JPS60100752A - Gas sensor - Google Patents

Gas sensor

Info

Publication number
JPS60100752A
JPS60100752A JP20956883A JP20956883A JPS60100752A JP S60100752 A JPS60100752 A JP S60100752A JP 20956883 A JP20956883 A JP 20956883A JP 20956883 A JP20956883 A JP 20956883A JP S60100752 A JPS60100752 A JP S60100752A
Authority
JP
Japan
Prior art keywords
gas sensor
sno2
vanadium
vanadium oxide
sensitivity
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP20956883A
Other languages
Japanese (ja)
Other versions
JPH0226184B2 (en
Inventor
Takashi Yamaguchi
隆司 山口
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
FUIGARO GIKEN KK
Figaro Engineering Inc
Original Assignee
FUIGARO GIKEN KK
Figaro Engineering Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by FUIGARO GIKEN KK, Figaro Engineering Inc filed Critical FUIGARO GIKEN KK
Priority to JP20956883A priority Critical patent/JPS60100752A/en
Publication of JPS60100752A publication Critical patent/JPS60100752A/en
Publication of JPH0226184B2 publication Critical patent/JPH0226184B2/ja
Granted legal-status Critical Current

Links

Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/12Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)

Abstract

PURPOSE:To stabilize sensitivity with H2 and alcohol with a gas sensor which utilizes the change in the resistance value of SnO2 by adding vanadium oxide at 40mug-10mg in terms of metallic vanadium for each 1g SnO2 to SnO2. CONSTITUTION:A gas sensitive film 6 consisting of SnO2 is coated on an insulating pipe 4 consisting of alumina, etc. and is then sintered to constitute a gas sensor 2. The resistance value of the film 6 is detected with a pair of electrodes 8 and 12. A heater 12 is inserted into the pipe 4 to heat the sensor 2 to a required temp. Vanadium oxide is added to SnO2 at 40mug-10mg in terms of metallic vanadium for each 1g SnO2. The sensitivity with alcohol and H2 is thus stabilized without spoiling the sensitivity and the deterioration of the sensor with age is prevented.

Description

【発明の詳細な説明】 この発明は、Sn 02をガス感応材料とするガスセン
サの改良に関スル。
DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a gas sensor using Sn 02 as a gas-sensitive material.

この明細書では、バナジウム酸化物の添加量を金属バナ
ジウムに換算して示し、かつSn021g当り1μgの
添加を1 ppmと、to−yの添加を1%として表示
する。
In this specification, the amount of vanadium oxide added is expressed in terms of metal vanadium, and the addition of 1 μg per 1 g of Sn02 is expressed as 1 ppm, and the addition of to-y is expressed as 1%.

Sn 02を用いたガスセンサが実用化されている。Gas sensors using Sn02 have been put into practical use.

このガスセンサバ、H2やアルコール(例tばエタノー
ル)への感度が経時的に増すという欠点が有る。
This gas sensor has the disadvantage that its sensitivity to H2 and alcohol (for example, ethanol) increases over time.

この発明は、Sn 02を用いたガスセンサの、H2や
アルコールへの感度を安定化することを目的とし、その
ため少量のバナジウム酸化物を添加する。
The purpose of this invention is to stabilize the sensitivity of a gas sensor using Sn 02 to H2 and alcohol, and for that purpose, a small amount of vanadium oxide is added.

バナジウム酸化物の添加による経時変化の防止は、5n
02に対してのみ有効で、他のガス感応材料、例えばI
 n203やZnOでは効果が得られない。
Prevention of aging by adding vanadium oxide is 5n
02 and other gas-sensitive materials, such as I
No effect can be obtained with n203 or ZnO.

まだSn 02に、バナジウム以外の酸化物、例えば5
b203、Nb2O5、Ta205、を添力0しても効
果は得られない。バナジウム酸化物の添加は50ppm
の添加でも大きな効果を持つが、1%以上添加するとガ
スセンサの抵抗値が増しかつ感度が低下する。従って添
加量は4 o ppm−1%の範囲に限られる。
Still in Sn02, oxides other than vanadium, e.g.
No effect can be obtained even if the addition of b203, Nb2O5, Ta205 is 0. Addition of vanadium oxide is 50 ppm
Although the addition of 1% or more has a large effect, the resistance value of the gas sensor increases and the sensitivity decreases. Therefore, the amount added is limited to 40 ppm-1%.

以下に実施例を説明する。Examples will be described below.

