JPH02188410A - Production of metal oxide - Google Patents

Abstract

PURPOSE:To inexpensively and extremely efficiently obtain the metal oxide by allowing a gaseous oxygen-contg. compd. to exist in the system of the gaseous substance of an org. metal compd. which induces an exothermic decomposition reaction and irradiating the compd. with energy rays. CONSTITUTION:The gaseous oxygen-contg. compd. is made to exist in the system of the org. metal compd. which has the concn. of >=10<15> molecule per 1ml, is gaseous and induces the exothermic decomposition reaction and the inside of this system is partly irradiated with the energy rays of the energy density of >=10<-4> joule per 1cm<2>. The active species of a high concn. occurring in the above-mentioned org. metal compd. are formed in a part within the system in this way, then the metal oxide is formed by the exothermic chain reaction of the org. metal compd. and the oxygen-contg. compd. induced by the active species. The above-mentioned org. metal compd. is exemplified by, for example, tetraalkyllead, trialkylbismuth, trialkylthallium, dialkylzinc, etc. Air is extremely advantageous in terms of easiness of handling and low cost as the oxygen-contg. compd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a novel method for producing metal oxides. More specifically, the present invention provides a method for inexpensively and extremely efficiently producing metal oxides useful as electronic materials, oxide ceramic materials, etc. from organometallic compound vapor using energy rays such as laser light. It is related to.

[Prior Art] Metal oxides have been widely used as electronic materials, oxide ceramic materials, and the like 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.
Publications) and methods for decomposing organometallic compounds using laser light [Chemistry and Industry (C
hem, andInd,) Volume 15, Page 247 (
1985)] are known.

However, in the conventional method of decomposing metal compound vapor, for example, in the case of laser light, one molecule of metal fine particles is generated! However, it requires at least one photon of energy, requires a large amount of energy from expensive laser light, is difficult to control, and has problems such as the production of by-products, making it uneconomical. It was disadvantageous in terms of target and quality.

[Problems to be Solved by the Invention] The purpose of the present invention is to provide a method for manufacturing metal oxides from vapors of metal compounds at low cost and extremely efficiently using energy sources such as laser light. It is a small thing.

[Means for Solving the Problem] The present inventor has previously conducted extensive research on a method for obtaining high-purity metal particles from the vapor of a metal compound. If you irradiate it with energy rays, it will be extremely energy efficient.
discovered that metal fine particles could be obtained economically,
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 inventor of the present invention has discovered that an oxygen-containing compound is contained in a system of gaseous organometallic compounds having a concentration higher than a specific concentration, and the oxygen-containing compound is irradiated with an energy source having a specific energy density or higher. It was 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.Based on this knowledge, the present invention has been developed. I was able to complete it.

That is, the present invention allows a gaseous oxygen-containing compound to exist in a system of an organometallic compound that causes a gaseous exothermic decomposition reaction at a concentration of 10'6 molecules or more per IIIl,
A part of this system is irradiated with energy rays with an energy density of 10 joules or more per cr12 to generate a high concentration of active species caused by the organometallic compound, and then 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 an organometallic compound and an oxygen-containing compound caused by the following.

The present invention will be explained in detail below.

The organometallic compound used in the method of the present invention is not particularly limited as long as it becomes gaseous and causes an exothermic reaction when decomposed into metal atoms. Examples of such organometallic compounds include tetraalkyl chains, trialkyl bismuth, trialkyl thallium, dialkyl zinc, dialkyl mercury, dialkyl cadmium, and the like.

Here, the alkyl group includes methyl group, ethyl group, n-
Examples include propyl group and isopropyl group, and they may be linear or branched.

The organometallic compound of the present invention must undergo an exothermic reaction when decomposed into metal atoms.

As a representative example of an organometallic compound, the general formula MI R1 is used (Ml: metal, R1: alkyl group, n: number of alkyl groups, usually an integer of 1 to 4).The reaction of this MR is the formula M'R', Suppose that it is expressed as +M'+ (n/2) R'-R'. Here, the bond dissociation energy in the reaction equation expressed by the formula M'R', +M'+nR' is DAl
! The recombination energy of radical R1 in the reaction formula expressed by Al formula nR'-+ (n/2)R'-R' is
Then, it becomes ΔH-DA-DB.

If ΔH becomes negative, an exothermic reaction will occur.

By using such an organometallic compound, a chain reaction due to heat proceeds, and the object of the present invention can be achieved. In order to smoothly start and proceed the chain decomposition reaction, it is preferable to use a material with a relatively high vapor pressure that can increase the raw material concentration. For example, an organometallic compound having a small number of carbon atoms in an alkyl group is preferable.

Furthermore, the larger the absolute value of ΔH of the organometallic compound, the better. Examples of such organometallic compounds include tetramethyl lead (ΔH = −33 kcsll/mol) and trimethyl bismuth (ΔH = −36 kcsll/mol).
Examples include.

