JP2002067000A - Metal nanowire and metal nanoparticle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide metal nanowire and metal nanoparticles, and a manufacturing method thereof without using a mold or fine processing technique. SOLUTION: A method for manufacturing nanowire and/or nanoparticles consists of irradiating with an electron beam on metal nanowire supported by a carrier at one end thereof and a metal ion carrier.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to metal nanowires, metal nanoparticles, and a method for producing them.

[0002]

2. Description of the Related Art Metal nanowires are known to be used as materials for electronic devices and as templates for carbon nanotubes. Conventionally, metal nanowires have been manufactured in carbon nanotubes, in narrow grooves of silica, and on films, so that only nanowires in the form of carbon nanotubes, silica, and films as templates can be inevitably manufactured. For example, EtO containing AgNO ₃
During H-H ₂ O solution, suspended silica powder having a groove nanoscale, stirred, and silver nanowires can be obtained by the heat treatment, the form of the wire in the form of a groove having a silica Was dependent. Also, gold nanowires utilizing microfabrication technology are known, but it is difficult to set the processing conditions to process nanometer gold, and it is difficult to manufacture nanowires easily as in the present invention. is there.

[0003]

SUMMARY OF THE INVENTION The present invention provides metal nanowires, without using molds or microfabrication techniques.
An object of the present invention is to provide metal nanoparticles and a method for producing the same.

[0004]

The present inventor has made intensive studies in view of the above-mentioned problems of the prior art. As a result, the metal ion carrier is irradiated with an electron beam, thereby eliminating the need for a mold. It has been found that metal nanowires and metal nanoparticles can be obtained.

That is, the present invention provides the following metal nanowires, metal nanoparticles, and a method for producing them. Item 1. Metal nanowires with one end supported by a carrier. Item 2. Item 2. The nanowire according to item 1, wherein the metal nanowire is a silver nanowire. Item 3. A method for producing metal nanowires and / or metal nanoparticles by irradiating a metal ion carrier with an electron beam. Item 4. Item 4. The production method according to Item 3, wherein the silver ion carrier is irradiated with an electron beam to produce silver nanowires and / or silver nanoparticles. Item 5. Silver ion carrier has the general formula _{(1): Ag a B c D e Si} f P g O h [1] [B is an alkali metal element, an alkaline earth metal element,
It is at least one selected from copper, zinc, hydrogen and ammonium, and D is at least one selected from metal elements that can be trivalent to pentavalent metal ions. The subscripts in the formula are 0 <a, 0 ≦ c, 1 <a + c ≦
4, 1 ≦ e ≦ 2, 0 ≦ f ≦ 3, 0 ≦ g <3, 10 ≦ h ≦
It is a number that satisfies 15. Item 4 which is a compound represented by the formula:
Production method described in 1.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, metal nanowires and metal nanoparticles are produced by irradiating a metal ion carrier with an electron beam. The mechanism of action is that the metal ions supported on the metal ion carrier are reduced by irradiation with an electron beam to become a metal, and the metal extends from the carrier to the outside world and extends, so that the metal nanowires and / or
Alternatively, it is presumed that metal nanoparticles are generated, but the present invention is not limited to this presumption.

The metal of the metal nanowire is not particularly restricted but includes silver, palladium, nickel, gold and the like.

[0008] The metal nanowire of the present invention is a nanowire one end of which is supported by a carrier. When the nanowires are extended by electron beam irradiation, the nanowires may come into contact with the carrier, but this contact does not correspond to the above-mentioned “supported”.

[0009] The metal nanowire of the present invention can be separated into a wire portion and a carrier portion by an appropriate separation method. Examples of the separation method include a method using specific gravity (such as centrifugal separation) and a physical separation method such as applying vibration.

The shape of the metal nanowire depends on the irradiation intensity, irradiation angle, and shape of the metal ion carrier (pore structure,
It can be controlled by appropriately combining the crystal structure) and the composition.

The metal ion carrier refers to a metal ion carried on a carrier.

There are various forms of loading, such as adsorption and ion exchange. If necessary, metal ions may be loaded in advance during the synthesis of the support.

