JPH0331649B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel vanadium-niobium compound material and a method for producing the same. In recent years, with the development of electronics and related technologies, research has been actively conducted on oxide-based ceramics mainly containing vanadium oxide (V ₂ O ₅ ) and their single crystals. Research is being conducted as a conversion element material in fields such as atmospheric gas-electricity, photoacoustic polarization, and X-ray spectroscopy, as well as as a catalyst material, magnetic material, and the like. V ₂ O ₅ and
As a stable compound with Nb ₂ O ₅ , only a few crystals have been described in a few documents.
Although many studies have been conducted on single crystallization, no studies have been conducted on compounds containing amorphous portions. The present invention provides a vanadium-niobium-based oxide, which is at least partially amorphous, and which has not been previously known. That is, the present invention
(V ₂ O ₅ ) _1-x・(Nb ₂ O ₅ ) _x (However, 0.85≧x>0) Vanadium-
Niobium compound material and (V ₂ O ₅ ) _1-x・(Nb ₂ O ₅ ) _x
(However, x is the same as above) After heating and melting a mixture of vanadium oxide and niobium oxide,
The present invention relates to a method for producing a vanadium-niobium compound material containing an amorphous portion, which is characterized by ultra-rapid cooling at a cooling rate of 10 ⁴ to 10 ⁶ °C/sec. The vanadium-niobium oxide of the present invention can be used for magnetic materials, photoresponsive magnetic elements, temperature-responsive magnetic elements,
magnetic memory materials, ion conductive materials, magnetic tapes,
It is useful as a catalyst, a light-transparent conductive material, a dielectric material, a photo-electrical switching device, a thermo-electrical switching device, etc. In the present invention, the term "vanadium-niobium compound 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 compound is amorphous alone. do. The vanadium-niobium oxide of the present invention is produced as follows. The raw material used in the present invention is a mixture of vanadium oxide and niobium oxide, and its composition ratio is (Nb ₂ O ₅ ) _x (V ₂ O ₅ ) _1-x (0.85≧x>
0). The raw material mixture of the above composition comparison is heated and melted, and then cooled very 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.
Heating is carried out at a temperature range of 200°C higher, particularly preferably 80-150°C 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 a new compound containing an amorphous portion. Ultra-rapid cooling 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-rapid cooling as long as it can be cooled at the above-mentioned cooling rate, and the melt of the raw material mixture is sprayed onto the surface of the roll rotating at high speed to solidify it into 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 spouting 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 climate 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 not in direct contact with the raw material melt may be high melting point ceramics, glass, or metal. The shape of the nozzle opening is appropriately determined depending on the target product; for example, a round shape is used for a thin linear material, and a slit-like shape is used for a wide product. 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 rapidly cooled on 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;
If it is more than mm, the angle is 0° to 45° with respect to the normal to the roll surface. Although these blowout angle adjustment mechanisms can be incorporated into the device itself as a mechanism that can set 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 it is too close to the melting point,
While the melt is being blown onto the roll surface, there is a risk that it will cool and solidify in the vicinity of the nozzle, and conversely, if the temperature is too high, it tends to be difficult to rapidly cool the melt on the roll surface. 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 you will not get uniform material, while 1.0mm
If it is larger than , the amount of paddle may be excessive,
Furthermore, if the thickness is greater than the thickness of the puddle formed by the interfacial tension of the composition melt, there may be a tendency for the puddle to be difficult to form. The material of the roll includes copper and its alloy with 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 a compound of the present invention physically 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 novel amorphous compound material according to the present invention usually has a thickness of about 50 to 10 μm 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 is 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 molten material 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 vanadium-niobium compound of the present invention has an atomic arrangement structure that varies greatly depending on the mixing ratio of raw materials, and can be broadly classified into the following types. First, if 0<x≦0.66, the amorphous compound is 100%
is obtained, and in the range of 0.66<x≦0.85
A polycrystalline mixed amorphous compound containing a Nb ₂ O ₅ crystalline phase is obtained, and when x>0.85, a material mainly consisting of a Nb ₂ O ₅ crystalline phase is obtained. FIG. 3 shows the production range of the material of the present invention. The peripheral speed of the quenching roll of the quenching device used is
Within the range of 5 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 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 a very small portion was observed using a scanning electron microscope. The features of the present invention will be further clarified by examples below. Example 1 V ₂ O ₅ (purity 99.9%) and Nb ₂ O ₅ (purity 99.9%) were blended in a predetermined composition, mixed uniformly, and then heated at 850°C.
The mixture was calcined for 30 minutes and used as a raw material for a composition. The obtained composition raw material was made into a platinum tube (diameter 10 mm x length 150 mm).
and installed in the dielectric heating coil, oscillating tube fiber voltage 13V, anode voltage 10KV, grid current 120~
Dielectric heating was performed under the conditions of 150 mA and anode current of 1.2 to 1.8 A. 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 and manufacturing conditions. Samples Nos. 1 to 23 in Tables 1 and 2 show compound materials of the present invention. Note that No. 21 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.
Moreover, Nos. 24 to 26 are comparative examples. Note that nozzle shape A indicates a slit-like nozzle of 0.2 mm x 4 mm, and nozzle shape B indicates a circular nozzle with a diameter of 0.2 mm.

