US3943387A
Expired / Lapsed
US
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Process for making a piezoelectric body
Assignee: Siemens AG
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Filing: 1974-03-28
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Granted: 1976-03-09
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Expires: 1994-03-28
Abstract
Abstract Process for the production of a piezoelectric body which contains a ferroelectric material which may be polarized in an aligned, permanent fashion and also contains a bonding material, the process comprises mixing a bonding material selected so that at least in a temperature range below the Curie temperature of the ferroelectric material, it has a specific electric conductivity σ B > E C × σ K /E B , where σ K is the specific conductivity of the ferroelectric material, E C is the coercivity field strength of the ferroelectric material, and E B is the electric breakdown field strength of the bonding material with a granular ferroelectric material having a known Curie temperature, forming a desired body shape from such mixture, heating the resultant body to a temperature at least sufficient for the bonding material to exhibit its specific conductivity and applying an electric voltage of sufficient intensity to the body to produce a permanent polarization alignment in the ferroelectric material within such body.
Inventors
- 👤 Richard Veith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 13:12
CPC Classifications
H; H01; H01G; H01G7/00; H01G7/02; H01G7/028; Y; Y10; Y10T; Y10T29/00; Y10T29/42
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
198 words
A process for producing a piezoelectric body which may be polarized in an aligned permanent fashion comprising: mixing a select amount of a granular ferroelectric material having a Curie temperature greater than 200° C. with a sufficient amount of a fluidized bonding material to bind said granular ferroelectric material into a cohesive body, said bonding material being characterized by a specific conductivity below said Curie temperature of the ferroelectric material in accordance with the formula σ.sub.B ≧ E.sub.C × .sub.K /E.sub.B wherein σ B is the specific conductivity of the bonding material; E c is the coercive field strength of the ferroelectric material; σ K is the specific conductivity of the ferroelectric material; and E b is the electric breakdown field strength of the bonding material; shaping said mixture into a solid predetermined body shape; heating said solid body to a temperature sufficient to exhibit said specific conductivity in the bonding material but below said Curie temperature of the ferroelectric material; and applying an electric voltage of sufficient intensity to said heated solid body to produce a permanent polarization alignment in the ferrorelectric material within said solid body but below that required to heat damage the bonding material.
Claim 2
Dependent Claim
198 words
A process for producing a piezoelectric body which may be polarized in an aligned permanent fashion comprising: mixing a select amount of a granular ferroelectric material having a Curie temperature greater than 200° C. with a sufficient amount of a fluidized bonding material to bind said granular ferroelectric material into a cohesive body, said bonding material being characterized by a specific conductivity below said Curie temperature of the ferroelectric material in accordance with the formula σ.sub.B ≧ E.sub.C × .sub.K /E.sub.B wherein σ B is the specific conductivity of the bonding material; E c is the coercive field strength of the ferroelectric material; σ K is the specific conductivity of the ferroelectric material; and E b is the electric breakdown field strength of the bonding material; shaping said mixture into a solid predetermined body shape; heating said solid body to a temperature sufficient to exhibit said specific conductivity in the bonding material but below said Curie temperature of the ferroelectric material; and applying an electric voltage of sufficient intensity to said heated solid body to produce a permanent polarization alignment in the ferrorelectric material within said solid body but below that required to heat damage the bonding material.
Claim 3
Dependent Claim
39 words
A process as defined in claim 1 wherein the specific conductivity σ B of the bonding material is determined in accordance with the equation: σ.sub.B = n × σ.sub.K wherein n is an integer ranging from 0.1 to 100.
Claim 4
Dependent Claim
53 words
A process as defined in claim 1 wherein the application of electric voltage to produce a permanent polarization alignment in the ferroelectric material within the solid body occurs while the solid body is maintained for at least one minute at a temperature sufficient for the bonding material to exhibit the specific conductivity thereof.
Claim 5
Dependent Claim
65 words
A process as defined in claim 3 wherein the application of electric current to produce a permanent polarization alignment in the ferroelectric material within the solid body occurs while the solid body is maintained at a temperature sufficient for the bonding material to exhibit the specific conductivity thereof and for a time period sufficient to establish a basically constant electric current through the solid body.
Claim 6
Dependent Claim
29 words
A process as defined in claim 1 wherein the applied electric voltage is of an intensity sufficient to only heat the solid body to a temperature below 100° C.
Claim 7
Dependent Claim
50 words
A process as defined in claim 1 wherein the granular ferroelectric material is subjected to a tempering process prior to mixing such material with the bonding material, said tempering process occurring at a temperature below that required to sinter such granular material into a mass and loose the grnularity thereof.
Claim 8
Dependent Claim
16 words
A process as defined in claim 1 wherein the bonding material comprises an organic synthetic material.
Claim 9
Dependent Claim
16 words
A process as defined in claim 7 wherein the organic synthetic material comprises an epoxy resin.
Claim 10
Dependent Claim
26 words
A process as defined in claim 1 wherein the granular ferroelectric material is formed of individual granules having a diameter ranging from 0.1 to 1 μm.
Claim 11
Dependent Claim
60 words
A process as defined in claim 1 wherein the bonding material exhibits a specific conductivity at room temperature in accordance with the equation: σ.sub.B = m×E.sub.O × E.sub.K /T wherein E K is the dielectric constant of the ferroelectric material; T is the time period for the applied electric voltage; and m is an integer ranging from 0.1 to 10.
Claim 12
Dependent Claim
31 words
A process as defined in claim 1 wherein the bonding material includes a homogeneously distributed electrically conductive component in an amount sufficient to achieve the specific conductivity of the bonding material.
Claim 13
Dependent Claim
42 words
A process as defined in claim 1 wherein the bonding material is dissolved in a suitable solvent therefore prior to mixing with the granular ferroelectric material and the solvent is evaporated prior to shaping such mixture into a solid predetermined body shape.
Claim 14
Dependent Claim
34 words
A process as defined in claim 1 wherein the shaping of the mixture into a solid predetermined body shape includes pressing the mixture into a desired body shape and hardening such pressed body shape.
Claim 15
Dependent Claim
30 words
A process as defined in claim 1 wherein the shaping of the mixture into a solid predetermined body shape comprises applying the mixture as a layer onto a base plate.
Claim 16
Dependent Claim
23 words
A process as defined in claim 14 wherein application of the mixture as a layer onto a base plate is accomplished by rolling.
Claim 17
Dependent Claim
15 words
A process as defined in claim 14 wherein the base plate is composed of aluminum.
Claim 18
Dependent Claim
17 words
A process as defined in claim 1 wherein the granular ferroelectric material is composed of lead titanate.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-03-09 | 1979-09-08 | 1980-03-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-03-09 | 1983-09-08 | 1984-03-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-03-09 | 1987-09-08 | 1988-03-09 | $7700.00 | Window Closed / Lapsed |