The support serves as a support for the wires and particles when the metal grows as wires and particles by irradiation with the electron beam.
Examples of the carrier include a compound having a NASICON-type structure.

Preferred metal ion carriers are a silver ion carrier, a palladium ion carrier, a nickel ion carrier, a gold ion carrier and the like. Further preferred are formula _{(1): Ag a B c D e Si} f P g O h [1] [B is an alkali metal element, an alkaline earth metal element,
It is at least one selected from copper, zinc, hydrogen and ammonium, and D is at least one selected from metal elements that can be trivalent to pentavalent metal ions. The subscripts in the formula are 0 <a, 0 ≦ c, 1 <a + c ≦
4, 1 ≦ e ≦ 2, 0 ≦ f ≦ 3, 0 ≦ g <3, 10 ≦ h ≦
It is a number that satisfies 15. And the like.

In the general formula [1], 0 <a. Preferred a is a value at which the Ag content in the compound represented by the general formula [1] is 0.36 mol% or more.

In the general formula [1], B is at least one selected from an alkali metal element, an alkaline earth metal element, copper, zinc, hydrogen and ammonium.
For example, there are alkali metal elements such as lithium, sodium and potassium, alkaline earth metal elements such as magnesium or calcium, copper, and zinc. Among these,
Copper, zinc, lithium, sodium, potassium, hydrogen and ammonium are preferred in view of the stability of the compound and availability at low cost.

In the general formula [1], 1 <a + c ≦
4, preferably 1.5 ≦ a + c ≦ 4, more preferably 2 ≦ a + c ≦ 4.

In the above general formula [1], D is 3 to 5
At least one metal element selected from the group consisting of metal elements that can be a multivalent metal ion. When two or more metal elements are used, the total amount of each metal element is e (1
.Ltoreq.e.ltoreq.2). Chromium, aluminum, and trivalent metal elements
Iron and the like are tetravalent metal elements such as titanium, zirconium,
Germanium, tin, hafnium and the like, and pentavalent metal elements include niobium and tantalum. Preferred specific examples include aluminum, zirconium, titanium, tin, niobium and the like, and in view of the safety of the compound, iron, zirconium or titanium is particularly preferred.

In the general formula [1], 1 ≦ e ≦ 2, preferably e = 2.

In the general formula [1], 0 ≦ f ≦ 3, preferably 0.5 ≦ f ≦ 3, and more preferably 1 ≦ f ≦ 2.5.

In the general formula [1], 0 ≦ g <3, preferably 0 <g ≦ 2.5, and more preferably 0.5 ≦ g ≦ 2.

In the above general formula [1], h is other A
It is appropriately determined according to the amounts of g, B, D, Si and P. Preferably 10 ≦ h ≦ 15, more preferably 11 ≦ h
h ≦ 13.

The device for supplying the electron beam is not particularly limited as long as it can supply electrons to the metal ion carrier. An example is an electron gun. As the electron gun, various types of electron guns including a thermoelectron gun and a field emission electron gun can be used. Preferred are thermionic and field emission electron guns.

After being emitted from the electron gun, the electron beam passes through an electron lens, a deflecting electrode or a deflecting electromagnet, and a velocity selector for aligning energy as necessary, and then strikes the target. The acceleration voltage depends on the degree of vacuum, but is 1 kV or more. Preferably 5 kV or more,
More preferably, it is 30 to 300 kV. Further, the degree of vacuum is 1 × 10 ⁻⁴ Pa or more, though it depends on the acceleration voltage. It is preferably 1 × 10 ^{−6 to} 5 × 10 ⁻⁵ Pa, and more preferably 1 × 10 ⁻⁶ to 2 × 10 ⁻⁵ Pa.

As an apparatus for causing an electron beam to collide with a target, an electron microscope, an X-ray microanalyzer (EPM)
A), photoelectron spectroscopy (ESCA), cyclotron, etc. can be used. Preferably, it is an electron microscope. It is preferable that the acceleration voltage and the degree of vacuum described above be applied also when using these devices. Examples of the electron microscope include a transmission electron microscope (TEM) and a scanning electron microscope (SE).
M) and a scanning transmission electron microscope (STEM). Preferred is a transmission electron microscope.