[ガスセンサの構造] 実施例で用いたガスセンサの構造を第1図に示す。この
ガスセンサ(2)は、アルミナ等の絶縁管(4)にSn
 02ガス感応膜(6)を塗布後焼結したもので、一対
の電極(8)、(lO)を介してSn 02ガス感応膜
(6)の抵抗値を検出する。そして絶縁管(4)にはヒ
ータ(12)を挿入し、ガスセンサ(2)を必要な温度
に加熱する。
[Structure of Gas Sensor] The structure of the gas sensor used in the examples is shown in FIG. This gas sensor (2) is made of an insulating tube (4) made of alumina etc.
The Sn 02 gas sensitive film (6) is applied and sintered, and the resistance value of the Sn 02 gas sensitive film (6) is detected through a pair of electrodes (8) and (lO). A heater (12) is then inserted into the insulating tube (4) to heat the gas sensor (2) to a required temperature.

ガスセンサ(2)の構造は、自由に変形できる。例えば
第1図において電極+81 、001を廃止し、ヒータ
(121と5n02ガス感応膜(6)との並列抵抗の抵
抗値を検出するようにしても良い。そのためには、ヒー
タ(1zを絶縁管(4)の外周に沿って巻き回せば良い
The structure of the gas sensor (2) can be freely modified. For example, in Fig. 1, the electrodes +81 and 001 may be omitted and the resistance value of the parallel resistance between the heater (121 and the 5n02 gas sensitive film (6)) may be detected. All you have to do is wind it around the outer periphery of (4).

[5n02の調整] 5nCN4水溶液をNH3で中和し、水洗を繰り返して
スズ酸ゾルとする。このゾルを750℃で2時間空気中
で加熱し、Sn 02を得る。金属バナジウムを硝酸に
溶解させ、塩化パラジウム水溶液と混合した後に、Sn
 02に含浸させる。これを650℃VtC50分間空
気中で加熱し、バナジウム酸化物とパラジウムとを担持
したSn 02を得る。
[Adjustment of 5n02] A 5nCN4 aqueous solution is neutralized with NH3 and washed with water repeatedly to obtain a stannic acid sol. This sol is heated at 750° C. for 2 hours in air to obtain Sn 02. After dissolving metal vanadium in nitric acid and mixing it with an aqueous palladium chloride solution, Sn
Impregnated with 02. This is heated in air at 650° C.VtC for 50 minutes to obtain Sn 02 carrying vanadium oxide and palladium.

バナジウムは、主としてV2O5として5n02に担持
される。しかしV2O5は還元され易い物質であり、実
際にはV2O5の他に微量のv2 o4等を含むと考え
られる。そして実施例では、バナジウムの添加量を5o
ppm、400 ppm、 700 ppm、0.1%
、0.3%、0.7%の6種について検討した。
Vanadium is supported on 5n02 primarily as V2O5. However, V2O5 is a substance that is easily reduced, and in reality, it is thought that in addition to V2O5, trace amounts of V2O4 and the like are included. In the example, the amount of vanadium added was 50
ppm, 400 ppm, 700 ppm, 0.1%
, 0.3%, and 0.7%.

また従来例としてバナジウム無添加のものを、比較例と
してバナジウムを1.5%添加のものを検討した。なお
バナジウム酸化物は、Sn 02への不純物としては希
れで、不純物としての存在量は1 ppm以下である。
Further, as a conventional example, a product without vanadium added was investigated, and as a comparative example, a product with 1.5% vanadium added was investigated. Note that vanadium oxide is a rare impurity to Sn 02, and the amount present as an impurity is 1 ppm or less.

さらに、パラジウムはガスへの感度と応答速度とを改善
するため加えたもので、その添加量は金属パラジウム換
算で5nu21 g当り3、、yである。
Furthermore, palladium was added to improve the sensitivity to gas and the response speed, and the amount added was 3.,y per 5 nu21 g in terms of metal palladium.

〔測定法] 測定には、25°Cで相対湿度65%の雰囲気を用い、
また各ガスの濃度を2000 ppmとする。
[Measurement method] For measurement, an atmosphere of 25°C and 65% relative humidity was used.
Further, the concentration of each gas is set to 2000 ppm.

結果は、5個のガスセンサt2) K対する平均値を示
す。
The results show the average value for five gas sensors t2) K.

〔経時特性] バナジウム無添力0のガスセンサ(2)を、400°C
に120日間空気中で通電した際の経時特性を第2回置
に示す。ガスセンサ(2)の抵抗値(Rs)は、エタノ
ールや水素雰囲気下で減少し、これらのガスへの感度が
増大してゆく。この現象は、Sn 02の調整法や添加
物の種類によらず一般的に生ずる。
[Aging characteristics] The gas sensor (2) with zero vanadium additive was heated at 400°C.
The characteristics over time when electricity was applied in the air for 120 days are shown in the second picture. The resistance value (Rs) of the gas sensor (2) decreases in an ethanol or hydrogen atmosphere, and the sensitivity to these gases increases. This phenomenon generally occurs regardless of the method of preparing Sn 02 or the type of additive.

