GB1565137A - Piezoelectric ceramic compositions - Google Patents
Piezoelectric ceramic compositions Download PDFInfo
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- GB1565137A GB1565137A GB25045/77A GB2504577A GB1565137A GB 1565137 A GB1565137 A GB 1565137A GB 25045/77 A GB25045/77 A GB 25045/77A GB 2504577 A GB2504577 A GB 2504577A GB 1565137 A GB1565137 A GB 1565137A
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- 239000000203 mixture Substances 0.000 title claims description 46
- 239000000919 ceramic Substances 0.000 title claims description 26
- NUJOXMJBOLGQSY-UHFFFAOYSA-N manganese dioxide Chemical compound O=[Mn]=O NUJOXMJBOLGQSY-UHFFFAOYSA-N 0.000 claims description 46
- 229910000011 cadmium carbonate Inorganic materials 0.000 claims description 20
- KOHRTFCSIQIYAE-UHFFFAOYSA-N cadmium;carbonic acid Chemical compound [Cd].OC(O)=O KOHRTFCSIQIYAE-UHFFFAOYSA-N 0.000 claims description 20
- 229910052793 cadmium Inorganic materials 0.000 claims description 9
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 7
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 claims description 6
- 239000011572 manganese Substances 0.000 claims description 5
- 229910052721 tungsten Inorganic materials 0.000 claims description 5
- 239000010937 tungsten Substances 0.000 claims description 5
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 4
- 229910052748 manganese Inorganic materials 0.000 claims description 4
- 238000005245 sintering Methods 0.000 description 38
- HTUMBQDCCIXGCV-UHFFFAOYSA-N lead oxide Chemical compound [O-2].[Pb+2] HTUMBQDCCIXGCV-UHFFFAOYSA-N 0.000 description 14
- 239000000463 material Substances 0.000 description 9
- 239000011148 porous material Substances 0.000 description 8
- 238000010897 surface acoustic wave method Methods 0.000 description 5
- 229910010252 TiO3 Inorganic materials 0.000 description 4
- 229910010293 ceramic material Inorganic materials 0.000 description 4
- 229910020565 PbCd Inorganic materials 0.000 description 3
- WMWLMWRWZQELOS-UHFFFAOYSA-N bismuth(iii) oxide Chemical compound O=[Bi]O[Bi]=O WMWLMWRWZQELOS-UHFFFAOYSA-N 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- ZNOKGRXACCSDPY-UHFFFAOYSA-N tungsten(VI) oxide Inorganic materials O=[W](=O)=O ZNOKGRXACCSDPY-UHFFFAOYSA-N 0.000 description 3
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 239000012612 commercial material Substances 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 230000001788 irregular Effects 0.000 description 2
- ZKATWMILCYLAPD-UHFFFAOYSA-N niobium pentoxide Chemical compound O=[Nb](=O)O[Nb](=O)=O ZKATWMILCYLAPD-UHFFFAOYSA-N 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 238000009834 vaporization Methods 0.000 description 2
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 229910052745 lead Inorganic materials 0.000 description 1
- YEXPOXQUZXUXJW-UHFFFAOYSA-N lead(II) oxide Inorganic materials [Pb]=O YEXPOXQUZXUXJW-UHFFFAOYSA-N 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- GNRSAWUEBMWBQH-UHFFFAOYSA-N nickel(II) oxide Inorganic materials [Ni]=O GNRSAWUEBMWBQH-UHFFFAOYSA-N 0.000 description 1
- QGLKJKCYBOYXKC-UHFFFAOYSA-N nonaoxidotritungsten Chemical compound O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1 QGLKJKCYBOYXKC-UHFFFAOYSA-N 0.000 description 1
- 238000001259 photo etching Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 229910001930 tungsten oxide Inorganic materials 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/80—Constructional details
- H10N30/85—Piezoelectric or electrostrictive active materials
- H10N30/853—Ceramic compositions
- H10N30/8548—Lead-based oxides
- H10N30/8554—Lead-zirconium titanate [PZT] based
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Compositions Of Oxide Ceramics (AREA)
- Inorganic Insulating Materials (AREA)
Description
(54) PIEZOELECTRIC CERAMIC COMPOSITIONS
(71) We, SONY CORPORATION. a corporation organised and existing under the laws of Japan, of 7-35 Kitashinagawa-6, Shinagawa-ku, Tokyo, Japan, do hereby declare the invention for which we pray that a patent may be granted to us. and the method for which it is to be performed, to be particularly described in and by the following statement:
This invention relates to piezoelectric ceramic compositions of perovskite crystalline structure, such compositions being suitable for use as surface acoustic wave filters or the like.
There is a piezoelectric ceramic composition already known having the formula: Pb(Nil,3Nb2,l)xTiyZrzOR where x + y + z = 1. Examples of similar compositions are PbTi,Zr,O, and Pb(MglX3Nb2,3)yTiXZrzO. These materials, however. have very high sintering tempera- tures, so that they cannot be conveniently produced despite their excellent piezoelectric properties.
Prior art perovskite piezoelectric ceramic materials which contain lead oxide (PbO) as their main component are low in price and relativelv easy to produce as compared with single crystal piezoelectric materials. In addition, there are various characteristics, for example, such as electro-mechanical coupling factor (Kp) dielectric constant (E) and the like which can be adjusted by proper selection of the composition. These materials are widely utilized for ignition elements, filters, pick-ups, and the like. Such commercial materials, however, contain a substantial quantity of PbO in their compositions.
Consequently. when the material is fired at a sintering temperature in the range of about 12500 to 13500C, PbO is violently vaporized to cause the generation of pores and a variation in the composition with the result that a uniform. fine ceramic composition cannot be obtained. If the firing temperature is lowered in order to suppress the vaporization of PbO, a gas remains in the ceramic composition due to the imperfect reaction, to produce a number of large pores. Accordingly. the ceramic compositions being produced in this area have a density which is substantially lower than the theoretical density. The commercial materials average about 95 to 96% of the theoretical density.
As will be described later. as the density becomes lower than the theoretical density, the piezoelectric modulus becomes more irregular. Consequently when such a ceramic composition is used as a high frequency vibrating source of more than 10 MHz, it characteristics are very irregular and its propagation loss is large due to the presence of pores each having a diameter of several tens of microns. When this ceramic composition is attached to a comb-like electrode. each tooth of which is less than 50 microns wide. to provide a surface acoustic wave filter, discontinuous portions appear in the electrode resulting in the deterioration of the performance of the element.
In the prior art, PbO. Bi2O3 or the like have been added in substantial amounts in order to lower the sintering temperature. In such case. however. these materials deposit in the grain boundaries and in forming a surface acoustic wave filter device. the PbO or Bi203 in such boundaries is dissolved awav when the surface is chemically washed. This etching of the grain boundaries by the cleansing liquid spoils the desired polished surface of the material.
According to the present invention there is provided a piezoelectric ceramic composition comprising a perovskite structure having the formula:
Pb1-ACdA(Ni1/3Nb2/3)xTivZrzO3 where x is in the range from 0.05 to 0.25
y is in the range from 0.30 to ().95
z is in the range from 0 to (1.65 and x + y + z = 1 in which the Pb is partially replaced by Cd such that A is in the range from 0.005 to 0.02.
The composition may include at least one additional element, the additional element being cadmium. manganese or tungsten. In the case of cadmium, the amount is in the range from 0.7 to 1.5 weight %, calculated as CdCO3, of the perovskite structure and including the amount specified in A. The amount of manganese, calculated as MnO2, is in the range from 0 to 1.5 weight % of the perovskite structure, the amount of tungsten, calculated as
WO3, is in the range from 0 to 1.0 weight % of the perovskite structure.
The invention will now be further described by way of example with reference to the accompanying drawings, in which:
Figure 1 is a tertiary system diagram of the system (Pb1 ACd)(Ni1 3Nb2/3) - (Pb1
ACdA)TiO3 - (Pb1-ACdA)ZrO3
Figure 2 is a graph showing the relationship between the centre frequency of an acoustic surface wave filter manufactured bv using a ceramic composition as its substrate and sintering density thereof; and
Figure 3 is a chart showing the centre frequency distribution of the acoustic surface wave filter using the ceramic composition produced according to the invention as its substrate.