The metal ion carrier irradiated with the electron beam is
A crack is formed on the surface, and the metal nanowires and / or metal nanoparticles extend from the crack. By adjusting the irradiation conditions of the electron beam, the composition of the metal ion carrier, and the like, both the metal nanowires and the metal nanoparticles can be manufactured simultaneously or separately. For example, when the silver ion carrier is irradiated with an electron beam, the silver ion content contained in the silver ion carrier is 0.1.
When it is at least 36 mol%, it is advantageous for the production of silver nanowires, and when it is less than 0.36 mol%, it is advantageous for the production of silver nanoparticles.

The aspect ratio of the metal nanowire of the present invention is 10 or more, preferably 100 to 10,000.
0.

The diameter of the metal nanowire of the present invention is 2 to
It is 500 nm, preferably 5 to 50 nm. Further, the length of the metal nanowire can be adjusted by the content of the metal ion contained in the metal ion carrier and the conditions for irradiating the electron beam (irradiation time, acceleration voltage, degree of vacuum, etc.). Preferably 20 nm to 1 mm, more preferably 50 n
m to 0.5 mm.

The particle size of the metal nanoparticles of the present invention is:
It is 2 to 100 nm, preferably 5 to 80 nm.

The metal nanowires and metal nanoparticles of the present invention can be used in various fields by utilizing their large surface area, electrical conductivity and thermal conductivity.
For example, it can be used for electronic device materials, catalysts, carbon nanotube templates, alloy materials, and the like. Preferably, it can be used for catalysts, electronic device materials, and the like.

The method for synthesizing the compound represented by the general formula [1] includes a solid phase method, a wet method and a hydrothermal method.
Although not particularly limited, it can be easily obtained, for example, as follows.

When synthesized by the solid phase method, a compound containing an alkali metal element or an alkaline earth metal element, a compound containing silicon, a compound containing a metal element which can be a trivalent to pentavalent metal ion, and phosphoric acid Are mixed at an appropriate mixing ratio, and this is mixed with 1000 to 130.
By baking at 0 ° C., a compound represented by the following general formula [2] is produced.

[0033] _{B 'a + c D e Si} f P g O h [2] [B' is at least one selected from the group consisting of alkali metal elements and alkaline earth metal elements, D,
a, c, e, f, g and h are as described above. In the production of the compound of the above general formula [2] by the solid phase method, the compound containing an alkali metal element or an alkaline earth metal element includes alkali metal or alkaline earth metal carbonate, hydrogen carbonate, hydroxide , Nitrates, nitrides and the like. Preferred are carbonates, bicarbonates and nitrates, and more preferred are carbonates such as sodium carbonate, potassium carbonate, calcium carbonate and magnesium carbonate, and sodium nitrate.

In the production of the compound of the above general formula [2] by the solid phase method, examples of the silicon-containing compound include silicon dioxide and silicate. Preferably silicon dioxide, sodium silicate, colloidal silica,
More preferred is silicon dioxide.

In the production of the compound of the general formula [2] by the solid phase method, the compound containing a metal element which can be a trivalent to pentavalent metal ion includes a trivalent to pentavalent metal oxide,
Examples thereof include metal hydroxides and carbonates. Preferred are zirconium oxide, titanium oxide, tin oxide, hydrous zirconium oxide, hydrous titanium oxide, niobium oxide, chromium oxide, chromium nitrate, aluminum oxide and the like, and more preferably zirconium oxide and titanium oxide.

In the production of the compound of the above general formula [2] by the solid phase method, examples of the compound containing phosphoric acid include phosphate, hydrogen phosphate and the like. Preferred are sodium phosphate, zirconium phosphate, titanium phosphate, potassium phosphate, sodium hydrogen phosphate, potassium hydrogen phosphate, ammonium hydrogen phosphate, etc., and more preferably sodium phosphate, zirconium phosphate, titanium phosphate , Ammonium hydrogen phosphate.

