JP5074727B2 - Tin-doped indium oxide nanoparticles - Google Patents
Tin-doped indium oxide nanoparticles Download PDFInfo
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- JP5074727B2 JP5074727B2 JP2006242794A JP2006242794A JP5074727B2 JP 5074727 B2 JP5074727 B2 JP 5074727B2 JP 2006242794 A JP2006242794 A JP 2006242794A JP 2006242794 A JP2006242794 A JP 2006242794A JP 5074727 B2 JP5074727 B2 JP 5074727B2
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- 239000002105 nanoparticle Substances 0.000 title claims description 99
- 229910003437 indium oxide Inorganic materials 0.000 title claims description 18
- PJXISJQVUVHSOJ-UHFFFAOYSA-N indium(iii) oxide Chemical compound [O-2].[O-2].[O-2].[In+3].[In+3] PJXISJQVUVHSOJ-UHFFFAOYSA-N 0.000 title claims description 18
- 238000010304 firing Methods 0.000 claims description 62
- 239000002994 raw material Substances 0.000 claims description 40
- 239000002245 particle Substances 0.000 claims description 33
- 238000000034 method Methods 0.000 claims description 24
- 239000011164 primary particle Substances 0.000 claims description 16
- 238000004519 manufacturing process Methods 0.000 claims description 15
- 238000010438 heat treatment Methods 0.000 claims description 13
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 11
- 239000001301 oxygen Substances 0.000 claims description 11
- 229910052760 oxygen Inorganic materials 0.000 claims description 11
- 239000000843 powder Substances 0.000 claims description 8
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims description 6
- 239000000428 dust Substances 0.000 claims description 5
- 238000002441 X-ray diffraction Methods 0.000 claims description 3
- 230000005540 biological transmission Effects 0.000 claims description 3
- 238000003860 storage Methods 0.000 claims description 3
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 claims description 3
- 238000004438 BET method Methods 0.000 claims description 2
- 239000012530 fluid Substances 0.000 claims 1
- 239000011248 coating agent Substances 0.000 description 13
- 238000000576 coating method Methods 0.000 description 13
- 239000010408 film Substances 0.000 description 11
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 7
- 238000001816 cooling Methods 0.000 description 6
- 239000007788 liquid Substances 0.000 description 6
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 5
- 230000007423 decrease Effects 0.000 description 5
- 229910001882 dioxygen Inorganic materials 0.000 description 5
- 230000004927 fusion Effects 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 238000002791 soaking Methods 0.000 description 4
- 239000000758 substrate Substances 0.000 description 4
- 239000010409 thin film Substances 0.000 description 4
- 239000013078 crystal Substances 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 230000001590 oxidative effect Effects 0.000 description 3
- 239000008188 pellet Substances 0.000 description 3
- 238000001878 scanning electron micrograph Methods 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 206010021143 Hypoxia Diseases 0.000 description 2
- 229910006404 SnO 2 Inorganic materials 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 239000010419 fine particle Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 2
- 238000005065 mining Methods 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000005169 Debye-Scherrer Methods 0.000 description 1
- 229910021626 Tin(II) chloride Inorganic materials 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 239000013590 bulk material Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 150000002471 indium Chemical class 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 239000011163 secondary particle Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 230000002123 temporal effect Effects 0.000 description 1
- 229910001887 tin oxide Inorganic materials 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G15/00—Compounds of gallium, indium or thallium
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82B—NANOSTRUCTURES FORMED BY MANIPULATION OF INDIVIDUAL ATOMS, MOLECULES, OR LIMITED COLLECTIONS OF ATOMS OR MOLECULES AS DISCRETE UNITS; MANUFACTURE OR TREATMENT THEREOF
- B82B1/00—Nanostructures formed by manipulation of individual atoms or molecules, or limited collections of atoms or molecules as discrete units
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
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- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G19/00—Compounds of tin
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/02—Details
- H01L31/0224—Electrodes
- H01L31/022466—Electrodes made of transparent conductive layers, e.g. TCO, ITO layers
- H01L31/022475—Electrodes made of transparent conductive layers, e.g. TCO, ITO layers composed of indium tin oxide [ITO]
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
- H01L31/1884—Manufacture of transparent electrodes, e.g. TCO, ITO
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y40/00—Manufacture or treatment of nanostructures
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- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2002/00—Crystal-structural characteristics
- C01P2002/50—Solid solutions
- C01P2002/52—Solid solutions containing elements as dopants
- C01P2002/54—Solid solutions containing elements as dopants one element only
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- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
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- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/10—Solid density
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- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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- C01P2006/12—Surface area
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- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/60—Optical properties, e.g. expressed in CIELAB-values
- C01P2006/62—L* (lightness axis)
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- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/60—Optical properties, e.g. expressed in CIELAB-values
- C01P2006/63—Optical properties, e.g. expressed in CIELAB-values a* (red-green axis)
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/60—Optical properties, e.g. expressed in CIELAB-values
- C01P2006/64—Optical properties, e.g. expressed in CIELAB-values b* (yellow-blue axis)
Description
本発明は、透明電極や電磁波シールドの材料として特に好適に用いられる錫ドープ酸化インジウム（以下、ＩＴＯという）ナノ粒子に関する。 The present invention relates to tin-doped indium oxide (hereinafter referred to as ITO) nanoparticles that are particularly preferably used as a material for transparent electrodes and electromagnetic wave shields.
ＩＴＯを用いた透明導電膜の製造方法には、ＩＴＯをターゲットとして用い、スパッタリングにより基板上に薄膜を形成する方法が知られている。この方法で製造された透明導電膜は、電気抵抗が低く且つ抵抗の経時変化が少ないという点において優れたものである。しかしこの方法は薄膜の形成に時間を要し、生産性が良いとは言えない。また、高真空の装置が必要となるので、製造経費を要し経済的とは言えない。 As a method for producing a transparent conductive film using ITO, a method of forming a thin film on a substrate by sputtering using ITO as a target is known. The transparent conductive film produced by this method is excellent in that the electrical resistance is low and the resistance change with time is small. However, this method takes time to form a thin film, and it cannot be said that productivity is good. In addition, since a high-vacuum device is required, manufacturing costs are required and it is not economical.
