Zuo-Guang. Ye Advanced Dielectric Piezoelectric and Ferroelectric Materials: Synthesis, Characterisation and Applications

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Handbook of dielectric, piezoelectric and ferroelectric materials30

Thus, the maximum amplitude of d

equals ±(d

–d

) at ϕ = ±45° or ±225°,

which is the sum of the absolute values of d

and d

32.

From the application

point of view, it is impressive that d

can be re-poled (poling electrode =

working electrode) in addition to the large piezoelectric coefficient.

To verify the above maximum values based on the theoretical calculation,

four sets of specimens were prepared according to the rotation angles where

the maximum d values occur. The experimental data confirm the calculated

results (Table 1.2), suggesting that the piezoelectric matrices of the 32

symmetric classes are applicable to the domain-engineered PMN–PT crystals

with 4mm or mm2 multi-domain symmetric configurations.

1.6 Conclusions and future trends

The modified Bridgman growth method has been successfully applied to the

growth of large PMN–PT crystals (76mm in diameter × 200 mm long) on an

industrial scale. Based on the conventional crystal growth method, two major

modifications have been made: multi-crucible configuration and zone leveling.

These successful developments in the crystal growth techniques have led to

the cost-effective manufacture of large PMN–PT crystals. The technical

progresses that have been made during the crystal-growth investigations

include: (1) the understanding of the reason for platinum crucible corrosion

by lead-containing melt and knowing how to reduce the leakages during

crystal growth; (2) the optimization of the furnace structure and growth

parameters to increase the crystal perfection; and (3) the <001> seeding

method that significantly improves the property uniformity of the (001)

crystal wafer.

The piezoelectric properties were systematically characterized. The database

of the physical properties of PMN–PT crystals has been documented. It has

Table 1.2

New cut directions to optimize piezoelectic performance

Vibration Longitudinal Transverse Longitudinal Transverse

mode extension extension shear shear

Symmetry

4mm mm2 mm2 3m

Cut direction

zxt

0°

zxt

0°

zxt

±45°

xzt

–22.5°

Calculated

(value 31% PT) 2000 pC/N –1750 pC/N 2600 pC/N 5190, 0pC/N

Measured value

(31% PT) 200 pC/N –1750 pC/N 2520 pC/N 5300, 60pC/N

Poling

Stress

LE TE LS TS

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Bridgman growth and properties 31

been determined that the most useful composition of the PMN–PT is in the

range of 26.5–32% PT, which corresponds to a T

range of 121–142 °C. The

majority of properties improved along the growth direction towards the MPB.

In the useful composition range, d

increased by > 80%,

by >50%, and

by >90%. By contrast, the k

and g

values were less sensitive (<20%)

to changes in composition.

The representation surfaces of the piezoelectric charge coefficient (d

)

were calculated for the <001>-, <011>- and <111>-poled PMN–PT crystals

and experimentally verified. It was discovered that the zxt ±45° cut for the

<011>-poled PMN–PT crystal gives a unique re-poleable shear piezoelectric

coefficient d

up to 2600pC/N. It was also found that an extraordinarily

high shear piezoelectric coefficient d

up to 5190pC/N

for the single domain

crystal (3m) occurred in the xzt 22.5° cut. The highest d

of –1750pC/N in

the zxt 0° cut was obtained in the <011>-poled crystals.

The achievements in the crystal growth and characterization of PMN–PT

crystals have built the foundation for the development of the next generation

of acoustic transduction devices. The future trends for the PMN–PT based

piezoelectric crystals lie largely in engineering developments that enhance

production yields and reduce costs by enlargement of crystal dimensions, i.e.

larger diameters (100 mm, 4 inches, or beyond) and longer length. Further

progress in the improvement of compositional segregation (e.g. by continuous

top-feeding Bridgman method

) is important for commercialization. In

addition, to broaden applications, the physical properties of PMN–PT-based

crystals need to be improved, in particular, the thermal stability and electrical

coercive field. To paraphrase, hardening of PMN–PT based crystals must be

developed using the Bridgman method. A straightforward approach is through

compositional modifications of a PMN–PT binary system with a third

component, such as PIN (lead indium niobate) or PYbN (lead ytterbium

niobate), to form a ternary MPB system. H. C. Materials has demonstrated

the feasibility of growing 50mm (2-inch) diameter crystals of PYbN–PMN–

PT (15/50/35) and PIN–PMN–PT (26/43/31) using the Bridgman method

Both crystals show higher developing temperatures above 110 °C and larger

coercive field of 5~6kV/cm compared with PMN–PT crystals (85~95°C and

2 kV/cm, respectively). It is expected that the success in the fabrication of

large-sized piezoelectric single crystals with modified compositions using

the Bridgman method will lead to omni-applications of these crystals in

acoustic transduction devices.

