JPH0390848A - Gas sensor - Google Patents
Gas sensorInfo
- Publication number
- JPH0390848A JPH0390848A JP22865789A JP22865789A JPH0390848A JP H0390848 A JPH0390848 A JP H0390848A JP 22865789 A JP22865789 A JP 22865789A JP 22865789 A JP22865789 A JP 22865789A JP H0390848 A JPH0390848 A JP H0390848A
- Authority
- JP
- Japan
- Prior art keywords
- gas
- platinum
- gas sensing
- sensing layer
- palladium
- 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.)
- Pending
Links
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims abstract description 32
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims abstract description 28
- 239000010410 layer Substances 0.000 claims abstract description 26
- 229910052697 platinum Inorganic materials 0.000 claims abstract description 16
- 229910052763 palladium Inorganic materials 0.000 claims abstract description 14
- 239000011247 coating layer Substances 0.000 claims abstract description 11
- 239000004065 semiconductor Substances 0.000 claims abstract description 11
- 239000000758 substrate Substances 0.000 claims abstract description 9
- 239000011810 insulating material Substances 0.000 claims description 3
- 239000010970 precious metal Substances 0.000 claims description 2
- 229910000510 noble metal Inorganic materials 0.000 abstract description 7
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 abstract description 6
- 229910001887 tin oxide Inorganic materials 0.000 abstract description 6
- 239000003054 catalyst Substances 0.000 abstract description 5
- 230000000694 effects Effects 0.000 abstract description 5
- 239000000843 powder Substances 0.000 abstract description 5
- 239000002245 particle Substances 0.000 abstract description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 abstract description 2
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 abstract description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 2
- 230000032683 aging Effects 0.000 abstract 1
- 239000007789 gas Substances 0.000 description 42
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 10
- 239000001301 oxygen Substances 0.000 description 10
- 229910052760 oxygen Inorganic materials 0.000 description 10
- NNPPMTNAJDCUHE-UHFFFAOYSA-N isobutane Chemical compound CC(C)C NNPPMTNAJDCUHE-UHFFFAOYSA-N 0.000 description 8
- 238000010586 diagram Methods 0.000 description 7
- 239000001282 iso-butane Substances 0.000 description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 230000007774 longterm Effects 0.000 description 3
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 229910052705 radium Inorganic materials 0.000 description 1
- HCWPIIXVSYCSAN-UHFFFAOYSA-N radium atom Chemical compound [Ra] HCWPIIXVSYCSAN-UHFFFAOYSA-N 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000011787 zinc oxide Substances 0.000 description 1
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
この発明はＬＰガス、都市ガス等を対象とするガスセン
サに係り、特に長期安定性と温度安定性に優れるガスセ
ンサに関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gas sensor for LP gas, city gas, etc., and particularly to a gas sensor with excellent long-term stability and temperature stability.
酸化スズ、酸化亜鉛等のｎ型金属酸化物半導体は、大気
中で３００〜５００℃の温度に加熱されると粒子表面に
大気中の酸素が活性化吸着して高抵抗化しているが、可
燃性ガスが接触すると吸着酸素と可燃性ガスとが反応し
て吸着酸素が脱離し抵抗値が減少する。このような性質
を利用して、酸化スズを用いたガスセンサはＬＰガス、
都市ガスなどのガス漏れ警報器に広く用いられている。When n-type metal oxide semiconductors such as tin oxide and zinc oxide are heated to a temperature of 300 to 500°C in the atmosphere, atmospheric oxygen is activated and adsorbed onto the particle surface, resulting in a high resistance, but they are not flammable. When a flammable gas comes into contact with the adsorbed oxygen, the adsorbed oxygen reacts with the combustible gas, the adsorbed oxygen is desorbed, and the resistance value decreases. Utilizing these properties, gas sensors using tin oxide can detect LP gas,
Widely used in gas leak alarms such as city gas.
この種のガスセンサは大気中のアルコール蒸気に対して
も大きな抵抗値の変化を示すことが知られており、調理
、燗等から発生するアルコール蒸気による誤動作を防ぐ
ためアルコール蒸気に対する感度（大気中の抵抗値／ア
ルコール蒸気接触時の抵抗値）を極力低減させ、ＬＰガ
ス、都市ガスなどを選択的に検知できるガスセンサが必
要とされる。It is known that this type of gas sensor exhibits a large change in resistance value even when exposed to alcohol vapor in the atmosphere. There is a need for a gas sensor that can selectively detect LP gas, city gas, etc. while minimizing the resistance value (resistance value upon contact with alcohol vapor).
ｎ型酸化物半導体からなる感ガス層には、対象ガスに対
する感度を高めるために貴金属が０．１〜１重量％加え
られるが、上述の問題を解決するために、感ガス層の上
にｎ型酸化物半導体からなる被覆層を形威し、この被覆
層に貴金属を感ガス層の触媒濃度より高めて（２〜１０
重量％）担持させたガスセンサが知られている。A noble metal of 0.1 to 1% by weight is added to the gas-sensitive layer made of an n-type oxide semiconductor in order to increase the sensitivity to the target gas. A coating layer made of a type oxide semiconductor is formed, and a noble metal is added to this coating layer to a concentration higher than that of the gas-sensitive layer (2 to 10
% by weight) supported gas sensors are known.
しかしながらこのような従来のセンサにあっては、セン
サ抵抗の温度依存性が大きい上に、センサ抵抗について
はこれが経時的に変化する場合があり、長期的信頼性に
欠けるという問題があった。However, in such conventional sensors, the sensor resistance has a large temperature dependence, and the sensor resistance may change over time, resulting in a lack of long-term reliability.
第２図はセンサ抵抗の経時変化を示す線図である＊Ｒｓ
ｏは０．２％のイソブタンガス中における初期のセンサ
抵抗であり、Ｒｓは０．２％イソブタンガス中における
所定時間経過後のセンサ抵抗である０曲線２１は感ガス
層中に白金が０．５重量％担持されているセンサの特性
１曲＆Ｉ２４はパラジウムが０．５重量％担持されてい
るセンサの特性である。Figure 2 is a diagram showing the change in sensor resistance over time *Rs
o is the initial sensor resistance in 0.2% isobutane gas, and Rs is the sensor resistance after a predetermined time in 0.2% isobutane gas. The 0 curve 21 indicates that platinum is present in the gas-sensitive layer at 0.2%. Characteristics of a sensor carrying 5% by weight of palladium Song 1 &I24 is a characteristic of a sensor carrying 0.5% by weight of palladium.
白金を担持したセンサは初期値に比し、抵抗が徐々に減
少することがわかる。パラジウムの場合は安定である。It can be seen that the resistance of the sensor carrying platinum gradually decreases compared to the initial value. Palladium is stable.
第３図はセンサ抵抗の温度依存性を示す線図である０曲
ｖＡ２５は感ガス層にパラジウムを０．５重量％含むセ
ンサの特性１曲線２６は白金を０．５重量％含むセンサ
の特性である。温度依存性が大きいことがわかる。FIG. 3 is a diagram showing the temperature dependence of sensor resistance. Curve 0 vA25 is the characteristic of a sensor containing 0.5% by weight of palladium in the gas-sensitive layer. Curve 1 26 is the characteristic of a sensor containing 0.5% by weight of platinum. It is. It can be seen that the temperature dependence is large.
この発明は上述の点に鑑みてなされ、その目的は感ガス
層の触媒に改良を加えることにより、センサ抵抗の温度
依存性が少なく、かつ経時安定性にも優れるガスセンサ
を提供することにある。The present invention has been made in view of the above-mentioned points, and its purpose is to provide a gas sensor in which sensor resistance has less temperature dependence and excellent stability over time by improving the catalyst of the gas-sensitive layer.
（課題を解決するための手段）
上述の目的はこの発明によれば、基板と、感ガス層と、
被覆層とを有するガスセンサであって、基板は絶縁材で
作られ感ガス層と被覆層が順次積層されるものであり、
感ガス層はｎ型酸化物半導体に白金とパラジウムを総量
で０．１−１重量％。(Means for Solving the Problem) According to the present invention, the above-mentioned object includes a substrate, a gas-sensitive layer,
A gas sensor having a coating layer, the substrate is made of an insulating material, and the gas-sensitive layer and the coating layer are sequentially laminated,
The gas-sensitive layer is an n-type oxide semiconductor containing platinum and palladium in a total amount of 0.1-1% by weight.
その比が１〜３の割合で担持したものであり、被覆層は
ｎ型酸化物半導体に貴金属を２〜１０重量％担持したも
のであるとすることにまり達成される。This is achieved by supporting the noble metal at a ratio of 1 to 3, and forming the coating layer by supporting an n-type oxide semiconductor with 2 to 10% by weight of the noble metal.