A description will first be given of the preparation of à ceramic composition according to this invention. In the first step. the materials are mixed and ground in the same manner as used in the preparation of prior art piezoelectric ceramic materials. That is, predetermined amounts of PbO, ZrO2, WO3, NiO, Nb2O5, TiO2, CdCO3, and MnO2 are weighed out to form the composition and are mixed together by either the wet or dry process. The calcination is then carried out at a temperature of 800 C to 850 C according to the nature of the composition. Then, grinding is carried out either by wet or dry process. The thus obtained calcined powder is moulded in a press at a pressure of 1 metric ton/cm and then fired for 1 to 3 hours at a predetermined firing temperature while oxygen gas is supplied at a rate of 1 to 5 litres per minute. This rate of oxygen flow is used when the moulded element is located in a cover having a cavity of 1 litre. As the capacity of the cover is increased, the flow rate must accordingly be increased.
Table 1 sets forth a series of measurement of sintering temperatures, sintering density and porosity relative to variations in composition in the ceramic element.
TABLE I
Composition Added Amount Sintering Sintering
Sample PbO CdO (mole) % (wt %) Temp. Density Porosity
No. (mole) (mole) (%)
X Y Z CdCO3 MnO2 WO3 ( C) (g/cc) 1 0.99 0.01 25 75 0 0.5 0.5 0 1150 8.011 0.69 0.99 0.01 25 75 0 0.5 0 0.5 1150 8.010 0.75 0.99 0.01 25 75 0 0.5 0.5 0.5 1150 8.015 0.64 2 0.99 0.01 25 60 15 0.5 0.5 0 1150 8.014 0.69 0.99 0.1 25 60 15 0.5 0 0.5 1150 8.009 0.71 0.99 0.01 25 60 15 0.5 0.5 0.5 1150 8.016 0.66 3 0.995 0.005 25 40 35 1.0 0.5 0 1050 8.039 0.55 0.995 0.005 25 40 35 1.0 0 0.5 1150 8.018 0.65 0.995 0.005 25 40 35 1.0 0.5 0.5 1100 8.027 0.59 0.99 0.01 25 40 35 0.5 0.5 0 1000 8.029 0.59 0.99 0.01 25 40 35 0.5 0 0.5 1150 8.020 0.66 0.99 0.01 25 40 35 0.5 0.5 0.5 1100 8.022 0.61 0.98 0.02 25 40 35 0 0.5 0 1050 8.019 0.68 0.98 0.02 25 40 35 0 0.5 0.5 1100 8.021 0.67 4 0.99 0.01 25 30 45 0.5 0.5 0 1050 8.019 0.69 TABLE (CONTINUED) - Page 2
Composition Added Amount Sintering Sintering
Sample PbO CdO (mole) % (wt %/ Temp. Density Porosity
No. (mole) (mole) (%)
X Y Z CdCO3 MnO2 Wo3 ( C) (g/cc) 0.99 0.01 25 30 45 0.5 0 0.5 1050 8.005 0.78 0.99 0.01 25 30 45 0.5 0.5 0.5 1050 8.022 0.61 5 0.99 0.01 15 85 0 0.5 0.5 0 1150 8.016 0.72 0.99 0.01 15 85 0 0.5 0 0.5 1150 8.007 0.75 0.99 0.01 15 85 0 0.5 0.5 0.5 1150 8.018 0.66 6 0.99 0.01 15 65 20 0.5 0.5 0.05 1150 8.019 0.66 0.99 0.01 15 65 20 0.5 0 0.5 1150 8.006 0.78 0.99 0.01 15 65 20 0.5 0.5 0 1150 8.020 0.63 7 0.99 0.1 10 45 45 0.5 0.5 0 1000 8.012 0.69 0.99 0.01 10 45 45 0.5 0 0.5 1150 8.021 0.59 0.99 0.01 10 45 45 0.5 0.5 0.5 1100 8.025 0.59 8 0.99 0.1 15 30 55 0.5 0.5 0 1000 8.019 0.68 0.99 0.01 15 30 55 0.5 0 0.5 1150 8.019 0.71 0.99 0.01 15 30 55 0.5 0.5 0.5 1100 8.022 0.65 9 0.99 0.01 5 95 0 0.5 0.5 0 1150 8.019 0.70 0.99 0.01 5 95 0 0.5 0 0.5 1150 8.002 0.76 TABLE 1 (CONTINUED) - Page 3
Composition Added Amount Sintering Sintering
Sample PbO CdO (mole) % (wt %) Temp. Density Porosity
No. (mole) (mole) X Y Z CdCO3 MnO2 WO3 ( C) (g/cc) (%) 0.99 0.01 5 95 0 0.5 0.5 0.5 1150 8.017 0.69 11 0.99 0.01 5 75 20 0.5 0.5 0 1150 8.035 0.59 0.99 0.01 5 75 20 0.5 0 0.5 1150 8.015 0.71 0.99 0.01 5 75 20 0.5 0.5 0.5 1150 8.031 0.60 13 0.99 0.01 5 67.5 27.5 0.5 0.5 0 1150 8.014 0.68 0.99 0.01 5 67.5 27.5 0.5 0 0.5 1150 8.009 0.74 13-3 0.99 0.01 5 67.5 27.5 0.5 0.5 0.5 1150 8.021 0.58 15 0.99 0.01 5 60 40 0.5 0.5 0 1100 8.029 0.58 0.99 0.01 5 60 40 0.5 0 0.5 1150 8.021 0.62 0.99 0.01 5 60 40 0.5 0.5 0.5 1100 8.032 0.57 16 0.995 0.005 5 52.5 42.5 1.0 0.5 0 1100 8.028 0.59 0.995 0.005 5 52.5 42.5 1.0 0 0.5 1150 8.022 0.69 0.995 0.005 5 52.5 42.5 1.0 0.5 0.5 1050 8.030 0.53 0.99 0.01 5 52.5 42.5 0.5 0.5 0 1050 8.033 0.60 0.99 0.01 5 52.5 42.5 0.5 0 0.5 1150 8.017 0.65 TABLE 1 (CONTINUED) - Page 4
Composition Added Amount Sintering Sintering
Sample PbO CdO (mole) % (wt %) Temp. Density Porosity
No. (mole) (mole) X Y Z CdCO3 MnO2 WO3 ( C) (g/cc) (%) 0.99 0.01 5 52.5 42.5 0.5 0.5 0.5 1050 8.031 0.59 0.98 0.02 5 52.5 42.5 0.5 0.5 0 1050 8.028 0.58 0.98 0.02 5 52.5 42.5 0.5 0 0.5 1150 8.010 0.74 0.98 0.02 5 52.5 42.5 0.5 0.5 0.5 1050 8.024 0.57 17 0.99 0.01 5 47.5 47.5 0.5 0.5 0 1050 8.036 0.55 0.99 0.01 5 47.5 47.5 0.5 0 0.5 1150 8.027 0.59 18 0.99 0.01 5 45 50 0.5 0.5 0 1100 8.031 0.51 0.99 0.01 5 45 50 0.5 0.5 0.5 1100 8.029 0.56 19 0.99 0.01 5 30 65 0.5 0 0.5 1150 8.019 0.68 0.99 0.01 5 30 30 0.5 0.5 0.5 1100 8.017 0.69 0.98 0.02 5 30 30 0.5 0.5 0 1100 8.012 0.75 0.98 0.02 5 30 30 0.5 0 0.5 1150 8.007 0.77 0.98 0.02 5 30 30 0.5 0.5 0.5 1100 8.015 0.71 In Table 1, X is Pb1-ACdA(Ni1/3Nb2/3)O3, Y is (Pb1-ACdA)TiO3 and Z is (Pb1-ACdA)ZrO3.
As will be noted from Table 1, depending on the composition, the sintering temperature is lowered by 200 to 300 C as compared with prior art sintering temperatures which occured in the range of 1250 C to 1350 C. Accordingly, a high sintering density is obtained. The theoretical density is about 7.9 to 8.1 which differs depending on the composition, but the sintering density of the compositions produced according to the invention is very close to the theoretical density.
Figure 1 illustrates a ternary system diagram of (Pbl ACdA) (Ni113Nb213)O3 - (Pbl ACdA)TiO3 - (Pb1-ACdA)ZrO3, in which the compositions of samples 1 to 19 of Table 1 are represented by reference numerals 1 to 19, respectively. The composition according to the invention is circumscribed by the lines a b c d a of Figure 1. The composition in the area above the line ab of Figure 1 has a very low Curie point so that its temperature characteristics deteriorate and also does not have the proper perovskite structure. The composition in the area at the right of the line bc has a low Curie point which, as mentioned, causes a deterioration in its temperature characteristic, and a composition in the area below the line cd has a low sintering density.
Table 2 shows a series of measured results of sintering temperature, sintering density and porosity relative to adding various amounts of CdCO3, MnO2 and WO3, to the composition
Pb1-ACdA(Ni1/3Nb2/3)xTiyZrzO3.
TABLE 2
Composition Added Amount Sintering Sintering
Sample PbO CdO (mole) % (wt %) Temp. Density Porosity
No. (mole) (mole) X Y Z CdCO3 MnO2 WO3 ( C) (g/cc) (%) 16 0.99 0.01 5 52.5 42.5 0 0.5 0 1150 7.787 6.51 0.99 0.01 5 52.5 42.5 0.2 0.5 0 1150 8.003 0.83 0.99 0.01 5 52.5 42.5 0.5 0.5 0 1150 8.045 0.53 0.99 0.01 5 52.5 42.5 1.0 0.5 0 1150 8.031 0.63 0.99 0.01 5 52.5 42.5 1.5 0.5 0 1150 7.856 5.51 0.99 0.01 5 52.5 42.5 0.5 0 0 1150 8.001 0.77 0.99 0.01 5 52.5 42.5 0.5 0.1 0 1150 8.042 0.52 0.99 0.01 5 52.5 42.5 0.5 0.3 0 1150 8.043 0.55 0.99 0.01 5 52.5 42.5 0.5 0.5 0 1150 8.048 0.51 0.99 0.01 5 52.5 42.5 0.5 1.0 0 1150 8.045 0.49 TABLE 2 (CONTINUED) - Page 2
Composition Added Amount Sintering Sintering
Sample PbO CdO (mole) % (wt %) Temp. Density Porosity
No. (mole) (mole) X Y Z CdCO3 MnO2 WO3 ( C) (g/cc) (%) 0.99 0.01 5 52.5 42.5 0.5 1.5 0 1150 8.013 0.68 0.99 0.01 5 52.5 42.5 0.5 2.0 0 1150 7.813 5.94 18 0.99 0.01 5 45 50 0.5 0 0 1150 8.003 0.70 0.99 0.01 5 45 50 0.5 0 0.1 1150 8.035 0.59 0.99 0.01 5 45 50 0.5 0 0.3 1150 8.027 0.69 0.99 0.01 5 45 50 0.5 0 0.5 1150 8.015 0.67 0.99 0.01 5 45 50 0.5 0 1.0 1150 8.009 0.80 0.99 0.01 5 45 50 0.5 0 1.5 1150 7.564 18.12 In Table 2, X is PbCd(Ni11d23Nb213)O3, Y is (PbCd)TiO3 and Z is (PbCd)ZrO3).
It will be noted from Table 2 that where the manganese dioxide is constant, and tungsten oxide is not added, if the total amount of cadmium, including the amount used in replacing the lead as well as the additional amounts is less than 0.7 weight %, calculated as CdCO3, or higher than 1.5 weight %, the sintering density is lowered and the porosity is substantially increased.
In the case where the amount of CdCO., was constant and WO3 was not added, if the additional amount of MnO2 was 1.5 weight % or less, good sintering occurred but if the additional amount of MnO2 exceeded 1.5 weight 8/o. the sintering was deteriorated. When
MnO2 was added in more than 1.5 weight %, its accumulation at the grain boundaries becomes great enough to increase the instability. In the case where the amount of CdCO3 was constant and MnO2 was not added, sintering proceeded well when the added amount of
WO3 was 1.0 weight % or less, but the sintering deteriorated and the porosity increased when the amount of WO3 exceeded 1.0 weight %. For these reasons, the amount of Cd calculated as CdCO3 should be confined to a range from 0.7 to 1.5 weight %, the amount of
Mn, calculated as MnO2 should be in the range from 1.5 weight %, and the weight of W, calculated as WO3 should be in the range from 0 to 1.0 weight %.
Table 3 sets forth a series of measured values of dielectric constant (e), dielectric loss (tan#), electro-mechanical coupling factor (Kp), frequency constant (fR) and mechanicl Q value (QM) in the situation where the amounts of CdCO3, MnO2 and WO3 are varied.
TABLE 3
Replacing Adding Amount
Sample Amount (wt %) #33 tan# P FR QM
No. (mole) CdCO3 MnO2 WO3 (%) (%) (kHz - mm) 3 0.01 0.5 0.5 0 1292 0.9 51 2320 651 0.01 0.5 0.7 0.5 1720 1.1 57 2319 483 5 0.01 0.5 0.5 0 230 0.9 11 2789 4325 0.01 0.5 0.5 0.5 241 1.2 13 2778 3987 7 0.01 0.5 0.5 0 1223 0.7 54 2327 960 0.01 0.5 0 0.5 2114 0.8 64 1991 90 0.01 0.5 0.5 0.5 1634 0.4 59 2013 908 11 0.01 0.5 0.5 0 241 0.6 15 2773 3950 0.01 0.5 0.5 0.5 259 0.9 17 2768 3004 12 0.01 0.5 0.5 0 265 0.8 20 2765 2840 TABLE 3 (CONTINUED) - Page 2
Replacing Adding Amount
Sample Amount (wt %) #33 tan# Kp fR QM
No. (mole) CdCO3 MnO2 WO3 (%) (%) (kHz - mm) 0.01 0.5 0.5 0.5 281 1.1 23 2759 2091 0.02 0.5 0.5 0 268 0.6 18 2770 2658 0.02 0.5 0.5 0.5 289 0.9 20 2757 2047 14 0.005 0.7 0.5 0 331 0.7 23 2739 2051 0.005 0.7 0 0.5 352 1.0 25 2735 1097 0.005 0.7 0.5 0.5 346 0.9 25 2739 1958 0.01 0.5 0.5 0 324 0.8 22 2755 2130 0.01 0.5 0 0.5 349 0.9 26 2738 898 0.02 0.2 0.5 0 323 0.6 22 2735 2154 0.02 0.2 0.5 0.5 340 0.8 25 2730 1873 TABLE 3 (CONTINUED) - Page 3
Replacing Adding Amount
Sample Amount (wt %) #33 tan# Kp fR QM
No. (mole) CdCO3 MnO2 WO3 (%) (%) (kHz - mm) 15 0.01 0.5 0.5 0 411 0.6 28 2714 1500 0.01 0.5 0.5 0.5 439 0.7 31 2710 1003 16 0.01 0.5 0.5 0 637 0.7 36 2630 1594 0.01 0.5 0.5 0.5 710 0.7 40 2530 864 18 0.01 0.5 0.5 0 1158 0.8 57 2350 1181 0.01 0.5 1.0 0 1026 0.8 52 2361 1597 0.01 0.5 0 0.5 1560 0.9 63 2001 97 0.01 0.5 0.5 0.5 1390 0.9 59 2013 594 19 0.01 0.5 0.5 0 419 1.2 33 2457 1390 0.01 0.5 0.5 0.5 433 0.9 35 2450 1251 From Table 3 it will be understood that the piezoelectric characteristics of K E and QM can be controlled by composite addition of CdCO3 and MnO2; CdCO3 and W O3; and
CdCO3; MnO2 and WO3. Sample numbers in Table 3 correspond to the points illustrated in
Figure 1 of the drawings.
In Table 4 there is shown a comparison between a piezoelectric ceramic element whose composition is Pb(Ni/3Nb2/3)0.1Ti0.45O3 and that of Sample No. 13-3 of Table 1, with r4espect to pore size and porosity.
TABLE 4
Size of pore Number of pores
(microns) Element on the market Sample No. 13-3
0 - 5 174 105 5 - 10 50 0
10 - 20 26 0
20 - 30 7 0
30 - 40 1 0
40 - 50 1 0
Porosity (%) 15.1 0.58
From Table 4, it will be evident that in the ceramic element according to the invention there are no large pores present, and the porosity is decreased by a factor of about 30. In the Table 4, the pores are measured by a microscope with respect to a ceramic element having an area of 300 microns by 300 microns, and the surface polished to a mirror finish.
Figure 2 shows the relationship between the sintering density and the centre frequency f0 with respect to surface acoustic wave filters made of materials of the same composition but with various sintering density. According to Figure 2. assuming that the sintering density of a ceramic element is 7.72 g/cc and varied #0.2% at the minimum, the centre frequency f0 would vary #60 kHz as indicated by #f2 in Figure 2. Since embodiments of ceramic compositions according to invention have a sintering density more than 8.00 g/cc, however, the centre frequency f0 varies only about #10 as indicated by #f1 even when the density is varied #0.2%. Thus with such ceramic compositions, the piezoelectric constants are less dependent on sintering density.
