JP6777982B2 - Composition for gas sensor - Google Patents
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- JP6777982B2 JP6777982B2 JP2015202817A JP2015202817A JP6777982B2 JP 6777982 B2 JP6777982 B2 JP 6777982B2 JP 2015202817 A JP2015202817 A JP 2015202817A JP 2015202817 A JP2015202817 A JP 2015202817A JP 6777982 B2 JP6777982 B2 JP 6777982B2
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- Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
Description
本発明は、ガスセンサの感ガス体用組成物に関する。 The present invention relates to a composition for a gas sensor for a gas sensor.
従来、ガスセンサとして、被検知ガスの濃度によって電気的特性（電気抵抗）が変化する特性を有する材料を感ガス体として利用したガスセンサが知られている。 Conventionally, as a gas sensor, a gas sensor using a material having a characteristic that the electrical characteristic (electrical resistance) changes depending on the concentration of the detected gas as a gas sensitive body is known.
例えば、特許文献１には、金属酸化物半導体層と、金属酸化物半導体層上に形成された貴金属層を有する感応層とを備えたガスセンサが記載されている。感応層の電気的特性は、被検知ガスによって変化する。金属酸化物半導体層の材質としては、酸化スズ（ＳｎＯ2）、酸化タングステン（ＷＯ3）、酸化インジウム（ＩｎＯ2）等が挙げられている。貴金属層は、例えば、パラジウム（Ｐｄ）又は白金（Ｐｔ）などを主成分として含んでいる。感応層は、発熱体による発熱によって活性化している。ガスセンサの使用時の発熱体の温度は２５０℃以上である。 For example, Patent Document 1 describes a gas sensor including a metal oxide semiconductor layer and a sensitive layer having a noble metal layer formed on the metal oxide semiconductor layer. The electrical characteristics of the sensitive layer change depending on the gas to be detected. Examples of the material of the metal oxide semiconductor layer include tin oxide (SnO 2 ), tungsten oxide (WO 3 ), and indium oxide (InO 2 ). The noble metal layer contains, for example, palladium (Pd) or platinum (Pt) as a main component. The sensitive layer is activated by heat generated by the heating element. The temperature of the heating element when the gas sensor is used is 250 ° C. or higher.
特許文献２には、膜状ヒーターを備えたアルミナ基板などの絶縁基板と、絶縁基板上において酸化スズなどの膜状酸化物半導体からなる感応層とを備えたガスセンサが記載されている。このガスセンサは、約４５０℃で動作している。 Patent Document 2 describes a gas sensor including an insulating substrate such as an alumina substrate provided with a film heater and a sensitive layer made of a film oxide semiconductor such as tin oxide on the insulating substrate. This gas sensor operates at about 450 ° C.
特許文献３には、基板の表面に所定の間隔を設けて形成した一対の電極と、当該電極間に形成された感応層とを備えたＴｏｔａｌ−ＶＯＣ検出用ガスセンサが記載されている。感応層は、白金、パラジウム、及び金が酸化スズ層に分散されて形成されている。このセンサは、３００℃で動作している。 Patent Document 3 describes a total-VOC detection gas sensor including a pair of electrodes formed on the surface of a substrate at predetermined intervals and a sensitive layer formed between the electrodes. The sensitive layer is formed by dispersing platinum, palladium, and gold in the tin oxide layer. This sensor is operating at 300 ° C.
特許文献１〜３に記載のガスセンサは、感応層を活性化させるために２５０℃以上の高温で動作されている。そこで、本発明は、比較的低温でのセンシングが可能なガスセンサの感ガス体用組成物を提供することを目的とする。 The gas sensors described in Patent Documents 1 to 3 are operated at a high temperature of 250 ° C. or higher in order to activate the sensitive layer. Therefore, an object of the present invention is to provide a composition for a gas-sensitive body of a gas sensor capable of sensing at a relatively low temperature.
本発明は、
周期表の第７族〜第１１族に属する元素を含む金属、合金、酸化物、及び複合酸化物からなる群から選ばれる少なくとも１種でできた被担持体が、Ｙ、Ｃｅ、Ｔｉ、Ｚｒ、Ｎｂ、Ｆｅ、Ｚｎ、Ａｌ、及びＳｉからなる群から選ばれる少なくとも１つの元素の酸化物である金属酸化物担体に担持されて形成された複合体粒子と、
極性溶媒と、を含有する、
ガスセンサの感ガス体用組成物を提供する。
The present invention
The supported body made of at least one selected from the group consisting of metals, alloys, oxides, and composite oxides containing elements belonging to groups 7 to 11 of the periodic table is Y, Ce, Ti, Zr. , Nb, Fe, Zn, Al, and Si, and composite particles formed by being supported on a metal oxide carrier, which is an oxide of at least one element selected from the group.
Containing a polar solvent,
A composition for a gas sensitive body of a gas sensor is provided.
上記の感ガス体用組成物によれば、比較的低温でのセンシングが可能なガスセンサを提供できる。 According to the above composition for a gas sensor, it is possible to provide a gas sensor capable of sensing at a relatively low temperature.
以下、本発明の実施形態について説明する。なお、以下の説明は本発明の一例に関するものであり、本発明はこれによって限定されるものではない。 Hereinafter, embodiments of the present invention will be described. The following description relates to an example of the present invention, and the present invention is not limited thereto.
図１に示すように、ガスセンサ１００は、基板３０と、一対の電極２０と、感ガス体１０とを備えている。基板３０は電気的絶縁体によってできている。基板３０は、例えばガラス基板又はアルミナ基板である。一対の電極２０は、基板３０上に形成されている。例えば、一対の電極２０は、基板３０上において所定の間隔で形成されている。電極２０は、例えばＩＴＯ（Indium Tin Oxide）などの所定値（例えばシート抵抗１００Ω／□）以下の電気抵抗を有する材料でできている。一対の電極間の距離は、例えば５μｍ〜１００μｍである。感ガス体１０は、周期表の第７族〜第１１族に属する元素を含む金属、合金、酸化物、及び複合酸化物からなる群から選ばれる少なくとも１種でできた被担持体が金属酸化物担体に担持されて形成された複合体粒子の集合体によって形成されている。なお、本明細書において「金属酸化物」には、ケイ素の酸化物も含まれるものとする。感ガス体１０は、一対の電極２０を接続している。ガスセンサ１００が動作するとき、一対の電極２０は、図１に示すように、例えば電源２００に接続され、一対の電極２０に所定の電圧が印加される。ガスセンサ１００の感ガス体１０の電気的特性（電気抵抗）は、感ガス体１０に接触するガスに含まれる被検知ガスの濃度によって変化する。これにより、例えば、ガスセンサ１００は、検査対象のガスに被検知ガスが所定の濃度以上含まれるか否かをセンシングできる。 As shown in FIG. 1, the gas sensor 100 includes a substrate 30, a pair of electrodes 20, and a gas sensitive body 10. The substrate 30 is made of an electrical insulator. The substrate 30 is, for example, a glass substrate or an alumina substrate. The pair of electrodes 20 are formed on the substrate 30. For example, the pair of electrodes 20 are formed on the substrate 30 at predetermined intervals. The electrode 20 is made of a material having an electric resistance of a predetermined value (for example, sheet resistance 100Ω / □) or less, such as ITO (Indium Tin Oxide). The distance between the pair of electrodes is, for example, 5 μm to 100 μm. In the gas-sensitive body 10, a supported body made of at least one selected from the group consisting of metals, alloys, oxides, and composite oxides containing elements belonging to groups 7 to 11 of the periodic table is metal-oxidized. It is formed by an aggregate of complex particles formed by being supported on a material carrier. In addition, in this specification, "metal oxide" shall also include an oxide of silicon. The gas sensitive body 10 connects a pair of electrodes 20. When the gas sensor 100 operates, the pair of electrodes 20 are connected to, for example, the power supply 200, and a predetermined voltage is applied to the pair of electrodes 20 as shown in FIG. The electrical characteristics (electrical resistance) of the gas sensitive body 10 of the gas sensor 100 change depending on the concentration of the detected gas contained in the gas in contact with the gas sensitive body 10. Thereby, for example, the gas sensor 100 can sense whether or not the gas to be inspected contains the gas to be detected at a predetermined concentration or more.
感ガス体１０は、比較的低温（例えば、１００℃以下）でも被検知ガスに対する感応性を有する。このため、ガスセンサ１００によれば、比較的低温でのセンシングが可能である。 The gas sensitive body 10 is sensitive to the detected gas even at a relatively low temperature (for example, 100 ° C. or lower). Therefore, according to the gas sensor 100, sensing at a relatively low temperature is possible.
