JPH0455306A - Production of metal oxide - Google Patents

Abstract

PURPOSE:To efficiently obtain a metal oxide from vapor of a metal compd. with an energy source at a low cost by causing an exothermic chain reaction of the metal compd. with an oxygen-contg. compd. under active seeds formed in a specified mode. CONSTITUTION:A gaseous oxygen-contg. compd. is made to exist in a system contg. a gaseous metal compd. causing an endothermic decomposition reaction at >=10<15> molecules 1ml concn. Part of the system is irradiated with energy beams having >=10<-4> J/cm<2> energy density and active seeds are formed from the metal compd. at high concn. at the irradiated part. An exothermic chain reaction of the metal compd. with the oxygen-contg. compd. is then caused under the active seeds to form a metal oxide. Since an oxidation reaction with oxygen takes place simultaneously with the decomposition of the metal compd. in the vapor phase, the metal oxide is easily obtd. Since the amt. of oxygen is easily controlled, the control of the amt. of the metal oxide is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a novel method for producing metal oxides. More specifically, the present invention relates to a method for manufacturing metal oxides useful as electronic materials, oxide ceramic materials, etc. from vapors of metal compounds at low cost and extremely efficiently using energy rays such as laser light. It is something.

BACKGROUND ART Conventionally, metal oxides have been widely used as electronic materials, oxide ceramic materials, etc. because they have various properties.

Various methods have been known for producing the metal oxide, one of which is a method of producing a metal oxide from a gas phase, such as a CVD method. However, in such conventional gas phase production methods, it is difficult to generate metal atoms in a high concentration in the gas phase, making it difficult to efficiently obtain metal oxides. It is necessary to input a large amount of energy such as light, constant light, plasma, electron beam, heat, etc., which inevitably leads to high manufacturing costs and also poses problems in terms of energy conservation.

On the other hand, there is a known method of producing fine metal particles by decomposing the vapor of a metal compound.
(No. 2) and a method of decomposing organometallic compounds using laser light [Chemistry and Industry (Ch.
ew, and lnd, Volume 15, Page 247 (1985)].

However, in the conventional method of decomposing metal compound vapor, for example, in the case of laser light, at least one photon of energy is required to generate one molecule of metal fine particles, and a large amount of expensive laser light is required. This method requires a large amount of energy, is difficult to control the reaction, and has problems such as the production of by-products, so it is disadvantageous economically and in terms of quality.

Problems to be Solved by the Invention The present invention has been made for the purpose of providing a method for producing metal oxides from vapors of metal compounds at low cost and extremely efficiently using an energy source such as laser light. It is.

Means for Solving the Problems The present inventors have previously conducted extensive research on a method for obtaining high-purity metal particles from the vapor of a metal compound. We discovered that fine metal particles can be obtained with extremely high energy efficiency and economic advantage by irradiating energy rays.
Furthermore, in the system of a gaseous organometallic compound having a specific concentration or more, another gaseous metal compound having a metal component different from that of the organometallic compound is made to exist, and this is exposed to energy rays having a specific energy density or more. It has been discovered that a composite metal compound can be obtained with extremely high energy efficiency and economical advantage by irradiating with .

As a result of further intensive research, the inventors of the present invention have found that by incorporating an oxygen-containing compound into the system of a metal compound that causes a gaseous endothermic decomposition reaction at a specific concentration or higher, the oxygen-containing compound is By irradiating energy rays,
The inventors discovered that a desired metal oxide can be produced inexpensively and extremely efficiently with little input energy, and that the amount of oxide produced can be easily controlled, and based on this knowledge, the present invention was completed. I ended up doing it.

That is, in the present invention, a gaseous oxygen-containing compound is present in a system of a metal compound that causes a gaseous endothermic decomposition reaction at a concentration of 10'' molecules or more per 1 m2, and a gaseous oxygen-containing compound is present in a part of this system. By irradiating energy rays with an energy density of 10-' joules or more per cm", a high concentration of active species caused by the metal compound is generated in a part of the system, and then the metal compound caused by this active species is The present invention provides a method for producing a metal oxide, characterized in that the metal oxide is produced by an exothermic chain reaction between the oxygen-containing compound and the oxygen-containing compound.

The present invention will be explained in detail below.

