JPS63270354A - Sintered pyroelectric ceramics - Google Patents

Abstract

PURPOSE:To obtain a calcined pyroelectric ceramic giving a sensor having excellent infrared detection capability, by adding NiSnO3 and MnO2 and/or Cr2O3 to a specific ternary oxide at specific ratios. CONSTITUTION:Raw materials necessary for giving an oxide of formula [0.55<=x<=0.79; 0.2<=y<=0.35; 0.01<=z<=0.1; (x+y+z=1)] are weighed and mixed. The mixture is mixed with 2-15mol. of NiSnO3 (based on 100mol. of the oxide) and 0.1-3pts.wt. of MnO2 and/or Cr2O3 (based on 100pts.wt. of the sum of NiSnO3 and the oxide of formula). The mixture is formed and calcined to obtain the objective pyroelectric ceramics. Since an infrared detection element produced by using the above ceramics has excellent infrared detection sensitivity and high Curie point, no deterioration in the function of the element occurs even by the heat of soldering.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a fired pyroelectric porcelain body suitable as a sensing element such as an infrared sensor used to detect the approach of a person or animal, the presence or absence of an object, etc.

Conventional Techniques Systems that can detect when a person or animal has invaded a specific area and notify the user of the intrusion have been used in, for example, a residence. An infrared sensor is used that can detect the emitted infrared rays.

Infrared sensors are also used for so-called non-contact temperature measurement, which detects infrared rays emitted by objects to determine their presence and movement.

Such infrared sensors include quantum type sensors that utilize semiconductor photoconduction and photovoltaic force, such as HgCdTe and P
Products using bS are known, and these have good sensitivity and excellent response, but they have problems with handling as they need to be cooled to an extremely low temperature before use, and their sensitivity is limited due to the wavelength of infrared rays. There is also the problem that they are different, so they lack versatility.

On the other hand, a pyroelectric infrared sensor has been developed, and although it is inferior to the above sensors in terms of performance such as sensitivity, it is superior in that it does not require cooling and its sensitivity is not wavelength dependent. There is.

The fired pyroelectric porcelain body used in this pyroelectric infrared sensor is an oxide with a composite perovskite structure represented by (pbl-Xcax)Ti03 (where X is a numerical value of 0.1 to 0.4). MnO, NiO-, NbzO
A fired body is known in which 0.01 to 2% by weight of one selected from s is added and blended. In general, the performance of a pyroelectric infrared sensor is determined by the evaluation index Fv=P/C,・ε(C・am/J) for the voltage generated by its pyroelectric effect.
) (Here, P (C/co?・”C) is the pyroelectric coefficient, Cv (J/, ffl・℃) is the constant volume specific heat, and ε is the dielectric constant.) When applying the pyroelectric porcelain fired body of F v = 3.5 to 5.5 (XIO-
"C-Cl1l/J), P=2~6(x1O-IC/
cI112·°C), ε=190 to 450. This pyroelectric infrared sensor is incorporated into an infrared detection device, but when soldering to a circuit board, the heat of the molten solder is transferred, so a high Curie temperature is desirable. The temperature of the above pyroelectric porcelain fired body is 200 to 400℃.
In particular, at the highest evaluation index, F v = 5.5 (XIO-"C cm/J)
, P = 3.5 (XIO-'C/d・℃), ε=1
90, and its curri point is 250″C.

Problems to be Solved by the Invention In recent years, a large number of intelligent buildings have been constructed, and many alarms have been used to prevent unauthorized entry into the buildings. However, alarm devices using the above-mentioned pyroelectric infrared sensors often malfunction. The main reason for this is that the infrared sensor inside the alarm device detects infrared rays and uses the generated signal with increased sensitivity of several tens of decibels to generate an alarm.
This is because it operates due to noise.

In order to solve this problem, it is possible to increase the evaluation index Fv to increase the infrared detection ability so that the sensitivity of the alarm signal does not need to be increased. It is desirable to reduce the dielectric constant ε and to raise the Curie temperature higher than the heat of solder when incorporating an infrared sensor.