ＩＴＯを用いた透明導電膜の別の製造方法として、ＩＴＯの粉末を溶媒及びバインダ等と混合してインク化し、これを基板上に塗布して塗膜を形成し、該塗膜を焼成する方法が知られている。この方法は、前記の方法に比較して生産性が良く、経済的にも有利である。しかし、電極の電気抵抗が比較的高く、また時間の経過と共に抵抗が上昇しやすい傾向にある。 As another method for producing a transparent conductive film using ITO, ITO powder is mixed with a solvent, a binder and the like to form an ink, which is applied onto a substrate to form a coating film, and the coating film is baked. It has been known. This method is more productive and economically advantageous than the above method. However, the electrical resistance of the electrode is relatively high, and the resistance tends to increase with time.
このような状況下、本出願人は先に高導電性であり、経時変化による導電性の劣化が少なく且つ光線に対する高い透過性を有するＩＴＯ薄膜の形成が可能なＩＴＯ粉末を提案した（特許文献１及び２参照）。しかしながら、高性能な透明導電膜に求められる特性はとどまるところを知らず、これまでよりも一層低抵抗で且つ抵抗の経時変化の少ないＩＴＯ薄膜が求められている。 Under such circumstances, the present applicant has previously proposed an ITO powder capable of forming an ITO thin film having high conductivity, little deterioration in conductivity due to change with time, and high transparency to light (Patent Document). 1 and 2). However, the characteristics required for a high-performance transparent conductive film are not limited, and there is a demand for an ITO thin film that has a lower resistance and less changes with time than before.
従って本発明の目的は、前述した従来技術よりも更に種々の性能が向上したＩＴＯナノ粒子を提供することにある。 Accordingly, an object of the present invention is to provide ITO nanoparticles having various performances improved as compared with the prior art described above.
本発明は、完全酸化状態にない錫ドープ酸化インジウムナノ粒子の原料粉末を、酸素雰囲気下、該錫ドープ酸化インジウムの完全酸化が可能な温度以上で且つ該錫ドープ酸化インジウム中の錫が昇華する温度未満の温度範囲で、瞬間焼成して得られたものであり、
透過型電子顕微鏡による観察で測定された一次粒子の平均粒径が５〜１００ｎｍであり、ピクノメーター法で測定された真密度が６．８〜７．２ｇ／ｃｍ3であり、
Ｌ＊ａ＊ｂ＊系表色系色座標においてＬ値が６０〜８５、ａ値が−５〜−３０、ｂ値が−５〜３０であることを特徴とする錫ドープ酸化インジウムナノ粒子を提供するものである。
In the present invention, the raw powder of tin-doped indium oxide nanoparticles that are not in a completely oxidized state is sublimated by tin in the tin-doped indium oxide at a temperature above the temperature at which the tin-doped indium oxide can be completely oxidized in an oxygen atmosphere. It was obtained by instantaneous firing in a temperature range below the temperature,
Transmission average particle size of the measured primary particles under an electron microscope by observation is 5 to 100 nm, Ri true density of 6.8~7.2g / cm 3 der measured by pycnometer method,
L * a * b * color system L value in the color coordinate 60 to 85, tin-doped indium oxide nanoparticles a value of -5 to-30, b value is characterized -5 to 30 der Rukoto Is to provide.
本発明によれば、電気抵抗が低く且つその経時変化が少ない透明導電膜の形成に特に好適なＩＴＯナノ粒子が提供される。 According to the present invention, ITO nanoparticles particularly suitable for forming a transparent conductive film having a low electrical resistance and little change with time are provided.
以下本発明を、その好ましい実施形態に基づき説明する。本発明のＩＴＯはナノ粒子の形態をしている。具体的には、本発明のＩＴＯは、透過型電子顕微鏡（以下、ＴＥＭという）による観察で測定された一次粒子の平均粒径が５〜１００ｎｍ、好ましくは１０〜６０ｎｍ、更に好ましくは２０〜５０ｎｍの粒子である。このようなナノ粒子を原料として調製されたインク等の塗布液を、基材に塗布して形成された塗膜は、その微細な粒径に起因して高い透明性を有するものとなる。一次粒子の平均粒径は、ＴＥＭによって撮影された粒子の写真を用い、個々の粒子のうち最も長い部分の長さを測定し、その平均値を算出することで求められる。測定に用いられるサンプル数はＮ＝３０以上とする。 Hereinafter, the present invention will be described based on preferred embodiments thereof. The ITO of the present invention is in the form of nanoparticles. Specifically, the ITO of the present invention has an average primary particle size of 5 to 100 nm, preferably 10 to 60 nm, more preferably 20 to 50 nm, as measured by observation with a transmission electron microscope (hereinafter referred to as TEM). Particles. A coating film formed by applying a coating liquid such as an ink prepared using such nanoparticles as a raw material to a substrate has high transparency due to its fine particle size. The average particle size of the primary particles can be obtained by measuring the length of the longest portion of each particle using a photograph of the particles taken by TEM and calculating the average value. The number of samples used for measurement is N = 30 or more.