Regarding the metal compounds used in the method of the present invention,
There are no particular limitations as long as it becomes gaseous and causes an endothermic reaction when decomposed into metal atoms. Examples of such metal compounds include metal carbonyl compounds such as iron pentacarbonyl, chromium hexacarbonyl, tetracarbonyl nickel, molybdenum hexacarbonyl, tungsten hexacarbonyl, manganese decacarbonyl, and cobalt octacarbonyl. Among these metal compounds, those having a relatively high vapor pressure that can increase the raw material concentration for smooth initiation and progress of the chain decomposition reaction, such as iron pentacarbonyl and tetracarbonyl nickel, especially iron pentacarbonyl, are preferable. be.

On the other hand, the oxygen-containing compound may be any compound that contains the oxygen element and becomes gaseous, and is not particularly limited, but a compound that has a high vapor pressure and is easily decomposed is desirable.

Among such compounds, gases containing oxygen or oxygen atoms, or compounds containing each, such as air, N, 0,
N01No, SO, etc. are advantageous because they have high vapor pressure and high reactivity with the metal atoms produced. In particular, air is extremely advantageous in terms of ease of handling and cost. One type of these oxygen-containing compounds may be used, or two or more types may be used in combination.

The presence of the metal compound and oxygen-containing compound as described above,
By irradiating a part of this system with an energy beam such as a laser described below, it becomes exothermic.

A chain reaction can proceed to produce metal oxides.

Here, the chain reaction is mainly a decomposition reaction and an oxidation reaction. Furthermore, "exothermic" means that the total heat balance in the reaction is negative.

For example, as a metal compound, general 2M(Co)n(M
: metal, n: positive rational number), an oxygen-containing compound, and 1. The molar ratio of l to X ( The reaction of the system mixed at the ratio of (X is a positive rational number) is M(Co)n +xRpoq -*MOr+yCO+zC02+Rpx,
・(I) (However, y-n-Xq+r, z-xq-r
.

r: positive rational number). Here, Rpx is px number of R atoms generated from X moles of oxygen-containing compound RpOq or px
In this reaction, an exothermic reaction occurs when DA+DII DCDD<O, which is the most stable compound generated from two molecules of X moles, and the heat advances a chain reaction to produce a metal oxide MOr. Here, DA is M(Co)n is l
+ncO is the bond dissociation energy, D8 is the bond dissociation energy that causes RpOq to decompose into pR+ (q/2)Ox, and DC is
2) O! is the binding energy generated by Nor from

In the method of the present invention, the vapor concentration of the metal compound in the system is 10" molecules/m (approximately 0.1 Torr) or more,
Preferably it is 101 molecules/112 or more, more preferably 1017 molecules/cod or more. If this concentration is lower than 1012 molecules/yaQ, the concentration of the chain-initiating active species is too low, making it difficult for the active species to react with oxygen-containing compounds during their lifetime, resulting in deactivation of the active species. It becomes difficult to start a chain reaction.

Appropriate conditions can be selected for the vapor concentration of the metal compound in relation to the energy absorption coefficient of the metal compound. For example, when the frequency of the energy beam is selected and irradiation is performed under conditions that provide high absorption efficiency, the chain decomposition reaction will start even if the vapor concentration is reduced.

On the other hand, the concentration of the oxygen-containing compound in the system is not particularly limited, but it is preferably 1/25 times the concentration of the metal compound or more in terms of oxygen molecules (02). For example, the metal compound may be Fe(CO), using l/25~1
In the case of 0/25 mole times iron tetroxide (FesOa)
) is 10/25-75/25 times by mole As above, Fen04 and γ-type diiron trioxide (γ-Fe, 03) are
When the mole ratio is 75/25 times or more, γ-Fe and O are produced as above.

In the method of the present invention, a diluent gas may be present in the system as desired. Examples of diluent gas include helium,
Nitrogen, hydrogen, argon, etc. can be used.

The concentration of this diluent gas is appropriately selected depending on the intensity of the energy rays to be irradiated, but is preferably lower in order to cause a chain decomposition reaction.

In the method of the present invention, the energy beam used for the chain initiation reaction is not particularly limited as long as it can generate active species at a high density. Such energy rays include, for example, laser light, incoherent light such as mercury lamps and xenon lamps, orbital synchrotron radiation, electromagnetic waves such as microwaves and radiation such as X-rays, ion beams, electron beams, plasma, etc. Among these, laser light, orbital synchrotron radiation, and X-rays are preferred, and laser light is particularly preferred.

