KR100867576B1 - SnO2-BASED SENSOR AND MANUFACTURING METHOD AT THE SAME - Google Patents

Abstract

The present invention relates to a tin oxide sensor and a method for manufacturing the tin oxide sensor with improved recovery ability while maintaining high sensitivity by adding another metal oxide to the tin oxide.

To this end, the present invention, the substrate, the electrode formed on the upper surface of the substrate, and covers the electrode, the detection made by adding antimony oxide (SbO ₂ ) and molybdenum oxide (MoO ₂ ) to tin oxide (SnO ₂ ) A tin oxide sensor including a sensing film formed of a material and a heater formed on a bottom surface of the substrate and a manufacturing method thereof are provided. As such, the sensing material prepared by adding antimony oxide and molybdenum oxide to tin oxide has good recoverability.

In addition, if the sensing material is prepared by adding nickel oxide to tin oxide, the sensitivity is good.

Gas sensor, tin oxide, pseudochemical agent, metal oxide

Description

Tin oxide sensor and its manufacturing method {SnO2-BASED SENSOR AND MANUFACTURING METHOD AT THE SAME}

1 is a graph showing the sensitivity characteristics with respect to the DMMP of the conventional SnO ₂ sensor over time,

2 is a view showing a SnO ₂ sensor according to an embodiment of the present invention, (a), (b), (c) is a plan view, a back and a cross-section of the sensor, respectively,

3 is a view showing the configuration of an apparatus for measuring a chemical agent-like gas according to the present invention;

4 is SnO ₂ for DMMP by adding a metal oxide such as _{NiO, Y 2 O 3, Nb} 2 O 5, Sb 2 O 3, MoO 3 using the apparatus of Figure 3 on SnO ₂ A graph showing the recovery characteristics of the sensor,

5 is a graph showing a reaction curve for 0.5 ppm DMMP at 350 ° C. by adding 3 wt% of Sb ₂ O ₃ and 3 wt% of another metal oxide to SnO ₂ according to one embodiment of the present invention;

6 is 0.5 ppm at 350 ° C. of a SnO ₂ sensor in which 5 wt% of MoO ₃ and Sb ₂ O ₃ are added in amounts of 1 wt%, 3 wt%, 5 wt%, and 7 wt% according to the present invention. Response curve for DMMP,

FIG. 7 shows SnO ₂ sensors with 3 wt%, 5 wt%, 10 wt% and 15 wt% of MoO _{3 added} to 1 wt% Sb ₂ O ₃ for 0.5 ppm DMMP at 350 ° C. according to the present invention. Response curve,

8 is a graph showing a sensitivity change with time for a SnO ₂ sensor to which two components of Mo (5 wt%) and Sb (1 wt%) are added according to a first embodiment of the present invention;

FIG. 9 is a graph showing a sensitivity change with time for DMMP of a SnO ₂ sensor to which Ni (2 wt%), Mo (5 wt%), and Sb (1 wt%) are added according to a second embodiment of the present invention. ,

Figure 10 shows the sensitivity variation with temperature of the SnO ₂ sensor metal oxide is added in accordance with the first and second embodiments of the present invention and the conventional SnO ₂ sensor graph,

Figure 11 is a graph showing the changes in sensitivity of the DMMP concentration of SnO ₂ sensors metal oxide is added in accordance with the first and second embodiments of the present invention and the conventional SnO ₂ sensor.

* Description of the main parts of the drawings *

10 substrate 20 comb-shaped electrode

30: detection film 40: heater

41 electrode 100 sensor

The present invention relates to a gas sensor, and more particularly, to a SnO ₂ sensor and a method of manufacturing the same, which have improved recovery capability while maintaining high sensitivity by adding another metal oxide to tin oxide.

With the first use of chlorine gas as a modernized chemical agent in World War I, chemical agents continued to be used until now in the Gulf War. Chemical agents are liquids or solids that emit toxic gases or vapors that can kill or injure people by inhalation or contact. In addition, the chemical agent is a substance that causes fatal damage to the human body even at low concentrations, and quickly becomes unconscious and lethal state when exposed.

