JPS58212101A - Moisture sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Regarding Sa, it is also UJ.

Conventional humidity sensors are mostly made of organic or ceramic materials as moisture sensing elements. Most humidity measurements utilize changes in blind resistance due to adsorption of water (a) and (v) onto a humidity sensitive body. Humidity sensors need to be able to easily absorb and desorb moisture, and it is necessary to return the surface to its pre-adsorption surface state by heating and cleaning. When an organic material is used as a moisture sensitive member, there is a drawback that heating cleaning is not possible due to poor heat resistance.

When using a ceramic material as a moisture sensitive body, it is also necessary that it can easily absorb and desorb moisture.

Even in the case of metal oxide ceramic materials, the surface structure of many materials changes due to high-temperature TJO thermal cleaning, and many materials cannot be used repeatedly.

In addition, in the conventionally known ceramic humidity sensing element, the change in conductivity due to changes in humidity is approximately // at humidity θ% to 100%.
It is of the order of 0'. However, in order to increase the sensitivity, it is necessary that the change in conductivity be even larger.Therefore, it has been desired to develop a material with a change in conductivity that is even larger than the above.

The strained invention has a porous structure and has good hygroscopicity.
, Zr2Si,PO1, , and sonoZ. r<Mg
．． T-darium is substituted with divalent elements such as Zn, trivalent elements such as rare earth elements and Sc, and divalent elements such as Ti. C.
To provide a humidity sensor that has high sensitivity and can withstand repeated use over a long period of time.

The present invention will be explained in detail below.

A moisture-sensitive body used for a humidity sensor must have a high dependence of electrical resistance on humidity and good moisture adsorption/desorption properties.Li, Zr28i, P
O,z Gt is originally a solid electrolyte with Li ion conductivity, and its crystal structure also has a three-dimensional network structure and exhibits a porous structure. Therefore, this type of material is extremely hygroscopic and has a hygroscopicity of 10-/! ; Moisture is easily removed by immediate heat treatment at around 0°C, and crystals are destroyed by repeating this process.
There is no change in the surface structure.

Li, Zr, 8i, PO,, 9J conductivity number, at room temperature and humidity 0%, ~mi x lOΩα1, but humidity jS
%, it increases to ko×fθ ΩclIL, and the amount of change reaches T on the order of ~lθ6σ.

Li3Zr, Si, PO,, c2, its Zry22 valence -
It can be replaced with trivalent and ferrovalent elements. Zn, Mg% rare earth elements (Snx (3d, Dy, La, etc.) Tii2,
Both n and Zr are substituted up to at% by Zr92 to obtain a solid solution.

Further, 8c is dissolved in solid solution at 2 jat% I.

Lt, Zr25+2P0,2('JZr k upper kl(l
Jj The dry part of the material substituted with sea urchin, the conductivity at humidity Q%, Lt, Zr25 +, PO,,'-'it rate]
-～-; T: ;h/ri. Also, since the conductivity at high humidity is almost the same, the conductivity changes due to changes in humidity! increases by substitution of Zr number at% σ].

Next, the present invention will be explained along with examples.
These are not intended to be limiting in any way.

Example 1 1e, wet body L/TE L 13Zr2S i, PO,,
2. Let's talk about e-bai. The element structure P is shown in FIG. The basic structure is that silver electrodes 1 are formed on both sides of the moisture sensitive body, and lead terminals 2 for measurement are attached to these. The electrode is
Not only silver, but also Au, Pi, AJI, Pd, A
It is also possible to use a device such as g-Pd, and measure the humidity by passing a minute current (CIO~lθ0μA) through this element and measuring the voltage change, or by directly measuring the resistance change. A giant monkey.

Next, the preparation of the humidity sensitive body will be described. Ding, starting material
Le Na, CO8, ZrO,, 5i (J2, NH, H, P
After being inserted and mixed so that the composition formula becomes O, +Na, Zr, Si, PO, □, it is burned in the air at 1000° C. for 6 hours. Grind this n and mix it with 10 times the weight ratio [,
1No3'? Add r and heat treat at 350℃ for 2g hours in a platinum crucible? ion replacement of Na and Li.

This? Excess LiNO3 and NaNO3 are removed by thoroughly washing with water, and then dried. Obtained nT-Li, Zr
25i2PO,, powder H-, tgθ℃! ;00k
It was produced by a hot press method for two hours at a press pressure of "g/cdσ". Using this material, a T-element shown in FIG. 1 was manufactured and its resistance was measured. Figure 2 shows the humidity dependence of resistance (T0 resistance value O), which changes exponentially with changes in humidity (T7). For example, if the temperature is 0°C, the humidity θ%
Notosa 17
3 indicates a 6-digit change. I'r-, the reversible surface also has a small resistance difference when scanning from high humidity to low humidity.
It is easily restored to its original state by heat treatment ET at lQO~tso''c.

Example 2 Li, Zr, Si, PO,, Zr 2Zn, ~ig,
Sm, Gd.

Sc, Ti substituted Sita, Li, Zr, JZn,), 5i
2PO1,, L 13Z rlJMg62812 P
C>12, L 13J) 5 Z rI, g Smo,
S 12 P 011, L l B, B5 Z r
HJGd6J812 P (J12, L 131Z r
l, 755C62s S12 P C%2・and Li,
A humidity sensor using Zr, JTi, 8i, PO, as a humidity sensor was fabricated. The structure is the same as in Example 1. Preparation of Ceramic Material as Humidity Sensing Body G=Additional elements were weighed and added according to the compositional formula at the stage of starting raw materials, and the rest was produced in the same manner as in Example 1.

The humidity dependence of the electrical resistance of a sensor using a stiff material as a humidity sensitive body is determined by the following equation: Li, Zr, Si2)
Although it is almost the same as when &0°P is used, the amount of change in electrical resistance with respect to humidity is large due to the small conductivity in the dry area.

As explained above, Li, Zr, 5i2 according to the present invention
PO,! The humidity sensor inside the thread material is L i, Z r
, S i, PU, , due to its good hygroscopicity and the large change in conductivity caused by adsorbed moisture, it is highly resistant to changes in humidity.
It exhibits a resistance change on the order of 6Ω or more. As described above, a humidity sensor using this material as a moisture sensitive element has high sensitivity.

[Brief explanation of drawings]

Figure 1 is a sectional view of the humidity sensor according to the present invention, and Figure 2 is L.
3 is a graph showing the humidity dependence of the resistance of an element using i, Zr, Si, POl, and the like. A...Moisture sensitive body, l...electrode, 2...
...Lead terminal. Dejojin Nippon Telegraph and Telephone Public Corporation Figure 1

Claims (1)

[Claims] 1. A humidity sensor characterized in that a porcelain composition of Li, Zr2Si, PO, etc. is used as a humidity sensor. 2. Li, Zr28 t2Po, , Zr is Q~
divalent, trivalent, φ-valent elements such as z'v1g, Zn, rare earth elements, and Ti, or θ in the range of gat%.
8c chairs or more than 1- in the range of ~ kota at%
A humidity sensor characterized by using a porcelain composition obtained by replacing the above as a humidity sensor.