This laser light is preferably from a high-output pulsed laser, and specifically includes an excimer laser that oscillates in the ultraviolet region, a nitrogen laser that oscillates in the infrared region, a carbon dioxide laser that oscillates in the infrared region, a carbon oxide laser, YAG laser
Examples include glass lasers, ruby lasers, alexandrite lasers, harmonics such as YAG lasers that oscillate in the visible region, copper vapor lasers, all vapor lasers, dye lasers, argon ion lasers, krypton ion lasers, and the like.

- Since the metal carbonyl compound inside the ship has a large absorption in the ultraviolet region, active species can be easily generated at a high density by using a laser that oscillates in the ultraviolet region.

An excimer laser has such an effect and has a high energy density, so it is particularly suitable. Also,
A carbon dioxide laser is also preferable because it can lead to decomposition by multiphoton excitation of the vibrational unit that the metal carbonyl compound has in the infrared region. Note that even if another laser is used to irradiate at a wavelength that has no excitation level, breakdown by the laser can generally be caused, so chain decomposition can be caused.

The energy beam in the present invention may be a continuous energy beam, but a pulsed beam is preferred because it can easily generate active species with high density.

The higher the energy density of energy ray irradiation in the present invention, the more advantageous it is.

In the present invention, it is preferable to keep the irradiation time very short to maintain a high concentration of active species generated per unit time, preferably within 10-3 seconds, particularly preferably within 10-4 seconds, and even more preferably within 10-4 seconds. is preferably within 10-' seconds. Even if the irradiation time is made longer than this value, the active species will be deactivated, so it may not be possible to increase the concentration of the active species.

Further, in this case, the irradiation energy density may be at least 10-' joules per cm", preferably at least 10-'joules; if the density is lower than this, the chain decomposition reaction will hardly start.

Moreover, it is desirable that the irradiation with this energy ray be carried out under conditions where the absorption coefficient (molar absorption coefficient when the energy ray is light such as a laser beam) of the metal compound to be irradiated is large. For example, when iron pentacarbonyl is used as a raw material, the absorption coefficient has a maximum value around a wavelength of about 196 nm, and in this case, it is preferable to use an ArF excimer laser with a wavelength of 193 nm.

Irradiation with such energy rays generates active species at a high concentration of 101s/mQ or more, preferably 10s/m or more, in a part of the system, and an exothermic chain reaction caused by the active species occurs. occurs sequentially, the metal compound is almost completely decomposed instantly, the metal active species and oxygen react, and fine particles of metal oxide are generated.

Furthermore, in the present invention, in addition to the above metal compound, other metal compounds may be present within a range that does not impair the object of the present invention. Such a metal compound is not particularly limited as long as it becomes gaseous. Examples of the other metal compounds include lead, bismuth, thallium, zinc, aluminum, cadmium, mercury, gold, silver, platinum, cobalt,
Organometallic compounds having metal-carbon bonds with alkyl groups of metals or metalloids such as nickel, iron, tin, silicon, germanium, etc., and hydrides, alkoxides, carbonylates, and metallocenes of these metals and metalloids. , halides, hydroxides, oxides, carbides, nitrides,
Examples include sulfides, and these metal compounds may be used alone or in combination of two or more.

Among these metal compounds, those whose decomposition reaction is exothermic, those whose bond dissociation energy is small, and those whose vapor pressure is relatively high are preferable. As such,
In addition to the organometallic compounds such as tetramethyl chloride, trimethyl bismuth, and trimethyl thallium, metal halides are preferable because they have a high vapor pressure. By using other metal compounds in this way, metal oxides made of multiple metals can be obtained.

The diameter of the metal oxide fine particles thus obtained is I
pra, but most of them are composed of particles with a weight of 13μ or less.

Effects of the Invention According to the method of the present invention, in the presence of a gaseous oxygen-containing compound,
By irradiating gaseous metal oxides with 1-pulse energy beams, metal oxides can be produced at low cost and extremely efficiently with low input energy, and the metal compounds decompose in the gas phase. At the same time, since an oxidation reaction occurs with oxygen, metal oxides can be easily obtained, and since the amount of oxygen can be easily controlled, it is easy to control the amount of metal oxides.

The metal oxide obtained by the method of the present invention is suitably used, for example, as an electronic material or a ceramic material.

Examples Next, the present invention will be explained in more detail with reference to examples.
The present invention is not limited in any way by these examples.