Types of such chemical agents include blood, suffocation, nerve, blistering agents, and chemical agents used for each and similar gases are shown in Table 1 below.

Classification of chemical agents Chemical agent Pseudo gas Blood agents HCN Acetonitrile Nerve agent Tabun Dimethyl methyl phosphonate Choking agent Phosgene Dichloromethane Blister Mustard Dipropylene glycol methyl ether

Equipment has long been developed to detect these highly toxic chemical agents. In order to detect this, the measuring equipment measures the chemical agent in the air by using GC, GC-MS, etc. for accurate analysis, and the portable equipment uses the detection paper or the detection tube (Detection paper) by using the substance reacting with the chemical agent. After detection in the detection tube), it was confirmed through the change of color, and it was used as equipment such as Flame Photometric Detection, Photoionization Detection, CAM using elemental analysis and mass spectrometry using the principle of analysis equipment. Chemical agents were detected. However, the equipment using the reaction with the chemical agent is inexpensive, but the chemical agent of low concentration is not detected, and the equipment using the principle of the analysis equipment has the disadvantage of being slow and expensive. In order to make up for these shortcomings, sensors using metal oxides and SAW sensors using polymer materials are being researched to detect chemical agents at low cost. Among them, metal oxide sensors have fast response characteristics to organic compounds such as chemical agents, and are currently being researched and developed in various fields.

Since Taguchi developed a gas sensor using semiconductors in 1972, studies have been conducted to detect low levels of reducing and toxic gases in the air. In particular, the SnO ₂ sensor, which is an n-type semiconductor, is known to be caused by a change in the electrical conductivity of an oxide due to the reaction of oxygen adsorbed on the surface with a reducing gas such as CO or a hydrocarbon. SnO ₂ sensor has the advantage of higher sensitivity and selectivity with lower power consumption and fast response speed by using various additives with higher sensing effect than other oxides. In particular, for acetonitrile (CH ₃ CN), SnO ₂ sensors have been reported to have better sensing performance than other metal oxide sensors.

However, there is a need to develop an economical sensor that is more precise, more selectable, and capable of operating at lower temperatures. For this purpose, a sensor having high sensitivity and high selectivity by using various kinds of additives to a parent material such as tin oxide is required. Efforts to manufacture the race are racing.

In addition, methods for producing a very fine particle size of the parent material itself have been reported to improve sensitivity and increase selectivity.

However, the SnO ₂ sensor does not recover after sensing of dichloromethane (CH ₂ Cl ₂ ), an organophosphorus compound that is the most similar neurochemical agent among nerve agents, and a similar chemical agent of the asphyxiating agent. This is due to the fact that Berger uses the organophosphorus dimethylmethyl phosphonate (DMMP) in the SnO ₂ sensor, and Kim is able to change the resistance of the organophosphorus DMMP in the TiO ₂ and WO ₃ sensors. Through the IR analysis, the mechanism did not recover after the reaction. This can be clearly seen with reference to the experimental graph showing the sensitivity characteristics with respect to the DMMP of the conventional SnO ₂ sensor over time, as shown in FIG. Here, in the experiment of FIG. 1, the experiment was performed at around 350 ° C., which is a temperature at which the resistance value is stable compared to the temperature change of the sensor, and to observe the sensitivity and recovery of the SnO ₂ gas sensor with respect to 0.5 ppm of DMMP. After 10 minutes of injection, measure the sensitivity and put the dried air to determine the recovery, the experiment was repeated three times the result is a graph.

Referring to FIG. 1, it can be seen that the conventional SnO ₂ sensor does not recover at all after the detection despite the high sensitivity of 60% for DMMP.

The present invention while maintaining a high sensitivity of as, SnO ₂ sensor made in view of solving the problems as described above, the recovery properties increase SnO ₂ It is an object to provide a sensor and a method of manufacturing the same.

In particular, it is an object of the present invention to provide a SnO ₂ sensor excellent in sensitivity and recovery ability in a low concentration gas such as a nerve agent of DMMP, and a manufacturing method thereof.