A surface acoustic wave filter of 10.i Mllz was formed from Sample No. 14 and the distribution of the centre frequency fo was displayed by the dots shown in Figure 3. Samples of two lots, each having 3 blocks, were used, to form 54 elements. In this case, only 2 elements were out of the range of #0.2%, and 96.3% of the total elements were included in the range of #0.2%. 77.8% of the elements being in the range of #0.15%. In this connection, the catalogue value of a filter on the market using a prior art ceramic material is 10.7 MHz 1 0.13 MHz which represents a scattering of about +1.2%. With such a large scatter, it will cost a considerable amount of labour to sort the filter elements, thus creating a higher price. In addition, several types of specifications are necessary for tuners to be used and the like. With embodiments of the invention. however. the scatter can be controlled to about 10.2% and this defect can be avoided.
Thus, with embodiments of the invention, the sintering temperature of the material is lowered and the sintering density is improved. The scatter of the centre frequency is decreased, and also the fineness of the product is increased. Consequently, the characteristics of the ceramic material are standardised. the reproducibility is improved, and the propagation efficiencv is enhanced. In addition, discontinuous portions of electrodes can be prevented from being formed, thereby increasing the yield. In producing a ceramic element, if the sintering is carried out in an oxygen containing gas. the vaporisation of PbO can be effectivelv suppressed.
Moreover, since a portion of the Pb is replaced by Cd, the ceramic composition is chemically stable even when the ceramic surface is washed or an acid etchant is used with the photoetching for selective formation of an electrode on the ceramic surface.
Claims (4)
1. A piezoelectric ceramic composition comprising a perovskite structure having the formula:
Pb1-ACDA(Ni1/3Nb2/3)xTiyZrzO3 where x is in the range from 0.05 to 0.25
y is in the range from 0.30 to 0.95
z is in the range from 0 to 0.65
and x + y + z = 1 in which the Pb is partially replaced by Cd such that :a is in the range from 0.005 to 0.02.
2. A composition according to claim 1 further including at least one additional element, said additional element being cadmium, manganese or tungsten, the amount of cadmium calculated as CdCO3 being in the range from 0.7 to 1.5 weight % of the perovskite structure, including the amount of A, the amount of manganese calculated as MnO2 being in the range from Oto 1.5 weight % of the perovskite structure, and the amount of tungsten calculated as W O3 being in the range from 0 to 1.0 weight 6SC of the perovskite structure.
3. A composition according to claim 1 further including from 0.2 to 1.() weight % of the perovskite structure of cadmium calculated as CdCO,. from 0 to 1.5 weight % of the perovskite structure of manganese calculated as MnO2, and from 0 to 1.0 weight % of the perovskite structure of tungsten calculated as WO3.
4. A piezoelectric ceramic composition substantially as any one of Samples 1 to 19 hereinbefore described.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP51070513A JPS5935124B2 (en) | 1976-06-16 | 1976-06-16 | piezoelectric ceramic composition |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1565137A true GB1565137A (en) | 1980-04-16 |
Family
ID=13433676
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB25045/77A Expired GB1565137A (en) | 1976-06-16 | 1977-06-15 | Piezoelectric ceramic compositions |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS5935124B2 (en) |
| DE (1) | DE2727321A1 (en) |
| FR (1) | FR2355379A1 (en) |
| GB (1) | GB1565137A (en) |
| NL (1) | NL7706603A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3444177A1 (en) * | 1984-12-04 | 1986-06-12 | Siemens AG, 1000 Berlin und 8000 München | PIEZOKERAMIK |
-
1976
- 1976-06-16 JP JP51070513A patent/JPS5935124B2/en not_active Expired
-
1977
- 1977-06-15 NL NL7706603A patent/NL7706603A/en not_active Application Discontinuation
- 1977-06-15 GB GB25045/77A patent/GB1565137A/en not_active Expired
- 1977-06-16 FR FR7718548A patent/FR2355379A1/en active Granted
- 1977-06-16 DE DE19772727321 patent/DE2727321A1/en not_active Withdrawn
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3444177A1 (en) * | 1984-12-04 | 1986-06-12 | Siemens AG, 1000 Berlin und 8000 München | PIEZOKERAMIK |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS52154099A (en) | 1977-12-21 |
| FR2355379A1 (en) | 1978-01-13 |
| DE2727321A1 (en) | 1977-12-29 |
| FR2355379B1 (en) | 1983-12-09 |
| JPS5935124B2 (en) | 1984-08-27 |
| NL7706603A (en) | 1977-12-20 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed [section 19, patents act 1949] | ||
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19950615 |