Implementation f11 Iron pentacarbonyl was added to a 100 m12 glass reaction vessel at a vapor concentration of 8.3 x 10” molecules/mff.
(25 Torr), and then add oxygen so that its concentration is 3.5X 10” (lo, 6 Torr) molecules/
mQ, and then irradiated with laser light (193no+) from an ArF excimer laser through a synthetic quartz window for 1 pulse (10-'' seconds), with extremely strong orange light emission. , - An explosive chain reaction occurred, producing 10 mg of fine particles of iron tetroxide as a black product.The energy density of the laser beam at this time was 5.0 x 10-"J/cm",
The irradiation intensity was 200 mJ.

When the particles were subjected to X-ray diffraction measurement, the first
The peaks shown in the table or their respective intensity ratios were observed. From this table, it became clear that iron tetroxide was produced.

Table 1 Literature values for iron tetroxide Example 2 Iron pentacarbonyl was added to a 100+*Q glass reaction vessel at a vapor concentration of 8.3X 10'7 molecules/m+
2 (25 Torr), and then add oxygen so that its concentration is 2.8x l Q I 1 molecule/ +a12 (
85 Torr), and then add Ar
Laser light (193 nm) from F excimer laser
When irradiated with 1 pulse (101 seconds) through a synthetic quartz window, an extremely strong orange light was emitted.
- An explosive chain reaction occurred, producing 11m+9 fine particles of γ-type diiron trioxide as a red product. The energy density of the laser beam at this time is 5. OX 10-”J/c
The irradiation intensity was 200W+J.

When the produced fine particles were subjected to X-ray diffraction measurement, the peaks shown in Table 2 were observed at their respective intensity ratios. From this table, it became clear that γ-type diiron trioxide was produced.

Table 2 Literature values for γ-type diiron trioxide Implementation f13 100m
(25 Torr), and then add oxygen so that its concentration is 1.3xlQ1M molecule/m12 (40 Torr).
), and then add ArF excimer to this.
When the laser beam (193 nm) from the laser was irradiated for 1 pulse (101 seconds) through a synthetic quartz window, an explosive chain reaction occurred with extremely strong orange light emission, and a blackish brown product was produced. Fine particles consisting of a mixture of iron tetroxide and γ-type diiron trioxide were produced. The energy density of the laser beam at this time is 5. OX 10-”
J/cll+2, and the irradiation intensity was 200 mJ.

Example 4 Iron pentacarbonyl was added to a 100+Q glass reaction vessel at a vapor concentration of 6.5XlO” molecules/+*Q(2
0Torr), and then add oxygen so that its concentration is 6.5xlQ11 molecules/yrQ (199Torr).
), and then add ArF excimer to this.
When laser light (193 nm) from a laser was irradiated for 1 pulse (101 seconds) through a synthetic quartz window, an explosive chain reaction occurred with intense orange light emission, resulting in a particle size of 0.5μ. Iron oxide 9119, which is a metal oxide below the rating, was produced. The energy density of the laser beam at this time was 2.5X 1O-2J/crtr'', and the irradiation intensity was 10001J.

When the generated fine particles were subjected to X-ray diffraction measurement, they were found to be γ-type diiron trioxide.

Comparative Example 1 When Example 1 was carried out in the same manner as in Example 1 except that oxygen was not mixed, a chain decomposition reaction did not proceed.

Comparative Example 2 In Example 1, the vapor concentration of iron pentacarbonyl was
．． 3X 1014 molecules/mff (0,01Torr)
The procedure was carried out in the same manner as in Example 1, except that
No chain reaction explosion was observed.

Comparative Example 3 In Example 1, laser light irradiation was performed at an energy density of 7.
．． 5X 10-'J/cm", irradiation intensity 0, 3rr
r J (7) % Example 1 except that "C' was carried out.
When carried out in the same manner as above, a chain decomposition reaction did not proceed.

Claims (1)

[Claims] 1. A gaseous oxygen-containing compound is present in a system of a metal compound that causes a gaseous endothermic decomposition reaction at a concentration of 10^1^5 molecules or more per ml, and 1cm in some parts
Irradiate energy rays with an energy density of 10^-^4 joules or more per 2 to generate a high concentration of active species caused by the metal compound in a part of the system, and then remove the metal compound caused by this active species. A method for producing a metal oxide, the method comprising producing a metal oxide through an exothermic chain reaction between the compound and an oxygen-containing compound. 2. The manufacturing method according to claim 1, wherein the metal compound is iron pentacarbonyl, and the metal oxide is triiron tetroxide or γ-diiron trioxide.