铁电体材料

SHAPE CHANGE FROM CUBIC PROTOTYPE m3m NO PIEZOELECTRICITY: ELECTROSTRICTION CUBIC Q11 Q12 Q44 S1 = Q11P12 + Q12 P22 + Q12 P32 S2 =Q12 P12 + Q11 P22 + Q12 P32 S3 = Q12 P12 +Q12 P22 +Q11 P32 S4 = Q44 P2 P3 S5 = Q44 P1 P3 S6 = Q44 P1 P2
ONE COMPLETELY INDEPENDENT ASSESSMENT OF THE QUALITY OF A RESEARCH INSTITUTION
How frequently are the Authors of its published research output cited in the references used by other Scientist/Engineers publishing in the same research field.
P
S Tkl
Sij
M
χM
Magneto-Elastic
FERROELASTIC FERROMAGNETIC SOFTENS THIS WHOLE BRANCH
H
Ferromagnet has very high Magnet susceptibility
Ferroelastic has very high Elastic Compliance
(a)
(b)
(c)
Ferroelectric, Ferromagnetic, & Ferroelastic Pi Ei Mi Hi Sij Tij
Ferroelectric & Ferroelastic Pi Ei Sij Tij
WHY MULTIFERROIC? E
FE S O RRO FT EL EN AS S T TI HI C F S W ER H RO Ele ctr OLE EL oe B R E CT las AN RI ti c CH C
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FERROMAGNETIC-FERROELASTIC SYSTEMS
Ferroelastic Martensites Magnetic Control of Martensite Twins Versality: High strain but low force
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FERROELECTRIC-FERROMAGNETIC SYSTEMS
Perovskite structure ferroelectrics. Electrostrictive coupling to Ferroelasticity. Important consequences for piezoceramics. Widespread applications. Single crystals.
Outline
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PRIMARY FERROICS
Defining Features: Domains responsible for hysteresis. Driving forces for switching. Why Multiferroics?
FERROELECTRIC-FERROELASTIC SYSTEMS
Government Agencies
Industrial Centers
Member Company Input
Materials Research Institute (MRI)
MRI is the focal point for materials at Penn State MRI builds infrastructure and provides resources MRI strives to enhance interdisciplinary research in: Biomedical Engineering Information Technology Energy and Transportation Environmental Science and Technology Manufacturing
THE INSTITUTE FOR SCIENTIFIC INFORMATION ISI (Part of the $8 Billion dollar Thomson Corp) Tracks from 300 publishers some 10,000 research journals FOR THE MATERIALS FIELD ISI Lists the 214 researchers with the highest citation count over the last 20 years called: HIGHLY CITED RESEARCHERS HOW DOES PENN STATE FARE
Example of an Industrial Center within the MRI – Center for Dielectric Studies New Materials High Frequency Device Modeling New Measurement Techniques Interfacial Characterization Prototyping
RECENT DEVELOPMENTS IN MULTIFERROIC CRYSTALS, CERAMICS, COMPOSITES AND THIN FILMS
L. Eric Cross Evan Pugh Professor Emeritus of Electrical Engineering Materials Research Institute The Pennsylvania State University University Park PA 16802 USA
Materials Research Institute Bldg.
Materials Research Laboratory Bldg.
MATERIALS RESEARCH INSTITUTE
Carlo Pantano, Director Michael Lanagan, Associate Director
A ferroic crystal exhibits, in an attainable range of temperature and pressure, one or more of the following quantities: a magnetization, polarization, or strain that is (are) stable in the absence of any applied fields, whether magnetic, electric, or mechanical stress. Upon applications of these fields or stresses, or combinations of them, one can switch the directions of spontaneous magnetization, the spontaneous polarization, or the spontaneous strain between equilibrium domain states.
INDUCED PIEZOELECTRICITY FOR NON ZERO P3 ∂ S 3 = b 33 = 2 Q 11 P 3 ∂ P3 ∂ S 3 ∂P3 ⋅ = d 33 = b 33 ε 33 = 2Q 11 P 3 ε ∂P3 ∂E 3
Ferroelectric has a very high Dielectric susceptibility
ET GN MA CH RO AN E R BR C F O LE RI CT WH c LE IS tr i OE TH lec RR NS neto E FE FTE g Ma SO
χE
FERROELECTRIC – FERROELASTIC SYSTEMS
Hale Waihona Puke Baidu
FERROIC BEHAVIOR
Idealized (a) ferromagnetic, (b) ferroelectric, and (c) ferroelastic hysteresis loops for single crystals switching between two reversible domain states
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SECONDARY FERROICS Possible reasons for renewed interest.
FERROIC BEHAVIOR
H Field rearranges Magnetic domains to change M
Tij Field rearranges Elastic Domain to Change Sij
“While the inherently interdisciplinary nature of Materials Science predictably leads to frequent cross-citation with other ISI categories, what my be less expected is the relative dominance of a few institutions in the field: Pennsylvania State University dominates the category, with an amazing 12 Highly-Cited Researchers in materials science based there. This is twice the number at the next-most influential institution, the University of Texas at Austin, with 6 Highly Cited materials scientists.
Difficult to realize in a single phase Boracite Family: Fantastic Physics. Low temperature realization. Improper ferroelectricity. Bismuth Ferrate. Single crystal vs. epitaxial film. Modified Bulk compositions with MPBs Composite Structures lamellar composites elastic coupling. Ultra-sensitive magnetic field sensors.
Ε Field re-arranges Polar Domains to change P
Materials Enabling Vision of Multiferroics
Ferroelectric & Ferromagnetic Pi Ei Mi Hi
Ferroelastic & Ferromagnetic Mi Hi Sij Tij
HIGHLY CITED SCIENTISTS FROM ISI “HIGHLY CITED” PRESS RELEASE APRIL 3, 2003 MATERIALS SCIENCE
Penn State Texas California – Santa Barbara Stanford MIT Penn Illinois Northwestern North Carolina State Oak Ridge Ohio State Wisconsin Michigan State Michigan Minnesota 8 in MRL 12 6 5 5 4 4 4 4 3 3 2 2 1 1 1