Recent development in piezoelectric materials used for actuators and sensors applications

Transcription

1 Recent development in piezoelectric materials used for actuators and sensors applications Dragan Damjanovic, Ceramics Laboratory, Materials Institute Swiss Federal Institute of Technology - EPFL Lausanne ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE 1 EPFL

2 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? Open questions 2 EPFL

3 New piezoelectric materials Pb(Zn 1/2 Nb 2/3 )O 3 -PbTiO 3, P(Mg 1/2 Nb 2/3 )O 3 -PbTiO 3 BiMeO 3 -PbTiO 3 langasite, GaPO 4 KNbO 3 Na 0.5 Bi 0.5 TiO 3 textured ceramics 3 EPFL

4 Perovskite structure ABO 3 PbTiO 3 O A B EPFL

5 Pb(Zn 1/2 Nb 2/3 )O 3 -PbTiO 3, Pb(Mg 1/2 Nb 2/3 )O 3 -PbTiO 3 single crystals [001] c [111] c rhombohedral d 33 >2000 pc/n k 33 >0.9 diel permittivity d 15 >4000 pc/n excellent for transducer arrays and actuators Park, Shrou 1997t 5 EPFL

6 Transducer applications arrays 1DIM 2DIM -better images -higher resolution -higher bandwidth 15-20%-? 6 EPFL

7 Advantages of relaxor-ferroelectric single crystals zero or small strain-field hystersis large strain excellent for actuator applications [001] c [111] c E E weak field d pm/v rhombohedral 7 EPFL

8 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 8 EPFL

9 Multidomain vs. Monodomain crystal -experimental data PMN-0.33PT Measurement direction? Measurement direction [ ] c = d ij 001 R. Zhang, B. Jiang, and W. Cao, J. Appl. Phys 90, 3471 (2001) [ ] c = d ij 111 R. Zhang, B. Jiang, and W. Cao, Appl.Phys.Lett 82, 787 (2003) 9 EPFL

10 Results of calculations for a monodomain crystal of 0.67PMN-0.33PT 10 EPFL

11 Multidomain vs. Monodomain crystal result of calculations [001]c d 33 = 2800 pm /V [001]c d 31 = 1300 pm /V 100% [001]c d 33 = 2310 pm /V [001]c d 31 = 1150 pm /V 82% 88% experiment calculations 11 EPFL

12 Monodomain vs multidomain response -the multidomain state (engineered domain state) contributes little to the piezoelectric d 31 and d 33 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. 12 EPFL

13 Domain wall engineering A P (b) 200µm (a) 200µm A P (c) 200µm Wada BaTiO3 (2003) Z / Ω Phase / deg. Z / Ω Phase / deg Frequency / khz coarse domains Frequency / khz fine domains EPFL

14 Tokyo Tech. [111] c direction [111] E-field [010] c [001] c 4mm BaTiO 3 single crystals Schematic Domain Configuration 90 domain wall of (011) c Satoshi Wada Tokyo Institute of Techn. [111] c [011] c Combination of of charged & uncharged 90 domain walls [211] c Same domain configurations of these BaTiO 3 crystals But These crystals have different densities of 90 domain walls 14

15 Tokyo Tech. 4mm BaTiO 3 single crystals Table I Piezoelectric properties of the BaTiO 3 single crystals poled along [001] c and [111] c directions. Satoshi Wada Tokyo Institute of Techn. BaTiO 3 single crystals [001] a) c (single-domain) b) [111] c (single-domain) [111] c (domain size > 40µm ε33 T E s d (pm 2 /N) (pc/n) , k 31 (%) [111] c (domain size of 13.3µm 2, [111] c (domain size of 6.5µm 2, [111] c (domain size of 5.5µm 2, c) soft PZT ceramics Pb (Ti 0.48 Zr 0.52 ) Nb O 3 1, a): measured by Zgonik et al. b): calculated using the values measured by Zgonik et al. c): measured by Jaffe et al. 15

16 PZT ceramics Temperature ( C) O A T A R F (low) R F (high) C P T F rhombohedral tetragonal PbZrO mol% PbTiO PbTiO Piezoelectric coefficient (pc/n) d d d mol% PbZrO 3 8 directions 6 directions high properties associated with the presence of the MPB 16 EPFL

17 Relaxor-ferroelectric compositions P(Zn 1/2 Nb 2/3 )O 3 -PbTiO 3, P(Mg 1/2 Nb 2/3 )O 3 -PbTiO 3 morphotropic phase boundary is present in many complex systems 17 EPFL

18 Morphotropic phase boundary 500 -can be strongly curved 400 C P -not a narrow boundary between tetragonal and rhombohedral phases; a monoclinic/orthorhombic phase separates rhombohedral and tetragonal phases Temperature ( C) O A T A R F (low) R F (high) rhombohedral tetragonal PbZrO mol% PbTiO 3 3 PbTiO 3 T F monoclinic Noheda, Shirane 18 EPFL

19 Similarity between temperature and composition phase diagrams M PZT R T R T barium titanate 19 EPFL

20 Why piezoelectric properties become exceptionally high along a nonpolar direction? Shear effect Electric field P d 33 P d 15 Longitudinal effect Transverse effect d 31 Electric field 20 EPFL

21 Why piezoelectric properties become exceptionally high along a nonpolar direction? ϑ P P ϑ P t ( ) = cosϑ d 15 d * 33 ϑ d 33 (ϑ) = a3i a 3 j a 3k d ijk ( sin 2 ϑ + d t 31 sin 2 ϑ + d t 33 cos 2 ϑ ) tetragonal 21 EPFL

22 Permittivity and shear piezoelectric coefficients- Case of BaTiO 3 t d 15 t = d 24 = ε 0 η t t 11 Q 44 P 3 R O/M T pre-transitional behavior r d 15 d o 15 = ε 0 η o o 11 Q 44 P 3 d o 24 = 2ε 0 η o o 22 (Q 11 Q 12 )P 3 = 1 ( 3 4Q 11 4Q 12 + Q 44 )ε 0 P r r 3 η EPFL

23 Tetragonal BaTiO3 on cooling toward the orthorhombic phase d 33 (T) P T P O 23 EPFL

24 Orthorhombic BaTiO3 on cooling from tetragonal toward the rhombohedral phase d 33 (T) P T P O P O P R 24 EPFL

25 Rhombohedral BaTiO3 on cooling from the orthorhombic phase d 33 (T) P R P o 25 EPFL

26 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 Budimir, Damjanovic Haun Bellaiche 26 EPFL

27 Origin of large d15 d15 is large when polarization can rotate easily Ortho.- Tetr. Tetr.- Ortho. Rhomb.-Ortho. Ortho.- Rhomb. 27 EPFL

28 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 d 33, d 31 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) 28 EPFL

29 Permittivity arguments r d 15 t d 15 t = d 24 t t = ε 0 η 11Q44 P 3 o d 15 = o o ε0 η 11Q44 P 3 o d 24 = o o 2ε0 η 22(Q11 Q 12 )P 3 = 1 ( 3 4Q 11 4Q 12 + Q 44 )ε 0 P r r 3 η 11 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 T ind P 1 ind P 2 ind P 3 = P 3 ε 11 ε 22 ε 33 E 1 E 2 E 3 [101] C O M C [001] C R [111] C M B M A 29 EPFL

30 Free energy arguments 500 T [001] C 400 C P [101] C O R [111] C M B Temperature ( C) T A R F (high) rhombohedral T F tetragonal M C O A R F (low) M A PbZrO mol% PbTiO 3 3 PbTiO 3 polarization rotates easily in the composition range where the free energies of different phases are close G R M T 30 EPFL

31 Electric field effects on piezoelectric anisotropy in perovskite materials BaTiO3 t d 15 t = d 24 = ε 0 η t t 11 Q 44 P 3 31 EPFL

32 Electric field effects on piezoelectric anisotropy in perovskite materials t ( ) = cosϑ d 15 d * 33 ϑ at 285 K at 365 K ( sin 2 ϑ + d t 31 sin 2 ϑ + d t 33 cos 2 ϑ ) DC Field applied anti parallel to polarization increases piezoelectric effect Budimir, Damjanovic EPFL

33 Absence of phase transitions-case of PbTiO3 No phase transitions: small d 15, small d 31,small d 33!!! Anisotropy is not a function of the temperature P T d33(θ) 80 K 300 K 33 EPFL

34 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 34 EPFL

35 What happens in ceramics? d 33 only some grains d 15, d 33 and d 31 most of the grains * d 33 ( ϑ,ϕ r ) = d 15 cosϑ sin 2 ϑ + r d22 sin 3 ϑ cos3ϕ + r +d 31 sin 2 ϑ cosϑ + r d33 cos 3 ϑ (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. 35 EPFL

36 Evolution of d33 surface in rhombohedral PZT with composition Anisotropy increases as MPB is approached PZT 90/10 PZT 60/40 P R 36 EPFL

37 Open problems with relaxor-ferroelectrics 37 EPFL

38 Properties of relaxor-ferroelectric materials near MPB O/M PMN-PT MPB R T PMN PT low temperature operation PNN-PT-PZ 38 EPFL

39 Alternative: BiScO 3 -PbTiO 3 single crystal Zhang, Randall, Shrout 39 EPFL

40 Hysteresis is sometimes present, especially in the presence of clamping stresses converse effect direct effect 40 EPFL

41 Lead free materials: (K,Na)NbO 3 ceramics KNN biocompatibility k t >40% d 33 >100 pc/n ρ= 4.5 gr/cm 3 LEAF FP5 project 41 EPFL

42 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 patents by Toyota 2003, EPFL

43 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! -new, high performance materials are being developed 43 EPFL