In order to achieve the above object, according to an aspect of the present invention, the substrate, the electrode formed on the upper surface of the substrate, and covers the electrode, the tin oxide (SnO ₂ ) to the antimony oxide (SbO ₂ ) and molybdenum Provided is a tin oxide sensor including a sensing film formed of a sensing material made by adding oxide (MoO ₂ ) and a heater formed on a bottom surface of the substrate. As such, the sensing material prepared by adding antimony oxide and molybdenum oxide to tin oxide has good recoverability.

In addition, the antimony oxide is in the range of 0.1 to 20% by weight, and the molybdenum oxide is in the range of 0.1 to 30% by weight relative to the total weight of the sensing material.

In addition, the sensing material is characterized in that it further comprises nickel oxide. At this time, the sensing material prepared by adding nickel oxide to tin oxide has good sensitivity.

In addition, the antimony oxide is in the range of 0.1 to 20% by weight, the molybdenum oxide is in the range of 0.1 to 30% by weight, and the nickel oxide is in the range of 0.1 to 5% by weight relative to the total weight of the sensing material. .

In addition, the substrate is an alumina substrate, the electrode is made of a pair of platinum electrodes, the heater is characterized in that the resistor made of platinum having a pair of electrodes.

According to another aspect of the invention, forming an electrode on the upper surface of the substrate, and covers the electrode, by adding antimony oxide (SbO ₂ ) and molybdenum oxide (MoO ₂ ) to the tin oxide (SnO ₂ ) to form a sensing film. It provides a method of manufacturing a tin oxide sensor comprising the step of forming, and forming a heater on the lower surface of the substrate.

Further, in the sensing film forming step, the antimony oxide is in the range of 0.1 to 20% by weight, and the molybdenum oxide is added in the range of 0.1 to 30% by weight based on the total weight.

In addition, in the forming of the sensing film, nickel oxide is further added.

In addition, in the sensing film forming step, the antimony oxide is in the range of 0.1 to 20% by weight, the molybdenum oxide is in the range of 0.1 to 30% by weight, nickel oxide is added in the range of 0.1 to 5% by weight relative to the total weight It features.

The sensing film may be formed by any one of a screen printing method and a plasma film deposition method.

In addition, the tin oxide sensor is characterized in that it is produced by a process by any one of the physical mixing method, impregnation method, co-precipitation method or a combination of two or more of these.

Hereinafter, a preferred embodiment of the present invention shown in the accompanying drawings will be described in detail.

First, Figure 2 is a view showing a SnO ₂ sensor 100 according to an embodiment of the present invention, (a), (b), (c) is a plane, back and cross-section of the sensor, respectively.

The sensor 100 is made of a sensing material according to the present invention, and an alumina (Al ₂ O ₃ ) substrate may be used as the substrate 10, and a pair of upper surfaces of the substrate 10 facing each other. A platinum (Pt) electrode 20 of a comb-tooth type (IDT (interdigit) type) is formed, and a heater 40 made of platinum is formed on the lower surface.

In addition, the substrate 10 may be a substrate such as SiO _{2 in} addition to the alumina, and the heater 40 may have a pair of platinum electrodes 41 and a platinum paste may be applied to a resistor having a resistance of 10 kV. .

In addition, the sensing material used in the sensor 100 may cover the comb portion of the pair of comb-shaped electrodes 20 and form the sensing film 30.

The sensing film 30 is pulverized the sensing material with agate mortar (agate mortar) to make a powder, and then to the powder by adding α-terpineol into a slurry having a suitable viscosity (slurry), the resulting slurry 6 × 5 A thick film can be formed on the substrate with a size of mm ² by screen printing. In this case, in addition to the screen printing method described above, various methods of forming the sensing film may include various sensing film deposition methods such as forming a sensing film through plasma deposition.

In order to grasp the characteristics of the SnO ₂ sensor 100 made as described above was configured the device as shown in FIG.

