DE2314152C2 - Piezo-ceramic fabric - Google Patents

Description

The invention relates to substances which can be used in RF technology, i. H. piezoceramic fabrics. These are in |

in acoustics (microphones and pickups), in hydroacoustics (underwater listening devices), in seismographs and other electromechanical transducers using the direct or reverse piezo effect

2 <> used. jf

It is known that substances have maximum piezoactivity, which in the morphotropic areas of 2- and 3-component systems of fixed solutions. As the number of system components increases, the dimension of the morphotropic area is increased and the area of the compositions with extremes Extended parameter values.

In the known piezo-ceramic materials, the 3-component systems PbTiOj-PbZrOi-PbB _'l aB "stoi representing wherein

B '- Nb ⁵ *, W ⁶ *

B "- Zn ² *, Mg ²⁺ , Co ²⁺ , Mn ²⁺ , Ni ²⁺
.κι χ = 1/2 for W ⁶ * and 1/3 for Nb ⁵⁺

is, the compositions belonging to the morphotropic range have the parameters listed in Table 1.
Table 1 shows that for most of these systems the values for the dielectric constant eji and for the electromechanical coupling factor Kp are not high enough. The Kp values, which are increased in some cases, are combined with insufficiently high elj values (systems 2, 3 and 9). The stated combinations of the parameters ε? Ι and Kp do not guarantee high values for the piezo module Xu and make the use of these substances in the stated devices (microphones, pickups, hydrophones, seismic receivers, etc.) ineffective.

With regard to the state of the art, the piezoceramic material according to the invention comes with the four-component |

component system PbTiO) -PbZrO ₅ -PbNb ₂ Z ₃ ZnI _n O ₃ -PbNb ₂₇₃ NiI ² JOj (DE-OS 20 40 573), whose compositions have higher dielectric constant values (eFj = 3142-3725) (Examples No. 87 to 90, Table 5 of DE-OS 20 40 573) than the three-component systems listed in Table 1. The values for the m

electromechanical coupling factor for the specified compositions of the four-component system I.

are however not high enough (Kp = 0.521-0.611), which is also insufficiently high values for the piezo module »

Äii has the consequence and an increase in the effectiveness of the use of these substances in the above-mentioned electromechanical Makes converting impossible.

The object of the invention is to provide highly effective substances with a high dielectric constant sfi, high electromechanical! Coupling factor Kp and high piezo module a _iu which both in acoustics and |

can be used effectively in seismo receivers as well as in other cases in which the piezo materials $

maximum requirements are made with regard to the piezo properties. |

The problem was solved by developing a piezoceramic material consisting of PbTiOj, PbZrOj, PbW _1/2 Nii _{/ 2} 0i and a fourth component, namely PbNb _2/3 Mg _2/3 O ,, where the individual components are as follows Quantities are in mol%:,

I.

PbTiO ₃ 37.5-42.5

PbZrO ₃ 30.0-42.0

PbW " ₂ Ni _1/2 0, 1.5-13.5

PbNb _2/3 Mgi _{/ 3} 0, 2.3-22.0.

The parameters of the piezoceramic substances according to the invention are summarized in Table 2. They have a high dielectric constant UJ ₃ = 3167-4262) with higher values for the electromechanical coupling factor (Kp = 0.633-0.722) than with the compositions of DE-OS 20 40 573, which means high values for the piezo module Ia ₁ , = (7, 50-9,38) ■ ΙΟ ' ⁶ CGSE units] guaranteed. The high ef ₃ -, Kp and a ₃₁ values of piezoelectric materials of the invention allow for increasing the effectiveness elektromechanlscher transducer and hydroacoustic transducers and other obligations V orrich. Indeed, the increase in the a _n and Kp values leads to an increase in the coefficient a ₃ i / Vef ₃ , which is proportional to the specific sensitivity of the receiving devices using the direct plezo effect. In addition, the increase in a ₃ , adds

an increase in the movements in the corresponding vibration exciters of movements, d. H. in linear and stepper motors, in devices for adjusting mirrors and other devices that do the reverse Use the piezo effect.

In addition, when piezo materials are used in low frequency devices, dielectric constant values are high required for an optimal adjustment of the transducer to the registering apparatus. Of the Piezoceramic material according to the invention is produced as follows:

The starting materials are used as metal oxides, carbonates and hydroxides, such as. B.

PbCO, or PbO TiO ₂ WO,

ZrO ₂ Mg (OH) ₂

Nb ₂ O ₅ NiO

The starting components selected according to the specified composition are wet Form mixed in ball mills for 10 hours. The substance is then synthesized. This will be after the usual ceramic technology carried out in a protective atmosphere of PbO. Conditions for the Synthesis: temperature 850 ° C, duration 4 + 10 hours.

To achieve a high quality piezoceramic material, the synthesized material is made by Hot pressing at 1100-1190 ° C, a pressure of 19 6133 MPa and sintered with a holding time of 40 minutes. The samples are then ground.

The polarization required to give the ceramic material piezoelectric properties, and to measure the electrophysical parameters, electrodes must be generated on the samples.

For this purpose, the samples are coated with a layer of silver paste and kept at a temperature of Held at 800 ° C.

The polarization is carried out in silicone oil, which is an organosilicon liquid, at a temperature of 100 to 140 ^° C. within 30 to 40 minutes in a field with a strength of 35.0 kV / cm.