感ガス体１０は、本発明に係る感ガス体用組成物を用いて形成される。感ガス体用組成物は、複合体粒子と、極性溶媒と、を含有している。複合体粒子は、周期表の第７族〜第１１族に属する元素を含む金属、合金、酸化物、及び複合酸化物からなる群から選ばれる少なくとも１種でできた被担持体が、Ｙ、Ｃｅ、Ｔｉ、Ｚｒ、Ｎｂ、Ｆｅ、Ｚｎ、Ａｌ、及びＳｉからなる群から選ばれる少なくとも１つの元素の酸化物である金属酸化物担体に担持されて形成されている。これにより、感ガス体１０が比較的低温でも被検知ガスに対する感応性を有する。 The gas-sensitive body 10 is formed by using the composition for a gas-sensitive body according to the present invention. The composition for a gas-sensitive body contains composite particles and a polar solvent. The composite particle is a supported body made of at least one selected from the group consisting of metals, alloys, oxides, and composite oxides containing elements belonging to groups 7 to 11 of the periodic table. It is formed by being supported on a metal oxide carrier which is an oxide of at least one element selected from the group consisting of Ce, Ti, Zr, Nb, Fe, Zn, Al, and Si. As a result, the gas sensitive body 10 has sensitivity to the detected gas even at a relatively low temperature.
感ガス体用組成物において、複合体粒子のＢＥＴ比表面積は、例えば、３０ｍ2／ｇ以上である。これにより、複合体粒子の被担持体が高い活性を有しやすく、感ガス体１０は、比較的低温でより確実に被検知ガスに対して感応性を有する。また、これにより、感ガス体１０の基板３０及び電極２０への密着性を向上させることができる。複合体粒子のＢＥＴ比表面積は、望ましくは５０ｍ2／ｇ以上であり、より望ましくは７０ｍ2／ｇ以上であり、さらに望ましくは９０ｍ2／ｇ以上であり、とりわけ望ましくは１００ｍ2／ｇ以上である。 In the composition for a gas-sensitive body, the BET specific surface area of the composite particles is, for example, 30 m 2 / g or more. As a result, the supported body of the composite particles tends to have high activity, and the gas-sensitive body 10 is more reliably sensitive to the detected gas at a relatively low temperature. Further, this makes it possible to improve the adhesion of the gas sensitive body 10 to the substrate 30 and the electrode 20. The BET specific surface area of the composite particles is preferably 50 m 2 / g or more, more preferably 70 m 2 / g or more, still more preferably 90 m 2 / g or more, and particularly preferably 100 m 2 / g or more. is there.
基板３０及び電極２０への感ガス体１０の密着性を向上させる観点から、金属酸化物担体はロッド形状であることが望ましい。なぜなら、金属酸化物担体がロッド形状であると、複合体粒子同士が接触して絡まりやすくなることに加え、基板３０又は電極２０との接触比率も高まるからである。例えば、金属酸化物担体は、５〜３０ｎｍの短軸長さ、２０〜１０００ｎｍの長軸長さ、及び２〜２００のアスペクト比を有するロッド形状である。 From the viewpoint of improving the adhesion of the gas sensitive body 10 to the substrate 30 and the electrode 20, it is desirable that the metal oxide carrier has a rod shape. This is because when the metal oxide carrier has a rod shape, the composite particles are likely to come into contact with each other and become entangled with each other, and the contact ratio with the substrate 30 or the electrode 20 is also increased. For example, the metal oxide carrier has a rod shape with a minor axis length of 5 to 30 nm, a major axis length of 20 to 1000 nm, and an aspect ratio of 2 to 200.
例えば、被担持体に含まれる元素は、Ｒｕ（ルテニウム）、Ｒｈ（ロジウム）、Ｉｒ（イリジウム）、Ｐｄ（パラジウム）、Ｐｔ（白金）、Ａｇ（銀）、及びＡｕ（金）からなる群から選ばれる少なくとも１つの元素である。これにより、感ガス体１０は、比較的低温でより確実に被検知ガスに対して感応性を有する。 For example, the element contained in the supported body consists of a group consisting of Ru (ruthenium), Rh (rhodium), Ir (iridium), Pd (palladium), Pt (platinum), Ag (silver), and Au (gold). At least one element of choice. As a result, the gas-sensitive body 10 is more reliably sensitive to the detected gas at a relatively low temperature.
例えば、金属酸化物担体がγ−アルミナであり、ロッド形状を有する場合、金属酸化物担体の原料として、ベーマイトナノロッドの分散液を用いることができる。具体的に、５〜３０ｎｍの短軸長さ、２０〜１０００ｎｍの長軸長さ、及び２〜２００のアスペクト比を有するロッド形状であるベーマイトナノロッドの分散液を、金属酸化物担体の原料として用いることができる。このようなベーマイトナノロッドの分散液は、例えば、以下のような方法で調製できる。 For example, when the metal oxide carrier is γ-alumina and has a rod shape, a dispersion of boehmite nanorods can be used as a raw material for the metal oxide carrier. Specifically, a dispersion of boehmite nanorods having a minor axis length of 5 to 30 nm, a major axis length of 20 to 1000 nm, and an aspect ratio of 2 to 200 is used as a raw material for a metal oxide carrier. be able to. Such a dispersion of boehmite nanorods can be prepared, for example, by the following method.
まず、アルミニウムのカルボン酸塩又はアルミニウムのβ−ジケトン錯体と、水を含み、かつ、アルカリ金属元素及びアルカリ土類金属元素を実質的に含まない溶液を調製する。場合によっては、この溶液に酢酸などのカルボン酸を添加してもよい。次に、この溶液を１００℃〜３００℃の温度で水熱処理する。これにより、金属酸化物担体の原料としてのベーマイトナノロッドの分散液を得ることができる。このベーマイトナノロッドを２００℃〜６００℃で焼成すると、ナノロッドの形状が維持されたまま水が抜けて、５〜３０ｎｍの短軸長さ、２０〜１０００ｎｍの長軸長さ、及び２〜２００のアスペクト比を有するロッド形状である、γ−アルミナのナノロッドが得られる。 First, a solution containing an aluminum carboxylate or an aluminum β-diketone complex and water and substantially free of alkali metal elements and alkaline earth metal elements is prepared. In some cases, a carboxylic acid such as acetic acid may be added to this solution. Next, this solution is hydrothermally treated at a temperature of 100 ° C. to 300 ° C. As a result, a dispersion of boehmite nanorods as a raw material for the metal oxide carrier can be obtained. When this boehmite nanorod is fired at 200 ° C. to 600 ° C., water drains while maintaining the shape of the nanorod, a minor axis length of 5 to 30 nm, a major axis length of 20 to 1000 nm, and an aspect ratio of 2 to 200. A γ-alumina nanorod having a ratio and a rod shape can be obtained.
例えば、金属酸化物担体に担持されている被担持体の結晶子径は３０ｎｍ以下である。これにより、複合体粒子のＢＥＴ比表面積が高まる。また、被担持体が凝集し過ぎずに金属酸化物担体に担持されるので、被担持体の活性が高まる。このため、感ガス体１０は、比較的低温でより確実に被検知ガスに対して感応性を有する。被担持体の結晶子径は、望ましくは２０ｎｍ以下であり、より望ましくは１５ｎｍ以下であり、さらに望ましくは１０ｎｍ以下である。金属酸化物担体に担持されている被担持体の結晶子径の下限値は、特に制限されないが、例えば０．５ｎｍである。結晶子径は、シェラー法などの公知の分析方法を用いて測定できる。 For example, the crystallite diameter of the supported body supported on the metal oxide carrier is 30 nm or less. This increases the BET specific surface area of the composite particles. Further, since the supported body is supported on the metal oxide carrier without being excessively aggregated, the activity of the supported body is enhanced. Therefore, the gas-sensitive body 10 is more reliably sensitive to the detected gas at a relatively low temperature. The crystallite diameter of the carrier is preferably 20 nm or less, more preferably 15 nm or less, and even more preferably 10 nm or less. The lower limit of the crystallite diameter of the supported body supported on the metal oxide carrier is not particularly limited, but is, for example, 0.5 nm. The crystallite diameter can be measured by using a known analytical method such as the Scheller method.
被担持体の金属酸化物担体への担持量は、特に制限されないが、感ガス体１０の被検知ガスへの感応性を高めるために被担持体の担持量は多い方がよい。他方、被担持体の分散性を高め、活性に寄与しない被担持体の量の増加を防止する観点から、被担持体の金属酸化物担体への担持量は所定値以下であることが望ましい。このため、複合体粒子における被担持体の担持率は、例えば、０．５質量％以上６０質量％以下であり、望ましくは１質量％以上５０質量％以下であり、より望ましくは、２質量％以上４０質量％以下であり、さらに望ましくは３質量％以上３０質量％以下であり、とりわけ望ましくは４質量％以上２０質量％以下である。ここで、複合体粒子における被担持体の担持率は、複合体粒子の質量と金属酸化物担体に担持されている被担持体の質量との割合と定義される。 The amount of the supported body supported on the metal oxide carrier is not particularly limited, but the amount of the supported body supported is preferably large in order to enhance the sensitivity of the gas-sensitive body 10 to the detected gas. On the other hand, from the viewpoint of enhancing the dispersibility of the supported body and preventing an increase in the amount of the supported body that does not contribute to the activity, it is desirable that the amount of the supported body supported on the metal oxide carrier is a predetermined value or less. Therefore, the carrying ratio of the supported body in the composite particles is, for example, 0.5% by mass or more and 60% by mass or less, preferably 1% by mass or more and 50% by mass or less, and more preferably 2% by mass. It is 40% by mass or more, more preferably 3% by mass or more and 30% by mass or less, and particularly preferably 4% by mass or more and 20% by mass or less. Here, the loading ratio of the supported body in the composite particles is defined as the ratio of the mass of the composite particles to the mass of the supported body supported on the metal oxide carrier.