The measurement gas was calculated using DMMP, a gas similar to that of a neurochemical agent, to calculate the vapor pressure of the measurement gas and temperature control with a water bath to vaporize the measurement material to a certain concentration in the saturator 5. Here, the measurement for the DMMP is taken as an example, but is not limited thereto, and may also be possible for dichloromethane, which is a similar gas of asphyxiation chemical agent.

The concentration was adjusted by first diluting the dried gas to air vaporized, and diluting a predetermined amount of the diluted gas with the dried air again. All experiments were performed under flow conditions of 1000 ml / min, the flow rates were all controlled with a mass flow controller (MFC) and quantified with a flow calibrator. The chamber (6) used in this experiment has a volume of 2L, and the material is made of stainless steel so that the flow of fluid can be circulated. After flowing and stabilizing, the measurement gas was injected for 10 minutes. The temperature of the sensor was controlled by flowing a DC current, and the temperature was confirmed by a spot thermometer. The electric circuit 7 applied a voltage of DC 5V from the power supply 9 and processed the signal of the sensor 100 measured by the computer 8. Reference numerals 1, 2, 3, and 4 are valves for gas flow control, respectively, check va1ve, three-way valve, two-way valve, and metering valve, respectively. ). In addition, a reference gas line connected to the valve to introduce the reference gas, a measurement gas line for introducing the measurement gas, a measurement line for introducing the reference gas or the measurement gas into the reaction tank, and the reference gas or measurement gas to the outside A vent line for venting.

The following equation was calculated as the change rate (%) of the resistance value (R _a ) in the dry air before the measurement gas was injected and the resistance value (R _g ) after the injection of the measurement gas by the sensitivity (S) of the sensor. The highest value of the minutes of sensitivity was calculated as the sensitivity of the sensor.

In the SnO ₂ sensor 100 according to the present invention, the sensing material is a metal oxide semiconductor, and another metal may be additionally added to SnO ₂ , which will be described below.

4 is SnO ₂ for DMMP by adding a metal oxide such as _{NiO, Y 2 O 3, Nb} 2 O 5, Sb 2 O 3, MoO 3 using the apparatus of Figure 3 on SnO ₂ This graph shows the recovery characteristics of the sensor.

As can be seen in Figure 4, the conventional SnO ₂ for DMMP, a pseudonerve The sensor did not recover after detection (see curve in FIG. 4 (a)). In addition, the sensor's recovery ability was calculated for an accurate comparison of recovery ability. The following equation was calculated as the percentage change in sensitivity (S _r ) after 7000 seconds with little change in sensitivity and maximum sensitivity (S _m ) of the sensor.

The experiment of FIG. 4 shows the sensitivity of 0.5 ppm DMMP at 350 ° C. for a sensor fabricated after adding 3 wt% of various metal oxides to SnO ₂ to determine the effect of the addition of metal oxides on the recovery of DMMP. Was measured and the results are shown.

Referring to FIG. 4, in the case of Ni3 (b), Y3 (c), and Nb3 (d) sensors in which 3 wt% of NiO, Y ₂ O ₃ , and Nb ₂ O ₅ were added to SnO ₂ , the conventional SnO ₂ sensor It showed better sensitivity (a), but hardly recovered. While 3 wt% of MoO ₃ Alternatively, Mo3 (e) and Sb3 (f) sensors, in which Sb ₂ O ₃ was added to SnO ₂ , showed some recoverability despite low sensitivity.

Table 2 compares the sensitivity of each of the sensing materials used in FIG. 4 with the sensitivity after 7000 seconds, and calculates the recovery capability using Equation 2.

Sensing substance Sensitivity (%) % Sensitivity after 7000 seconds Recovery Ability (%) (a) SnO ₂ 55 54 2 (b) Ni3 83 83 0 (c) Y3 78 77 One (d) Nb3 70 74 -6 (e) Mo3 35 25 29 (f) Sb3 40 10 67

According to Table 2, as a result of comparing the recovery capacity, the recovery capacity is the highest (67%) for the Sb3 sensor (f) in which Sb ₂ O ₃ is added to SnO ₂ . Therefore, it can be confirmed that Sb ₂ O ₃ affected the recovery of SnO ₂ .

In addition, experiments were performed by adding another metal additive to Sb3 in order to obtain higher recovery ability by adding other metal oxides in addition to Sb ₂ O ₃ which increased the recovery ability to DMMP.

FIG. 5 is a graph showing a reaction curve for 0.5 ppm DMMP at 350 ° C. by adding 3 wt% Sb ₂ O ₃ and 3 wt% of other metal oxides to SnO ₂ .

As shown in FIG. 5, the Mo ₃ Sb 3 sensor added 3 wt% MoO ₃ to 3 wt% Sb ₂ O ₃ showed higher sensitivity and recoverability than the sensor added 3 wt% other metal oxide. .

Table 3 compares the sensitivity of each of the sensing materials used in FIG. 5 with the sensitivity after 7000 seconds and calculates the recovery capacity by the above equation.

Sensing substance Sensitivity (%) % Sensitivity after 7000 seconds Recovery Ability (%) (a) Mo3Sb3 50 21 58 (b) Ni3Sb3 34 24 29 (c) Y3Sb3 33 20 39 (d) Nb3Sb3 30 20 33

When compared with Table 3, 3 wt% of NiO, Y ₂ O ₃ , and Nb ₂ O ₅ were added to 3 wt% Sb ₂ O ₃ , resulting in less than 0% sensitivity and recoverability. Mo3Sb3 sensor with ₃ added showed the highest sensitivity and recovery with 50% sensitivity and 58% recovery. Therefore, when MoO ₃ and Sb ₂ O ₃ are added together, the highest sensitivity is 50% and the recovery capacity is 58%.

Accordingly, as a first embodiment, a metal oxide in which two components of Mo and Sb are added to SnO ₂ oxide may be added. At this time, the weight of the metal atom added in the first embodiment may be various modifications in the range of 0.1 to 30% by weight for the metal atom Mo and 0.1 to 20% by weight for Sb.

6 and 7 after confirming that the addition of MoO ₃ and Sb ₂ O ₃ affect the recovery, the sensitivity is measured by varying the amount of each addition to know the effect on the addition amount of MoO ₃ and Sb ₂ O ₅ respectively. One result is shown.

6 shows 0.5 ppm DMMP at 350 ° C. of a SnO ₂ sensor with varying amounts of 5 wt% MoO ₃ and Sb ₂ O ₃ at 1 wt%, 3 wt%, 5 wt%, 7 wt%. Response curve. Was fully recovered both of the above sensor, after 7000 seconds, more especially Sb ₂ O ₃ showed the highest sensitivity to 1, 41% wt% into Mo5Sb1 sensors increase the amount of Sb ₂ O ₃ was reduced sensitivity.

Table 4 compares the highest sensitivity of the sensor with 5 wt% MoO ₃ and the different amounts of Sb ₂ O ₃ used in FIG. 6 and the sensitivity after 7000 seconds, and calculates the recovery capacity according to the above equation.

Sensing substance Sensitivity (%) % Sensitivity after 7000 seconds Recovery Ability (%) (a) Mo5Sb1 41 One 98 (b) Mo5Sb3 37 2 95 (c) Mo5Sb5 30 2 93 (d) Mo5Sb7 26 2 92

As can be seen from Table 4, Mo5Sb1 sensor has the highest sensitivity of 41% and the highest recovery capacity of 98%. Therefore, it can be confirmed that Sb ₂ O ₃ can obtain the highest sensitivity when 1 wt% is added.

FIG. 7 is a response curve of a SnO ₂ sensor adding 3 wt%, 5 wt%, 10 wt%, and 15 wt% of MoO ₃ to 1 wt% of Sb ₂ O ₃ for 0.5 ppm DMMP at 350 ° C. FIG. . In this experiment, the sensitivity and recovery for DMMP were observed by varying the amount of MoO ₃ added with 1 wt% of Sb ₂ O ₃ , which showed the highest sensitivity. When 3 wt% of MoO ₃ was added, the recovery was very slow and did not completely recover even after 7000 seconds. There was no significant difference in recovery capacity when 5 wt% or more was added. However, sensitivity increased slightly as the amount of MoO ₃ added.

