Recent development in piezoelectric materials used for actuators and sensors applications

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Dragan Damjanovic,

Ceramics Laboratory, Materials Institute Swiss Federal Institute of Technology - EPFL

Lausanne

ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE

Recent development in piezoelectric materials

used for actuators and sensors applications

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Outline

• What is new in piezoelectric materials?

• New ideas about morphotropic phase boundary

• Improvement in piezoelectric properties

• Why is the new knowledge on crystals important

for ceramics?

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“New” piezoelectric materials

Pb(Zn_1/2Nb_2/3)O₃-PbTiO₃, P(Mg_1/2Nb_2/3)O₃-PbTiO₃ BiMeO₃-PbTiO₃ langasite, GaPO₄ KNbO₃ Na_0.5Bi_0.5TiO₃ textured ceramics

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Perovskite structure ABO

₃

O A+1...+3 B+3…+6

5 EPFL LC Pb(Zn_1/2Nb_2/3)O₃-PbTiO₃, Pb(Mg_1/2Nb_2/3)O₃-PbTiO₃ single crystals rhombohedral d₃₃>2000 pC/N k₃₃>0.9 diel permittivity 2000-9000 d₁₅>4000 pC/N excellent

for transducer arrays and actuators

[001]_c

[111]_c

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Transducer applications

arrays

1DIM

2DIM -better images

-higher resolution -higher bandwidth

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Advantages of relaxor-ferroelectric single crystals

zero or small strain-field hystersis

large strain

excellent for actuator applications

rhombohedral [001]_c [111]_c E E weak field d₃₃ 2500 pm/V

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Large piezoelectric effect in ferroelectric single crystals

along nonpolar directions: eg. d

_33,

d

₃₁

, k

_33,

k

₃₁

Park, Shrout (PMN-PT,PZN-PT)

Wada (BaTiO3)

Nakamura (KNbO3)

Du, Belegundu Uchino (PZT)

Taylor, Damjanovic (exp. PZT films)

large properties observed near the morphotropic phase boundary

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Multidomain vs. Monodomain crystal

-experimental data PMN-0.33PT

d_ij[ ]111 c = − 0 0 0 0 4100 −2680 1340 1340 0 4100 0 0 −90 −90 190 0 0 0 ⎛ ⎝ ⎜ ⎜ ⎞ ⎠ ⎟ ⎟

R. Zhang, B. Jiang, and W. Cao, J. Appl. Phys 90, 3471 (2001)

R. Zhang, B. Jiang, and W. Cao, Appl.Phys.Lett 82, 787 (2003) Measurement direction Measurement direction

?

d_ij[ ]001 c = 0 0 0 0 146 0 0 0 0 146 0 0 −1330 −1330 2820 0 0 0 ⎛ ⎝ ⎜ ⎜ ⎞ ⎠ ⎟ ⎟

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Results of calculations for a monodomain

crystal of 0.67PMN-0.33PT

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Multidomain vs. Monodomain crystal

result of calculations

d₃₃[001]c = 2800 pm/V d₃₁[001]c =1300 pm/V d₃₃[001]c = 2310 pm/V d₃₁[001]c =1150 pm/V experiment _calculations 100% 82% 88%

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-the multidomain state (engineered domain state) contributes little to the piezoelectric d₃₁ and d₃₃

coefficients of 0.67PMN-0.33PTsingle crystals along [001]c=[111]r axis.

-At least 82-88%of the large piezoelectric response along [001]c=[111]r axis in multidomain rhombohedral crystal is due to piezoelectric anisotropy

(large shear coefficients), i.e.intrinsic lattice effects of a single domain.

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Domain wall engineering

Wada BaTiO3 (2003) 200µm (a) 200µm A P (b) 200µm A P (c) 100 1000 104 -90 -60 -30 0 30 60 90 500 600 700 Frequency / kHz Phase / deg. |Z| / Ω 100 1000 104 -90 -60 -30 0 30 60 90 500 600 700 Frequency / kHz Phase / deg. |Z| / Ω

14 Tokyo Tech.

Tokyo Tech.

Schematic Domain Configuration

4mm

BaTiO

₃

single crystals

[111]_c

[211]_c [011]_c

90˚ domain wall of (011)_c

Same domain configurations of these BaTiO₃ crystals

But

These crystals have different densities of 90˚ domain walls

Combination of charged & uncharged 90˚ domain walls

Combination of charged & uncharged 90˚ domain walls

[111]_c direction [111] E-field [001]_c [010]_c Satoshi Wada Tokyo Institute of Techn.

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Tokyo Tech.

4mm

BaTiO

₃

single crystals

Table I Piezoelectric properties of the BaTiO₃ single crystals poled along [001]_c and [111]_c

directions.

b) a)

a): measured by Zgonik et al.

b): calculated using the values measured by Zgonik et al. c): measured by Jaffe et al. c) [001]c (single-domain) ε33T s11 _(pC/N)d31 k_(%)31 E (pm2_/N)

BaTiO₃ single crystals

[111]_c (domain size > 40µm [111]_c (domain size of 13.3µm [111]c (domain size of 5.5µm 129 2,185 2,087 2,762 7.4 7.37 7.68 9.58 -33.4 -97.8 -134.7 -230.0 ---25.9 35.7 47.5 [111]_c (single-domain) --- --- -62.0 ---”soft“ PZT ceramics Pb0.988(Ti0.48Zr0.52)0.976Nb0.024O3 1,700 16.4 -171.0 34.4 [111]c (domain size of 6.5µm 2,441 8.80 -180.1 41.4 Satoshi Wada Tokyo Institute of Techn.

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PZT ceramics

0 100 200 300 400 500 0 20 40 60 80 100 Temperature (°C) mol% PbTiO 3 PbZrO 3 PbTiO3 C P T F R_F (high) R_F (low) O A T A tetragonal rhombohedral 8 directions 6 directions 0 100 200 300 400 500 48 50 52 54 56 58 60 Piezoelectric coefficient (pC/N) mol% PbZrO 3 d15 d33 d31

high properties associated with the presence of the MPB

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Relaxor-ferroelectric compositions

P(Zn_1/2Nb_2/3)O₃-PbTiO₃, P(Mg_1/2Nb_2/3)O₃-PbTiO₃

morphotropic phase boundary is present in many complex systems

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Morphotropic phase boundary

0 100 200 300 400 500 0 20 40 60 80 100 Temperature (°C) mol% PbTiO 3 PbZrO 3 PbTiO3 C P T F R_F (high) R_F (low) O A T A tetragonal rhombohedral

-can be strongly curved

-not a narrow boundary between tetragonal and rhombohedral phases;

a monoclinic/orthorhombic

phase separates rhombohedral and tetragonal phases

monoclinic

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Similarity between temperature and composition

phase diagrams

T R PZT barium titanate T R M

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Why piezoelectric properties become

exceptionally high along a nonpolar direction?

P Shear effect Electric field Longitudinal effect Transverse effect P Electric field d₃₁ d₃₃ d₁₅

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Why piezoelectric properties become

exceptionally high along a nonpolar direction?

d₃₃*

( )

ϑ = cosϑ

(

d₁₅t sin2ϑ + d₃₁t sin2ϑ + d₃₃t cos2ϑ

)

tetragonal

P

ϑ

P





ϑ

P d 33 ∗ _{(ϑ) = a} 3ia3ja3kdijk

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Permittivity and shear piezoelectric

coefficients-Case of BaTiO

₃ d₁₅t = d₂₄t =ε₀η₁₁t Q₄₄P₃t d₁₅r = 1 3

(

4Q11 − 4Q12 +Q44

)

ε0P3 r_η 11r d₁₅o =ε₀η₁₁o Q₄₄P₃o d₂₄o = 2ε₀η₂₂o (Q₁₁ −Q₁₂)P₃o R O/M T pre-transitional behavior

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Tetragonal BaTiO3 on cooling toward the orthorhombic

phase

d₃₃(T)

P_T

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Orthorhombic BaTiO3 on cooling from tetragonal toward

the rhombohedral phase

d₃₃(T)

P_O

P_T PO

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Rhombohedral BaTiO3 on cooling from the orthorhombic

phase

d₃₃(T)

P_R

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Origin of large d15

Haun Bellaiche Budimir, Damjanovic

Origin of large d15

d15 becomes high near a phase transition induced by temperature

d15 becomes high near a phase transition induced by composition

change

d15 becomes high

near phase transitions induced by electric field

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Origin of large d15

d15 is large when polarization can rotate easily

Tetr.-Ortho. Ortho.-Tetr. Rhomb.-Ortho. Ortho.-Rhomb.

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Origin of large piezoelectric activity along

nonpolar directions

1. in proximity of phase transitions induced by temperature

composition field

some materials possess very large shear piezoelectric coefficients

large shear coeff. large d₃₃, d₃₁ along nonpolar axes

This mechanism is not related to the presence of engineered domain structure!

2. high density of engineered domain states can further increase response given by mechanism 1. (result of Satoshi Wada; ECP)

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Permittivity arguments

d₁₅t = d₂₄t =ε₀η₁₁t Q₄₄P₃t d₁₅r = 1 3

(

4Q11 − 4Q12 +Q44

)

ε0P3 r_η 11r d₁₅o =ε₀η₁₁o Q₄₄P₃o d₂₄o = 2ε₀η₂₂o (Q₁₁ −Q₁₂)P₃o

shear d coefficients are high

because permittivity perpendicular to polarization is high;

as a consequence of high

permittivity perp. to polarization, the polarization rotation is high

P₁ind P₂ind P₃ind ⎛ ⎝ ⎜ ⎜ ⎜ ⎞ ⎠ ⎟ ⎟ ⎟ = 0 0 P₃ ⎛ ⎝ ⎜ ⎜ ⎞ ⎠ ⎟ ⎟ + ε₁₁ ε₂₂ ε₃₃ ⎛ ⎝ ⎜ ⎜ ⎞ ⎠ ⎟ ⎟ E₁ E₂ E₃ ⎛ ⎝ ⎜ ⎜ ⎞ ⎠ ⎟ ⎟ T [101]_C [001]_C M_A [111]_C M_B M_C R O

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Free energy arguments

0 100 200 300 400 500 0 20 40 60 80 100 Temperature (°C) mol% PbTiO 3 PbZrO 3 PbTiO3 C P T F R_F (high) R_F (low) O A T A tetragonal rhombohedral T R G M T [101]_C [001]_C M_A [111]_C M_B M_C R O

polarization rotates easily

in the composition range where

the free energies of different phases are close

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Electric field effects on piezoelectric anisotropy

in perovskite materials

d₁₅t = d₂₄t =ε₀η₁₁t Q₄₄P₃t

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Electric field effects on piezoelectric anisotropy

in perovskite materials

DC Field applied anti parallel to polarization increases

piezoelectric effect

at 285 K _{at 365 K}

d₃₃*

( )

ϑ = cosϑ

(

d₁₅t sin2ϑ + d₃₁t sin2ϑ + d₃₃t cos2ϑ

)

Budimir,

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Absence of phase transitions-case of PbTiO3

No phase transitions: small d₁₅, small d₃₁,small d₃₃ !!!

Anisotropy is not a function of the temperature

300 K 80 K

P_T

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Why are properties high at the MPB in ceramics?

Usual textbook explanation of the large piezoelectric response at MPB:

-ease of domain re-orientation (8 rhombohedral, 6 tetragonal, 24 monoclinic states)

-large remanent polarization

-extrinsic contributions from moving domain walls

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What happens in ceramics?

d₃₃ only

d₁₅, d₃₃ and d₃₁ most of the grains

(d33)_ave of misoriented grains is high if d15 of the single crystal is high. d15 is high near phase transitions induced by temperature, composition,

or field.

Therefore, importance of MPB! Hint how to design better materials.

some grains

d₃₃*

( )

ϑ,ϕ = d₁₅r cosϑ sin2ϑ + d₂₂r sin3ϑ cos 3ϕ +

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Evolution of d33 surface in rhombohedral PZT

with composition

PZT 90/10 PZT 60/40 Anisotropy increases as MPB is approached P_R

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Properties of relaxor-ferroelectric materials near MPB

low temperature operation

PMN-PT MPB

PMN PT

R _T

O/M

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Alternative: BiScO

₃

-PbTiO

₃

single crystal

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Hysteresis is sometimes present, especially in the

presence of clamping stresses

converse effect

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Lead free materials: (K,Na)NbO

₃

ceramics

biocompatibility k_t>40% d₃₃>100 pC/N ρ= 4.5 gr/cm3 LEAF FP5 project KNN

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Lead free materials

(KNaLi)(NbTaSb)O3

-a morphotropic phase boundary exists in LiTaO3-KNaNbO3 system

-kp as large as 60% -d33>300 pC/N

-strain comparable to that in PZT for the same driving field

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Conclusions

-exciting new developments

-our knowledge of perovskite materials is huge,

but new, important discoveries are still being made -what are the requirements for high performance? new hints!