従来、上述の範囲の粒径を有するＩＴＯナノ粒子は、還元雰囲気下での焼成によって製造されていた。還元雰囲気下での焼成とは、例えば特許文献２に記載されているように、インジウム塩及び錫塩を含む酸性水溶液にアルカリ水溶液を添加することにより共沈水酸化物を析出させ、洗浄し、固液分離した後、微還元性雰囲気下、３００〜１０００℃で一次焼成を行い、引き続き微還元性雰囲気又は不活性雰囲気下、６００〜１０００℃で二次焼成することを言う。このような方法で製造されたＩＴＯナノ粒子は、その製造方法に起因して酸素欠損が生じている。酸素欠損は、ＩＴＯナノ粒子の導電性を高める観点からは有利ではあるものの、その反面、時間の経過と共に導電性が低下する現象が観察される。これに対して本発明のＩＴＯナノ粒子は、従来のＩＴＯナノ粒子と異なり、時間の経過による導電性の低下が抑制されたものである。この理由は次の通りである。 Conventionally, ITO nanoparticles having a particle size in the above range have been produced by firing in a reducing atmosphere. Firing under a reducing atmosphere is, for example, as described in Patent Document 2, by adding an alkaline aqueous solution to an acidic aqueous solution containing an indium salt and a tin salt to precipitate a coprecipitated hydroxide, washing, and solidifying. After liquid separation, primary firing is performed at 300 to 1000 ° C. in a slightly reducing atmosphere, and then secondary firing is performed at 600 to 1000 ° C. in a slightly reducing or inert atmosphere. The ITO nanoparticles produced by such a method have oxygen deficiency due to the production method. Although oxygen deficiency is advantageous from the viewpoint of increasing the conductivity of ITO nanoparticles, on the other hand, a phenomenon is observed in which the conductivity decreases with the passage of time. In contrast, the ITO nanoparticles of the present invention are different from conventional ITO nanoparticles in that the decrease in conductivity with the passage of time is suppressed. The reason is as follows.
従来の還元雰囲気下での焼成によって製造されていたＩＴＯナノ粒子は、酸素欠損を有しているので、完全酸化体とはなっていない。これに対し本発明のＩＴＯナノ粒子は、完全酸化体又はそれに近く、その構造は非常に安定である。その結果、外部環境からの影響を受けづらく、時間の経過による導電性の低下が抑制されたものとなる。 ITO nanoparticles produced by firing in a conventional reducing atmosphere have oxygen vacancies and are not completely oxidized. In contrast, the ITO nanoparticles of the present invention are fully oxidized or close to it, and the structure is very stable. As a result, it is difficult to be affected by the external environment, and the decrease in conductivity over time is suppressed.
ＩＴＯナノ粒子を完全酸化体又はそれに近い構造とするためには、焼成を高温で行えばよい。しかし高温焼成を行うと、ナノ粒子の溶融に起因して粒子どうしが融着してしまい、もはやナノ粒子とは呼べない程度に粒径の大きな粒子となってしまう。そのような粒径の大きなＩＴＯ粒子を原料としてインク等の塗布液を調製しても、ＩＴＯ粒子の分散性が良好でないために均一な塗布液とすることができない。またそのような塗布液から塗膜を形成しても、該塗膜の透明性は十分に高いものとはならない。しかも該塗膜は表面平滑性にも劣るものとなる。このように、従来の技術では、完全酸化体又はそれに近い構造を有するＩＴＯナノ粒子を得ることができなかった。換言すれば、ＩＴＯをナノ粒子にすることと、ＩＴＯを完全酸化体にすることは、二律背反の関係にあった。これに対して本発明によれば、驚くべきことに、後述する瞬間焼成法により酸化雰囲気下での焼成を行うことによって、ナノ粒子の微細な粒径を損なうことなく完全酸化体ないしそれに近い構造のＩＴＯナノ粒子を得ることができる。 In order to make the ITO nanoparticles into a completely oxidized form or a structure close thereto, firing may be performed at a high temperature. However, when firing at a high temperature, the particles are fused due to the melting of the nanoparticles, and the particles are so large that they can no longer be called nanoparticles. Even if a coating liquid such as ink is prepared using such ITO particles having a large particle size as a raw material, a uniform coating liquid cannot be obtained because the dispersibility of the ITO particles is not good. Moreover, even if a coating film is formed from such a coating solution, the transparency of the coating film is not sufficiently high. Moreover, the coating film is inferior in surface smoothness. As described above, in the conventional technique, ITO nanoparticles having a completely oxidized form or a structure close thereto cannot be obtained. In other words, there was a trade-off between making ITO into nanoparticles and making ITO into a fully oxidized form. On the other hand, according to the present invention, surprisingly, by performing firing in an oxidizing atmosphere by the instantaneous firing method to be described later, a completely oxidized body or a structure close thereto is obtained without impairing the fine particle size of the nanoparticles. ITO nanoparticles can be obtained.
ＩＴＯが完全酸化体又はそれに近い構造であることは、ＩＴＯの真密度を尺度として判断することができる。本発明におけるＩＴＯナノ粒子の真密度は６．８〜７．２ｇ／ｃｍ3である。この範囲の真密度は、ＩＴＯの完全酸化体又はそれに近い構造を有しているものであると当該技術分野において共通に認識されている材料であるＩＴＯのバルク体の真密度の範囲とほぼ重複している。つまり、本発明のＩＴＯ粒子は、ナノ粒子でありながら、完全酸化体又はそれに近い構造を有している。 It can be judged by using the true density of ITO as a measure that ITO is a completely oxidant or a structure close thereto. The true density of the ITO nanoparticles in the present invention is 6.8 to 7.2 g / cm 3 . The true density in this range almost overlaps with the true density range of ITO bulk material, a material commonly recognized in the art as having a fully oxidized ITO or a structure close thereto. is doing. That is, the ITO particles of the present invention are nano-particles but have a completely oxidized form or a structure close thereto.
本発明においてＩＴＯナノ粒子の真密度はピクノメーター法によって測定される。具体的な測定の手順は、ＪＩＳ Ｒ１６２０（ファインセラミックス粉末の粒子密度測定方法）に準拠した。 In the present invention, the true density of the ITO nanoparticles is measured by a pycnometer method. The specific measurement procedure was based on JIS R1620 (a method for measuring the particle density of fine ceramic powder).