The samples are examined 24 hours after polarization.

For a better understanding of the invention, an example of the production of the piezoceramic according to the invention is provided Substance listed.

example 1

Production of a piezoceramic substance, which in mol%

PbTiO ₃ -40.0 PbW _1/2 Ni, / ₂ O ₃ -9.84 PbZrO ₃ -35.4 PbNb _2/3 Mg _1/3 O ₃ -14.76

contains.

The starting materials are used according to the given composition as metal oxides, carbonates and hydroxides [PbCO ₃ , TiO ₂ , ZrO ₂ , Nb ₂ O ₅ , WO ₃ , Mg (OH) ₂ , NiO] and mixed wet in ball mills for 10 hours . This is followed by the synthesis of the substance. This is carried out according to the usual ceramic technology in a protective atmosphere of PbO. Synthesis conditions: temperature 850 ° C, duration 4 + 10 hours. The synthesized material is sintered by hot pressing at 1190 ⁰ C, a pressure of 19-6133MPa and at a holding time of 40 minutes. The polarization is in silicone oil at a temperature of 14O ⁰ C within 40 minutes in a field having a strength of 35 kV / cm performed. The electrophysical parameters of the substance of the specified composition have the following values:

eF ₃ = 3860, Kp = 0.7222, "" = 9.38 x 10 " ⁶ CGSE units.

Further examples for the production of the piezoceramic material are given in Table 2, in which the Ratios for the main components, the synthesis, sintering and polarization conditions as well as the electrophysical parameters are given.

Table 1

i_ "D" aui literature

No. in the triple system

Electrophysical Kall parameters 55

Dlelektl- electromechanical dielectric

mechanical quality, Q losses

constant coupling (in the weak

ε], factor, Kp field

tg <5, % 60

1 PbNb _2/3 Zn, _{/ 3} O, Japanese patent specification
9511/72 1570-3120 0.568-0.714 _ 2 PbNb _2n Mg ₁₇₃ O ₃ H. Ouchi. J. AmCuam. Soc,
51, 169 (1968) 2137 0.638 65 3 PbNb _2/3 Co _1/3 O ₃ Japanese patent specification
No. 13 146/70
Class 62 C 23 1360-2030 0.64 -0.73 305-420

1.87

continuation

Lid. PbBV ₁ BHaO, Lileratur

No. in the triple system

Electrophysical parameters

Dielectric- elec- tromechanical dielectric

quotation mechanical gate, Q losses

constant coupling (in the weak

Cu factor, Kp field

lgö, "..

4 PbNb ₂₇₃ Mn ₁₇₃ O ₁ Japanese Patent Publication

No. 35 472/71

5 PbNb ₂₇₃ Ni ₁₇₃ O ₃ Japanese Patent

No. 45-14 465
K. 62 C 23

6 PbW ₁₇₂ Zn ₁₇₂ Oj French patent

Document No. 1554730 class C 04 B

7 PbW ₁₇₂ Mg ₁₇₂ O ₃ French patent

Document No. 15 51 976 K. C 04 B.

8 PbW ₁₇₂ Ni | ₇₂ O ₃ French patent

Document No. 1554 730 class C 04 B.

9 PbW ₁₇₂ Co ₁₇₂ O ₃ Japanese Patent

No. 46-2 354
Class 62 C 23

Table 2

630-1000 0.35 -0.61 1900-2030 J, 1-2.3 720-3200 0.4 -0.61 95-161

1500-2500 0.52 -0.59 72 -80

0.25 -0.5 295-300

1090-1800 0.4 -0.6

1130-1980 0.42-0.63

15-80

At- composition, mol%

game PbTiO, PbZrO, PbW _1/2 Ni, ₇₂ O, PbNb _2/3 Mg ,, ₃ O, No.

Conditions Syn- Sintethese tion 7 "° C ι, min

T ⁰ C ι. St.

Polarization

r ° c

ι, min P. MPa E, kV / cm

Electrophysical

parameter

Kp au ■ 10 '

CGSE units

1 2

IO

1 40.00 35.40 9.84 14.76

2 37.50 31.25 12.50 18.75

3 40.00 30.00 12.00 18.00

4 42.50 41.70 13.50 2.30

5 38.75 30.62 8.63 22.00

6 40.00 42.00 1.50 17.50

1190

19.61 1100

19.61 1100

19.61 1100

19.61 1100

19.61 1190

19.61

140 40 35

100 30 35

100 30

35

100 30 35

100 30 35

140 40 35

3860

3468

4197

3217

4262

3167

0.722 9.38

0.668 7.88

0.633 7.96

0.664 7.53

0.675 8.82

0.668 7.50

Claims (1)

Claim: Piezoceramic material, consisting of PbTiO ₃ . PbZrO ₃ , PbW _{! / 2} Ni, _{/ 2} Oi and a fourth component, characterized in that it additionally contains _{PbNb 2/3} Mg _{I / 3} Oi as a fourth component to increase the dielectric constant and the electromechanical coupling factor of the piezo module has the following aggregation in mol-t: PbTiO, 37.5-42.5 PbZrO ₃ 30, (M2,0 1 »PbW _{l / 2} Ni _1/2 O ₃ 1.5 to 13.5 PbNb _2/3 Mg _{] / 3} O ₅ 2.3-22.0.