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, oxygen or gases containing oxygen atoms, or compounds containing each, such as air, N, 0
1No, NO! , S02, 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.

When all of the organometallic compounds and oxygen-containing compounds mentioned above are present, and a part of this system is irradiated with energy rays such as the laser described below, an exothermic chain reaction progresses and metal oxides are produced. can do.

Here, the chain reactions are mainly decomposition reactions and oxidation reactions.

Furthermore, "exothermic" means that the total heat balance in the reaction is negative.

The specific explanation is as follows.

As an organometallic compound, for example, the general formula, M2 R2 (M2
: metal, R2, alkyl group, m: positive rational number), and oxygen-containing compounds such as the general formula, R',
O, (R3: pro or positive rational number, which is a nitrogen atom, sulfur atom, etc., although there is no particular restriction, q: a positive rational number)
The reaction of a system in which the compound represented by is mixed at a molar ratio of 1:x (x is a positive rational number) is M ``R2m+ x R', 0 , + [M 2-o , , ] + [R ”□10R3,, (or R2
, -R3□)]...It is assumed that it is represented by the formula ■.

Here, R2□ is the most stable alkane compound produced by the recombination reaction of R2 radicals of m molecules produced by the decomposition reaction, and R'pm is the oxygen-containing compound R" of X moles, O,
It is the most stable compound generated from the R3 atom of the pxIK child or the R3 molecule of the px molecule.

Further, R 2 R3,w is the most stable compound produced by the reaction between the R2 radical of the m molecule and the R3 molecule of the pxi molecule or the R3 molecule of the px molecule.

In this reaction DA + D m -D c -D
When o < O, an exothermic reaction occurs, and the heat causes a chain reaction to proceed, producing metal oxide M2-0□. Here, DA is M2R2ffi is M ” + m R
It is the bond dissociation energy that decomposes into 2, and Dll is R'
, O, is 1) X times the bond dissociation energy that decomposes into R' ten (Q/2)02, and DC is M2 and x (q/2)
M2-01 from Ox. , and DD is the binding energy to generate R2ヮ, the most stable alkane compound, from mR2, and R32, the most stable compound from pxR3. is the sum of the bond energies that produce .

However, when Rz−R3pm is generated in Equation 1, D is R2IN 13t from m R2 and pxR”
is the binding energy that produces y.

In the method of the present invention, it is necessary that the vapor concentration of the organometallic compound in the system is 1015 molecules/mQ (approximately ITorr) or more, preferably IQ 16 molecules/m1 or more, and more preferably IQ 17 molecules/mQ or more. be. If this concentration is lower than 101'' molecules/mQ, the concentration of chain-initiating active species is too low, and during the lifetime of the active species, reaction with oxygen-containing compounds is difficult to occur, and the active species are deactivated. This makes it difficult for a chain reaction to start.

Appropriate conditions can be selected for the vapor concentration of the organometallic compound in relation to the energy absorption coefficient of the organometallic 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 equal to or more than the same molar concentration of the organometallic compound in terms of oxygen molecules (02).

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, there are no particular limitations on the energy rays used for the chain initiation reaction as long as they 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, an excimer laser that oscillates in the ultraviolet region, a nitrogen laser, a carbon dioxide laser that oscillates in the infrared region, a carbon oxide laser, or a 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.

In general, organometallic compounds have large absorption in the ultraviolet region, and therefore, among the lasers described above, when a laser that oscillates in the ultraviolet region is used, active species can be easily generated at a high density. An excimer laser is particularly suitable because it has such an effect and a high energy density. Further, a carbon dioxide laser is also preferable because it can lead to decomposition by multiphoton excitation of the vibrational unit that the organometallic 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.
This is preferably within 10-3 seconds, particularly preferably within 10-4 seconds, and even more preferably within 10-6 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.

In addition, at that time, the energy density of the irradiation beam is 1 cm2
The density may be at least 10@-4 joules per unit, preferably at least 10@-3 joules, and chain decomposition reactions will hardly start if the density is lower than this.

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 tetramethyl lead is used as a raw material, the absorption coefficient has a maximum value around a wavelength of about 200 nm, and in this case, it is preferable to use an ArF excimer laser with a wavelength of 193 nm.

By irradiating such energy rays, a part of the system is exposed to 1olS particles/m1 or more, preferably IQ16 particles/m1.
The above high concentration of active species is generated, and an exothermic chain reaction caused by the active species occurs sequentially.The organometallic compound is almost completely decomposed instantly, and the metal active species reacts with oxygen. , fine particles of metal oxide are generated.

Further, in the present invention, other metal compounds may be present in addition to the organometallic compound as long as the object of the present invention is not impaired. Such a metal compound is not particularly limited as long as it becomes gaseous. Examples of the other metal compounds include alkyl groups of metals or semimetals such as lead, bismuth, thallium, zinc, aluminum, cadmium, mercury, gold, silver, platinum, cobalt, nickel, iron, tin, silicon, and germanium. Organometallic compounds having a metal-carbon bond between them, and hydrides, alkoxides, carbonylates, metallocene compounds, halides, hydroxides, oxides, carbides, nitrides of these metals and metalloids,
Examples include sulfides, and these metal compounds may be used alone or in combination of two or more.