本発明におけるＩＴＯナノ粒子は、微小な単結晶が集合してなる多結晶集合体である。この単結晶は一般に結晶子と呼ばれており、多結晶集合体は一次粒子と呼ばれている。本発明者らの検討によれば、結晶子径が一次粒子径に近ければ近いほど、時間の経過による導電性の低下を防止し得ることが判明している。この観点から、本発明のＩＴＯナノ粒子は、一次粒子の平均粒径が上述の範囲内であることを条件として、結晶子径が２〜７０ｎｍ、特に１５〜３５ｎｍであることが好ましい。結晶子径はＩＴＯナノ粒子のＸ線回折から測定される。 The ITO nanoparticles in the present invention are a polycrystal aggregate formed by assembling minute single crystals. This single crystal is generally called a crystallite, and the polycrystalline aggregate is called a primary particle. According to the study by the present inventors, it has been found that the closer the crystallite diameter is to the primary particle diameter, the more it is possible to prevent a decrease in conductivity over time. From this point of view, the ITO nanoparticles of the present invention preferably have a crystallite diameter of 2 to 70 nm, particularly 15 to 35 nm, provided that the average particle diameter of the primary particles is within the above-mentioned range. The crystallite diameter is measured from X-ray diffraction of ITO nanoparticles.
時間の経過による導電性の低下が抑制された本発明のＩＴＯ粒子は、３００℃大気焼成後の圧粉抵抗値が好ましくは２Ω・ｃｍ未満、更に好ましくは３×１０-1Ω・ｃｍ未満であり、引き続き室温（２５℃，相対湿度５０％）で３００時間保存した後の圧粉抵抗値の変化率が好ましくは１０％以下、更に好ましくは５％以下であるという優れた特性を示すものとなる。圧粉抵抗値の測定方法は、後述する実施例において説明する。 The ITO particles of the present invention in which the decrease in conductivity with the passage of time is suppressed preferably have a dust resistance value after firing at 300 ° C. in the air of less than 2 Ω · cm, more preferably less than 3 × 10 −1 Ω · cm. The rate of change in the dust resistance value after storage for 300 hours at room temperature (25 ° C., relative humidity 50%) is preferably 10% or less, more preferably 5% or less. Become. The measuring method of the dust resistance value will be described in the examples described later.
本発明のＩＴＯナノ粒子は、一次粒子の平均粒径が上述の範囲内であり、且つ好適には後述する瞬間焼成法によって製造されたものなので、その比表面積が大きいことでも特徴付けられる。本発明のＩＴＯナノ粒子は、ＢＥＴ法で測定された比表面積が好ましくは１５〜３５ｍ2／ｇ、更に好ましくは２０〜３０ｍ2／ｇという大きな比表面積を有するものである。本発明のＩＴＯ粒子がこのような範囲の比表面積を有することは、粒子の融着が瞬間焼成のために抑制されていること、即ち高温焼成工程を経ても、一次粒子径がナノオーダーであることを意味する。よって得られたナノ粒子によれば、これを溶媒中に高分散させ易いという有利な効果が奏される。 The ITO nanoparticles of the present invention are also characterized by having a large specific surface area because the average particle size of the primary particles is within the above-mentioned range and is preferably produced by the instantaneous firing method described later. ITO nanoparticles of the invention have been ratio is preferably the surface area measured by BET method 15 to 35 m 2 / g, more preferably those having a large specific surface area of 20 to 30 m 2 / g. The fact that the ITO particles of the present invention have a specific surface area in such a range means that the fusion of the particles is suppressed for instantaneous firing, that is, the primary particle diameter is nano-order even after a high temperature firing step. Means that. Therefore, according to the obtained nanoparticles, there is an advantageous effect that it can be easily dispersed in a solvent.
完全酸化体又はそれに近い構造を有する本発明のＩＴＯナノ粒子は、外観の面からも、従来のＩＴＯナノ粒子と異なるものである。酸素欠損を有する従来のＩＴＯナノ粒子は、青色系や黄色系の外観を呈するものであるのに対し、本発明のＩＴＯナノ粒子はうぐいす色系の外観を呈している。このように外観が異なる理由は明確ではないが、完全酸化体又はそれに近い構造を有する本発明のＩＴＯナノ粒子は、その構造に起因してＩＴＯ結晶の格子定数や構造中の欠陥量が従来のＩＴＯナノ粒子と異なるためであると本発明者らは推測している。本発明のＩＴＯナノ粒子が呈する色を、Ｌ＊ａ＊ｂ＊系表色系色座標（光源：Ｄ６５、視野角：１０°）で表すと、Ｌ値が６０〜８５、特に７０〜８０であり、ａ値が−５〜−３０、特に−５〜−１５であり、ｂ値が−５〜３０、特に１０〜２０であることが好ましい。 The ITO nanoparticles of the present invention having a completely oxidized form or a structure close thereto are also different from conventional ITO nanoparticles in terms of appearance. Conventional ITO nanoparticles having oxygen vacancies have a blue or yellow appearance, whereas the ITO nanoparticles of the present invention have a faint appearance. The reason why the appearances are different is not clear, but the ITO nanoparticle of the present invention having a completely oxidized form or a structure close thereto has a conventional lattice constant of ITO crystal and the amount of defects in the structure due to the structure. The present inventors speculate that this is because it is different from ITO nanoparticles. When the color exhibited by the ITO nanoparticles of the present invention is represented by L * a * b * color system color coordinates (light source: D65, viewing angle: 10 °), the L value is 60 to 85, particularly 70 to 80. It is preferable that the a value is -5 to -30, particularly -5 to -15, and the b value is -5 to 30, particularly 10 to 20.