Table 5 compares the highest sensitivity of the sensor with 1 wt% Sb ₂ O ₃ and different amounts of MoO ₃ used in FIG. 7 and the sensitivity after 7000 seconds, and calculates the recovery capacity according to the above equation.

Sensing substance Sensitivity (%) % Sensitivity after 7000 seconds Recovery Ability (%) (a) Mo3Sb1 56 21 63 (b) Mo5Sb1 41 One 98 (c) Mo10Sb1 37 6 84 (d) Mo15Sb1 28 3 89

Table 5 shows the sensitivity and the recovery ability according to the change of MoO ₃ addition amount, and the highest sensitivity and the recovery capacity were shown when 1 wt% Sb ₂ O ₃ and 5 wt% MoO ₃ were added to C-SnO ₂ . It was. The addition of Sb ₂ O ₃ 1 wt% and MoO ₃ 5 wt% is the optimal composition of the SnO ₂ sensor for DMMP detection.

On the other hand, in the second embodiment, in addition to the two components of Mo and Sb, a metal oxide added with three components further including Ni may be added. It is best to add the Mo and Sb metals described above with respect to the recovery ability, and when Ni is added thereto, the sensitivity may be improved while maintaining the recovery capability. In this case, the weight of the metal atoms added in the second embodiment may be various modifications to the Ni, Mo, Sb metal atoms, the optimum weight ratio for the Ni, M0, Sb is 2wt%, 5wt, respectively % And 1wt%. In addition, the added specific gravity of Ni may be applied in the range of 0.1 to 5wt% or less relative to the total weight.

Hereinafter, the experimental results of the sensitivity and the recoverability characteristics, etc. for the DMMP of the SnO ₂ sensor according to the first and second embodiments of the present invention will be described.

FIG. 8 is a graph showing a sensitivity change with time for a SnO ₂ sensor to which two components of Mo (5 wt%) and Sb (1 wt%) are added according to a first embodiment of the present invention. Referring to FIG. 8, it can be seen that the recovery capacity for DMMP is increased (98% recovery capacity) than the conventional SnO ₂ sensor.

FIG. 9 is a graph showing a sensitivity change with time for DMMP of a SnO ₂ sensor to which Ni (2 wt%), Mo (5 wt%), and Sb (1 wt%) are added according to a second embodiment of the present invention. to be.

Referring to FIG. 9, the sensor according to the second embodiment maintains a higher recovery capacity (71%) for DMMP than the existing SnO ₂ sensor like the sensor according to the first embodiment, and according to the addition of Ni, according to the first embodiment. It may have improved sensitivity characteristics than the example. That is, it can be seen that about 30% is increased from about 40% to about 70% of the first embodiment.

Table 6 summarizes the sensors according to the first and second embodiments of the present invention described above.

Sensor name Parent material Weight (wt)% Metal (Metal Oxide Catalyst) Weight (wt)% First Embodiment (Mo5Sb1) SnO ₂ 94 Mo (MoO ₃ ) 5 Sb (Sb ₂ O ₃ ) One Second Embodiment (Mo5Sb1Ni2) SnO ₂ 92 Ni (NiO) 2 Mo (MoO ₃ ) 5 Sb (Sb ₂ O ₃ ) One

Here, the tin oxide base material (SnO ₂₎ is, there is a SnO ₂ produced commercially _{SnO 2 (99.9%, 325 mesh} ) and the precipitation method may be used.

In addition, a method of manufacturing a SnO ₂ sensor according to the first and second embodiments of the present invention by adding a metal to SnO ₂ as a parent material may use a physical mixing method, an impregnation method, a coprecipitation method, a sol-gel method, or the like. have. In this case, the SnO ₂ sensor may be manufactured by a process by a combination of two or more of the physical mixing method, impregnation method, coprecipitation method, sol-gel method.