エタノールやH2への経時変化の原因は不明で、ガスセ
ンサ(2)の加熱温度とともに経時変化が著しくなるこ
とがわかっている。
The cause of the change over time to ethanol and H2 is unknown, but it is known that the change over time becomes more significant as the heating temperature of the gas sensor (2) increases.

バナジウム酸化物をioooppm添加したガスセンサ
(2)への、同じ条件での経時特性を第2図(B)に示
す。エタノールやH2への高感度化は防止嘔れ、ガスセ
ンサ(2)の抵抗値(Rs)や、各ガスへの感度は変化
しない。
Figure 2 (B) shows the aging characteristics of the gas sensor (2) to which ioooppm of vanadium oxide was added under the same conditions. High sensitivity to ethanol and H2 is prevented, and the resistance value (Rs) of the gas sensor (2) and sensitivity to each gas do not change.

第3図に、バナジウム酸化物の添加量の影響を示す。図
は400℃で120日間空気中に通電した際のエタノー
ルやH2への抵抗値の変化を示し、最初の抵抗値(Rs
o)と120日後の抵抗値(Rsf)の比を縦軸とする
。バナジウム酸化物の添加効果は、50 ppmの添加
でも著しく、1000 ppm付近から飽和する。
FIG. 3 shows the influence of the amount of vanadium oxide added. The figure shows the change in resistance to ethanol and H2 when electricity is applied in air at 400℃ for 120 days, and the initial resistance value (Rs
The vertical axis is the ratio of resistance value (Rsf) after 120 days. The effect of adding vanadium oxide is significant even at 50 ppm, and saturates from around 1000 ppm.

バナジウム酸化物の効果は、Sn 02との組み合せで
のみ生じ、In20BやZnOには効果がない。
The effect of vanadium oxide occurs only in combination with Sn02, and has no effect on In20B or ZnO.

まだバナジウム酸化物に代えて、Nb2o5やTa20
5.5b2o3をSn 02 に加えても、経時変化は
抑制されない。バナジウム酸化物の効果は、添加方法と
は無関係で、例えばv2 o5の粉末を5n02粉末と
混合して担持させても良い。5n02には種々の添加物
、例えば実施例で用いたパラジウム、あるいは焼結剤と
してのシリカゾノペを加えても良く、Ajl’20aや
石英等の骨材を加えても良い。バナジウム酸化物の影響
は、Sn 02への添加物や混合物とは無関係である。
Still, instead of vanadium oxide, Nb2o5 or Ta20
Even if 5.5b2o3 is added to Sn 02 , the change over time is not suppressed. The effect of vanadium oxide is independent of the method of addition; for example, v2 o5 powder may be mixed with 5n02 powder and supported. Various additives may be added to 5n02, such as palladium used in the examples, or silica zonope as a sintering agent, and aggregates such as Ajl'20a and quartz may be added. The effect of vanadium oxide is independent of additives and mixtures to Sn02.

つぎに、バナジウム酸化物により経時変化が防止される
原因は、不明である。第1に、Sn 02がエタノール
やH2に対して経時変化する原因が不明である。第2に
、バナジウム酸化物との組み合せのみが有効である原因
も不明である。
Next, the reason why vanadium oxide prevents changes over time is unknown. First, the reason why Sn 02 changes over time with respect to ethanol and H2 is unknown. Secondly, the reason why only the combination with vanadium oxide is effective is also unknown.

[ガス感度] 第4装置に、バナジウム酸化物を1.0001)I)m
添加したガスセンサ(2)の、製造直後の抵抗値(Rs
 )と各ガスへの感度を示す。結果は、バナジウム酸化
物無添加のものと、はとんど同一である。
[Gas Sensitivity] Vanadium oxide was added to the fourth device at 1.0001)I)m
The resistance value (Rs
) and the sensitivity to each gas. The results are almost identical to those without the addition of vanadium oxide.

第4図(B)に、バナジウム酸化物を1.5%添加した
ものの、特性を示す。バナジウム酸化物の大量添加によ
り、ガスセンサ(2)の抵抗値(Rs)が増し、ガスへ
の感度も減少することがわかる。
FIG. 4(B) shows the characteristics of a sample to which 1.5% of vanadium oxide was added. It can be seen that by adding a large amount of vanadium oxide, the resistance value (Rs) of the gas sensor (2) increases and the sensitivity to gas also decreases.