感ガス体用組成物は、例えば２０ｎｍ以下の結晶子径を有するベーマイト粒子をさらに含有する。これにより、感ガス体用組成物を基板３０及び電極２０に塗布して形成された感ガス体１０の基板３０及び電極２０への密着性が向上する。すなわち、ベーマイト粒子が、感ガス体用組成物においてバインダー成分として望ましい特性を発揮する。ベーマイト粒子の結晶子径は、望ましくは３０ｎｍ以下であり、より望ましくは２０ｎｍ以下である。ベーマイト粒子の結晶子径の下限値は、例えば、０．５ｎｍである。特に、金属酸化物担体がアルミナでできている場合、金属酸化物担体とベーマイト粒子との親和性が高く、感ガス体１０において複合体粒子同士の密着性が高い。これにより、感ガス体１０の基板３０及び電極２０への密着性が向上するとともに、複合体粒子同士のつながりによるネットワークがより容易に形成される。その結果、ガスセンサ１００の性能が高まる。 The composition for a gas-sensitive body further contains boehmite particles having a crystallite diameter of, for example, 20 nm or less. As a result, the adhesion of the gas-sensitive body 10 formed by applying the gas-sensitive composition to the substrate 30 and the electrode 20 to the substrate 30 and the electrode 20 is improved. That is, the boehmite particles exhibit desirable properties as a binder component in the composition for a gas-sensitive body. The crystallite diameter of the boehmite particles is preferably 30 nm or less, more preferably 20 nm or less. The lower limit of the crystallite diameter of the boehmite particles is, for example, 0.5 nm. In particular, when the metal oxide carrier is made of alumina, the metal oxide carrier and the boehmite particles have a high affinity, and the gas-sensitive body 10 has a high adhesion between the composite particles. As a result, the adhesion of the gas-sensitive body 10 to the substrate 30 and the electrode 20 is improved, and a network is more easily formed by connecting the composite particles. As a result, the performance of the gas sensor 100 is improved.
感ガス体用組成物における複合体粒子の質量Ｗｃに対するベーマイト粒子の質量Ｗｂの比Ｗｂ／Ｗｃは特に制限されない。ベーマイト粒子は基板３０及び電極２０に対する感ガス体１０の密着性を向上させるので、ベーマイト粒子は、感ガス体１０において所定の割合以上で含まれていることが望ましい。この観点から、感ガス体用組成物における、Ｗｂ／Ｗｃは、例えば、０．０１以上であり、望ましくは０．０２以上であり、より望ましくは０．０５以上である。また、被担持体の活性を確保するためには、ベーマイト粒子が感ガス体用組成物において所定の割合以下で含まれていることが望ましい。この観点から、Ｗｂ／Ｗｃは、例えば、１以下であり、望ましくは０．５以下であり、より望ましくは０．３以下である。 The ratio Wb / Wc of the mass Wb of the boehmite particles to the mass Wc of the composite particles in the composition for a gas-sensitive body is not particularly limited. Since the boehmite particles improve the adhesion of the gas sensitive body 10 to the substrate 30 and the electrode 20, it is desirable that the boehmite particles are contained in the gas sensitive body 10 in a predetermined ratio or more. From this point of view, the Wb / Wc in the gas-sensitive composition is, for example, 0.01 or more, preferably 0.02 or more, and more preferably 0.05 or more. Further, in order to secure the activity of the supported body, it is desirable that the boehmite particles are contained in the composition for the gas-sensitive body in a predetermined ratio or less. From this point of view, Wb / Wc is, for example, 1 or less, preferably 0.5 or less, and more preferably 0.3 or less.
感ガス体組成物によって形成された感ガス体１０は、例えば、有機ガスの吸着によって電気抵抗が変化する。すなわち、感ガス体１０は、有機ガスに対して感応性を有する。有機ガスは、例えばアセトンである。 The electric resistance of the gas-sensitive body 10 formed by the gas-sensitive body composition changes, for example, due to the adsorption of organic gas. That is, the gas-sensitive body 10 is sensitive to organic gas. The organic gas is, for example, acetone.
感ガス体用組成物に含有される極性溶媒は、複合体粒子を分散させることができる限り特に限定されない。極性溶媒は、例えば、水又はアルコール類である。極性溶媒としては、水、メタノール、エタノール、ｎ−プロパノール、イソプロパノール、ｎ−ブチルアルコール、ｔｅｒｔ−ブチルアルコール、ｎ−ペンチルアルコール、ｎ−ヘキシルアルコール、ｎ−ヘプチルアルコール、ｎ−オクチルアルコール、ｎ−ノニルアルコール、１−デカノール、１−ドデカノール、２−エチルヘキサノール、フェノール、ベンジルアルコール、エチレングリコール、プロピレングリコール、ジエチレングリコール、ジメチルセロソルブ、エチルセロソルブ、プロピルセロソルブ、ブチルセロソルブ、フェニルセロソルブ、グリセリン、及びテルピネオールを例示できる。 The polar solvent contained in the composition for a gas-sensitive body is not particularly limited as long as the composite particles can be dispersed. The polar solvent is, for example, water or alcohols. Polar solvents include water, methanol, ethanol, n-propanol, isopropanol, n-butyl alcohol, tert-butyl alcohol, n-pentyl alcohol, n-hexyl alcohol, n-heptyl alcohol, n-octyl alcohol, n-nonyl. Examples thereof include alcohol, 1-decanol, 1-dodecanol, 2-ethylhexanol, phenol, benzyl alcohol, ethylene glycol, propylene glycol, diethylene glycol, dimethyl cellosolve, ethyl cellosolve, propyl cellosolve, butyl cellosolve, phenyl cellosolve, glycerin, and terpineol.
感ガス体用組成物の製造方法の一例について説明する。まず、金属酸化物担体若しくは金属酸化物担体の前駆物質の粉体、又は、これらが分散された分散液を準備し、これを、被担持体の分散液又は被担持体に含まれる元素の金属塩の溶液と混合する。この混合液から溶媒を除去して固形物を得る。被担持体の分散液としては、例えば、ポリビニルピロリドン（ＰＶＰ）、ポリエチレンイミン（ＰＥＩ）、若しくはポリアクリル酸（ＰＡＡ）等の高分子又はテトラメチルアンモニウム（ＴＭＡ）等の分散剤によって被担持体の粒子が安定的に分散しているコロイド液を用いることができる。また、被担持体に含まれる元素の金属塩の溶液としては、被担持体に含まれる元素の有機塩又は無機塩の溶液を用いることができる。複合体粒子において被担持体の結晶子径を小さくして感ガス体１０の感応性を高めるためには、被担持体のコロイド液を用いることが望ましい。また、被担持体に含まれる元素の金属塩の溶液を用いる場合でも、複合体粒子において被担持体の結晶子径を小さくして感ガス体１０の感応性を高めるために、塩素などのハロゲン元素を含まない金属塩を用いることが望ましく、特に金属塩が有機塩である溶液を用いることが望ましい。 An example of a method for producing a composition for a gas-sensitive body will be described. First, a powder of a metal oxide carrier or a precursor of a metal oxide carrier, or a dispersion in which these are dispersed is prepared, and this is used as a dispersion of a carrier or a metal of an element contained in the carrier. Mix with a solution of salt. The solvent is removed from this mixture to obtain a solid. As the dispersion liquid of the supported body, for example, a polymer such as polyvinylpyrrolidone (PVP), polyethyleneimine (PEI), or polyacrylic acid (PAA) or a dispersant such as tetramethylammonium (TMA) may be used as the dispersion liquid of the supported body. A colloidal solution in which particles are stably dispersed can be used. Further, as the solution of the metal salt of the element contained in the supported body, a solution of the organic salt or the inorganic salt of the element contained in the supported body can be used. In order to reduce the crystallite diameter of the supported body and enhance the sensitivity of the gas-sensitive body 10 in the composite particles, it is desirable to use a colloidal solution of the supported body. Further, even when a solution of a metal salt of an element contained in the supported body is used, a halogen such as chlorine is used in order to reduce the crystallite diameter of the supported body and enhance the sensitivity of the gas-sensitive body 10 in the composite particles. It is desirable to use a metal salt containing no element, and it is particularly desirable to use a solution in which the metal salt is an organic salt.