As in the case of the organometallic compounds, these metal compounds are preferably those whose decomposition reaction is exothermic, those whose bond dissociation energy is small, and those whose vapor pressure is relatively high. In addition to the above-mentioned organometallic compounds such as tetramethyl lead, trimethyl bismuth, and trimethyl thallium, metal halides are preferable because of their high vapor pressure, and metal carbonyl compounds such as iron carbonyl, nickel carbonyl, Chromium carbonyl, molybdenum carbonyl, tungsten carbonyl, and the like are preferred because they have low bond dissociation energy for decomposing into metal atoms. If other metal compounds are used in this way,
A metal oxide consisting of multiple metals is obtained.

The diameter of the metal oxide fine particles thus obtained is 1
The particle size is 0.3 μm or less, but most of the particles are 0.3 μm or less.

[Example] 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.

Example 1 Tetramethyl lead was added to a 100 mQ glass reaction vessel at a vapor concentration of 3.3 x 1017 molecules/rnQ (
10 Torr r), and then add air (20% by volume of oxygen) to a concentration of 5.7 x 1 O1e molecule/
After mixing the mixture to ml (155 Torr),
Laser light from an ArF excimer laser (19
3 nm) through a synthetic quartz window for one pulse (10-'
When irradiated for only 1 second), an explosive chain reaction occurred accompanied by extremely strong white light emission, and the particle size was 0.2 seconds.
9 mg of lead oxide, which is a metal oxide with a size of 5 μm or less, was produced.

The energy density of the laser beam at this time is 5. OXl 0
-2J 7cm2, and the irradiation intensity was 200mJ.

Elemental analysis of the generated fine particles was performed using plasma emission spectrometry (ICP).
) and CHN coder, it was found that no CHN was detected and 84% lead was present. Note that in the fine particles obtained without mixing air, 98% of lead was present, so this difference is recognized to be due to the formation of oxides. Furthermore, when this fine particle was analyzed by X-ray photoelectron spectroscopy (XPS), it was found that 0
(1s) was observed around 529.5 eV, and it became clear that an oxide was formed.

Example 2 Trimethyl bismuth was added to a 100 mQ glass reactor at a vapor concentration of 6.6 x 10" molecules/mα (20
Add air so that the concentration is 4.6 x 10" molecules/nl (140 Torr)
When this was mixed with laser light (193 nm) from an ArF excimer laser for one pulse (10 seconds) through a synthetic quartz window, extremely strong white light was emitted. However, a chain explosion reaction occurred, and bismuth oxide 25H, a metal oxide with a particle size of 0.3 μm or less, was produced.

The energy density of the laser beam at this time is 3.8 x 10-
"It was 17 cm2, and the irradiation intensity was 150 mJ.

When the generated fine particles were compared with a standard sample of Bi2O and analyzed by XPS, the results shown in Table 1 were obtained. From this table, it became clear that Bi2O3 was generated.

Comparative Example 1 in Table 1 In Example 1, laser light irradiation was performed at an energy density of 7.5 x 10-51 /CIl+2 and an irradiation intensity of 0.
When carried out in the same manner as in Example 1 except that the test was carried out under the condition of 3 mJ, no chain decomposition reaction proceeded.

Comparative Example 2 When the same procedure as in Example 1 was carried out except that nitrogen was used instead of air, a chain decomposition reaction did not proceed.

Comparative Example 3 In Example 1, the vapor concentration of tetramethyl lead was set to 3.3.
When the procedure was carried out in the same manner as in Example 1 except that X10''molecules/ml'o, o ITor r), no chain explosive reaction was observed.

[Effect of the invention] According to the method of the invention, in the presence of a gaseous oxygen-containing compound,
By irradiating a gaseous organometallic compound with a single pulse of energy rays, metal oxides can be produced inexpensively and extremely efficiently with a small amount of input energy. Simultaneously with decomposition, an oxidation reaction with oxygen occurs, so metal oxides can be easily obtained, and the amount of oxygen can be easily controlled, making it 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.

Claims (1)

[Claims] 1. In a system of an organometallic compound that causes a gaseous exothermic decomposition reaction at a concentration of 10^1^5 molecules or more per ml,
A gaseous oxygen-containing compound is present, and 1
By irradiating energy rays with an energy density of 10^-^4 joules or more per cm^2, a high concentration of active species caused by the organometallic compound is generated in a part of the system, and then the active species caused by this active species is A method for producing a metal oxide, the method comprising producing a metal oxide through an exothermic chain reaction between an organometallic compound and an oxygen-containing compound. 2. The manufacturing method according to claim 1, wherein the metal oxide is in the form of fine particles.