The purpose of the present invention is that the evaluation index Fv is, for example, 6.0×10−
(C-cm/J) or more, and the Curie temperature can be made to be 250°C or more.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides an oxide having the general formula %: (where X + y + z = 1) and Te N1
5n032 to 15 mol parts, this N15nO, and 100 parts by weight of the above oxide, MnO□ and Cr, 0
The object of the present invention is to provide a fired pyroelectric porcelain body characterized by containing 0.1 to 3.0 parts by weight of at least one of the following.

Next, the present invention will be explained in detail.

In the present invention, PbTi0+ CaTi0=
Although it contains a ternary oxide of PbCu+/Jbz/:+03, the presence of PbCuIyxNbty*Ox increases the pyroelectric coefficient P, thereby increasing Fv. In addition, by increasing this P, the temperature of a single point of Curie can be increased to 250° C. or higher. The proportions of each of the above oxides are as follows: PbTiO3 is 55 mol% or more and 79 mol% or less, CaTi0z is 20 mol% or more and 35 mol% or less, PbCu 17*Nbzyx03 is 1 mol% or more and 10
If the proportion of PbCu+zJbzz03 used is less than the lower limit of the above range or exceeds the upper limit of this range, Fv cannot be increased to 6 or more. Also, P
When bTi0a is less than 55 mol%, one curri point is 25
The temperature will drop below 0℃.

Such PbTi03CaTi03 PbCu+/
N15nO+ is added to the ternary oxide of 3Nbz/zO:+, which has the effect of lowering the dielectric constant ε, thereby making it possible to further increase Fv.

Further, at least one type of MnO□ and Cr2O2, that is, one or both of them, can be used, and by using these, the sinterability can be improved. The proportion used is 0.1 to 3.0 parts by weight per 100 parts by weight of the above ternary oxide.

If it is less than 0.1, the sinterability will be poor and it cannot be used as a sensor element. On the other hand, if it exceeds 3.0, abnormal particle growth occurs, Fv becomes less than 6.0, and the pyroelectric effect deteriorates.

To produce the fired pyroelectric porcelain body of the present invention, the above-mentioned component powders are mixed using a pulverizing means such as an alumina pore mill. At this time, for example, the mixture may be wet-mixed with water, and after this mixing, water and drying may be performed.

Thereafter, this mixture is calcined for 1 to 2 hours at 800 to 900°C, and then pulverized by the above-mentioned pulverizing means to obtain a raw material powder, which may be formed into a sheet by pressing, or the above-mentioned mixture may be mixed with a resin such as polyvinyl alcohol. They may be mixed and granulated, and then formed into a sheet.

A disk of a predetermined shape is punched out from these sheets, placed in a container made of magnesia, and heated at 1100°C to 100°C, for example.
After firing at 250° C. for 0.5 to 4 hours, both surfaces of the obtained disk are polished, and a metal such as silver is deposited on the polished surfaces to form a deposited film, which is used as an electrode.

In addition, for example, silver paste is applied to the sheet and dried,
After forming the electrode coating film, it may be baked at, for example, 600 to 800°C.

The fired body with electrodes formed thereon is immersed in an insulator such as silicone oil, subjected to a polarization treatment by applying a voltage for a certain period of time, and further subjected to an aging treatment. Thereafter, it is cut into a 31×3 fin corner piece, for example, to complete a pyroelectric infrared sensor as an infrared detection element.

When this pyroelectric infrared sensor is used by incorporating it into an alarm, for example, the polarization of the infrared detection element changes due to the heat of the infrared rays, generating a potential difference, which can be detected to determine the presence or absence of infrared rays and its intensity. .

Example Next, the present invention will be explained in detail.