本発明のＩＴＯナノ粒子は、酸化錫が添加された酸化インジウムからなる。ＩＴＯナノ粒子におけるＳｎの含有量は、ＳｎＯ2換算で好ましくは２〜２０重量％、更に好ましくは５〜１０重量％である。Ｓｎの含有量をこの範囲内に設定することで、Ｓｎの固溶を十分とした上でＩＴＯの導電性を向上させることができる。 The ITO nanoparticles of the present invention are made of indium oxide to which tin oxide is added. The content of Sn in the ITO nanoparticles is preferably 2 to 20% by weight, more preferably 5 to 10% by weight in terms of SnO 2 . By setting the content of Sn within this range, it is possible to improve the conductivity of ITO after sufficient Sn solid solution.
本発明のＩＴＯナノ粒子は、その一次粒子の形状に特に制限はなく、球状や針状であり得る。 The shape of the primary particles of the ITO nanoparticles of the present invention is not particularly limited, and may be spherical or acicular.
次に、本発明のＩＴＯナノ粒子の好適な製造方法について説明する。本製造方法は急速加熱及び急速冷却工程を含む瞬間焼成法によって特徴付けられる。具体的には、完全酸化状態にないＩＴＯの原料ナノ粒子を、酸素雰囲気下、該ＩＴＯの完全酸化が可能な温度以上で且つ該ＩＴＯ中の錫が昇華する温度未満の温度範囲で、瞬間焼成する方法を採用することによって目的とするＩＴＯ粒子を得ることができる。 Next, the suitable manufacturing method of the ITO nanoparticle of this invention is demonstrated. This manufacturing method is characterized by a flash firing method including rapid heating and rapid cooling steps. Specifically, ITO raw material nanoparticles that are not in a completely oxidized state are instantaneously fired in an oxygen atmosphere at a temperature that is higher than the temperature at which the ITO can be completely oxidized and less than the temperature at which tin in the ITO sublimes. By adopting this method, the desired ITO particles can be obtained.
本製造方法における急速加熱の速度は５００〜２００００℃／秒、特に１０００〜１００００℃／秒であることが、原料のナノ粒子の融着を防止する観点から好ましい。同様の理由により、急速冷却の速度は、５００〜２００００℃／秒、特に１０００〜１００００℃／秒であることが好ましい。焼成時間についても、原料のナノ粒子の融着を防止する観点から短時間であることが好ましく、具体的には０．００１〜１０秒、特に０．０１〜１秒であることが好ましい。 The rapid heating speed in this production method is preferably 500 to 20000 ° C./second, particularly 1000 to 10,000 ° C./second, from the viewpoint of preventing fusion of the raw material nanoparticles. For the same reason, the rapid cooling rate is preferably 500 to 20000 ° C./second, more preferably 1000 to 10,000 ° C./second. The firing time is also preferably a short time from the viewpoint of preventing fusion of the raw material nanoparticles, specifically 0.001 to 10 seconds, particularly preferably 0.01 to 1 second.
原料のナノ粒子は、焼成中、静置状態に置かれてもよく、或いは流動状態に置かれてもよい。原料のナノ粒子の融着を一層効果的に防止する観点からは、流動状態下に焼成を行うことが好ましい。 The raw material nanoparticles may be placed in a stationary state or in a fluidized state during firing. From the viewpoint of more effectively preventing the fusion of the raw material nanoparticles, it is preferable to perform firing in a fluidized state.
焼成の雰囲気は上述の通り酸素雰囲気であるところ、この雰囲気は１００％酸素の雰囲気であることを要せず、酸素の他に窒素等の不活性ガスが少量、例えば２０体積％を上限として含まれていてもよい。尤も、原料のＩＴＯナノ粒子を完全酸化体又はそれに近い状態にまで確実に酸化させる観点からは、１００％酸素の雰囲気下に焼成を行うことが好ましい。 The firing atmosphere is an oxygen atmosphere as described above. This atmosphere does not need to be a 100% oxygen atmosphere, and contains a small amount of inert gas such as nitrogen in addition to oxygen, for example, up to 20% by volume. It may be. However, from the viewpoint of reliably oxidizing the ITO nanoparticles as a raw material to a completely oxidized form or a state close thereto, it is preferable to perform firing in an atmosphere of 100% oxygen.
焼成温度は上述の通り、原料のＩＴＯの完全酸化が可能な温度以上で且つ該ＩＴＯ中の錫が昇華する温度未満の範囲とする。この温度範囲は、急速加熱及び急速冷却の速度や焼成時間にもよるが、一般に１０００〜１６００℃、特に１３００〜１５００℃であることが好適である。なお、この温度は原料ナノ粒子の温度そのものではなく、焼成炉の加熱温度のことである。 As described above, the firing temperature is set to a range not lower than the temperature at which the raw material ITO can be completely oxidized and lower than the temperature at which tin in the ITO sublimes. This temperature range is generally 1000 to 1600 ° C., particularly 1300 to 1500 ° C., although it depends on the speed of rapid heating and rapid cooling and the firing time. This temperature is not the temperature of the raw material nanoparticles itself but the heating temperature of the firing furnace.
本製造方法に用いられる原料であるＩＴＯのナノ粒子は完全酸化状態にないものである。このようなＩＴＯは、先に述べた共沈水酸化物の焼成によって容易に製造できる。その具体的な手順は先に述べた通りなので、ここでは重ねて説明しない。完全酸化状態にないＩＴＯは一般に青色系や黄色系の色を呈している。なお、完全酸化状態にないＩＴＯのナノ粒子の製造方法がこれに限られないことは言うまでもない。 ITO nanoparticles, which are raw materials used in this production method, are not in a completely oxidized state. Such ITO can be easily produced by firing the coprecipitated hydroxide described above. Since the specific procedure is as described above, it will not be described again here. ITO that is not in a completely oxidized state generally exhibits a blue or yellow color. Needless to say, the production method of ITO nanoparticles not in a completely oxidized state is not limited to this.