【table】

【table】

【table】

[Table] Reference Example 1 (V ₂ O ₅ ) _{1-x ・}(Nb ₂ O ₅ ) Samples Nos. 8, 10, 12, 13 and
The X-ray diffraction results for 15 are shown in FIG. The peripheral speed of the quenching roll starts from 5.18m/sec (No.8)
It is clear that there is no significant change in the atomic arrangement structure of the material obtained within the range of 34.54 m/s (No. 15). Reference Example 2 FIG. 5 shows the differential thermal analysis results of sample No. 17 of Example 1, which corresponds to x=0.33 in (V ₂ O ₅ ) _1-x ·(Nb ₂ O ₅ ) _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. 7 of Example 1, which corresponds to x=0.25 in (V ₂ O ₅ ) _1-x ·(Nb ₂ O ₅ ) _x , is shown as a reference drawing. Reference Example 4 Scanning electron micrographs (20,000x and 870x) of sample No. 7 of Example 1 are shown as reference drawings and 870x, respectively. Reference Example 5 FIG. 6 shows the infrared absorption spectrum of Sample No. 3 of Example 1, which corresponds to x=0.25 in (V ₂ O ₅ ) _1-x ·(Nb ₂ O ₅ ) _x . Reference Example 6 Figure 7 shows the DC electrical conductivity at 15°C of sample No. 16 of Example 1 above, which corresponds to x=0.33 in (V ₂ O ₅ ) _1-x・(Nb ₂ O ₅ ) _x . , and the dielectric constant (A) and dielectric loss (B) versus frequency at 15°C are shown in Figure 8. The thickness of the sample was 0.0024 cm, and Au electrodes with an area of 0.0491 cm ² were formed on both the front and back surfaces by plating.

[Brief explanation of the drawing]

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.
FIG. 3 is a diagram showing the composition range of the material of the present invention; FIG. 4 is an X-ray diffraction diagram of some of the material of the present invention; FIG. 5 is a diagram of the quenching device according to the invention. The differential thermal analysis diagram of one material, FIG. 6, and the infrared absorption spectrum of another material according to the present invention, FIG.
8 is a graph showing the DC electrical conductivity of another material according to the present invention, and FIG. 8 is a graph showing the dielectric constant and dielectric loss versus frequency of a material similar to that shown in FIG. 7. 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 spouting 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 (V ₂ O ₅ ) _1-x・(Nb ₂ O ₅ ) _x (0.85≧x>
0) A vanadium-niobium compound material containing an amorphous portion and having the composition: 2. The vanadium-niobium compound material according to claim 1, wherein 0<x≦0.66. 3. The vanadium-niobium compound material according to claim 1, wherein 0.66<x≦0.85. 4. (V ₂ O ₅ ) _1-x , characterized by heating and melting a mixture of vanadium oxide and niobium oxide, and then ultra-quenching the melt at a cooling rate of 10 ⁴ to 10 ⁶ °C/sec.
A method for producing a vanadium-niobium compound material containing an amorphous portion and having a composition of (Nb ₂ O ₅ ) _x (0.85≧x>0). 5. The method for producing a vanadium-niobium compound material according to claim 4, wherein the raw material melt is ultra-quenched by contacting it with a solid. 6. Inject the raw material mixture into a heating tube equipped with a nozzle with a slit-shaped, circular or oval outlet, heat and melt at a temperature 50 to 200°C higher than the melting point of the mixture, and then heat at 5 m/sec. The method for producing a vanadium-niobium compound material according to claim 4 or 5, wherein the melt is blown out through the nozzle onto the surface of a roll rotating at a circumferential speed of ~35 m/sec for ultra-quenching. .