Example 1 PbTiOx 187.92g (62 mol parts), Ca
TiO344,87g (33 mole parts), PbCu1/
xNbzisOx 16.92g (5 mole parts), N15
nOz 22.54g (10 mole parts), MnOz 1
．． 39 g (0.5% by weight) was stirred and mixed with 500 ml of water in a ball mill for 20 hours, and then dehydrated and dried. 20 parts by weight of a 10% by weight aqueous solution of polyvinyl alcohol was added to 100 parts by weight of the powder obtained by drying, and after granulation with a press, a disk with a diameter of 10 m and a thickness of 0.5 mm was formed. By firing in the atmosphere for an hour, a ceramic substrate with a diameter of 8.5 mm and a thickness of 0.43 fl was obtained.

This ceramic substrate was polished to a thickness of 0.2 fl, and silver paste (11 parts by weight of silver powder, 2 parts by weight of lead, boron, silicon-based glass frit, 9 parts by weight of butyl calpitol acetate and ethyl cellulose) was applied to both the front and back surfaces. A composition containing 20 parts of an organic vehicle mixed with
Baking was performed at ℃ for 10 minutes.

The ceramic substrate on which electrodes were formed in this way was heated at 100°C for 1
Perform polarization treatment at 800V in silicone oil for 0 minutes,
A pyroelectric infrared sensor was created by cutting it into 3 fl square pieces using a cutter, and one Curie point was measured.The pyroelectric coefficient P and relative permittivity ε were also measured to calculate Fv, and these are shown in Table 2. show. For calculation, C, = 3. I J/cl
−℃ was adopted.

The measurement method is as follows.

First, the relative dielectric constant ε is calculated from capacitance measurements based on JIS C-5102, and the Curie point is determined by examining the change in capacitance at each temperature level in a constant temperature bath, and determining the highest capacitance. This was determined by searching for . Next, the pyroelectric coefficient P was obtained by reading the current value generated at a constant temperature increase of 5 (° C./min) with a picoammeter and determining the change in the value in the range of 0 to 150° C.

Examples 2 to 16 In Example 1, PbTiO311CaTi03, P
bCu + 7ffNbz/30s, NiSnO3, M
Infrared sensors were produced in the same manner except that n0z and/or CrzCh were used in the proportions shown in Table 1,
This was processed in the same manner as in Example 1, and the results of measuring each item and the calculated results are shown in Table 2.

Note that PbTi0. , CaTiOx, Pb
The composition of Cu+7Jbz/:+Oz is shown in the triangular diagram in the figure in correspondence with each example number.

Table 1 (Jitsusan I formulation) Table 2 From the above results, it can be seen that all of the examples had an Fv of 6 or more and a Curie temperature of 260° C. or more.

Effects of the Invention According to the present invention, PbTiOz-CaTiO, -PbC
By adding NiSnO3 to the u, zJbzz, 0:+ system, it is possible to provide a fired porcelain body containing at least one of MnO2 and Crz02 as a main component.
:+ Evaluation index F even higher than that of CaTi0z series
The larger v is, the more infrared light will be detected.

Since the output sensitivity can be increased, when this is used in an alarm, there is no need to increase the gain of the alarm signal, and malfunctions of the alarm due to noise can be reduced. Furthermore, the Curie temperature is 250°C or higher, which means that soldering can be done at a higher temperature than normal, so it can be done without impairing the function as an infrared sensor.

[Brief explanation of drawings]

The figure shows a PbTiOs pyroelectric porcelain fired body according to an example of the present invention.
, CaTi0. , PbCu+zzNbz/J3 is a triangular diagram showing the composition of the three components. - The numbers in the figure indicate the numbers of the examples. April 30, 1985

Claims (1)

[Claims] (1) General formula xPbTiO_3-yCaTiO_3-zPbCu_1
_/_3Nb_2_/_3O_3, x, y, z
is 0.55≦x≦0.79 0.20≦y≦0.35 0.01≦z≦0.10 (however, x+y+z=1) and per 100 mole parts of this oxide. Ni
MnO_2 and C for a total of 100 parts by weight of SnO_32 to 15 mol parts, this NiSnO_3 and the above oxide.
A fired pyroelectric ceramic body characterized by containing 0.1 to 3.0 parts by weight of at least one of r_2O_3.