US4983839A
Expired / Lapsed
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Pyroelectric materials
Assignee: United States Department of the Army
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Filing: 1989-08-18
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Granted: 1991-01-08
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Expires: 2009-08-18
Abstract
Abstract The invention provides a new low Curie temperature pyroelectric material and related sensing devices based on lead titanate doped with various percentages of calcium, lanthanum, bismuth, cobalt and tungsten processed to provide a fine grain structure.
Inventors
- 👤 Krishna K. Deb
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 22:51
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/46; C04B35/462; C04B35/475; H; H01; H01J; H01J29/00; H01J29/02; H01J29/10; H01J29/36; H01J29/39; H01J29/45; H01J29/458
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
51 words
An improved pyroelectric material comprising: modified lead titanate having an average grain size between 1 and 2 microns and wherein at least twenty percent of the lead has been replaced by calcium to lower the temperature at which the pyroelectric coefficient peaks occur and thus provide an improved Figure of Merit.
Claim 2
Dependent Claim
51 words
An improved pyroelectric material comprising: modified lead titanate having an average grain size between 1 and 2 microns and wherein at least twenty percent of the lead has been replaced by calcium to lower the temperature at which the pyroelectric coefficient peaks occur and thus provide an improved Figure of Merit.
Claim 3
Dependent Claim
34 words
A pyroelectric material according to claim 1 wherein: the composition of said material is Pb 0 .70 Ca 0 .30 Ti 0 .96 (Co 0 .5 W 0 .5) 0 .4 O 3 .
Claim 4
Dependent Claim
34 words
A pyroelectric material according to claim 1 wherein: the composition of said material is Pb 0 .80 Ca 0 .20 Ti 0 .96 (Co 0 .5 W 0 .5) 0 .4 O 3 .
Claim 5
Dependent Claim
31 words
A pyroelectric material according to claim 1 wherein: the composition of said material is (Pb 0 .62 Ca 0 .30 La 0 .06 Bi 0 .02)Ti 0 .98 O 3 .
Claim 6
Dependent Claim
75 words
An electromagnetic radiation sensor comprising: a thin plate of lead-calcium-titanate having an average grain size between 1 and 2 microns, a thickness of approximately 25 microns and an atomic ratio of lead to calcium no greater than 4; said plate being electrically polarizable normal to its broad surfaces; and a separate electrode of highly conductive material intimately contacting each of the two opposed broad surfaces of said plate to form an anode and a cathode.
Claim 7
Dependent Claim
75 words
An electromagnetic radiation sensor comprising: a thin plate of lead-calcium-titanate having an average grain size between 1 and 2 microns, a thickness of approximately 25 microns and an atomic ratio of lead to calcium no greater than 4; said plate being electrically polarizable normal to its broad surfaces; and a separate electrode of highly conductive material intimately contacting each of the two opposed broad surfaces of said plate to form an anode and a cathode.
Claim 8
Dependent Claim
29 words
A sensor according to claim 5 further including means to measure the change in resistance between said anode and cathode as a function of radiation incident on said plate.
Claim 9
Dependent Claim
30 words
A sensor according to claim 5 further including means to measure the change in capacitance between said anode and said cathode as a function of radiation incident on said plate.
Claim 10
Dependent Claim
27 words
A sensor according to claim 5 further including: means to measure the change in electric polarization of said plate in response to incident radiation on said plate.
Claim 11
Dependent Claim
15 words
A sensor according to claim 5 wherein: said ratio of lead to calcium is 7/3.
Claim 12
Dependent Claim
21 words
A sensor according to claim 5 wherein: about four percent of said titanate is replaced by oxides of cobalt and tungsten.
Claim 13
Dependent Claim
19 words
A sensor according to claim 5 wherein said lead-calcium -titanate contains approximately eight mole percent of lanthanum and bismuth.
Claim 14
Dependent Claim
45 words
A pyroelectric imager with an array of ferroelectric sensors, wherein: each sensor includes a thin layer of lead-calcium-titanate having an average grain size between 1 and 2 microns, a thickness of approximately 25 microns and an atomic ratio of lead to calcium less than four.
Claim 15
Dependent Claim
45 words
A pyroelectric imager with an array of ferroelectric sensors, wherein: each sensor includes a thin layer of lead-calcium-titanate having an average grain size between 1 and 2 microns, a thickness of approximately 25 microns and an atomic ratio of lead to calcium less than four.
Claim 16
Dependent Claim
16 words
An imager according to claim 12 wherein: said atomic ratio of lead to calcium is 7/3.
Claim 17
Dependent Claim
18 words
An imager according to claim 12 wherein: said lead-calcium-titanate contains approximately four mole percent of cobalt and tungsten.
Claim 18
Dependent Claim
18 words
An imager according to claim 13 wherein: said lead-calcium-titanate contains approximately four mole percent of cobalt and tungsten.
Claim 19
Dependent Claim
25 words
An imager according to claim 13 wherein: some of said lead in said sensor is replaced by approximately eight mole percent of lanthanum and bismuth.
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) | 1994-01-07 | 1994-07-09 | 1995-01-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-01-07 | 1998-07-09 | 1999-01-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-01-07 | 2002-07-09 | 2003-01-08 | $7700.00 | Window Closed / Lapsed |