次に、上記のようにして得られた固形物を焼成し、粉砕する。これにより、複合体粒子の粉体が得られる。固形物の焼成温度及び焼成時間は特に限定されない。焼成温度は、例えば、２００〜６００℃であり、焼成時間は、例えば、０．１時間〜５時間である。 Next, the solid matter obtained as described above is calcined and pulverized. As a result, a powder of the composite particles is obtained. The firing temperature and firing time of the solid material are not particularly limited. The firing temperature is, for example, 200 to 600 ° C., and the firing time is, for example, 0.1 hour to 5 hours.
次に、複合体粒子の粉体を極性溶媒に添加し分散処理する。これにより、感ガス体用組成物が得られる。感ガス体用組成物がベーマイト粒子をさらに含有している場合、複合体粒子の粉体及びベーマイト粒子が分散されたゾル液を極性溶媒に添加し分散処理してもよい。これにより、ベーマイト粒子が含有された、感ガス体用組成物を得ることができる。複合体粒子を極性溶媒に分散させるための分散処理は、特に制限されないが、例えば、ペイントシェーカーなどの分散機によって行うことができる。この場合、分散処理において、複合体粒子の粉体、極性溶媒、及び必要に応じてベーマイト粒子が分散されたゾル液を含む混合液に、ジルコニアビーズが加えられてもよい。分散処理の時間は、特に制限されないが、例えば５分間〜２００分間である。なお、ベーマイト粒子が極性溶媒に分散されたゾル液の使用に代えて、複合体粒子の粉体及びベーマイト粒子の粉体を極性溶媒に添加した後に、攪拌によって複合体粒子の粉体及びベーマイト粒子の粉体を極性溶媒に分散させて感ガス体用組成物を得てもよい。 Next, the powder of the composite particles is added to the polar solvent for dispersion treatment. As a result, a composition for a gas-sensitive body can be obtained. When the composition for a gas-sensitive body further contains boehmite particles, the powder of the composite particles and the sol solution in which the boehmite particles are dispersed may be added to the polar solvent for dispersion treatment. Thereby, a composition for a gas-sensitive body containing boehmite particles can be obtained. The dispersion treatment for dispersing the composite particles in the polar solvent is not particularly limited, and can be performed by, for example, a disperser such as a paint shaker. In this case, in the dispersion treatment, the zirconia beads may be added to the mixed solution containing the powder of the complex particles, the polar solvent, and, if necessary, the sol solution in which the boehmite particles are dispersed. The time of the dispersion treatment is not particularly limited, but is, for example, 5 minutes to 200 minutes. Instead of using a sol solution in which boehmite particles are dispersed in a polar solvent, the powder of the composite particles and the powder of boehmite particles are added to the polar solvent, and then the powder of the composite particles and the boehmite particles are stirred. The powder of the above may be dispersed in a polar solvent to obtain a composition for a gas-sensitive body.
次に、ガスセンサ１００の製造方法の一例について説明する。まず、基板３０上に一対の電極２０を形成する。基板３０上に一対の電極２０を形成する方法は、特に制限されない。例えば、基板３０がガラス基板であり、電極２０がＩＴＯでできている場合、ＩＴＯ膜付ガラス基板に対してフォトリソグラフィ及びエッチングを施すことによって、基板３０上に一対の電極２０を所定の間隔で形成できる。この場合、フォトリソグラフィ及びエッチングとしては、ＩＴＯのパターニングに用いられる公知の方法を利用できる。この他、所定値以上の電気導電率を有する成分を含有するインクを用いてインクジェット法により、基板３０上に一対の電極２０を所定の間隔で形成してもよい。 Next, an example of a method for manufacturing the gas sensor 100 will be described. First, a pair of electrodes 20 are formed on the substrate 30. The method of forming the pair of electrodes 20 on the substrate 30 is not particularly limited. For example, when the substrate 30 is a glass substrate and the electrodes 20 are made of ITO, a pair of electrodes 20 are placed on the substrate 30 at predetermined intervals by performing photolithography and etching on the glass substrate with an ITO film. Can be formed. In this case, known methods used for patterning ITO can be used for photolithography and etching. In addition, a pair of electrodes 20 may be formed on the substrate 30 at predetermined intervals by an inkjet method using an ink containing a component having an electric conductivity equal to or higher than a predetermined value.
次に、一対の電極２０のそれぞれの少なくとも一部及び一対の電極２０間の基板３０の上にひとかたまりの感ガス体用組成物を塗布する。感ガス体用組成物を塗布する方法は特に制限されないが、例えば、ドロップキャスト法を用いて感ガス体用組成物を一対の電極２０及び基板３０に塗布するとよい。この場合、感ガス体１０の厚みが大きくなりやすく、ガスセンサ１００の性能を向上させやすい。次に、塗布した感ガス体用組成物を所定の温度で焼成する。これにより、感ガス体１０を形成できる。感ガス体用組成物を焼成する温度は、例えば１５０℃〜６５０℃であり、感ガス体用組成物を焼成する時間は、例えば０．１時間〜３時間である。このようにして、ガスセンサ１００を製造できる。 Next, a mass of the composition for a gas-sensitive body is applied onto at least a part of each of the pair of electrodes 20 and the substrate 30 between the pair of electrodes 20. The method for applying the gas-sensitive composition is not particularly limited, but for example, the gas-sensitive composition may be applied to the pair of electrodes 20 and the substrate 30 by using the drop casting method. In this case, the thickness of the gas sensitive body 10 tends to increase, and the performance of the gas sensor 100 tends to be improved. Next, the applied composition for a gas-sensitive body is fired at a predetermined temperature. As a result, the gas sensitive body 10 can be formed. The temperature for firing the composition for a gas-sensitive body is, for example, 150 ° C. to 650 ° C., and the time for firing the composition for a gas-sensitive body is, for example, 0.1 hour to 3 hours. In this way, the gas sensor 100 can be manufactured.
以下に、実施例を用いて本発明を詳細に説明する。なお、以下の実施例は本発明の一例であり、本発明は以下の実施例に限定されない。 Hereinafter, the present invention will be described in detail with reference to examples. The following examples are examples of the present invention, and the present invention is not limited to the following examples.
＜実施例１＞
塩基性の酢酸アルミニウム（シグマアルドリッチ社製）２２．６ｇ及び酢酸（和光純薬工業社製）１．２ｇを水５６０ｇに添加して溶液を調製した。この溶液をオートクレーブに入れて、２００℃で２４時間の水熱処理を行った。その後、オートクレーブを室温まで冷却し、反応溶液をオートクレーブから取り出した。この反応溶液の一部を乾燥させて乾燥物を得た。図２は、この乾燥物をＦＥ−ＳＥＭ（電界放射型走査電子顕微鏡）で観察した写真である。図３は、この乾燥物のＸＲＤ（Ｘ線回折）による測定結果を示す。図２及び図３に示す結果から、この乾燥物は、ベーマイトナノロッドの集合体であることが確認された。また、この乾燥物を５５０℃で１時間焼成することによって白色の粉体が得られた。この白色の粉体に対し、ＸＲＤ（Ｘ線回折）による測定を行ったところ、γ−アルミナの回折ピークが認められた。また、この白色の粉体を透過型電子顕微鏡によって観察したところ、５〜３０ｎｍの短軸長さ、２０〜１０００ｎｍの長軸長さ、及び２〜２００のアスペクト比を有するロッド形状を有していた。
<Example 1>
A solution was prepared by adding 22.6 g of basic aluminum acetate (manufactured by Sigma-Aldrich) and 1.2 g of acetic acid (manufactured by Wako Pure Chemical Industries, Ltd.) to 560 g of water. This solution was placed in an autoclave and hydrothermally treated at 200 ° C. for 24 hours. The autoclave was then cooled to room temperature and the reaction solution was removed from the autoclave. A part of this reaction solution was dried to obtain a dried product. FIG. 2 is a photograph of this dried product observed with an FE-SEM (field emission scanning electron microscope). FIG. 3 shows the measurement result by XRD (X-ray diffraction) of this dried product. From the results shown in FIGS. 2 and 3, it was confirmed that this dried product was an aggregate of boehmite nanorods. Further, the dried product was calcined at 550 ° C. for 1 hour to obtain a white powder. When this white powder was measured by XRD (X-ray diffraction), a diffraction peak of γ-alumina was observed. Further, when this white powder was observed with a transmission electron microscope, it had a rod shape having a minor axis length of 5 to 30 nm, a major axis length of 20 to 1000 nm, and an aspect ratio of 2 to 200. It was.
