JPH0250051B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a bismuth-gallium compound material. In recent years, with the development of electronics and related technologies, research has been actively conducted on oxide-based ceramics, mainly bismuth oxide (Bi ₂ O ₃ ), and their single crystals. It has been actively researched as a conversion element material in fields such as atmospheric gas-electricity, photoacoustic polarization, and X-ray spectroscopy, and as a catalyst material. Stable compounds of Bi ₂ O ₃ and Ga ₂ O ₃ have only been described in a few documents, and although research into single crystallization of these compounds has been actively conducted, only amorphous compounds exist. Not much research has been conducted on compounds containing moieties. The present invention provides a method for producing a bismuth-gallium compound that is at least partially amorphous. That is, the present invention is characterized in that after a mixture of bismuth oxide and gallium oxide is heated and melted, it is ultra-quenched at a cooling rate of 10 ⁴ to ^{10 6} °C/sec (Bi ₂ O ₃ ) _1-x . (Ga ₂ O ₃ ) _x (However, 0.60≧x≧0.05)
Bismuth containing an amorphous portion having the composition
This invention relates to a method for producing gallium-based compound materials. The bismuth-gallium-based compound material obtained by the present invention has a high optical resistance. It is useful as electrical conversion elements, optical sensors, optical memory materials, display materials, catalysts, etc. In the present invention, the term "bismuth-gallium compound material containing an amorphous portion" includes not only a case where a polycrystalline phase is included in the amorphous portion, but also a case where the amorphous portion is present alone. The method for producing the bismuth-gallium compound material of the present invention will be described below. The raw material used in the present invention is a mixture of bismuth oxide and gallium oxide, and its composition ratio is (Bi ₂ O ₃ ) _1-x・(Ga ₂ O ₃ ) _x (0.60≧x≧
0.05). A raw material mixture having the above composition ratio is heated and melted, and then cooled extremely rapidly. The heating and melting may be carried out at a temperature higher than the temperature at which these raw material mixtures are sufficiently melted, preferably at a temperature of 50 to 50°C higher than the melting temperature.
Temperature range as high as 200℃, especially preferably 80~150℃
Heat at a temperature about ℃ higher. There are no particular restrictions on the atmosphere during heating, and heating is usually performed in air. Next, the melt of the raw material mixture is ultra-quenched. Ultra-quenching is an essential requirement of the method of the present invention, and only through this is it possible to obtain an amorphous-containing compound material. Ultra-quenching is usually performed at a cooling rate of about 10 ⁴ to ^{10 6} °C/sec. A wide variety of methods can be used for this ultra-quenching as long as it can be cooled at the above-mentioned cooling rate, and the melt of the raw material mixture is blown out onto the surface of the roll rotating at high speed and solidified in the atomic arrangement of the liquid state. The method can be cited as a representative example. An example of a quenching apparatus for a molten raw material mixture used in carrying out the method of the present invention will be described below with reference to the drawings. FIG. 1 shows a front view of the rapid cooling device main body 3 installed on the pedestal 1. As shown in FIG. The quenching device includes a dielectric heating coil 5, a raw material heating tube 7, a support 9 for the tube 7, a nozzle 11 for blowing out the molten raw material, a quenching roll 13, a cooling nozzle 15 for the nozzle 11, an eddy current prevention air nozzle 17, Fine adjustment mechanism 1 of nozzle 11
9, an air cylinder 21, a receiving box 23 for the cooled material, a cooling material outlet 25, etc. are the main components. By installing a fan for cooling the roll inside the cooling roll 13 and providing an air blowing port at the end of the roll surface, the molten raw material can be rapidly cooled stably. FIG. 2 shows details of the support 9. In FIG. 2, the support 9 is
A cooling water introduction path 29 equipped with a valve 27, a cooling water discharge path 31, a blow air introduction path 35 equipped with a needle valve 33, a mechanism 37 for finely adjusting the distance between the surface of the roll 13 and the nozzle 11, and a mechanism for uniformly pressing the raw material melt. It is equipped with a perforated plate 39 for rectifying the flow. When carrying out the method of the present invention using the quenching device 3 shown in FIGS. 1 and 2, a raw material mixture of a predetermined composition is first stored in a tube 7 having a nozzle 11 for blowing out the melt. The tube 7 is preferably made of a material that is sufficiently durable under high-temperature oxidizing atmosphere conditions, such as platinum, platinum-rhodium, iridium, silicon nitride, boron nitride, or the like. Note that the material of the portion that does not come into direct contact with the raw material melt may be high melting point ceramics, glass, or metal. The shape of the nozzle opening is determined depending on the target product; for example, for thin wire materials, it is circular;
For wide products, use a slit-shaped one. The shape of the nozzle opening may be oval or other shape. The raw material mixture stored in the tube 7 is then heated to a temperature equal to or higher than its melting point to form a melt, and then is poured from the mouth of the nozzle 11 onto the surface of the roll 13 rotating at high speed under constant gas pressure. It is blown out and quenched onto the roll surface.
The blowing angle of the raw material melt between the nozzle opening and the roll surface may be perpendicular to the roll surface if the width of the target compound is approximately 3 mm or less, and perpendicular to the roll surface if the width is approximately 3 mm or more. It is between 0° and 45°.
Although these blowout angle adjustment mechanisms can be incorporated into the device itself as a configuration capable of setting a predetermined angle, it is preferable to process the nozzle itself. The heating method for the raw material mixture is not particularly limited, but it is usually carried out in a furnace equipped with a heating element, a dielectric heating furnace, or a condensing heating furnace. The temperature of the raw material melt is preferably 50 to 200°C, preferably 80 to 150°C higher than its melting point. At this time, if the temperature of the melt is too close to the melting point, there is a risk that the melt will cool and solidify near the nozzle while being blown onto the roll surface.
On the other hand, if the temperature is too high, rapid cooling on the roll surface tends to become difficult. The pressurizing gas used to blow the melt onto the roll surface is preferably an inert gas, such as argon, nitrogen, helium, etc., but in order to maintain the melt raw material in an oxidized state, dry compression is recommended. Air is preferred. The gas pressure depends on the size of the nozzle opening, but is usually 0.1 to 2.0 Kg/ ^cm2 , preferably 0.5 to 1.0.
It is about Kg/ ^cm2 . Further, the distance between the nozzle opening and the roll surface when blowing out the raw material melt is preferably about 0.01 to 1.0 mm, more preferably about 0.05 to 0.5 mm. If smaller than 0.01mm, the paddle amount will be very small and uniform material cannot be obtained, while 1.0
If the thickness is larger than mm, the amount of puddles becomes excessive, and if the thickness exceeds the puddle thickness formed by the interfacial tension of the composition melt, there may be a tendency for puddles to be difficult to form. The material of the roll includes copper and its alloy having good thermal conductivity, the above-mentioned materials having a hard chrome plating layer, steel, stainless steel, and the like. The circumferential speed of the roll is 5 m/sec to 35 m/sec, preferably 10 m/sec.
By rapidly cooling the raw material melt at a speed of 20 m/sec to 20 m/sec, the target compound material containing a high-quality amorphous portion can be obtained. At this time, if the roll circumferential speed is 5 m/sec or less, it tends to be difficult to become amorphous.
I don't like it very much. When the circumferential speed of the roll is higher than 35 m/sec, the shape of the target material obtained becomes extremely thin and becomes scaly or fine powder, but in terms of material structure, it is still the compound material of the present invention. When producing the compound of the present invention under reduced pressure or high vacuum or in an inert gas atmosphere as the atmosphere in which the melt raw material is blown onto the rotating roll surface, reduction of the raw material melt at high temperature occurs, Oxygen atoms in the composition atoms decrease, and the resulting material becomes colored purple or black. However, this colored product is also physically a compound material of the present invention and can be used in a colored state. When heating and melting the raw material mixture in a tube, it is necessary to completely melt the mixture. However, before the mixture is completely molten, some of the molten material may flow out from the nozzle tip, so the nozzle tip is locally cooled to prevent the melt from flowing out. It is preferable to do so. A typical means for locally cooling the nozzle is to blow a cooling gas onto the tip of the nozzle, and the gas may be an inert gas such as argon, helium, nitrogen, etc., but dry, cold compressed air is more preferable. The compound material obtained by the present invention usually has a
It is approximately 10 μm thick and is a very brittle material. For this reason, after the material is rapidly cooled and solidified on the roll surface, it is preferable that stress is not applied to the material as much as possible. One of the causes of stress addition is the large turbulent flow in the air layer on the roll surface caused by the wind phenomenon caused by roll rotation in the atmosphere. In order to prevent this turbulence and to improve the adhesion between the molten raw material mixture to be rapidly cooled and the roll surface, a countercurrent blowout nozzle for preventing wind blowing, that is, an air nozzle 17 for preventing swirling as shown in FIG. 1 may be installed. , a fan is fixedly installed inside the roll. In the latter case, the turbulent flow generated inside the roll due to rotation of the roll is absorbed into the roll through a variable-diameter air inlet provided at the end of the roll surface, and is discharged from the front of the roll axis, allowing air to flow over the roll surface. By moving the melt into the interior, the melt is pressed more tightly against the roll surface, and the roll itself can also be cooled by air blowing and movement. Further, in order to maintain the dimensional uniformity of the obtained material, if grooves for cutting the material are provided on the roll surface at right angles to the rotation direction, the material can be cut to a constant size. The atomic arrangement structure of the bismuth-gallium compound material obtained by the present invention varies greatly depending on the mixing ratio of raw materials, and specifically, it can be roughly classified as follows. First, when 0.15≦x≦0.60, a 100% amorphous compound is obtained, and when 0.05≦x<
In the range of 0.15, a mixture of a small amount of δ-Bi ₂ O ₃ polycrystalline phase and an amorphous compound is obtained. Also 0<x<0.05
In the range of , a mixture containing a δ-Bi ₂ O ₃ polycrystalline phase is obtained. FIG. 3 shows the production range of the compound material obtained by the present invention. The peripheral speed of the quenching roll of the quenching device used is 5.
Within the range of m/sec to 35 m/sec, no major changes are observed in the structure of the material obtained in each composition range. In order to identify the structure of the compound material of the present invention, the presence or absence of crystallinity was confirmed and structural analysis was performed using X-ray diffraction and a polarizing microscope, and the extremely small portion was observed using a basic electron microscope. The features of the present invention will be further clarified by Examples and Reference Examples below. Example Bi ₂ O ₃ (purity 99.9%) and Ga ₂ O ₃ (purity 99.9%) were used and mixed in a prescribed composition, mixed uniformly, then calcined at 850°C for 30 minutes, and then left to cool. It was ground and used as a raw material for a composition. The obtained composition raw material was filled into a platinum tube (diameter 10 mm x length 150 mm), placed inside a dielectric heating coil, and heated with an oscillating tube fiber voltage of 13 V, anode voltage of 10 KV, grid current of 120 to 150 mA, and anode current of 1.2
Dielectric heating was performed under conditions of ~1.8A. The completely molten raw material was blown out onto the surface of a rotating rapid cooling roll using dry compressed air to rapidly cool it. Tables 1 and 2 show the composition, manufacturing conditions, shape of the obtained material, etc. Samples Nos. 1-20 and 29 show ribbon-shaped amorphous-containing compound materials. Sample No.
24 is a thin piece due to the high roll rotation speed, but it can be used in fields such as catalysts where there are no restrictions on shape. In addition, nozzle shape A is 0.2mm x 4mm.
The nozzle shape B indicates a circular nozzle with a diameter of 0.2 mm.

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[Table] Reference Example 1 X-ray diffraction results for Samples No. 7, 8, 9, and 10 of the above example corresponding to x=0.40 at (Bi ₂ O ₃ ) _1-x・(Ga ₂ O ₃ ) _x is shown in Figure 4. The peripheral speed of the quenching roll ranged from 5.18 m/sec (quenching rate = 2.5 x 10 ⁴ °C/sec; sample No. 10) to 34.54 m/sec (quenching rate = 7.1 x 10 ⁴ °C/sec; sample No. 7). It is clear that there is no significant change in the atomic arrangement structure of the material obtained within the range of . Reference Example 2 FIG. 5 shows the differential thermal analysis results of sample No. 8 of the above example, which corresponds to x=0.40 in (Bi ₂ O ₃ ) _1-x ·(Ga ₂ O ₃ ) _x . In FIG. 5, Tc represents the crystallization temperature, Tg represents the glass transition point, and mp represents the melting point. Reference Example 3 A photograph showing the appearance of sample No. 1 of the above example corresponding to x=0.60 in (Bi ₂ O ₃ ) _1-x ·(Ga ₂ O ₃ ) _x is shown as a reference drawing. Reference Example 4 A scanning electron micrograph (20,000x magnification) of sample No. 2 of the above example is shown as a reference drawing. Reference Example 5 (Bi ₂ O ₃ ) _1-x・(Ga ₂ O ₃ ) Sample No. 1 and No. of the above example corresponding to x=0.60 and x=0.40 in _x .
The infrared absorption spectrum of No. 8 is shown in FIG.

[Brief explanation of drawings]

FIG. 1 is a front view of an example of a quenching device for melted raw materials used in the method of the present invention, and FIG.
3 is a drawing showing the composition range of the compound material of the present invention, FIG. 4 is an X-ray diffraction diagram of some of the compound material of the present invention, and FIG. FIG. 6 shows the infrared absorption spectrum of a material according to the present invention. DESCRIPTION OF SYMBOLS 1... Frame, 3... Rapid cooling device main body, 5... Dielectric heating coil, 7... Raw material heating tube, 9...
...Support for raw material heating tube, 11... Nozzle for blowing out molten raw material, 13... Roll for rapid cooling, 15...
... Cooling nozzle for nozzle 11, 17 ... Eddy current prevention air nozzle, 19 ... Fine adjustment mechanism for nozzle 11,
21...Air cylinder, 23...Cooled material receiving box, 25...Cooled material outlet, 27...
... Valve, 29 ... Cooling water introduction path, 31 ... Cooling water discharge path, 33 ... Needle valve, 35 ... Blow air introduction path, 37 ... Roll 13 and nozzle 1
Fine adjustment mechanism for spacing with 1, 39... perforated plate for rectification.

Claims (1)

[Claims] 1. A method characterized by heating and melting a mixture of bismuth oxide and gallium oxide, and then ultra-quenching the melt at a cooling rate of 10 ⁴ to 10 ⁶ °C/sec (Bi ₂ O ₃ ) _1-
A method for producing a bismuth-gallium-based compound material containing an amorphous portion and having a composition of x _· (Ga ₂ O ₃ ) _x (where 0.60≧x≧0.05). 2. A method according to claim 1, in which a mixture of bismuth oxide and gallium oxide is heated and melted, and then the melt is brought into contact with a solid to be ultra-quenched at a cooling rate of 10 ⁴ to ^{10 6} °C/sec. A method for producing a bismuth-gallium compound material containing an amorphous portion. 3. A mixture of bismuth oxide and gallium oxide was placed in a heating tube equipped with a nozzle with a slit-shaped, circular, or oval outlet, and the mixture was heated and melted at a temperature 50 to 200°C higher than the melting point of the mixture. After that, the melt is blown out through the nozzle onto the surface of a roll rotating at a circumferential speed of 5 to 35 m/sec.
A method for producing a bismuth-gallium compound material containing an amorphous portion according to claim 1 or 2, wherein the material is ultra-quenched at a cooling rate of 10 ⁴ to ^{10 6} °C/sec.