JPS5855643B2 - Kanshitsusoshi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a humidity sensing element that is made of an oxide semiconductor and detects humidity as a change in electrical resistance.

As is well known, this is generally a metal oxide (Fe3O4).

Fe2O3+ Al2O3, Cr2O3, etc.) have excellent water absorption properties and can be used as moisture sensing elements.

In other words, this method takes advantage of the fact that the electrical resistance of a layer formed by depositing this type of metal oxide fine powder on the surface of an inorganic insulating substrate having a pair of opposing electrodes changes significantly in response to changes in humidity. It is something.

Moisture sensing elements using fine powder of the above metal oxides are physically
Although it is chemically and thermally stable, it generally has a high specific resistance, so even if there is a slight change in resistance due to moisture absorption and desorption, it is difficult to detect this electrically with high precision.

Therefore, several attempts have been made to lower the resistivity. For example, alkali metal oxides (Li2O, K2O,
No. 20, etc.) have been added.

However, in this case, there are disadvantages that not only the humidity cycle history becomes significantly large, but also the reproducibility is poor and the change over time is large.

Accordingly, the present invention aims to provide a moisture-sensitive element in which the above-mentioned drawbacks are eliminated.

The humidity sensing element of the present invention comprises a sintered body made of Li2MeMn30B and at least one pair of electrodes, and L12MeMn30B 5 mol% or more (excluding 100 mol%), Zn095 mol % (excluding 0 mol %) is a moisture sensing element comprising at least one pair of electrodes provided on a sintered body having a composition of
e is at least one of Co, Cu, Mg, Ni, and Zn).

That is, the moisture sensing element of the present invention has a pseudospinel structure formed by sintering at least one of cobalt carbonate, copper oxide, magnesium carbonate, nickel oxide, and curved lead oxide, as well as notium carbonate and manganese carbonate. M e M
The main body is obtained by using n 30 g as an essential component, mixing zinc oxide if necessary, press molding, and sintering.

LiMeO powder which is the main component in the present invention is, for example, Li2CO32MeO (Me=Co, Cu2MgNi,
at least one type of Zn) and M n CO3
: accurately weighed in a molar ratio of 1:3, mixed well in a ball mill, pre-calcined at a temperature of about 700°C for about 1 hour, and pulverized (this makes it easy to obtain). .

Therefore, the moisture sensitive element of the present invention has the above-mentioned Li2MeMn30
It can be obtained by press molding and firing using only 8 powder or a mixture of L i2 M e M 130 B powder and Zno powder as raw materials.

However, when adding and mixing the ZnO component, the composition ratio needs to be selected to be 95 mol % or less.

The reason for this is that if the composition ratio of ZnO is 95 mol % or more, the range of change in resistance value with respect to humidity becomes small, making it unsuitable for practical use.

Next, the present invention will be explained by giving specific examples.

First, Li2CO3, MeO (Me=Co, Cu, M
g.

At least one of Ni and Zn) and MuCO3 were accurately weighed at a molar ratio of 1:1:3, and thoroughly mixed using a ball mill.

Thereafter, this mixture was pre-calcined at 700°C for 1 hour and then ground in a ball mill to obtain Li2MeMng.
06 (at least one of MeCo, Cu, Mg, Ni, and Zn) was obtained.

The L i2 M e M n 30 B powder thus obtained and the ZnO powder were selected and mixed in the composition ratio (mol %) shown in the following table, and 48 types of raw materials including comparative examples were prepared and prepared.

Next, polyvinyl alcohol (binder, 1) was added to the raw material powder and press-molded at a pressure of 1 ton/-.
Heat and sinter at a temperature of 800 to 1300℃ for 2 hours to a thickness of 1
During this time, a disk-shaped sintered body with a diameter of 20 mm was obtained.

Iron paste was baked on the main surface of this disc-shaped sintered body, a pair of electrodes were provided, and lead wires were soldered to each to produce a moisture-sensitive element.

FIG. 1 is a plan view of the above-mentioned humidity sensing element, in which 1 is a sintered body, 2 and 2' are electrodes, and 3 and 3' are lead wires.

Table 2 shows the relationship between relative humidity and resistance value for the humidity sensing elements obtained as described above.

FIG. 2 shows the relative humidity-resistance value characteristics of Example 31.

It showed stable characteristics with no deviations due to humidity cycles.

FIG. 2 (For reference, a magnetite colloid type case is also shown as a conventional example.

Further, Examples 21, 33, and 3'H were left for 1000 hours at 40 DEG C. and 95% relative humidity, and the changes in characteristics (resistance value-humidity relationship) over time were determined, as shown in FIG.

As is clear from the figure, Li2MeMn according to the present invention
The 308 series moisture sensing element shows almost no change in resistance value and remains stable over time.

As described above, the humidity sensing element according to the present invention always exhibits the required characteristics, does not deviate due to humidity cycles, and has a large resistance change with respect to humidity changes, so it is possible to accurately measure humidity. In combination with its ease of manufacture and ease of handling, it can be said that it brings many practical advantages.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an example of the configuration of a moisture-sensitive element according to the present invention;
FIG. 2 is a characteristic diagram showing an example of the relationship between relative humidity and resistance value for the humidity sensing element according to the present invention, and FIG. 3 is a diagram showing an example of the aging characteristics of the humidity sensing element according to the present invention. .

Claims (1)

[Scope of Claims] A moisture-sensitive element comprising at least one pair of electrodes on a sintered body made of I Li2MeMn308 (Me=at least one selected from Co, Cu, Mg, Ni, and Zn). 2 L i2 M e M n 30 g (Me=C
o, Cu, Mg, Ni, Zn) 5 mol% or more (excluding 100 mol%), Z
A moisture sensing element comprising at least one pair of electrodes on a sintered body having a composition of n095 mol% or less (excluding 0 mol%).