アルコールによる干渉は上記被覆層により除去される。The interference caused by alcohol is removed by the above-mentioned coating layer.
ｎ型酸化物半導体の表面では貴金属触媒の働きでイソブ
タンと吸着酸素との結合による吸着酸素の脱離、空気中
酸素の供給による酸素の吸着の再反応が同時に進行して
おり、従来の触媒では酸素吸着反応の活性が劣化してセ
ンサ抵抗の経時的減少や温度依存性の増大がおこるが、
白金とパラジウムの合金触媒では酸素＠着反応の活性は
安定化されると推定される。On the surface of the n-type oxide semiconductor, the noble metal catalyst simultaneously desorbs adsorbed oxygen by combining isobutane and adsorbed oxygen, and re-adsorbs oxygen by supplying atmospheric oxygen. The activity of the oxygen adsorption reaction deteriorates, causing a decrease in sensor resistance over time and an increase in temperature dependence.
It is presumed that the activity of the oxygen deposition reaction is stabilized with an alloy catalyst of platinum and palladium.
次にこの発明の実施例を図面に基いて説明する。 Next, embodiments of the present invention will be described based on the drawings.
第１図はこの発明の実施例に係るガスセンサを示す断面
図である。FIG. 1 is a sectional view showing a gas sensor according to an embodiment of the invention.
中心粒径２ｎの酸化スズ粉末に白金とパラジウムをそれ
ぞれ０．２５１！３１％となるように担持し、次いでこ
の粉末に水とシリカゾルを加えペースト状としてアルミ
ナ基板３の電極１１．１２上に厚さ約７０−となるよう
に塗布し、７５０℃で３０分加熱して感ガス層を形成し
た。同様に白金を３重量％担持させた酸化スズをペース
ト状にし、感ガスＮ２を被覆するように豹５０μの厚さ
に塗布し７５０℃で３０分加熱して被覆層４を形成した
。さらに第１図と同様のｎｔ造を有し、感ガス層２の貴
金属添加の総量は同じで白金／パラジウム比が３の素子
をも作成した。Platinum and palladium were supported on tin oxide powder with a center particle size of 2n at a concentration of 0.251!31%, respectively, and then water and silica sol were added to this powder to form a paste, which was spread thickly onto the electrode 11.12 of the alumina substrate 3. The film was coated to give a coating thickness of about 70° C. and heated at 750° C. for 30 minutes to form a gas-sensitive layer. Similarly, tin oxide carrying 3% by weight of platinum was made into a paste, applied to a thickness of 50 μm so as to cover the sensitive gas N2, and heated at 750° C. for 30 minutes to form a coating layer 4. Furthermore, an element was also prepared which had the same nt structure as shown in FIG. 1, had the same total amount of noble metal added to the gas-sensitive layer 2, and had a platinum/palladium ratio of 3.
この実施例におけるセンサの特性を示すために、素子を
ヒータ５を用いて所定温度に保ち、０．２％イソブタン
ガス中でセンサ抵抗を求めた。In order to show the characteristics of the sensor in this example, the element was kept at a predetermined temperature using the heater 5, and the sensor resistance was determined in 0.2% isobutane gas.
第２図はセンサ抵抗の経時変化を示す線図である。Ｒｓ
ｏは前述のように初期のセンサ抵抗であり、Ｒｓは所定
時間経過したあとのセンサ抵抗である。FIG. 2 is a diagram showing changes in sensor resistance over time. Rs.
o is the initial sensor resistance as described above, and Rs is the sensor resistance after a predetermined period of time has elapsed.
曲線２２は白金とパラジウムの比が３である場合。Curve 22 is for a platinum to palladium ratio of 3.
曲ｋｌＡ２３はその比が１の場合の特性である。ともに
経時変化がないことがわかる。The song klA23 has the characteristics when the ratio is 1. It can be seen that there is no change over time in either case.
第３図はセンサ抵抗の温度依存性を示す線図である。
Ｒｓ （４００℃）は温度４００℃におけるセンサ抵抗
である０曲線２７１曲線２８はそれぞれ白金とパラジウ
ムの比が３と１の場合の特性である。温度依存性は従来
のものより少なくなっている。FIG. 3 is a diagram showing the temperature dependence of sensor resistance.
Rs (400° C.) is the sensor resistance at a temperature of 400° C. 0 curve 271 and curve 28 are the characteristics when the ratio of platinum to palladium is 3 and 1, respectively. Temperature dependence is less than that of the conventional method.
この発明によれば、基板と、感ガス層と、被覆層とを有
するガスセンサであって、基板は絶縁材で作られ感ガス
層と被覆層が順次積層されるものであり・感ガス層はｎ
型酸化物半導体に白金とノ〈ラジウムを聡量で０．１〜
１重量％、その比が１〜３の割合で担持したものであり
、被覆層はｎ型酸化物半導体に貴金属を２〜１０重景％
担持したものであるので、感ガス層における触媒活性が
長期間にわたり、また低温度においても維持され、その
結果長期安定性と温度安定性に優れるガスセンサが得ら
れる。According to this invention, there is provided a gas sensor having a substrate, a gas-sensitive layer, and a covering layer, wherein the substrate is made of an insulating material, and the gas-sensitive layer and the covering layer are sequentially laminated. n
type oxide semiconductor with platinum and radium of 0.1~
1% by weight, the ratio of which is 1 to 3, and the coating layer is an n-type oxide semiconductor with a precious metal of 2 to 10% by weight.
Since the catalyst is supported, the catalytic activity in the gas-sensitive layer is maintained over a long period of time, even at low temperatures, and as a result, a gas sensor with excellent long-term stability and temperature stability can be obtained.
第１図はこの発明の実施例に係るガスセンサを示す断面
図、第２図はこの発明の実施例に係るガスセンサにつき
その抵抗の経時変化を従来のセンサの経時変化と比較し
て示す線図、第３図はこの発明の実施例に係るガスセン
サにつきその抵抗の温度依存性を従来のセンサの温度依
存性と対比して示す線図である。
２：感ガス層、３：基板、４：被覆層。
第
図FIG. 1 is a sectional view showing a gas sensor according to an embodiment of the present invention, and FIG. 2 is a diagram showing a change in resistance over time of the gas sensor according to an embodiment of the invention in comparison with a change over time in a conventional sensor. FIG. 3 is a diagram showing the temperature dependence of the resistance of the gas sensor according to the embodiment of the present invention in comparison with the temperature dependence of a conventional sensor. 2: gas sensitive layer, 3: substrate, 4: coating layer. Diagram
Claims (1)
であって、 基板は絶縁材で作られ感ガス層と被覆層が順次積層され
るものであり、 感ガス層はｎ型酸化物半導体に白金とパラジウムを総量
で０．１〜１重量％、その比が１〜３の割合で担持した
ものであり、 被覆層はｎ型酸化物半導体に貴金属を２〜１０重量％担
持したものであることを特徴とするガスセンサ。[Claims] 1) A gas sensor comprising a substrate, a gas-sensitive layer, and a covering layer, wherein the substrate is made of an insulating material and the gas-sensitive layer and the covering layer are sequentially laminated, The layer is an n-type oxide semiconductor carrying platinum and palladium in a total amount of 0.1 to 1% by weight, with a ratio of 1 to 3. The coating layer is an n-type oxide semiconductor carrying precious metals of 2 to 1% by weight. A gas sensor characterized in that it carries 10% by weight.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22865789A JPH0390848A (en) | 1989-09-04 | 1989-09-04 | Gas sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22865789A JPH0390848A (en) | 1989-09-04 | 1989-09-04 | Gas sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0390848A true JPH0390848A (en) | 1991-04-16 |
Family
ID=16879768
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP22865789A Pending JPH0390848A (en) | 1989-09-04 | 1989-09-04 | Gas sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0390848A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03162656A (en) * | 1989-11-20 | 1991-07-12 | Fuji Electric Co Ltd | Gas sensor |
| KR19990057110A (en) * | 1997-12-29 | 1999-07-15 | 구자홍 | Hydrocarbon Gas Sensor Manufacturing Method |
| KR100551225B1 (en) * | 2002-05-10 | 2006-02-09 | 전자부품연구원 | Method for the preparation of catalyst-dopped tin oxide powders for a semiconductor-type gas sensor |
-
1989
- 1989-09-04 JP JP22865789A patent/JPH0390848A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03162656A (en) * | 1989-11-20 | 1991-07-12 | Fuji Electric Co Ltd | Gas sensor |
| KR19990057110A (en) * | 1997-12-29 | 1999-07-15 | 구자홍 | Hydrocarbon Gas Sensor Manufacturing Method |
| KR100551225B1 (en) * | 2002-05-10 | 2006-02-09 | 전자부품연구원 | Method for the preparation of catalyst-dopped tin oxide powders for a semiconductor-type gas sensor |
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