When the compound is synthesized by a wet method, a compound containing an alkali metal element or an alkaline earth metal element,
A compound containing silicon, a compound containing a metal element that can be a trivalent to pentavalent metal ion, and a compound containing phosphoric acid are mixed at an appropriate mixing ratio, and the mixture and water are sealed in a pressure-resistant container. The compound represented by the above general formula [2] can be obtained by reacting at 300 ° C under hydrothermal conditions for 10 to 30 hours, preferably 20 hours.

In the production of the compound of the above general formula [2] by a wet method, the compound containing an alkali metal element or an alkaline earth metal element may be an alkali metal or alkaline earth metal hydroxide, carbonate, hydrogen carbonate or the like. Salts, nitrates and the like are exemplified. Preferred are carbonates and nitrates, and more preferred are sodium silicate, sodium carbonate, sodium nitrate, magnesium nitrate, calcium nitrate and the like.

In the production of the compound of the above general formula [2] by the wet method, examples of the silicon-containing compound include silicates, silicon dioxide and the like. Preferred are sodium silicate and colloidal silica, and more preferred is sodium silicate.

In the production of the compound of the above general formula [2] by the wet method, the compound containing a metal element which can be a trivalent to pentavalent metal ion includes trivalent to pentavalent metal salts, phosphates, chlorides and the like. Substances, nitrates and the like. Preferably zirconium phosphate, zirconium oxychloride, titanium chloride, aluminum chloride, aluminum nitrate, tin chloride,
Tantalum chloride and the like, and more preferably α-type zirconium phosphate, zirconium oxychloride and titanium chloride.

In the production of the compound of the above general formula [2] by the wet method, examples of the compound containing phosphoric acid include phosphoric acid, phosphates, hydrogen phosphate and the like. Preferred are zirconium phosphate, titanium phosphate and sodium phosphate, and more preferred are zirconium phosphate and sodium phosphate.

The above general formula [2] obtained by a solid phase method, a wet method, etc.
In the production of the compound of formula (I), the mixing ratio of these compounds is appropriately selected according to the desired compound of general formula [2].
For example, in the solid-phase method, sodium carbonate (Na ₂ CO ₃ ),
Silicon dioxide (SiO ₂ ), zirconium oxide (ZrO ₂ ) and α-type zirconium phosphate (Zr (HPO ₄ ) ₂ .H ₂ O)
The mixture is mixed at a molar ratio of 1.25: 1.5: 1.25: 0.75, and the mixture is calcined at 1000 to 1300 ° C., preferably gradually heated from room temperature to 1000 to 1000
By firing at 1300 ° C., a compound of the following general formula [3] can be obtained.

Na _2.5 Zr ₂ Si _1.5 P _1.5 O ₁₂ [3] A compound represented by the general formula [2] obtained by a solid phase method, a wet method, or the like is converted into a compound having a predetermined acidity at room temperature to 100 ° C. After treating with an acidic solution adjusted to a concentration of, for example, 0.1 to 3 N, for example, for 2 to 7 days to obtain a proton-type compound, subsequently, containing silver ions adjusted to a predetermined silver ion concentration, for example, 0.1 to 3 N The compound represented by the general formula [1] can be obtained by immersing in, for example, an aqueous solution for 2 to 7 days and performing ion exchange. Examples of the acidic solution used at this time include hydrochloric acid and nitric acid, and more preferably hydrochloric acid. As the silver ion-containing aqueous solution, an aqueous silver nitrate solution is preferable.

Alternatively, the acidic solution treatment of the compound represented by the general formula [2] obtained by a solid phase method, a wet method, a hydrothermal method or the like is omitted, and the compound is immersed in an aqueous solution containing silver ions. The compound represented by the general formula [1] can be obtained.

Further, the above-mentioned proton type compound is added to a copper ion-containing aqueous solution adjusted to a predetermined copper ion concentration, for example, about 0.1 to 3 N, and stirred for about 1 to 10 hours to carry copper ions. Subsequently, a silver-copper compound represented by the general formula [1] can be obtained by stirring for about 1 to 10 hours in a silver ion-containing aqueous solution adjusted to about 0.01 to 3 N. Copper nitrate, copper chloride and the like are used as the aqueous solution containing copper ions used at this time, and an aqueous silver nitrate solution is preferable as the aqueous solution containing silver ions.

