local cooling effects.

With this method, LiNbO3 single crystal.

30μmφX120m++n in the <0001> direction.

For BaB2O+ single crystal, 20μmφ×60mn+ are each 0. 1-2mm/ll1in, 0. 01~
0. 3mm/ll1in, 0, 04-1
A single crystal fiber is obtained by pulling at a rate of mm/min.

Here, for convenience of explanation, "melt" refers to a liquid having the same composition as the target single crystal fiber.

The term "solution" refers to a liquid having a composition different from the desired composition, as will be described later, and from which a single crystal having the desired composition precipitates as the temperature decreases.

[Problem to be solved by the invention] Fejer (1982) S described in the prior art
The methods of Ai F i (1986) and Ohmen (1987) all employ the method of pulling fiber single crystals by direct assimilation from the raw material melt, and in this sense, they are difficult to pull from stoichiometric melt. It's growth.

In addition, in the method described in Omen and 5aifi, B
It is claimed that aB2O4 or BaTiOi crystals do not require growth from a non-stoichiometric melt since a crystal with a low-temperature phase structure is directly obtained when fiberized.

However, in general, decomposed melt compounds such as KT i OP 04, BaTi0. In order to grow single crystal fibers of phase change type compounds (low temperature phase structure) such as, solid solution compounds such as LiNbO3, even if single crystal fibers are grown from the above-mentioned stoichiometric melt, it is originally necessary. In many cases, it is not possible to obtain such single crystal fibers.

Therefore, the technical problem of the present invention is that compounds obtained from stoichiometric melts, as well as monocrystalline fibers from stoichiometric melts such as bicomponent melt compounds, phase change compounds, solid solution compounds, etc. An object of the present invention is to provide a method and apparatus for manufacturing single crystal fibers, which can easily produce single crystal fibers of compounds that have been difficult to manufacture.

[Means for Solving the Problems] Accordingly, 1. the present invention has been made to achieve the above-mentioned objects, and 1. the method for producing a single crystal fiber of the present invention is such that a desired single crystal fiber can be obtained. A raw material solution having a composition is pooled in a protrusion of a heating element having micropores, and is extended from the micropores, and a raw material solution having substantially the same composition as the single crystal fiber and in the same amount as the single crystal fiber to be grown. The method is characterized in that a single crystal fiber is grown while supplying the above-mentioned water to the pool.

In addition, there is an apparatus for producing single crystal fiber according to the present invention.

A protrusion for pooling a raw material solution having a composition such that a desired single crystal fiber can be obtained, a heating element provided in the protrusion and having micropores, and supplying the raw material to the raw material solution pooled in the protrusion. It is characterized by comprising a raw material supply section and a stretching section that grows a single crystal fiber while stretching the raw material solution that has passed through the micropores.

Furthermore, specifically, in the present invention, a starting material solution is formed on the projection part of a heating element, and a seed crystal is brought into contact with this melting part to pull down (or pull up) a single crystal fiber. 2 In the present invention, instead of a raw material solution, a solution having a composition that allows the desired single crystal to precipitate is used, and the raw material is used to maintain a state in which the solution composition does not change as the fiber single crystal is pulled down (or pulled up). This is a manufacturing method and apparatus configured to enable supply.

In the conventional method of pulling single crystal fibers from a melt, the amount of melt is limited to a minute amount, and a protrusion is provided on the surface of a platinum heating element, which melts the raw material in contact with it and covers the surface with the solution. Wet it and use this protrusion for seeding.
However, the amount will be increased.

In the present invention, as shown in FIG. 1, a minute through hole is provided in the center of this protrusion, and a pool of solution having a composition such that the desired single crystal is precipitated is provided at the end of the hole.

Similar to the method for pulling single crystal fibers from this solution, the crystal fibers are pulled down (or pulled up, hereinafter referred to as "upper") from the protrusions of the platinum heating element, but the crystal fibers adhere to the minute protrusions. The composition of the solution becomes depleted in single crystal components as the fiber single crystal is pulled down (upward), but to compensate for this, the raw material rod contacts and melts on the solution surface.

Raw materials are supplied to the solution pool so as to offset the concentration difference, and the composition of the pool solution is always kept constant.

The raw material is supplied to this solution pool by melting the raw material rod, but in order to keep the composition of the solution pool constant, the raw material rod holder must be rotated to ensure homogenization. .

Furthermore, when melting this raw material rod in a solution pool, it is necessary to take into account the drop in liquid temperature due to the escape of heat from the raw material rod. By heating, a drop in liquid temperature is prevented.

With the manufacturing method and apparatus as described above, it is possible to pull down (raise) single crystal fibers of a solid solution compound decomposed molten compound and a phase change compound having a certain composition.

[Work] In the single crystal fiber pulling apparatus of the present invention.

A platinum heater and pool is installed between the single crystal fiber and the raw material to interpose a solution with a chemical composition adjusted to precipitate the composition of the fiber single crystal. Measure the melt and at the other end,
By measuring the production of single crystal fibers, the composition of the solution does not change, so it is possible to grow solid solution single crystal fibers with a constant composition, and by using a low melting point solvent, it is possible to grow solid solution single crystal fibers with a constant composition. It is also possible to grow single crystal fibers from decomposed molten compounds.

[Example] Embodiments of the present invention will be described with reference to the drawings.

FIGS. 1(a) and 1(b) are diagrams showing essential parts of a single crystal fiber manufacturing apparatus according to an embodiment of the present invention.

FIG. 1(a) is a sectional view, and FIG. 1(b) is a front view.

In these figures, the platinum heater 1 has a protrusion 2 whose negative side is sunken and the other side opposite to it is protruded so that raw materials and solutions can be pooled. Although the shape of the protrusion 2 is not particularly limited, it is preferable that the cross section is trapezoidal or circular in order to improve temperature distribution.

The protrusion 2 has a microhole 3 . Micropore 3.

There is no particular restriction as long as the size of the solution 4 is maintained by surface tension, but about 10 to 50 μm is preferable.

A raw material solution 4 is pooled in the micropores 3 of the protrusion 2, and raw material is continuously supplied to the raw material solution 4 from the raw material rod 5.

Further, the raw material rod 5 is heated by an auxiliary heater 6 and held by a raw material rod holder 7.

Then, the single crystal fiber 8 is continuously manufactured from the raw material solution 4 by pulling down the single crystal.

FIG. 2 is a diagram showing an example of the overall configuration of the single crystal fiber manufacturing apparatus of the present invention.

In FIG. 2, the single crystal fiber manufacturing apparatus includes a raw material rod supply section, a solution preparation section, and a stretching section.

0 The raw material supply section includes a raw material rod holder 7 connected to an upper XY stage 9 driven by a pulse motor drive section 15.

This raw material rod holder 7 is connected to the upper XY stage 9 and is movable two rotations and vertically.

The extension section is a fiber holder 1 connected to a lower XY stage 11 driven by a pulse motor drive section 16.
0.

Single crystal fiber 8 is held in a fiber holder 10 connected to a lower XY stage 11.

Like the upper XY stage 9, this lower XY stage 11 can be rotated and moved in the vertical direction by a pulse motor drive section 16.

Further, the solution preparation section is surrounded by a cylindrical refractory 13, and the two heating plates 12 can be observed using a stereoscopic microscope 14.

Next, an example of manufacturing a single crystal fiber using the above-mentioned single crystal fiber manufacturing apparatus will be explained using LiNbO, which is a solid solution compound.
3.

1 4 to 5 N each (99,99% to 99.999%
) using L f CO3 and Nb2O5 reagents with purity.

A sintered body of L i N b O3 having a stoichiometric composition was prepared as a raw material for a single crystal fiber. The method is to first mix equal moles of each of Li2CO3 and Nb205 in an agate to make an amount of about 10 g, and then mold this into a round bar shape using a hydrostatic press method (rubber press method). It was set in a vertical electric furnace and sintered. The sintering was carried out in an oxygen flow of 0.21)/min, and the temperature was first raised to 900° C. in about 1 hour, held for 2 to 3 hours, and after sintering, the temperature was lowered to room temperature in about 1 hour.

This sintered material was pulverized as finely as possible using an agate bee, and the same method as above was repeated.
Sintering was carried out at 70 to 1180° C. for 2 to 3 hours (the temperature was raised and lowered for 10 hours each) to produce a sintered rod with a density of 95%.

The sintered rod created in this way is cut into pieces with a diameter of 1 and a length of 1.
A raw material rod of about 0 mm was created.

In addition, a sintered rod for solution raw material consisting of 42.5 mo1% 2 Nb2 O and 52.5 mo1% Li2O was created by the same method.

Using the sintered rod for raw material created as described above.

Figure 1 (a) shows how to set the raw material sintered rod in the holder.
(See (b)), the solution raw material sintered rod is brought into contact with the platinum heater heated in advance (1150 to 1200° C.), melted, and the platinum heater portion is sufficiently wetted to form a solution pool. The temperature at this time is monitored by a thermocouple placed close to the heater.

The temperature at this time is determined by a thermocouple placed close to the heater.
Monitor.

Next, reset the raw material sintered rod into the holder, and slowly heat the raw material sintered rod body with the auxiliary heater.
contacted the solution pool.

At this time, it is necessary to observe carefully.

If the raw material sintered rod melts too much, adjust it while lowering the temperature of the platinum heater. After confirming that the raw material sintered rod does not melt or assimilate even if it is in contact with the solution in the pool, the seed crystal cut in the C-axis direction is placed between platinum heaters and sintered for raw material. The surface of the pool solution was contacted from the opposite side of the knot.

The tip of the protrusion on the other hand was gently transferred. After staying like this for a while.

Drawdown of the seed crystal was started at a speed of about 0.5-1.0 mm/h. As a result, it was possible to grow a L i N b O3 single crystal fiber having a stoichiometric composition of 30 μmφ and a length of 15 mm.

In this example, the case of a solid solution compound was described.

In the case of a decomposition melt compound or a phase transfer type compound, a single crystal fiber can be produced using the same method and apparatus as in this example.

[Effects of the Invention] As explained above, according to the method and apparatus for producing single crystal fiber of the present invention, it is possible to produce a monocrystalline fiber from a non-stoichiometric melt or solution, which has been difficult with the conventional method for producing single crystal fiber. too.

A homogeneous solid solution compound bicomponent molten compound having a desired chemical composition and a single crystal fiber of a phase change type compound can be produced very easily.

4

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are views showing essential parts of a manufacturing apparatus according to an embodiment of the present invention, and FIG. 1(a) is a sectional view. (b) is a front view, and FIG. 2 is a diagram showing the overall configuration of a single crystal fiber manufacturing apparatus according to an embodiment of the present invention. In the figure, 1... platinum heater, 4... raw material solution, 5...
... Sintered rod for raw material, 8... Single crystal fiber Fig. 2 5 Pulse motor drive section

Claims (1)

[Claims] 1. Pooling a raw material solution having a composition such that a desired single crystal fiber can be obtained in a protrusion of a heating element having micropores,
The method is characterized in that the single crystal fiber is grown while extending from the micropores and supplying to the pool a raw material having substantially the same composition as the single crystal fiber and the same amount as the single crystal fiber to be grown. Method of manufacturing single crystal fiber. 2. A protrusion for pooling a raw material solution having a composition such that a desired single crystal fiber can be obtained, and a heating element having micropores provided in the protrusion; and a heating element having a micropore provided in the protrusion; 1. An apparatus for producing a single crystal fiber, comprising: a raw material supply section that supplies a raw material; and a stretching section that grows a single crystal fiber while stretching the raw material solution that has passed through the micropores.