図１には、本発明の製造方法を実施するために好適に用いられる装置の一例が示されている。この装置１０は縦型焼成炉１１を基本構成としている。焼成炉１１は筒状であり、その高さ方向の一部に加熱手段１２を備えた焼成ゾーン１３を有している。焼成炉１１内には、該焼成炉１１の高さとほぼ同様の長さを有し、且つ所定の内径を有する管体１４が配置されている。管体１４は、その周囲が上述の加熱手段１２によって取り囲まれている。管体１４としては熱伝導性の低い耐火材料を用いることが、原料ナノ粒子の急速加熱及び急速冷却を首尾良く行う点から好ましい。そのような材料として例えばアルミナを用いることができる。 FIG. 1 shows an example of an apparatus suitably used for carrying out the manufacturing method of the present invention. This apparatus 10 has a vertical firing furnace 11 as a basic configuration. The firing furnace 11 has a cylindrical shape, and has a firing zone 13 provided with a heating means 12 in a part in the height direction. In the firing furnace 11, a tube body 14 having a length substantially the same as the height of the firing furnace 11 and having a predetermined inner diameter is disposed. The periphery of the tube body 14 is surrounded by the heating means 12 described above. It is preferable to use a refractory material with low thermal conductivity as the tube body 14 from the viewpoint of successfully performing rapid heating and rapid cooling of the raw material nanoparticles. For example, alumina can be used as such a material.
管体１４はその上下が開孔している。管体１４の上端の開口部は、ホッパー１５に接続されている。ホッパー１５内には、原料である完全酸化状態にないＩＴＯのナノ粒子が仕込まれている。ホッパー１５の下端部には電磁フィーダー（図示せず）が取り付けられており、所定量の原料ナノ粒子が管体１４内に投入されるようになっている。また管体１４の上端付近には、酸素ガスの導入口１６が設けられている。図示しない酸素ガス源から供給された酸素ガスは導入口１６を通じて管体１４内に導入され、管体１４内を上から下に向けて流通する。 The upper and lower sides of the tube body 14 are open. The opening at the upper end of the tube body 14 is connected to the hopper 15. In the hopper 15, ITO nanoparticles that are not in a completely oxidized state as a raw material are charged. An electromagnetic feeder (not shown) is attached to the lower end portion of the hopper 15 so that a predetermined amount of raw material nanoparticles are introduced into the tube body 14. An oxygen gas inlet 16 is provided near the upper end of the tube body 14. Oxygen gas supplied from an oxygen gas source (not shown) is introduced into the tube body 14 through the introduction port 16 and circulates in the tube body 14 from top to bottom.
以上の構成を有する装置１０を用いたＩＴＯナノ粒子の製造方法について説明すると、ホッパー１５内に仕込まれている原料ナノ粒子は、一定量ずつ管体１４内に投入される。この状態では原料ナノ粒子は室温状態にある。管体１４内に投入された原料ナノ粒子は重力によって自由落下し、焼成ゾーン１３の位置まで到達する。焼成ゾーン１３に備えられている加熱手段１２によって焼成ゾーン１３は所定温度、例えば上述の通り１３００〜１４００℃に加熱されている。管体１４は上述の通り熱伝導性の低い材料から構成されているので、原料ナノ粒子は焼成ゾーン１３に到達して初めて加熱される。つまり急速加熱される。急速加熱の速度は既に述べた通りである。 The production method of ITO nanoparticles using the apparatus 10 having the above configuration will be described. The raw material nanoparticles charged in the hopper 15 are put into the tube body 14 by a certain amount. In this state, the raw material nanoparticles are at room temperature. The raw material nanoparticles thrown into the tube body 14 fall free by gravity and reach the position of the firing zone 13. The firing zone 13 is heated to a predetermined temperature, for example, 1300 to 1400 ° C. as described above, by the heating means 12 provided in the firing zone 13. Since the tube body 14 is made of a material having low thermal conductivity as described above, the raw material nanoparticles are heated only after reaching the firing zone 13. That is, it is rapidly heated. The rapid heating rate is as described above.
管体１４内は酸素ガス雰囲気になっているので、焼成ゾーン１３に到達した原料ナノ粒子は、酸素雰囲気下で焼成され、完全酸化体又はそれに近い状態の構造となる。焼成は、原料ナノ粒子が焼成ゾーン１３内に通過する間だけ行われる。つまり焼成時間が極めて短い瞬間焼成が行われる。その上、原料ナノ粒子は自由落下による流動状態で焼成ゾーン１３を通過する。これらに起因して、原料ナノ粒子の焼成時に粒子どうしが融着することが効果的に防止される。このように、前記の温度範囲に加熱された焼成ゾーン１３を通過するように、ＩＴＯの原料ナノ粒子を焼成ゾーン１３上から自由落下させ、落下した該ナノ粒子を該焼成ゾーン１３において瞬間焼成することで、原料ナノ粒子の粒径がほぼ維持されたままで、完全酸化体又はそれに近い構造のＩＴＯナノ粒子が得られる。なお、焼成ゾーン１３を通過するときの原料ナノ粒子の温度を測定することは極めて困難なので、本発明においては、焼成ゾーン１３に備えられている加熱手段１２の温度をもって焼成温度に代えている。 Since the inside of the tube body 14 is in an oxygen gas atmosphere, the raw material nanoparticles that have reached the firing zone 13 are fired in an oxygen atmosphere to form a completely oxidized body or a structure close thereto. Firing is performed only while the raw material nanoparticles pass into the firing zone 13. That is, instantaneous firing is performed with an extremely short firing time. In addition, the raw material nanoparticles pass through the firing zone 13 in a fluidized state due to free fall. As a result, it is possible to effectively prevent the particles from fusing at the time of firing the raw material nanoparticles. Thus, the ITO raw material nanoparticles are freely dropped from the firing zone 13 so as to pass through the firing zone 13 heated to the above temperature range, and the dropped nanoparticles are instantaneously fired in the firing zone 13. Thus, ITO nanoparticles having a completely oxidized form or a structure close thereto can be obtained while the particle diameter of the raw material nanoparticles is substantially maintained. Since it is extremely difficult to measure the temperature of the raw material nanoparticles when passing through the firing zone 13, in the present invention, the temperature of the heating means 12 provided in the firing zone 13 is replaced with the firing temperature.
管体１４が熱伝導性の低い材料から構成されていることは上述の通りであるところ、焼成ゾーン１３よりも下側に位置する管体１４は、その熱伝導性の低さに起因してほぼ室温状態になっている。従って、焼成ゾーン１３を通過したＩＴＯナノ粒子は直ちに室温まで冷却される。つまり急速冷却される。これによって焼成後にＩＴＯナノ粒子同士が融着することも効果的に防止される。 As described above, the tube body 14 is made of a material having low thermal conductivity. The tube body 14 located below the firing zone 13 is caused by the low thermal conductivity. It is almost at room temperature. Therefore, the ITO nanoparticles that have passed through the firing zone 13 are immediately cooled to room temperature. That is, it is rapidly cooled. This effectively prevents the ITO nanoparticles from fusing together after firing.
このようにして製造されたＩＴＯナノ粒子は、後述する実施例の結果から明らかなように、一次粒子の融着がほとんど生じておらず、粒成長がほとんど認められない。つまり、原料のナノ粒子の粒径が概ね維持されている。また、本方法で製造されたＩＴＯナノ粒子は、その製造方法に起因して、一次粒子どうしの凝集の程度が極めて低い、単分散状態に近いものであるか、又は一次粒子どうしが凝集して二次粒子になっていたとしても、一次粒子どうしの凝集力は弱く、容易に解砕可能な程度にしか凝集していない。従って、前記の方法で製造されたＩＴＯナノ粒子を原料としてインク等の塗布液を調製する場合には、該粒子の分散性が良好になる。 As is apparent from the results of Examples described later, the ITO nanoparticles produced in this manner hardly cause primary particle fusion, and almost no grain growth is observed. That is, the particle size of the raw material nanoparticles is generally maintained. In addition, the ITO nanoparticles produced by this method, due to the production method, the degree of aggregation of primary particles is extremely low, close to a monodispersed state, or primary particles are aggregated. Even if the particles are secondary particles, the cohesive force between the primary particles is weak, and the particles are aggregated only to such an extent that they can be easily crushed. Accordingly, when preparing a coating liquid such as ink using the ITO nanoparticles produced by the above method as a raw material, the dispersibility of the particles is improved.
このようにして製造されたＩＴＯナノ粒子は、例えば各種の溶媒と混合されてインク等の塗布液の形態で用いられる。この塗布液を基材に塗布し所定温度で焼成することで、透明性及び導電性が高い電極や電磁波シールドを得ることができる。 The ITO nanoparticles produced in this way are mixed with various solvents and used in the form of a coating liquid such as ink. By applying this coating solution to a substrate and baking it at a predetermined temperature, an electrode or an electromagnetic wave shield with high transparency and conductivity can be obtained.
以下、実施例により本発明を更に詳細に説明する。しかしながら本発明の範囲はかかる実施例に制限されない。 Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited to such examples.
〔実施例１〕
図１に示す装置を用いてＩＴＯナノ粒子を製造した。１０ｃｍの均熱帯１２を有する縦型管状炉１１内にアルミナ管１４を設置した。このとき、アルミナ管１４のほぼ中央部に均熱帯１２が位置するようにした。アルミナ管１４は全長８００ｍｍ、外径１３ｍｍ、内径９ｍｍのものであった。均熱帯１２は１３８０℃に加熱されていた。アルミナ管１４内には酸素ガスを１００ｍｌ／ｍｉｎで上から下に向けて吹き込んだ。ホッパー１５に備えられている電磁フィーダーにより原料であるＩＴＯナノ粒子を０．５ｇ／ｍｉｎの速度でアルミナ管の上部から投入した。原料ナノ粒子としては、三井金属鉱業株式会社製のパストランＩＴＯ（ＴＹＰＥ−Ｂ）を用いた。このＩＴＯ粒子は還元処理された青色系のものであり、Ｓｎの含有量がＳｎＯ2換算で８重量％、一次粒子の平均粒径が３０ｎｍであった。原料ナノ粒子はアルミナ管内を自由落下し、均熱帯１２を通過するときに瞬間焼成された。このようにして得られたＩＴＯナノ粒子はうぐいす色を呈していた。
[Example 1]
ITO nanoparticles were produced using the apparatus shown in FIG. An alumina tube 14 was installed in a vertical tubular furnace 11 having a 10 cm soaking zone 12. At this time, the soaking zone 12 was positioned substantially at the center of the alumina tube 14. The alumina tube 14 had a total length of 800 mm, an outer diameter of 13 mm, and an inner diameter of 9 mm. Soaking 12 was heated to 1380 ° C. Oxygen gas was blown into the alumina tube 14 from top to bottom at 100 ml / min. ITO nanoparticles as a raw material were introduced from the upper part of the alumina tube at a rate of 0.5 g / min by an electromagnetic feeder provided in the hopper 15. As the raw material nanoparticles, Pastorran ITO (TYPE-B) manufactured by Mitsui Mining & Smelting Co., Ltd. was used. The ITO particles were blue-type particles that had been subjected to reduction treatment. The Sn content was 8% by weight in terms of SnO 2 and the average particle size of primary particles was 30 nm. The raw material nanoparticles freely dropped in the alumina tube and were instantaneously fired when passing through the soaking zone 12. The ITO nanoparticles thus obtained had a light blue color.