In this method, an aqueous solution containing silver ions, an aqueous solution containing zinc ions, an aqueous solution containing iron ions, or the like is appropriately used to obtain a zinc-type, silver-zinc-type, iron-type or silver-iron-type general formula [1]. It is also applicable when preparing the compound shown, zinc chloride, zinc nitrate, zinc sulfate and the like are used as the zinc ion-containing aqueous solution used in this case, and iron nitrate, zinc chloride And ferrous iron.

[0047]

By irradiating the metal ion carrier with an electron beam, it becomes possible to produce metal nanowires and / or metal nanoparticles without using a template or a fine processing technique.

[0048]

EXAMPLES Production Example _{1 Ag 2.3 Na 0.2 Zr 2 Si} 1.5 P 1.5 O 12 during manufacture 0.288 mol / l disodium hydrogen phosphate (Na ₂ HPO ₄₎ solution of zirconium oxychloride (ZrOCl ₂ · 8H ₂ O) and
A mixture of sodium silicate (Na ₂ O.3SiO ₂ ) and sodium hydroxide (NaOH) was mixed with Zr: Si: P = 2: 1.5:
Simultaneous dropping was carried out at a molar ratio of 1.5, the resulting reaction product was washed with water, dried, and then calcined at 1200 ° C. to form a sodium-type sodium represented by Na _2.5 Zr ₂ Si _1.5 P _1.5 O ₁₂ . A sample (hereinafter, referred to as NCC-Na) was obtained.

The obtained NCC-Na was treated with hydrochloric acid to perform protonation. That is, 3 g of NCC-Na and 1000 ml of 1N-HCl
And stirred at room temperature for 3 hours. After stirring, filtration, washing, drying, proton type of the sample represented by _{H 2.5 Zr 2 Si 1.5 P 1.5} O 12 ( hereinafter, referred to as NCC-H) was obtained.

3.0 g of the obtained NCC-H was added to 300 ml of a 0.1 N silver nitrate solution, and the mixture was stirred at room temperature for 3 hours. After stirring, the mixture was filtered, washed and dried to obtain Ag _2.3 Na _0.2 Zr ₂
A silver sample represented by Si _1.5 P _1.5 O ₁₂ was obtained. Silver ion was quantified by atomic absorption spectrophotometry, and was calculated as the amount of silver ion exchanged per gram of the support from the difference between the initial concentration of silver ion and the equilibrium concentration after ion exchange.

Production Example 2 In the same manner as in Example 1, NCC-H (H _2.5 Zr ₂ Si _1.5
A proton type sample represented by P _1.5 O ₁₂ ) was obtained.

2 g of NCC-H was added to 200 ml of a 0.2 M aqueous solution of copper nitrate, stirred at room temperature for 3 hours, filtered, washed with water and dried using a 1.0 μm membrane filter to prepare a copper-carrying sample. did.

Subsequently, 1.9 g of a copper-carrying sample was added to 200 ml of a 0.01 N silver nitrate aqueous solution, and the mixture was stirred at room temperature for 30 minutes.
Using a 1.0μm membrane filter, filtration, washing with water,
After drying, Ag _0.587 Cu _0.141 H _1.772 Zr ₂ Si
A silver / copper type sample represented by _1.5 P _1.5 O ₁₂ was obtained.

Production Example 3 In the same manner as in Example 1, NCC-H (H _2.5 Zr ₂ Si _1.5
A proton type sample represented by P _1.5 O ₁₂ ) was obtained.

2 g of NCC-H was added to a 0.2 M ferric chloride aqueous solution 200
After stirring for 3 hours at room temperature, the mixture was filtered, washed with water and dried using a 1.0 μm membrane filter.
An iron-carrying sample was prepared.

Subsequently, 1.9 g of an iron-carrying sample was added to 200 ml of a 0.01 N silver nitrate aqueous solution, and the mixture was stirred at room temperature for 30 minutes.
Using a 1.0μm membrane filter, filtration, washing with water,
After drying, Ag _0.688 Fe _1.276 H _0.536 Zr ₂ Si
A silver / iron type sample represented by _1.5 P _1.5 O ₁₂ was obtained.

