Compositions – Piezoelectric
Reexamination Certificate
2001-03-02
2003-02-11
Wood, Elizabeth D. (Department: 1755)
Compositions
Piezoelectric
C501S134000, C501S135000, C501S136000
Reexamination Certificate
active
06517737
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to piezoelectric materials and devices that use piezoelectric materials.
2. Discussion of the Related Art
Piezoelectric materials respond to applied electric fields by physically deforming. The magnitude of the deformations that electric fields generate in single-crystal perovskites such as Pb(Mg
1/3
Nb
2/3
)O
3
—PbTiO
3
(PMN-PT) and Pb(Zn
1/3
Nb
2/3
)O
3
—PbTiO
3
(PZN-PT) are an order of magnitude larger than those that the fields generate in polycrystalline piezoelectrics such as PbZrO
3
—PbTiO
3
(PZT). The size of their piezoelectric responses make the crystalline perovskites promising materials for new piezoelectric devices.
Unfortunately, the fabrication of crystalline perovskites is complicated and expensive. On the one hand, high fabrication costs make the crystalline perovskites too expensive for use in many types of electromechanical devices. On the other hand, polycrystalline PZN-PT typically require high-pressure synthesis, which is prohibitively expensive to some commercial applications of PZN-PT.
Herein, PMN refers to Pb(Mg
1/3
Nb
2/3
)O
3
and PT refers to PbTiO
3
.
Herein, chemical symbols are used for lead (Pb), niobium (Nb), zinc (Zn), zirconium (Zr), magnesium (Mg), titanium (Ti), and oxygen (O).
SUMMARY OF THE INVENTION
In one aspect, the invention features a device that includes a polycrystalline body. The body has a stoichiometry described by [Pb(Mg
1/3
Nb
2/3
)O
3
]
(1−x)
[PbTiO
3
]
x
. The value of x is in the range of about 0.31 to about 0.47.
In another aspect, the invention features a process to fabricate a solid body. The process includes forming a mixture of powdered oxides. The oxides include lead, magnesium, niobium, and titanium. The process also includes sintering the mixture to produce a polycrystalline body with a [Pb(Mg
1/3
Nb
2/3
)O
3
]
(1−x)
[PbTiO
3
]
x
stoichiometry. The value of x is in the range of about 0.31 to about 0.47.
In another aspect, the invention features an electromechanical device. The electromechanical device includes a support structure, a component moveable with respect to the support structure, and a piezoelectric device mechanically coupled to both the support structure and the component. The piezoelectric device includes a polycrystalline body and electrodes located on the body. The body has a composition with a stoichiometry described by [Pb(Mg
1/3
Nb
2/3
)O
3
]
(1−x)
[PbTiO
3
]
x
. The value of x is in the range of about 0.31 to about 0.47.
REFERENCES:
patent: 5032558 (1991-07-01), Bailey et al.
patent: 5759432 (1998-06-01), Kumar et al.
patent: 5804907 (1998-09-01), Park et al.
“The Inket color Image, Born in a Rainbow of Tiny Drops” by Matt Lake, published at www.nytimes.com, (Dec. 5, 2000), 5 pages.
“Materials Science: Shape-Changing Crystals Get Shiftler” by Robert F. Service, Science vol. 275, (1997), p. 1878, No month.
“Ferroelectric Ceramics: History and Technology” by Gene H. Haertling, Journal of the American Ceramic Society, vol. 82(4), (1999), pp. 797-818, No month.
“Ultrahigh strain and piezoelectric behavior in relaxor based ferroelectric single crystals” by Seung-Eek Park et al, Journal of Applied Physics, vol. 82(4), (Aug. 15, 1997), pp. 1804-1811.
Cheong Sang-Wook
Koo Tae-Yeong
Lucent Technologies - Inc.
McCabe John F.
Wood Elizabeth D.
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