上記の反応溶液の半量にＰｔＰＶＰコロイド水溶液（田中貴金属工業社製、Ｐｔ含有量：４．０ｗｔ％）９．８７ｇを投入して混合した。その後、この混合液を、ロータリーエバポレーターによって減圧した１００℃の環境に置いて、この混合液から溶媒を除去して固形物を得た。次に、得られた固形物を５５０℃の温度の空気雰囲気で１時間焼成した後粉砕し、複合体粒子Ａを得た。この複合体粒子ＡにおけるＰｔの担持率は１０質量％であった。図４は、複合体粒子ＡのＸＲＤによる測定結果を示す。図４に示す通り、Ｐｔの回折ピーク及びγ−アルミナの回折ピークが認められた。２θ＝３９．８°付近のＰｔ（１１１）面の回折ピークからＰｔの結晶子径を算出したところ、Ｐｔの結晶子径は、４．７ｎｍであった。また、複合体粒子ＡのＢＥＴ比表面積は、１０９ｍ2／ｇであった。 9.87 g of a PtPVP colloidal aqueous solution (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., Pt content: 4.0 wt%) was added to half of the above reaction solution and mixed. Then, the mixed solution was placed in an environment of 100 ° C. under reduced pressure by a rotary evaporator, and the solvent was removed from the mixed solution to obtain a solid substance. Next, the obtained solid matter was calcined in an air atmosphere at a temperature of 550 ° C. for 1 hour and then pulverized to obtain composite particles A. The loading ratio of Pt in the composite particles A was 10% by mass. FIG. 4 shows the measurement result of the complex particle A by XRD. As shown in FIG. 4, a diffraction peak of Pt and a diffraction peak of γ-alumina were observed. When the crystallite diameter of Pt was calculated from the diffraction peak of the Pt (111) plane near 2θ = 39.8 °, the crystallite diameter of Pt was 4.7 nm. The BET specific surface area of the composite particles A was 109 m 2 / g.
複合体粒子Ａ５．０ｇ、ベーマイト粒子のゾル液（日産化学工業社製、アルミナ含有量：２０重量％、商品名：アルミナゾル５２０）１．５ｇ、及びプロピレングリコール４５．０ｇと、直径１ｍｍのジルコニアビーズとをガラス容器に入れて、ペイントシェーカーによって２時間分散処理を行った。その後、ろ過によりジルコニアビーズを分離し、実施例１に係る感ガス体用組成物を得た。実施例１に係る感ガス体用組成物において、ベーマイトの質量と複合体粒子Ａの質量との比（ベーマイトの質量／複合体粒子Ａの質量）は、０．０７であった。図５は、少量のアルミナゾル５２０を乾燥して得られた固形物のＸＲＤによる測定結果を示す。図５に示す通り、この固形物はベーマイト（ＡｌＯ（ＯＨ））であることが確認された。アルミナゾル５２０は、２３．５質量％のベーマイト粒子を含有する分散液であることが確認された。図５の２θ＝３８．３°付近の回折ピークから算出されるベーマイト粒子の結晶子径は１１．８ｎｍであった。 Composite particles A 5.0 g, boehmite particle sol solution (manufactured by Nissan Chemical Industries, Ltd., alumina content: 20% by weight, trade name: alumina sol 520) 1.5 g, propylene glycol 45.0 g, and zirconia beads having a diameter of 1 mm. The particles were placed in a glass container and dispersed with a paint shaker for 2 hours. Then, the zirconia beads were separated by filtration to obtain the composition for a gas-sensitive body according to Example 1. In the gas-sensitive composition according to Example 1, the ratio of the mass of boehmite to the mass of the composite particles A (mass of boehmite / mass of composite particles A) was 0.07. FIG. 5 shows the measurement result by XRD of the solid matter obtained by drying a small amount of alumina sol 520. As shown in FIG. 5, it was confirmed that this solid matter was boehmite (AlO (OH)). It was confirmed that the alumina sol 520 was a dispersion containing 23.5% by mass of boehmite particles. The crystallite diameter of the boehmite particles calculated from the diffraction peak near 2θ = 38.3 ° in FIG. 5 was 11.8 nm.
ＩＴＯ膜付ガラス基板（ＩＴＯ膜の厚み：０．２μｍ、ガラス基板の厚み：０．７ｍｍ）に対してフォトリソグラフィ及びエッチングを行って、電極間の距離が１０μｍである、ＩＴＯでできた一対の電極をガラス基板上に形成した。電極の幅は２ｍｍであった。次に、一対の電極間のギャップ上から実施例１に係る感ガス体用組成物を約１μＬ滴下し、その後、感ガス体用組成物を２００℃で１時間又は５００℃で１時間の条件で焼成した。このようにして、実施例１に係るガスセンサを得た。 A pair of ITO films with an ITO film (ITO film thickness: 0.2 μm, glass substrate thickness: 0.7 mm) subjected to photolithography and etching, and the distance between the electrodes is 10 μm. The electrodes were formed on a glass substrate. The width of the electrode was 2 mm. Next, about 1 μL of the gas-sensitive composition according to Example 1 was dropped from the gap between the pair of electrodes, and then the gas-sensitive composition was added under the conditions of 200 ° C. for 1 hour or 500 ° C. for 1 hour. It was fired in. In this way, the gas sensor according to Example 1 was obtained.
＜実施例２＞
複合体粒子Ａ５．０ｇ、ベーマイト粒子のゾル液（日産化学工業社製、アルミナ含有量：１０重量％、商品名：アルミナゾル２００）３．０ｇ、及びエチレングリコール４５．０ｇと、直径１ｍｍのジルコニアビーズとをガラス容器に入れて、ペイントシェーカーによって２時間分散処理を行った。その後、ろ過によりジルコニアビーズを分離し、実施例２に係る感ガス体用組成物を得た。実施例２に係る感ガス体用組成物において、ベーマイトの質量と複合体粒子Ａの質量との比（ベーマイトの質量／複合体粒子Ａの質量）は、０．０７であった。図６は、少量のアルミナゾル２００を乾燥して得られた固形物のＸＲＤによる測定結果を示す。図６に示す通り、この固形物はベーマイト（ＡｌＯ（ＯＨ））であることが確認された。アルミナゾル２００は、１１．８質量％のベーマイト粒子を含有する分散液であることが確認された。図６の２θ＝３８．５°付近の回折ピークから算出されるベーマイト粒子の結晶子径は３．６ｎｍであった。
<Example 2>
Composite particle A 5.0 g, boehmite particle sol solution (manufactured by Nissan Chemical Industries, Ltd., alumina content: 10% by weight, trade name: alumina sol 200) 3.0 g, ethylene glycol 45.0 g, and zirconia beads having a diameter of 1 mm. The particles were placed in a glass container and dispersed with a paint shaker for 2 hours. Then, the zirconia beads were separated by filtration to obtain the composition for a gas-sensitive body according to Example 2. In the gas-sensitive composition according to Example 2, the ratio of the mass of boehmite to the mass of the composite particles A (mass of boehmite / mass of composite particles A) was 0.07. FIG. 6 shows the measurement result by XRD of the solid matter obtained by drying a small amount of alumina sol 200. As shown in FIG. 6, it was confirmed that this solid matter was boehmite (AlO (OH)). It was confirmed that the alumina sol 200 was a dispersion liquid containing 11.8% by mass of boehmite particles. The crystallite diameter of the boehmite particles calculated from the diffraction peak near 2θ = 38.5 ° in FIG. 6 was 3.6 nm.
ＩＴＯ膜付ガラス基板（ＩＴＯ膜の厚み：０．２μｍ、ガラス基板の厚み：０．７ｍｍ、拡散防止用のＳｉＯ2コート（厚さ約０．１μｍ）あり）に対してフォトリソグラフィ及びエッチングを行って、電極間の距離がそれぞれ１０μｍ、２０μｍ、及び３０μｍである、ＩＴＯでできた複数対の電極をガラス基板上に形成した。電極の幅は２ｍｍであった。次に、複数対の電極のそれぞれの電極間のギャップ上から実施例２に係る感ガス体用組成物を約１μＬ滴下し、その後、感ガス体用組成物を５００℃で１時間の条件で焼成した。このようにして、実施例２に係るガスセンサを得た。 Photolithography and etching are performed on a glass substrate with an ITO film (IT film thickness: 0.2 μm, glass substrate thickness: 0.7 mm, SiO 2 coating for diffusion prevention (thickness: about 0.1 μm)). Therefore, a plurality of pairs of electrodes made of ITO having a distance between the electrodes of 10 μm, 20 μm, and 30 μm, respectively, were formed on the glass substrate. The width of the electrode was 2 mm. Next, about 1 μL of the gas-sensitive composition according to Example 2 was dropped from the gap between the electrodes of the plurality of pairs of electrodes, and then the gas-sensitive composition was added at 500 ° C. for 1 hour. It was fired. In this way, the gas sensor according to the second embodiment was obtained.
＜ガスセンサの性能測定＞
（測定装置及び測定方法）
図７に示す測定装置９を用いて、実施例１に係るガスセンサ及び実施例２に係るガスセンサの性能を測定した。測定装置９は、容器１、ピコアンメータ２、コンピュータ３、温度調節器４、バブリング装置５、第一マスフローコントローラ６ａ、第二マスフローコントローラ６ｂ、窒素ガスタンク７、ストップバルブ８ａ、及びストップバルブ８ｂを備えていた。容器１の内部空間の容積は５１ｃｍ3であった。容器１の蓋１ａに実施例１又は２に係るガスセンサＳａを固定した後、蓋１ａで本体１ｂを覆った。ガスセンサＳａの一対の電極はそれぞれピコアンメータ２に接続され、ガスセンサＳａの一対の電極に所定の電圧が印加されたときにガスセンサＳａの一対の電極の間に流れる電流値がピコアンメータ２によって測定された。ピコアンメータ２による電流値の測定結果は、ピコアンメータ２と通信可能に接続されたコンピュータ３に出力された。
<Gas sensor performance measurement>
(Measuring device and measuring method)
Using the measuring device 9 shown in FIG. 7, the performances of the gas sensor according to the first embodiment and the gas sensor according to the second embodiment were measured. The measuring device 9 includes a container 1, a pico ammeter 2, a computer 3, a temperature controller 4, a bubbling device 5, a first mass flow controller 6a, a second mass flow controller 6b, a nitrogen gas tank 7, a stop valve 8a, and a stop valve 8b. Was there. The volume of the internal space of the container 1 was 51 cm 3 . After fixing the gas sensor Sa according to Example 1 or 2 to the lid 1a of the container 1, the main body 1b was covered with the lid 1a. Each pair of electrodes of the gas sensor Sa is connected to the picoammeter 2, and the current value flowing between the pair of electrodes of the gas sensor Sa is measured by the picoammeter 2 when a predetermined voltage is applied to the pair of electrodes of the gas sensor Sa. It was. The measurement result of the current value by the pico ammeter 2 was output to the computer 3 communicatively connected to the pico ammeter 2.
ガスセンサＳａの一対の電極に所定の電圧が印加されているときに、窒素ガスタンク７から容器１の内部空間に窒素ガスが供給された。このとき、温度調節器４によって容器１の内部空間の温度が所定の温度に調節された。窒素ガスタンク７から排出された窒素ガスの全部または一部は、バブリング装置５を経由せずに容器１の内部空間に直接供給された。第一マスフローコントローラ６ａ及びストップバルブ８ａによって、バブリング装置５を経由せずに容器１の内部空間に直接供給される窒素ガスの流量が調整された。一方、窒素ガスタンク７から排出された窒素ガスの一部は、バブリング装置５の内部に貯留された所定の液体に吹き込まれたうえで、容器１の内部空間に供給された。これにより、バブリング装置５に貯留された液体に由来する窒素ガス以外のガスが窒素ガスとともに容器１の内部空間に供給された。第二マスフローコントローラ６ｂ及びストップバルブ８ｂによって、バブリング装置５の内部に貯留された所定の液体に吹き込まれる窒素ガスの流量（バブリング量）が調整された。なお、第一マスフローコントローラ６ａ及び第二マスフローコントローラ６ｂはそれぞれ、制御用電源（図示省略）に接続されていた。 When a predetermined voltage was applied to the pair of electrodes of the gas sensor Sa, nitrogen gas was supplied from the nitrogen gas tank 7 to the internal space of the container 1. At this time, the temperature of the internal space of the container 1 was adjusted to a predetermined temperature by the temperature controller 4. All or part of the nitrogen gas discharged from the nitrogen gas tank 7 was directly supplied to the internal space of the container 1 without passing through the bubbling device 5. The flow rate of nitrogen gas directly supplied to the internal space of the container 1 was adjusted by the first mass flow controller 6a and the stop valve 8a without passing through the bubbling device 5. On the other hand, a part of the nitrogen gas discharged from the nitrogen gas tank 7 was blown into a predetermined liquid stored in the bubbling device 5 and then supplied to the internal space of the container 1. As a result, a gas other than the nitrogen gas derived from the liquid stored in the bubbling device 5 was supplied to the internal space of the container 1 together with the nitrogen gas. The flow rate (bubbling amount) of the nitrogen gas blown into the predetermined liquid stored inside the bubbling device 5 was adjusted by the second mass flow controller 6b and the stop valve 8b. The first mass flow controller 6a and the second mass flow controller 6b were each connected to a control power supply (not shown).
（測定例１）
２００ｍｌ／分の窒素ガスを窒素ガスタンク７から容器１の内部空間に供給しながら、実施例１に係るガスセンサ（感ガス体用組成物の焼成温度：５００℃）の性能を測定装置９によって測定した。バブリング装置５の内部に所定量のアセトンを貯留し、２００ｍｌ／分の窒素ガスのうち、図８の下方のグラフに示す流量の窒素ガスをバブリング装置５に貯留されたアセトンに断続的に吹き込んだ。バブリング量は、２０ｍｌ／分、４０ｍｌ／分、６０ｍｌ／分、８０ｍｌ／分、及び１００ｍｌ／分と、段階的に増加させた。一対の電極間の電圧は１００Ｖに設定した。容器１の内部空間の温度を温度調節器４によってそれぞれ３０℃、５０℃、及び７０℃に調節した場合のそれぞれについてガスセンサの性能を測定した。図８の上方のグラフは、ピコアンメータ２によって測定された一対の電極間の電流値の時間的変化を示す。図８に示すように、容器１の内部空間に供給されるべき窒素ガスの一部がアセトンに吹き込まれたのに同期して、一対の電極間の電流値が増加した。このため、実施例１に係るガスセンサの感ガス体は、３０℃、５０℃、及び７０℃において、検査対象ガスに含まれるアセトンに対して感応性を有することが示唆された。また、バブリング量が増えるに従って一対の電極間の電流値の増加幅が大きくなった。
(Measurement example 1)
While supplying 200 ml / min of nitrogen gas from the nitrogen gas tank 7 to the internal space of the container 1, the performance of the gas sensor (firing temperature of the composition for a gas sensitive body: 500 ° C.) according to Example 1 was measured by the measuring device 9. .. A predetermined amount of acetone was stored inside the bubbling device 5, and out of 200 ml / min of nitrogen gas, the flow rate of nitrogen gas shown in the lower graph of FIG. 8 was intermittently blown into the acetone stored in the bubbling device 5. .. The bubbling amount was gradually increased to 20 ml / min, 40 ml / min, 60 ml / min, 80 ml / min, and 100 ml / min. The voltage between the pair of electrodes was set to 100V. The performance of the gas sensor was measured when the temperature of the internal space of the container 1 was adjusted to 30 ° C., 50 ° C., and 70 ° C. by the temperature controller 4, respectively. The upper graph of FIG. 8 shows the temporal change of the current value between the pair of electrodes measured by the picoammeter 2. As shown in FIG. 8, the current value between the pair of electrodes increased in synchronization with a part of the nitrogen gas to be supplied to the internal space of the container 1 being blown into acetone. Therefore, it was suggested that the gas-sensitive body of the gas sensor according to Example 1 is sensitive to acetone contained in the gas to be inspected at 30 ° C., 50 ° C., and 70 ° C. Further, as the bubbling amount increased, the increase width of the current value between the pair of electrodes increased.
（測定例２）
感ガス体用組成物の焼成温度が２００℃である実施例１に係るガスセンサを用いた以外は、測定例１と同様にしてガスセンサの性能を測定した。測定結果を図９に示す。図９の上方のグラフは、ピコアンメータ２によって測定された一対の電極間の電流値の時間的変化を示し、図９の下方のグラフは、バブリング量の時間的変化を示す。この場合も、容器１の内部空間に供給されるべき窒素ガスの一部がアセトンに吹き込まれたのに同期して、一対の電極間の電流値が増加した。このため、感ガス体用組成物の焼成温度が２００℃である実施例１に係るガスセンサの感ガス体は、３０℃、５０℃、及び７０℃において、検査対象ガスに含まれるアセトンに対して感応性を有することが示唆された。測定例１の測定結果と測定例２の測定結果との対比から、感ガス体用組成物の焼成温度が高いと、ガスセンサの感ガス体の感応性が向上することが示唆された。
(Measurement example 2)
The performance of the gas sensor was measured in the same manner as in Measurement Example 1 except that the gas sensor according to Example 1 in which the firing temperature of the composition for a gas sensitive body was 200 ° C. was used. The measurement results are shown in FIG. The upper graph of FIG. 9 shows the temporal change of the current value between the pair of electrodes measured by the pico ammeter 2, and the lower graph of FIG. 9 shows the temporal change of the bubbling amount. In this case as well, the current value between the pair of electrodes increased in synchronization with the fact that a part of the nitrogen gas to be supplied to the internal space of the container 1 was blown into acetone. Therefore, the gas-sensitive body of the gas sensor according to Example 1 in which the firing temperature of the composition for the gas-sensitive body is 200 ° C. is based on acetone contained in the gas to be inspected at 30 ° C., 50 ° C., and 70 ° C. It was suggested that it was sensitive. From the comparison between the measurement result of Measurement Example 1 and the measurement result of Measurement Example 2, it was suggested that the sensitivity of the gas sensor to the gas sensor was improved when the firing temperature of the composition for the gas sensor was high.