Example 1 Using a transmission electron microscope, the silver-type sample (Ag content: 3.20 mmol / g) obtained in Production Example 1 was irradiated with an electron beam under the following conditions to obtain a silver nano sample. A wire was obtained (FIG. 1). The diameter of the obtained silver nanowire was about 50 nm, and the length was about 10 μm. Acceleration voltage: 300 kV Degree of vacuum: 1-3 × 10 ^-5 Pa Irradiation time: about 10 seconds Example 2 The quantitative analysis of the silver nanowire portion and the carrier portion obtained in Example 1 was performed. For the quantitative analysis, an energy dispersive X-ray spectrometer attached to a transmission electron microscope was used. As a result of the quantitative analysis, the Ag content in the silver nanowires was 99.35 mol%, and the Ag content in the carrier was 6.
It was 69 mol%.

Example 3 Using a scanning electron microscope, the silver type sample (Ag content: 3.20 mmol / g) obtained in Production Example 1 was irradiated with an electron beam under the following conditions, A wire was obtained (FIG. 2). The diameter of the obtained silver nanowire was about 10 nm, and the length was about 1 μm. Acceleration voltage: 5 kV Degree of vacuum: 1 × 10 ⁻⁵ Pa Irradiation time: about 30 seconds Example 4 Using a scanning electron microscope, the silver-type compound obtained in Production Example (Ag content: 3.20 mmol / g) ) Was irradiated with an electron beam under the following conditions to obtain silver nanowires and silver nanoparticles (FIGS. 3 and 4). The diameter of the obtained silver nanowire was about 40 nm, and the length was about 50 μm.
The particle size of the obtained silver nanoparticles is 5 to 80 n.
m. Acceleration voltage: 30 kV Degree of vacuum: 1 × 10 ⁻⁵ Pa Irradiation time: about 30 seconds

[Brief description of the drawings]

FIG. 1 is an electron micrograph showing a silver nanowire and a carrier obtained in Example 1.

FIG. 2 is an electron micrograph showing a silver nanowire and a carrier obtained in Example 3.

FIG. 3 is an electron micrograph showing a silver nanowire and a carrier obtained in Example 4.

FIG. 4 is an electron micrograph showing silver nanoparticles and a carrier obtained in Example 4.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Osamu Inokai 2217-14 Hayashi-cho, Takamatsu-shi, Kagawa Prefecture Industrial Science Institute Shikoku Institute of Industrial Technology (72) Inventor Kenta Oi 22217-14 Hayashi-cho, Takamatsu-shi, Kagawa Kogyo (72) Inventor Akira Okubo 85-1 Maruyama, Setocho, Naruto-shi, Tokushima Pref.Tomita Pharmaceutical Co., Ltd. (72) Nozomi Hashimoto Maruyama, Setocho, Naruto-shi, Tokushima Pref. 85-1 Tomita Pharmaceutical Co., Ltd.

Claims (5)

[Claims] 1. A metal nanowire having one end supported by a support. 2. The nanowire according to claim 1, wherein the metal nanowire is a silver nanowire. 3. A method for producing metal nanowires and / or metal nanoparticles by irradiating a metal ion carrier with an electron beam. 4. The method according to claim 3, wherein the silver ion carrier is irradiated with an electron beam to produce silver nanowires and / or silver nanoparticles. 5. The silver ion carrier has the general formula _{(1): Ag a B c D e Si} f P g O h [1] [B is an alkali metal element, an alkaline earth metal element,
It is at least one selected from copper, zinc, hydrogen and ammonium, and D is at least one selected from metal elements that can be trivalent to pentavalent metal ions. The subscripts in the formula are 0 <a, 0 ≦ c, 1 <a + c ≦
4, 1 ≦ e ≦ 2, 0 ≦ f ≦ 3, 0 ≦ g <3, 10 ≦ h ≦
It is a number that satisfies 15. The method according to claim 4, which is a compound represented by the formula: