Motivation

Jacob L. Jones, University of Florida

Domain Wall Evolution in Phase Transforming Oxides

• Motivation– Sensors and actuators are used in several military

functions including surveillance, reconnaissance, navigation, etc.

– Phase-transforming oxides, including ferroelectric materials, exhibit unique potential for multi-functionality (see figure).

• Scientific challenge– One of the fundamental structural features that

defines functionality in these materials are domain walls (see figure).

– However, very few experiments are currently able to characterize domain wall evolution during real operating conditions of sensors and actuators (e.g., cycling fields of low amplitude).

Electric Field

Temperature Change

Magnetization

MechanicalStress

Pyroelectricity

Pyro

mag

netis

m

MagnetoelectricityThermal Expan sion

Electric Field

Temperature Change

Magnetization

MechanicalStress

Pyroelectricity

Pyro

mag

netis

m

MagnetoelectricityThermal Expan sion

Domain

Wall

Ps

Ps



• Objectives1. to enhance the basic

understanding which underlies the linkage between domain architectures and macroscopic properties (structure-property relationships) in bulk, phase-transforming oxides,

2. to explore new methods to control domain structures, and

3. to identify unique domain configurations with previously unrealizable properties.

V

piezoelectric effect

domain

domain wall motion

grain boundary

Macroscopic property (e.g., e-field-induced

strain)



• Approach– Utilize advanced, real-time

characterization techniques including in situ X-ray and neutron diffraction during thermal, electrical, mechanical, and/or magnetic field application.

– These unique in situ measurements of domain wall behavior then provideinsights into materials development for enhanced functionality.

– Prior state-of-the-art involved application of static electric fields at high electric field amplitudes.

– Our approach involves studying domain wall motion during dynamic loading and at operation-relevant field amplitudes (often below the coercive field).



• Scientific Accomplishments– Time-resolved observation of domain variants {002}/{200} of

tetragonal Pb(Zr,Ti)O3 ceramics demonstrate the motion of ferroelectric/ferroelastic domain walls during application of weak electric field amplitudes.

– Quantitative analysis of diffraction data leads to a complete account of the contributions to the ceramic piezoelectric coefficient, d33.

0.00.5

1.0

3.873.97

4.07Time, seconds2degrees)

+E-E

-E

Diff

ract

ed In

tens

ity

Measurement performed at the European Synchrotron Radiation Facility

200 400 600 8000.0

0.1

0.2

0.3

0.4

Frac

tiona

l non

linea

r co

ntrib

utio

n

Strain from 90 domain wall motion

Lattice strain

200

400

600

800

Cum

ulat

ive

cont

ribut

ions

to

d33

(pm

/V)

200

400

600

800

Apparent piezoelectric coefficient

Strain from 90domain wall motion

Cumulative strain from 90 domain wall motion and electric-field-induced lattice strain

d 33(p

m/V

)


Lattice strain

Respective nonlinear contributions calculatedfrom (a) and (b)

(a)

(b)

from 90 domain wall motion

from lattice strain

Linear contributionNonlinear contribution


(c)

Electric Field Amplitude (V/mm)

200 400 600 8000.0

0.1

0.2

0.3

0.4

Frac

tiona

l non

linea

r co

ntrib

utio

n


Lattice strain

200

400

600

800

Cum

ulat

ive

cont

ribut

ions

to

d33

(pm

/V)

200

400

600

800




d 33(p

m/V

)


Lattice strain


(a)

(b)


from lattice strain



(c)


Macroscopic Property Relative Contributions:



200 400 600 8000.0

0.1

0.2

0.3

0.4

Frac

tiona

l non

linea

r co

ntrib

utio

n


Lattice strain

200

400

600

800

Cum

ulat

ive

cont

ribut

ions

to

d33

(pm

/V)

200

400

600

800




d 33(p

m/V

)


Lattice strain


(a)

(b)


from lattice strain



(c)


200 400 600 8000.0

0.1

0.2

0.3

0.4

Frac

tiona

l non

linea

r co

ntrib

utio

n


Lattice strain

200

400

600

800

Cum

ulat

ive

cont

ribut

ions

to

d33

(pm

/V)

200

400

600

800




d 33(p

m/V

)


Lattice strain


(a)

(b)


from lattice strain



(c)


Macroscopic Property Relative Contributions:

• Scientific Accomplishments– The linear component of the e-field-induced lattice strains is the

only component which may be intrinsic piezoelectricity (since intrinsic PE is field-independent).

– Closer inspection of lattice strain measurements indicate this is not likely the intrinsic piezoelectric coefficient, but rather an elastic intergranular coupling.

– Remarkably, the piezoelectric d33 coefficient in this common soft PZT composition is mostly attributed to domain wall motion, not the intrinsic piezoelectric effect of the lattice.

In review as a Feature Article for J. American Ceramic Society



• Scientific Accomplishments– Synthesis, high-resolution structural measurement, and refinement of

(1-x)Na0.5Bi0.5TiO3-xBaTiO3 (BNT-xBT) piezoelectric ceramics.– Crystallographic refinement of the NBT indicates a monoclinic Cc

space group, not widely-assumed R3c. – Implies complex ferroelectric/ferroelastic domain structure in BNT-

based materials. May explain nanodomains and relaxor-like behavior.– Also suggests “monoclinic” not a sufficient condition for high d33.

High-resolution X-ray measurements at the Advanced Photon Source, Argonne National Laboratory



• Scientific Accomplishments– Acceptor-doping in Na0.5Bi0.5TiO3(BNT)-based ceramics show

unexpected behavior of thermal stability.– Piezoelectric coefficient

d33 as a function of temperature shows increased thermal stability for small (<1%) Fe2O3 doping concentration.

– Because of negligible lowering of initial (room temperature) d33, this material has a high piezoelectric coefficient at elevated temperatures.

Enhanced thermal stability

0 50 100 150 200 250 300 3500

20

40

60

80

100

120

140 Undoped 0.5 mol% Fe

2O

3

1.0 mol% Fe2O

3

1.5 mol% Fe2O

3

2.0 mol% Fe2O

3

d 33 (p

m/V

)

Temperature (degrees C)



• Transitions– The PI gave several seminars at national

laboratories including:• User Science Seminar, Advanced Photon

Source, Argonne National Laboratory, July 30, 2010.

• Lujan Neutron Scattering Center, Los Alamos National Laboratory, July 27, 2010.

– The PI participated and delivered an invited talk at a symposium organized by ARL personnel from the Aberdeen Proving Ground (XIX International Materials Research Congress, Cancun, Mexico, August 15-19, 2010.)

– The PI hosted Dr. Melanie Cole from the Army Research Laboratory, Aberdeen Proving Ground, on Sept 12, 2008. She met with several faculty members and the PI and gave a departmental research seminar titled, “Compositionally Tailored Material Properties To Enable Performance Enhanced Tunable Microwave Devices.”

PI Jones and PhD student Elena Aksel at Los Alamos

National Laboratory



• PI Awards– Presidential Early Career Award for Scientists and Engineers

(PECASE), Awarded January 13, 2010.– Defense Program Awards of Excellence, nominated through the

Los Alamos National Laboratory and presented by Donald Cook (Deputy Administrator for Defense Programs, NNSA), August 30, 2010, “for discovering important new physics in ferroelectric ceramics used in neutron generators through clever neutron scattering experiments.”

– Faculty Excellence Award, April 22, 2010. Department of Materials Science and Engineering, University of Florida.

– Excellence Award for Assistant Professors, April 27, 2010, one of 10 recipients at the University of Florida.

– 11 invited talks acknowledging ARO support at international conferences, national laboratories, and universities.



• Future Research Plans– Recent time-dependent pulse

poling measurements discriminate between 180° and non-180° domain wall motion (see figure).

– Use of pulsed electric fields of various durations during the electrical poling process will coerce domains into unique configurations.

– This time-dependent experiment builds upon our existing electromechanical poling studies.

100 102 104 106

0

0.2

0.4

0.6

0.8

1

Time (microseconds)

Nor

mal

ized

Lon

gitu

dina

l Str

ain

PLZT Longitudinal Strain in Responseto Instantaniously Applied E-Fields

2.0 kV/mm1.9 kV/mm1.8 kV/mm1.6 kV/mm1.5 kV/mm1.4 kV/mm

180° domain switching occurs first during pulsed fields

Non-180° domain switching occurs last after pulsed field application



• Future Research Plans– Analysis of structure and resulting

domain structures in BNT-xBT using high-resolution X-ray diffraction.

– In situ X-ray and neutron diffraction measurements to understand origin of electromechanical behavior at x=7.

– We hypothesize that high piezoelectric d33 at x=7 is not related to the morphotropic phase boundary, but due to domain wall contributions (similar to PZT).

– This implies that the design of high-d33 ceramics should include domain wall contributions.

W. Jo, J. L. Jones, et al., in review at J. Applied Physics

Peak in permittivity and d33 at x=7

Documents

Motivation