（測定例３）
容器１の内部空間の温度を温度調節器４によって３０℃に調節し、容器１の内部空間に供給される窒素ガスの流量及びバブリング量を調整して、実施例１に係るガスセンサ（感ガス体用組成物の焼成温度：５００℃）の性能を測定装置９によって測定した。測定結果を図１０Ａ及び図１０Ｂに示す。図１０Ａの上方及び図１０Ｂのグラフにおける細い実線は、窒素ガスの流量が２００ｍｌであり、かつ、バブリング量を図１０Ａの下方の実線のグラフに示す通り、２０ｍｌ／分、４０ｍｌ／分、６０ｍｌ／分、８０ｍｌ／分、及び１００ｍｌ／分と、段階的に増加させた場合の一対の電極間の電流値の時間的変化を示す。図１０Ａの上方及び図１０Ｂのグラフにおける太い実線は、窒素ガスの流量が１０００ｍｌであり、かつ、バブリング量を図１０Ａの下方のグラフの実線に示す通り、２０ｍｌ／分、４０ｍｌ／分、６０ｍｌ／分、８０ｍｌ／分、及び１００ｍｌ／分と、段階的に増加させた場合の一対の電極間の電流値の時間的変化を示す。図１０Ａの上方及び図１０Ｂのグラフにおける破線は、窒素ガスの流量が２００ｍｌであり、かつ、バブリング量を図１０Ａの下方のグラフの破線に示す通り、４ｍｌ／分、８ｍｌ／分、１２ｍｌ／分、１６ｍｌ／分、及び２０ｍｌ／分と、段階的に増加させた場合の一対の電極間の電流値の時間的変化を示す。
(Measurement example 3)
The temperature of the internal space of the container 1 is adjusted to 30 ° C. by the temperature controller 4, and the flow rate and bubbling amount of the nitrogen gas supplied to the internal space of the container 1 are adjusted to adjust the gas sensor (gas sensor) according to the first embodiment. The performance of the firing temperature (500 ° C.) of the composition for use was measured by the measuring device 9. The measurement results are shown in FIGS. 10A and 10B. The thin solid lines in the upper part of FIG. 10A and the graph of FIG. 10B show that the flow rate of nitrogen gas is 200 ml and the bubbling amount is 20 ml / min, 40 ml / min, 60 ml / min as shown in the lower solid line graph of FIG. 10A. The temporal changes in the current value between the pair of electrodes when gradually increased to minutes, 80 ml / min, and 100 ml / min are shown. The thick solid lines in the upper part of FIG. 10A and the graph in FIG. 10B indicate that the flow rate of nitrogen gas is 1000 ml and the bubbling amount is 20 ml / min, 40 ml / min, 60 ml / min as shown in the solid line in the lower graph of FIG. 10A. The temporal changes in the current value between the pair of electrodes when gradually increased to minutes, 80 ml / min, and 100 ml / min are shown. The dashed lines in the upper part of FIG. 10A and the graph of FIG. 10B show that the flow rate of nitrogen gas is 200 ml and the bubbling amount is 4 ml / min, 8 ml / min, and 12 ml / min as shown by the broken line in the lower graph of FIG. 10A. , 16 ml / min, and 20 ml / min, showing the temporal change of the current value between the pair of electrodes when gradually increased.
測定例３によれば、窒素ガスのバブリング量が比較的小さい場合でも、実施例１に係るガスセンサの感ガス体がアセトンに対して感応性を有することが示唆された。また、窒素ガスの流量が増えると窒素ガスのアセトンへの吹き込みの開始又は停止からより短い時間で一対の電極間の電流値が急激に（ステップ状に）変化し、実施例１に係るガスセンサの応答性が高まることが示唆された。 According to Measurement Example 3, it was suggested that the gas-sensitive body of the gas sensor according to Example 1 is sensitive to acetone even when the bubbling amount of nitrogen gas is relatively small. Further, when the flow rate of the nitrogen gas increases, the current value between the pair of electrodes suddenly (steps) changes in a shorter time from the start or stop of blowing the nitrogen gas into acetone, and the gas sensor according to the first embodiment It was suggested that the responsiveness was increased.
（測定例４）
バブリング装置５の内部に所定量のエタノールを貯留し、図１１の下方のグラフに示す流量の窒素ガスをバブリング装置５に貯留されたエタノールに断続的に吹き込んだ以外は、測定例１と同様にして、実施例１に係るガスセンサ（感ガス体用組成物の焼成温度：５００℃）の性能を測定装置９によって測定した。図１１の上方のグラフに示されるように、実施例１に係るガスセンサの感ガス体はエタノールに対してもある程度感応性を示すことが示唆された。また、バブリング装置５に貯留された液体がエタノールである場合の一対の電極間の電流値の変化量は、バブリング装置５に貯留された液体がアセトンである場合の一対の電極間の電流値の変化量よりも小さいので、実施例１に係るガスセンサは、ガス選択性を有し、アセトンに対して優れた感度を示すことが示唆された。
(Measurement example 4)
The same as in Measurement Example 1 except that a predetermined amount of ethanol was stored inside the bubbling device 5 and the flow rate of nitrogen gas shown in the lower graph of FIG. 11 was intermittently blown into the ethanol stored in the bubbling device 5. Then, the performance of the gas sensor (firing temperature of the composition for gas sensitive body: 500 ° C.) according to Example 1 was measured by the measuring device 9. As shown in the upper graph of FIG. 11, it was suggested that the gas-sensitive body of the gas sensor according to Example 1 also showed some sensitivity to ethanol. Further, the amount of change in the current value between the pair of electrodes when the liquid stored in the bubbling device 5 is ethanol is the current value between the pair of electrodes when the liquid stored in the bubbling device 5 is acetone. Since it is smaller than the amount of change, it is suggested that the gas sensor according to Example 1 has gas selectivity and exhibits excellent sensitivity to acetone.
（測定例５）
バブリング装置５の内部に所定量の水を貯留し、図１２の下方のグラフに示す流量の窒素ガスをバブリング装置５に貯留された水に断続的に吹き込んだ以外は、測定例１と同様にして、実施例１に係るガスセンサの性能を測定装置９によって測定した。図１２の上方のグラフに示されるように、実施例１に係るガスセンサの感ガス体は水（水蒸気）に対してもある程度感応性を示すことが示唆された。容器１の内部空間の温度が３０℃に調節されているときに、実施例１に係るガスセンサの感ガス体の水（水蒸気）に対する感度が特に高いことが示唆された。
(Measurement example 5)
The same as in Measurement Example 1 except that a predetermined amount of water was stored inside the bubbling device 5 and nitrogen gas having a flow rate shown in the lower graph of FIG. 12 was intermittently blown into the water stored in the bubbling device 5. Then, the performance of the gas sensor according to the first embodiment was measured by the measuring device 9. As shown in the upper graph of FIG. 12, it was suggested that the gas-sensitive body of the gas sensor according to the first embodiment shows some sensitivity to water (water vapor). It was suggested that the sensitivity of the gas sensor according to Example 1 to water (water vapor) was particularly high when the temperature of the internal space of the container 1 was adjusted to 30 ° C.
（測定例６）
バブリング装置５の内部に所定量の水又は所定量の水とアセトンとの混合液（水：９９質量％、アセトン：１質量％）を貯留し、図１３Ａ及び図１３Ｂの下方のグラフに示す流量の窒素ガスをバブリング装置５に貯留された液体に断続的に吹き込んだ以外は、測定例１と同様にして、実施例１に係るガスセンサの性能を測定装置９によって測定した。なお、温度調節器４によって容器１の内部空間の温度を３０℃に調節した。図１３Ａ及び図１３Ｂの上方のグラフの実線は、バブリング装置５の内部に所定量の水を貯留した場合の一対の電極間の電流値の時間的変化を示し、図１３Ａ及び図１３Ｂの上方のグラフの破線は、バブリング装置５の内部に水とアセトンとの混合液を貯留した場合の一対の電極間の電流値の時間的変化を示す。図１３Ａ及び図１３Ｂに示すように、少量のアセトンと、水との混合液が貯留されている場合、バブリング装置５の内部に水のみが貯留された場合と比べて、一対の電極間の電流値の変化量が大きかった。このため、実施例１に係るガスセンサによれば、検査対象ガスに水蒸気が含まれアセトンが含まれていない場合と、検査対象ガスに水蒸気及びアセトンが含まれている場合とを区別できることが示唆された。
(Measurement example 6)
A predetermined amount of water or a mixture of a predetermined amount of water and acetone (water: 99% by mass, acetone: 1% by mass) is stored inside the bubbling device 5, and the flow rates shown in the lower graphs of FIGS. 13A and 13B are shown. The performance of the gas sensor according to Example 1 was measured by the measuring device 9 in the same manner as in Measurement Example 1 except that the nitrogen gas of No. 1 was intermittently blown into the liquid stored in the bubbling device 5. The temperature of the internal space of the container 1 was adjusted to 30 ° C. by the temperature controller 4. The solid line in the upper graph of FIGS. 13A and 13B shows the temporal change of the current value between the pair of electrodes when a predetermined amount of water is stored inside the bubbling device 5, and is shown above in FIGS. 13A and 13B. The broken line in the graph shows the temporal change of the current value between the pair of electrodes when the mixed solution of water and acetone is stored inside the bubbling device 5. As shown in FIGS. 13A and 13B, when a mixed solution of a small amount of acetone and water is stored, the current between the pair of electrodes is higher than that when only water is stored inside the bubbling device 5. The amount of change in the value was large. Therefore, according to the gas sensor according to the first embodiment, it is suggested that the case where the gas to be inspected contains water vapor and does not contain acetone can be distinguished from the case where the gas to be inspected contains water vapor and acetone. It was.
図１４は、一対の電極間の電流値の変化量と、バブリング量と容器１の内部空間に供給される窒素ガスの流量との体積比（バブリング量／容器１の内部空間に供給される窒素ガスの流量）との関係を示している。図１４において、バブリング装置５の内部に水のみが貯留された場合の結果が白抜き三角の印でプロットされ、バブリング装置５の内部に水とアセトンとの混合液（水：９９質量％、アセトン：１質量％）を貯留した場合の結果が黒丸印でプロットされている。図１４に示すように、バブリング量が増加するほど、バブリング装置５の内部に水のみが貯留された場合の電流値の変化量とバブリング装置５の内部に水とアセトンとの混合液が貯留された場合の電流値の変化量との差が大きくなった。 FIG. 14 shows a volume ratio (bubbling amount / nitrogen supplied to the internal space of the container 1) between the amount of change in the current value between the pair of electrodes and the flow rate of the nitrogen gas supplied to the internal space of the container 1. The relationship with the gas flow rate) is shown. In FIG. 14, the result when only water is stored inside the bubbling device 5 is plotted with a white triangular mark, and a mixed solution of water and acetone (water: 99% by mass, acetone) inside the bubbling device 5 is plotted. The results when 1% by mass) are stored are plotted with black circles. As shown in FIG. 14, as the bubbling amount increases, the amount of change in the current value when only water is stored inside the bubbling device 5 and the mixed solution of water and acetone are stored inside the bubbling device 5. The difference from the amount of change in the current value became large.
（測定例７）
容器１に水で濡らした紙を入れて、２００ｍｌ／分の窒素ガスを窒素ガスタンク７から容器１の内部空間に供給しながら、実施例１に係るガスセンサ（感ガス体用組成物の焼成温度：５００℃）の性能を測定装置９によって測定した。温度調節器４によって容器１の内部空間の温度を３０℃に調節した。バブリング装置５の内部に所定量のアセトンを貯留し、２００ｍｌ／分の窒素ガスのうち、図１５の下方のグラフに示す流量の窒素ガスをバブリング装置５に貯留されたアセトンに断続的に吹き込んだ。一対の電極間には２Ｖの電圧を印加した。図１５の上方のグラフは、ピコアンメータ２によって測定された一対の電極間の電流値の時間的変化を示す。図１５に示すように、容器１の内部空間に供給されるべき窒素ガスの一部がアセトンに吹き込まれたのに同期して、一対の電極間の電流値が増加した。実施例１に係るガスセンサの感ガス体は、一対の電極に印加される電圧が比較的小さくても、３０℃において、アセトンに対して感応性を有することが示された。
(Measurement example 7)
A paper moistened with water is placed in the container 1, and 200 ml / min of nitrogen gas is supplied from the nitrogen gas tank 7 to the internal space of the container 1, while the gas sensor according to the first embodiment (firing temperature of the composition for a gas sensitive body: The performance at 500 ° C.) was measured by the measuring device 9. The temperature of the internal space of the container 1 was adjusted to 30 ° C. by the temperature controller 4. A predetermined amount of acetone was stored inside the bubbling device 5, and out of 200 ml / min of nitrogen gas, the flow rate of nitrogen gas shown in the lower graph of FIG. 15 was intermittently blown into the acetone stored in the bubbling device 5. .. A voltage of 2 V was applied between the pair of electrodes. The upper graph of FIG. 15 shows the temporal change of the current value between the pair of electrodes measured by the picoammeter 2. As shown in FIG. 15, the current value between the pair of electrodes increased in synchronization with a part of the nitrogen gas to be supplied to the internal space of the container 1 being blown into acetone. It was shown that the gas-sensitive body of the gas sensor according to Example 1 is sensitive to acetone at 30 ° C. even if the voltage applied to the pair of electrodes is relatively small.
（測定例８）
２００ｍｌ／分の窒素ガスを窒素ガスタンク７から容器１の内部空間に供給しながら、実施例２に係るガスセンサの性能を測定装置９によって測定した。バブリング装置５の内部に所定量のアセトンを貯留し、２００ｍｌ／分の窒素ガスのうち、図１６の下方のグラフに示す流量の窒素ガスをバブリング装置５に貯留されたアセトンに断続的に吹き込んだ。一対の電極間の電圧は１００Ｖに設定した。容器１の内部空間の温度を温度調節器４によって３０℃に調節した。図１６の上方のグラフは、ピコアンメータ２によって測定された一対の電極間の電流値の変化を示す。図１６に示すように、容器１の内部空間に供給されるべき窒素ガスの一部がアセトンに吹き込まれたのに同期して、一対の電極間の電流値が増加した。このため、実施例２に係るガスセンサの感ガス体は、３０℃において、検査対象ガスに含まれるアセトンに対して感応性を有することが示唆された。また、バブリング量が増えるに従って一対の電極間の電流値の増加幅が大きくなった。
(Measurement Example 8)
The performance of the gas sensor according to Example 2 was measured by the measuring device 9 while supplying 200 ml / min of nitrogen gas from the nitrogen gas tank 7 to the internal space of the container 1. A predetermined amount of acetone was stored inside the bubbling device 5, and out of 200 ml / min of nitrogen gas, the flow rate of nitrogen gas shown in the graph below in FIG. 16 was intermittently blown into the acetone stored in the bubbling device 5. .. The voltage between the pair of electrodes was set to 100V. The temperature of the internal space of the container 1 was adjusted to 30 ° C. by the temperature controller 4. The upper graph of FIG. 16 shows the change in current value between the pair of electrodes measured by the picoammeter 2. As shown in FIG. 16, the current value between the pair of electrodes increased in synchronization with a part of the nitrogen gas to be supplied to the internal space of the container 1 being blown into acetone. Therefore, it was suggested that the gas-sensitive body of the gas sensor according to Example 2 has sensitivity to acetone contained in the gas to be inspected at 30 ° C. Further, as the bubbling amount increased, the increase width of the current value between the pair of electrodes increased.
１０ 感ガス体
２０ 一対の電極
３０ 基板
１００ ガスセンサ
10 Gas sensor 20 Pair of electrodes 30 Substrate 100 Gas sensor
Claims (7)
周期表の第７族〜第１１族に属する元素を含む金属、合金、酸化物、及び複合酸化物からなる群から選ばれる少なくとも１種でできた被担持体が、Ｙ、Ｃｅ、Ｔｉ、Ｚｒ、Ｎｂ、Ｆｅ、Ｚｎ、Ａｌ、及びＳｉからなる群から選ばれる少なくとも１つの元素の酸化物である金属酸化物担体に担持されて形成された複合体粒子と、
極性溶媒と、を含有し、
前記金属酸化物担体は、５〜３０ｎｍの短軸長さ、２０〜１０００ｎｍの長軸長さ、及び２〜２００のアスペクト比を有するロッド形状である、
ガスセンサの感ガス体用組成物。 A composition for a gas-sensitive body arranged between a pair of electrodes in a gas sensor.
The supported body made of at least one selected from the group consisting of metals, alloys, oxides, and composite oxides containing elements belonging to groups 7 to 11 of the periodic table is Y, Ce, Ti, Zr. , Nb, Fe, Zn, Al, and Si, and composite particles formed by being supported on a metal oxide carrier, which is an oxide of at least one element selected from the group.
Containing with polar solvent,
The metal oxide carrier has a rod shape having a minor axis length of 5 to 30 nm , a major axis length of 20 to 1000 nm, and an aspect ratio of 2 to 200.
Composition for gas sensor body.
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