First, according to the physical mixing method, a certain amount of MoO ₃ , Sb ₂ O ₃ or NiO, MoO ₃ , Sb ₂ O ₃ is physically mixed with SnO ₂ for at least 1 hour, and then agate mortar for at least 1 hour. It was pulverized to, and can be prepared by firing at 600 ℃ for 4 hours at a temperature increase rate of 3 ℃ / min to increase the stability of the material. At this time, in the first embodiment, the weight% of the added metal atoms to the total weight is preferably Mo (5 wt%) and Sb (1 wt%), respectively. Further, as the second embodiment, Ni (2 wt%), Mo (5 wt%), and Sb (1 wt%) are preferable.

Next, a method for producing a sensing material by the impregnation method will be described.

The sensing material prepared by the impregnation method supported Mo and Sb or Ni, Mo and Sb in SnO ₂ . In addition, in the case of the sensing material manufactured by the impregnation method in order to be equal to the added amount of the material produced by the physical mixing method, the weight of the metal atoms is the same as the material produced by the physical mixing method, respectively, to determine the amount of the added material. .

This detection material Ammonium in distilled water molybdate Tetrahydrate Antimony (Ⅲ) to _{(H 24 Mo 7 N 6 O} 24 · 4H 2 O, 99.0%) solution and 10g of the nitric acid _{(HNO 3, 64% ~ 66} %) dissolved in acetate ( A solution of (CH ₃ CO ₂ ) ₃ Sb, 99.99%) was mixed with SnO ₂ powder in 100 g of distilled water and dried by evaporation of water using an evaporator. It may be prepared by firing at 600 ° C. for 4 hours at a temperature increase rate of ° C./min.

Sensing materials prepared by coprecipitation are prepared in a similar manner as the previous precipitation method. The sensing material prepared by the coprecipitation method precipitated Sn, Mo, Sb or Sn, Ni, Mo, Sb aqueous solution together, and the amount of the additive was adjusted to the weight percent of each metal atom in the same manner as the impregnation method, and the preparation method thereof. Was prepared by dissolving Molybdenum (Ⅴ) chloride (MoCl ₅ , 98%) in distilled water and Antimony (III) acetate ((CH ₃ CO ₂ ) ₃ Sb, 99.99%) in nitric acid (HNO ₃ , 64% ~ 66%). The dissolved solution was mixed with distilled water with SnCl ₄ solution to make a 10 wt% aqueous solution, and then 28 wt% aqueous ammonia (NH ₄ OH, 28%) was added to pH 10 to form a precipitate, and the resulting precipitate was precipitated. It can be prepared by treating in the same manner as in the method, and firing at 600 ° C for 4 hours at a temperature increase rate of 3 ° C / min.

10 is a graph showing a sensitivity variation with temperature of the SnO ₂ sensor metal oxide is added in accordance with the first and second embodiments of the present invention and the conventional SnO ₂ sensor.

In order to find the optimal sensing condition of the sensor according to the first and second embodiments of the present invention, the measurement temperature is changed to show a response curve for each sensor with respect to 0.5 ppm DMMP. Measurements were made for 0.5 ppm DMMP at 350 ° C and 400 ° C.

Referring to Figure 10, the existing Sn0 ₂ Sensors were tested at 250 ° C, 350 ° C and 400 ° C, and showed sensitivity of 63%, 60%, and 64% for each temperature for DMMP. From these results, the sensitivity of conventional SnO ₂ sensors to DMMP was not affected by temperature changes.

On the other hand, the first embodiment (Mo5Sb1) sensor of the present invention showed the sensitivity of 15%, 40%, 41% for each temperature for DMMP as a result of the experiment at 250 ℃, 350 ℃, 400 ℃. These results show that, for DMMP, the sensitivity of the first embodiment sensor of the present invention increases in proportion to the increase in temperature.

In addition, the second embodiment (Mo5Sb1Ni2) sensor of the present invention was tested at 250 ℃, 350 ℃, 400 ℃, the DMMP showed 60%, 70%, 57% sensitivity for each temperature. As a result, for DMMP, the sensitivity of the second embodiment sensor of the present invention is proportional to the increase in temperature, but the sensitivity of the second embodiment sensor at 400 ° C. is 57%, which is lower than the sensitivity 70% at 350 ° C. Sensitivity was shown. Therefore, since the second embodiment exhibits a low sensitivity of 400 ° C., it can be confirmed that optimal recovery is possible and the optimum temperature condition is measured in the sensor according to the first and second embodiments in the higher sensitivity range of 350 ° C. .

Figure 11 is a graph showing the changes in sensitivity of the DMMP concentration of SnO ₂ sensors metal oxide is added in accordance with the first and second embodiments of the present invention and the conventional SnO ₂ sensor.

As shown in FIG. 11, the reaction characteristics of tin oxide to the pseudochemical agent at low concentrations can be seen.

In addition, SnO ₂ at 0.2 ppm and 0.5 ppm DMMP at 350 ° C. The sensitivity of the sensor, the first embodiment (Mo5Sb1) and the second embodiment (Mo5Sb1Ni2) according to the present invention increased linearly, and further changes in sensitivity were observed for DMMPs of 0.5 ppm to 0.8 ppm or more. It is judged that it is in a saturation state which does not occur. This is because when the sensitivity change according to the concentration change is linear, the concentration of DMMP can be confirmed by the sensitivity of the SnO ₂ sensor. In particular, it can be seen that the sensors according to the first and second embodiments of the present invention have high sensitivity characteristics in the low concentration DMMP measurement of 0.5 ppm or less, and show the possibility of being used as a measuring instrument capable of measuring the DMMP concentration.

The metal oxide sensor according to the first and second embodiments of the present invention showed the excellent performance as a DMMP measurement sensor, and is not limited to the nerve agent-like gas DMMP, but the other It can be extended to detection.

According to the present invention, it is possible to obtain a tin oxide (SnO ₂ ) sensor with improved recovery while maintaining high sensitivity to chemical agents. In particular, when the sensing material of the sensor is prepared by adding Mo or Sb metal oxide to tin oxide, recoverability is better.

In addition, the addition of nickel oxide to produce a sensing material is better sensitivity characteristics while maintaining improved recovery.

Claims (11)

delete delete A substrate; An electrode formed on an upper surface of the substrate; A sensing film covering the electrode and formed of a sensing material made by adding antimony oxide (SbO ₂ ), molybdenum oxide (MoO ₂ ) and nickel oxide (NiO) to tin oxide (SnO ₂ ); A heater formed on the bottom surface of the substrate; Tin oxide sensor comprising a. The method of claim 3, The tin oxide, characterized in that the antimony oxide is in the range of 0.1 to 20% by weight, the molybdenum oxide is in the range of 0.1 to 30% by weight, and the nickel oxide is in the range of 0.1 to 5% by weight. sensor. The method of claim 3, The substrate is an alumina substrate, the electrode is made of a pair of platinum electrodes, the heater is a tin oxide sensor, characterized in that the resistor made of platinum having a pair of electrodes. delete delete Forming an electrode on the upper surface of the substrate; Forming a sensing layer covering the electrode by adding antimony oxide (SbO ₂ ), molybdenum oxide (MoO ₂ ), and nickel oxide (NiO) to tin oxide (SnO ₂ ); Forming a heater on a bottom surface of the substrate; Method for producing a tin oxide sensor comprising a. The method of claim 8, In the sensing film forming step, the antimony oxide is in the range of 0.1 to 20% by weight, the molybdenum oxide is in the range of 0.1 to 30% by weight, and the nickel oxide is added in the range of 0.1 to 5% by weight based on the total weight. Method for producing a tin oxide sensor. The method of claim 8, The sensing film is a method of manufacturing a tin oxide sensor, characterized in that formed by any one of a screen printing method or a plasma film deposition method. The method of claim 8, The tin oxide sensor is manufactured by any one of a physical mixing method, impregnation method, coprecipitation method, sol-gel method or a process by a combination of two or more thereof.

Images