US3856693A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for producing lead zirconate titanate polycrystalline ceramics
Assignee: AT&T Inc
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Filing: 1972-12-18
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Granted: 1974-12-24
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Expires: 1992-12-18
Abstract
Abstract A combination of critical calcining and firing conditions together with control of particle size of the calcined material and control of the harmful impurities SiO2 and Al2O3 enables processing of polycrystalline ceramic bodies of lead zirconate titanate (PZT) containing about 1 percent Nb2O5 to densities of at least 99.7 percent of theoretical density. In addition, such PZT bodies exhibit a radial coupling coefficient greater than 60 percent. Applications include use as a piezoelectric element in microphone transducers.
Inventors
- 👤 Y Kim
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 05:25
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/622; C04B35/626; C04B35/62605; C04B35/62645; C04B35/62675; C01; C01G; C01G25/00; C01G25/006; C04B35/01; C04B35/48; C04B35/49; C04B35/491; C04B35/493; C04B35/6261; H; H10; H10N; H10N30/00; H10N30/01; H10N30/09; H10N30/093; H10N30/097; H10N30/80; H10N30/85; H10N30/853; H10N30/8548; H10N30/8554; C01P; C01P2006/00; C01P2006/10; C01P2006/40; C04B2235/00; C04B2235/02; C04B2235/30; C04B2235/32; C04B2235/3217; C04B2235/3231; C04B2235/3251; C04B2235/34; C04B2235/3418; C04B2235/50; C04B2235/54; C04B2235/5418; C04B2235/5436; C04B2235/65; C04B2235/656; C04B2235/6567; C04B2235/658; C04B2235/6583; C04B2235/6585; C04B2235/6586; C04B2235/70; C04B2235/72; C04B2235/74; C04B2235/76; C04B2235/768; C04B2235/77
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
164 words
A PROCESS FOR PRODUCING A P PIEZOELECTRIC LEAD ZIRCONATE TITANATE POLYCRYSTALLINE BODY COMPRISING SINTERING A STRUCTURE ALLY INTEGRATED BODY OF COMMINUTED MATERIAL, SAID MATERIAL HAVING BEEN PRODUCED BY: FORMING A MIXTURE OF OXIDES OR COMPOUNDS WHICH UPON HEATING YIELD THE OXIDES BY COMBINING CONSTITUENTS EQUIVALENT TO 65 TO 70 WEIGHT PERCENT PBO, 19.5 TO 21.1 WEIGHT PERCENT ZRO2, 9 TO 13.8 WEIGHT PERCENT TIO2 AND 0.4 TO 1.5 WEIGHT PERCENT NB2O; CALCINING THE MIXTURE AND COMMINUTING THE CALCINED MATERIAL; CHARACTERIZED IN THAT; CALCINING IS CARRIED OUT AT A TEMPERATURE OF FROM 900* TO 1100* C FOR FROM 2 TO 20 HOURS; COMMINUTING IS CARRIED OUT TO ACHIEVE A GRANULE SIZE OF UP TO 44 MICRONS; SINTERING IS CARRIED OUT IN A SUBSTANTIALLY PURE OXYGEN ATOMSPHERE AT A TEMPERATURE OF FROM 1240* TO 1300*C FOR FROM 1 TO 8 HOURS; AND FURTHER CHARACTERIZED IN THAT AMOUNTS OF SIO2 AND AL2O3 IN THE SINTERED PRODUCT ARE LIMITED TO 0.07 WEIGHT PERCENT AND 0.15 WEIGHT PERCENT, RESPECTIVELY.
Claim 2
Dependent Claim
164 words
A PROCESS FOR PRODUCING A P PIEZOELECTRIC LEAD ZIRCONATE TITANATE POLYCRYSTALLINE BODY COMPRISING SINTERING A STRUCTURE ALLY INTEGRATED BODY OF COMMINUTED MATERIAL, SAID MATERIAL HAVING BEEN PRODUCED BY: FORMING A MIXTURE OF OXIDES OR COMPOUNDS WHICH UPON HEATING YIELD THE OXIDES BY COMBINING CONSTITUENTS EQUIVALENT TO 65 TO 70 WEIGHT PERCENT PBO, 19.5 TO 21.1 WEIGHT PERCENT ZRO2, 9 TO 13.8 WEIGHT PERCENT TIO2 AND 0.4 TO 1.5 WEIGHT PERCENT NB2O; CALCINING THE MIXTURE AND COMMINUTING THE CALCINED MATERIAL; CHARACTERIZED IN THAT; CALCINING IS CARRIED OUT AT A TEMPERATURE OF FROM 900* TO 1100* C FOR FROM 2 TO 20 HOURS; COMMINUTING IS CARRIED OUT TO ACHIEVE A GRANULE SIZE OF UP TO 44 MICRONS; SINTERING IS CARRIED OUT IN A SUBSTANTIALLY PURE OXYGEN ATOMSPHERE AT A TEMPERATURE OF FROM 1240* TO 1300*C FOR FROM 1 TO 8 HOURS; AND FURTHER CHARACTERIZED IN THAT AMOUNTS OF SIO2 AND AL2O3 IN THE SINTERED PRODUCT ARE LIMITED TO 0.07 WEIGHT PERCENT AND 0.15 WEIGHT PERCENT, RESPECTIVELY.
Claim 3
Dependent Claim
37 words
The process of claim 1 in which the constituents are equivalent to 67 to 68.5 weight percent PbO, 19.5 to 20.1 weight percent ZrO2, 11 to 11.5 weight percent TiO2 and 0.4 to 1.2 weight percent Nb2O5.
Claim 4
Dependent Claim
26 words
The process of claim 1 in which calcining is carried out at a temperature of from 900* C to 1000* C for 8 to 16 hours.
Claim 5
Dependent Claim
23 words
The process of claim 1 in which comminuting the calcined product is carried out to a granule size of up to 37 microns.
Claim 6
Dependent Claim
26 words
The process of claim 1 in which sintering is carried out at a temperature of from 1280* C to 1300* C for 2 to 4 hours.
Claim 7
Dependent Claim
26 words
The process of claim 1 in which the amounts of SiO2 and Al2O3 in the sintered product are limited to 0.03 and 0.07 weight percent, respectively.
Claim 8
Dependent Claim
24 words
The process of claim 1 in which process PbO is added to the mixture to compensate for loss of PbO by volatilization during processing.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-23 | 1978-06-24 | 1978-12-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-23 | 1982-06-24 | 1982-12-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-23 | 1986-06-24 | 1986-12-24 | $7700.00 | Window Closed / Lapsed |