得られたＩＴＯナノ粒子について、上述の方法で一次粒子の平均粒径及び真密度を測定したところ、平均粒径は４０ｎｍ、真密度は７．１８ｇ／ｃｍ3であった。またＸ線回折測定を行い、シェラー法により結晶子径の算出を行った結果、２５ｎｍであった。更にＢＥＴ多点法により比表面積測定を行った結果、２６．７ｍ2／ｇであった。更に、色座標を測定した結果、Ｌ＊：７７．４、ａ＊：−１１．１、ｂ＊：１７．１であった。 About the obtained ITO nanoparticle, when the average particle diameter and true density of primary particles were measured by the above-mentioned method, the average particle diameter was 40 nm, and the true density was 7.18 g / cm 3 . Further, X-ray diffraction measurement was performed, and the crystallite diameter was calculated by the Scherrer method. As a result, it was 25 nm. Furthermore, the specific surface area was measured by the BET multipoint method. As a result, it was 26.7 m 2 / g. Furthermore, as a result of measuring the color coordinates, they were L *: 77.4, a *: −11.1, b *: 17.1.
更に、得られたＩＴＯナノ粒子を１５ｋＮ／ｃｍ2の圧力で１分間プレスし、直径１６ｍｍ、厚み１．５ｍｍペレットを作製した。このペレットを３００℃で、１時間大気中で焼成した。このようにして得られたペレットの抵抗値を四探針法により測定した結果、１．９６×１０-1Ω・ｃｍであった。引き続き室温で３００時間保存した後、抵抗値を再測定したところ、１．９７×１０-1Ω・ｃｍであり、経時的な抵抗上昇はみられなかった。 Furthermore, the obtained ITO nanoparticles were pressed at a pressure of 15 kN / cm 2 for 1 minute to produce pellets having a diameter of 16 mm and a thickness of 1.5 mm. The pellet was fired at 300 ° C. for 1 hour in the air. The resistance value of the pellet thus obtained was measured by a four-probe method and found to be 1.96 × 10 −1 Ω · cm. Subsequently after storage for 300 hours at room temperature, it was re-measured resistance value is 1.97 × 10 -1 Ω · cm, temporal increase in resistance was observed.
以上の結果をまとめて以下の表１に示す。同表には、原料のＩＴＯナノ粒子について行った同様の測定結果も示されている。更に図２に、原料ＩＴＯナノ粒子及び本実施例で得られたＩＴＯナノ粒子の走査型電子顕微鏡（ＳＥＭ）像を示す。図２に示す結果から明らかなように、得られたＩＴＯナノ粒子には、粒子どうしの融着が起こっておらず、原料ナノ粒子の粒径がほぼ維持されていることが判る。 The above results are summarized in Table 1 below. In the same table, the same measurement results of the raw material ITO nanoparticles are also shown. Further, FIG. 2 shows scanning electron microscope (SEM) images of the raw material ITO nanoparticles and the ITO nanoparticles obtained in this example. As is clear from the results shown in FIG. 2, it can be seen that the obtained ITO nanoparticles are not fused with each other, and the particle diameter of the raw material nanoparticles is substantially maintained.
〔比較例１〕
実施例１で用いた原料ＩＴＯナノ粒子（三井金属鉱業株式会社製のパストランＩＴＯ（ＴＹＰＥ−Ｂ））を、大気中、静置炉で焼成した。昇温速度は６００℃／分、焼成温度は１３８０℃、焼成時間は１分とした。焼成後の冷却は自然冷却とした。このようにして得られたＩＴＯのＳＥＭ像を図３に示す。図３は図２と同倍率である。図３に示す結果から明らかなように、得られたＩＴＯにおいては原料ナノ粒子の融着が甚だしく、もはやナノ粒子と呼べない状態になっていることが判る。
[Comparative Example 1]
The raw material ITO nanoparticles (Pastran ITO (TYPE-B) manufactured by Mitsui Mining & Smelting Co., Ltd.) used in Example 1 were baked in a stationary furnace in the atmosphere. The heating rate was 600 ° C./min, the firing temperature was 1380 ° C., and the firing time was 1 minute. Cooling after firing was natural cooling. The SEM image of the ITO thus obtained is shown in FIG. FIG. 3 is the same magnification as FIG. As is apparent from the results shown in FIG. 3, it can be seen that in the obtained ITO, the raw material nanoparticles are extremely fused, and can no longer be called nanoparticles.
１０ 製造装置
１１ 縦型焼成炉
１２ 加熱手段
１３ 焼成ゾーン
１４ 管体
１５ ホッパー
DESCRIPTION OF SYMBOLS 10 Manufacturing apparatus 11 Vertical firing furnace 12 Heating means 13 Firing zone 14 Tubing body 15 Hopper
Claims (6)
透過型電子顕微鏡による観察で測定された一次粒子の平均粒径が５〜１００ｎｍであり、ピクノメーター法で測定された真密度が６．８〜７．２ｇ／ｃｍ3であり、
Ｌ＊ａ＊ｂ＊系表色系色座標においてＬ値が６０〜８５、ａ値が−５〜−３０、ｂ値が−５〜３０であることを特徴とする錫ドープ酸化インジウムナノ粒子。 A raw material powder of tin-doped indium oxide nanoparticles that are not in a completely oxidized state is at a temperature not lower than the temperature at which the tin-doped indium oxide can be completely oxidized in an oxygen atmosphere and lower than the temperature at which tin in the tin-doped indium oxide sublimes Range, obtained by instantaneous firing,
Transmission average particle size of the measured primary particles under an electron microscope by observation is 5 to 100 nm, Ri true density of 6.8~7.2g / cm 3 der measured by pycnometer method,
L * a * b * color system L value in the color coordinate 60 to 85, tin-doped indium oxide nanoparticles a value of -5 to-30, b value is characterized -5 to 30 der Rukoto .
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| PCT/JP2007/060865 WO2008029543A1 (en) | 2006-09-07 | 2007-05-29 | Tin-doped indium oxide nanoparticle |
| KR1020097003513A KR20090103990A (en) | 2006-09-07 | 2007-05-29 | Tin-doped indium oxide nanoparticle |
| TW096120642A TW200812914A (en) | 2006-09-07 | 2007-06-08 | Tin-doped indium oxide nanoparticle |
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