第5図に、バナジウム酸化物の添加量による、抵抗値(
Rs)とガスへの感度(空気中とガス中との抵抗値の比
)とを示す。1000 ppm以上のバナジウム酸化物
の添加で、ガスセンサ(2)は高抵抗化し、感度も低下
する。そしてこの効果は、添加量1%を境に著しく増大
する。従って、バナジウム酸化物の添加量は1%以下と
することが必要で、好ましくは0.4%以下とする。
Figure 5 shows the resistance value (
Rs) and sensitivity to gas (ratio of resistance values in air and gas). Addition of 1000 ppm or more of vanadium oxide increases the resistance of the gas sensor (2) and lowers its sensitivity. This effect increases significantly when the addition amount reaches 1%. Therefore, the amount of vanadium oxide added must be 1% or less, preferably 0.4% or less.

バナジウムは主として5価で存在し、原子価制御理論か
らすれば、SnO2はバナジウムの添加により低抵抗化
するはずである。しかし得られた結果は、予想と一致し
ない。
Vanadium mainly exists in a pentavalent state, and according to valence control theory, the resistance of SnO2 should be lowered by adding vanadium. However, the results obtained do not match expectations.

この発明では、5n02に少量のバナジウム酸化物を添
加することにより、感度を損うことなく、アルコールや
水素への経時変化を防止できる。
In this invention, by adding a small amount of vanadium oxide to 5n02, it is possible to prevent changes over time to alcohol and hydrogen without impairing sensitivity.

【図面の簡単な説明】[Brief explanation of the drawing]

第1図は実施例のガスセンサの部分切り欠き図で、第2
図(5)、(B)〜第5図はガスセンサの特性図である
。 第1図 第2 図(A) 一−@ −−air −O−IS o 20 40 60 80 100 120Time
(dad) 第2 図(B) −・−air−o−IB Timのay) 第3図 第4 図(A) 第4 図(B) 250 300 350 400 450 500 T
s(’C)第5図 ト (k
Fig. 1 is a partially cutaway diagram of the gas sensor of the embodiment;
Figures (5) and (B) to Figure 5 are characteristic diagrams of the gas sensor. Figure 1 Figure 2 (A) 1-@ --air -O-IS o 20 40 60 80 100 120Time
(dad) Fig. 2 (B) -・-air-o-IB Tim's ay) Fig. 3 Fig. 4 (A) Fig. 4 (B) 250 300 350 400 450 500 T
s('C) Figure 5 t(k

Claims (1)

【特許請求の範囲】 [11Sn 02の抵抗値の変化を利用したガスセンサ
において、 5n 02には、バナジウムの酸化物を、SnO21g
当り金属バナジウム換算で40μg〜10招1添加した
ことを特徴とするガスセンサ。
[Claims] [In a gas sensor that utilizes a change in the resistance value of 11Sn02, 5n02 contains vanadium oxide, SnO21g
A gas sensor characterized in that 40 μg to 10 μg of vanadium is added in terms of metal vanadium.
JP20956883A 1983-11-08 1983-11-08 Gas sensor Granted JPS60100752A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP20956883A JPS60100752A (en) 1983-11-08 1983-11-08 Gas sensor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP20956883A JPS60100752A (en) 1983-11-08 1983-11-08 Gas sensor

Publications (2)

Publication Number Publication Date
JPS60100752A true JPS60100752A (en) 1985-06-04
JPH0226184B2 JPH0226184B2 (en) 1990-06-07

Family

ID=16574982

Family Applications (1)

Application Number Title Priority Date Filing Date
JP20956883A Granted JPS60100752A (en) 1983-11-08 1983-11-08 Gas sensor

Country Status (1)

Country Link
JP (1) JPS60100752A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0206236A2 (en) * 1985-06-24 1986-12-30 Figaro Engineering Inc. Gas sensor

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5736812A (en) * 1980-08-15 1982-02-27 Tokyo Shibaura Electric Co KANSHITSUSOSHI

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5736812A (en) * 1980-08-15 1982-02-27 Tokyo Shibaura Electric Co KANSHITSUSOSHI

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0206236A2 (en) * 1985-06-24 1986-12-30 Figaro Engineering Inc. Gas sensor
US4731226A (en) * 1985-06-24 1988-03-15 Figaro Engineering Inc. Gas sensor

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Publication number Publication date
JPH0226184B2 (en) 1990-06-07

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