1.7 Appendix

The following data are very useful for the device designer to select PMN–PT

crystals correctly and to use the giant piezoelectric property effectively. The

physical properties of the crystals strongly depend on the cut directions and

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Handbook of dielectric, piezoelectric and ferroelectric materials32

Table 1.3

Property comparisons between <001>-poled 33-mode, and <011>-poled 31-mode

<001>-poled 33-mode <011>-poled 31-mode

Property Type A Type B Property Type A Type B

5000 6500

3200 4600

tanδ 0.0040 0.0060 tanδ 0.0035 0.0024

[pC/N] 1600 2400

[pC/N] –1100 –1750

[pC/N] –580 –900

[pC/N] 301 564

0.88 0.91

0.69 0.90

[10

–12

/N] 38 60

[10

–12

/N] 53 84

[10

–12

/N] 9.8 12

[10

–12

/N] 26 30

[10

–3

V m/N] 32 37

[10

–3

V m/N] –34 –38

coercive [kV/cm] 2.5 2.3

coercive [kV/cm] 4.5 4.0

Depoling [°C] 93 85 Depoling [°C] 95 85

Acoustic imp. mrayl 28 277 Acoustic imp. mrayl 32 30

<001> <001>

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Bridgman growth and properties 33

vibration modes. Three symmetric poling directions provide totally different

piezoelectric properties like different materials even though the crystals

have same chemical compositions. The chemical composition, i.e. PT content,

also impacts on the physical properties. It can be seen in the property table

below. Type A and B crystals sorted by compositions are 28% PT and 31%

PT respectively.

The data and information in Table 1.3 and Figs 1.16 and 1.17 are a brief

summary of the most important physical properties of the PMN–PT crystals.

1.16

Anisotropic difference between <001>-poled 31-mode and

<011>-poled 31-mode: (a) 3D plot of

for <001> poled PMN–PT

(left), 2D plot, Z-cut (right); (b) 3D plot of d

for <110> poled PMN–

PT (left), 2D plot, Z-cut (right).

(100)

010

–1000 –500 0 500 1000

(a)

200

–200

–500

500

–500

<001>

<010>

<001>

= d

= –700 ~ – 900 pC/N

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Handbook of dielectric, piezoelectric and ferroelectric materials34

900

[011] 0

–900

[011 ]

900

0 [110]

900

1800

011

450

–450

450

(b)

1.16

(Continued)

330°

300°

270°

240°

210°

180°

150°

120°

90°

60°

30°

0°

[011]

–

[100]

1000 1500500

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Bridgman growth and properties 35

1.8 References

1. The US Navy ‘Piezoelectric Crystal Planning Workshop’, Washington Dulles Airport

Marriott, May 14–16, 1997.

2. S.-E. Park and T.R. Shrout, ‘Ultrahigh strain and piezoelectric behavior in relaxor

based ferroelectric single crystals’, J. Appl. Phys., 82, 1804–1881 (1997).

3. S.-E Park and T.R. Shrout, ‘Characteristics of relaxor-based piezoelectric single

crystals for ultrasonic transducers’, IEEE Trans. UFFC, 44, 1140–1147 (1997).

4. T.R. Shrout, Z.P. Chang, N. Kim, and S. Markgraf, ‘Dielectric behavior of single

crystals near the (1–x) Pb(Mg

1/3

2/3

–(x)PbTiO

morphotropic phase boundary’,

Ferroelectric Lett., 12, 63–69 (1990).

5. P.M. Bridenbaugh, J. Rottenberg and G.M. Loiacono, ‘Single crystal growth of

PMN–PT solid solutions’, US Navy ‘Piezoelectric Crystal Planning Workshop’,

Washington Dulles Airport Marriott, May 14–16, 1997.

6. M. Dong and Z.G. Ye, ‘High-temperature solution growth and characterization of

the piezo-/ferroelectric (1–x)Pb(Mg

1/3

2/3

–xPbTiO

[PMNT] single crystals’ J.

Crystal Growth, 209, 81–90 (2000).

7. D.R. Gabbe, ‘Top-seeded solution growth of PMN–PT single crystals’, US Navy

Workshop on Acoustic Transduction Materials and Devices, at Baltimore, MA, May

14–16, 2001.

8. L.C. Lim, ‘Flux growth of large-size high homogeneity PMN–PT single crystals’,

US Navy Workshop on Acoustic Transduction Materials and Devices, at State College,

PA, May 6–8, 2003.

9. K. Harada, S. Shimanuki, T. Kobayashi, S. Saitoh and Y. Yamashita, ‘Crystal growth

and electrical properties of Pb[(Zn

1/3

2/3

)

0.91

0. 09

single crystals produced by

solution Bridgman method’, J. Am. Cer. Soc., 81, 2785–2873 (1998).

10. R. Soundararajan, R.N. Das, R. Tjossem, A. Bandyopadhyay, K.G. Lynn, E.E. Eisser

and J. Lazaroff, ‘Growth and characterization of single-crystal lead magnesium

niobate-lead titanate via high-pressure vertical Bridgman method’, J. Mater, 9–12,

605–619 (2004).

11. P.W. Bridgman, ‘Certain physical properties of single crystals of tungsten, antimony,

bismuth, tellurium, cadmium, zinc, and tin’, Proc. Am. Acad. Arts Sci., 60, 305–383

(1925).

(001) Poling

(001)

(111)

(011) Poling

(011)

(111) Poling

(111)

4mm

multi-domain symmetry

engineered by (001) poling 4

of 8 possible polarizations

mm2

multi-domain symmetry

engineered by (011) poling 2

of 8 possible polarizations

multi-domain symmetry

engineered by (111) poling 1

of 8 possible polarizations

1.17

Domain states engineered in three configurations.

WPNL2204

Handbook of dielectric, piezoelectric and ferroelectric materials36

12. D.C. Stockbarger, ‘Production of large single crystals of lithium fluoride’, Rev. Sci.

Instr., 7, 133–136 (1936).

13. Z.G. Ye, P. Tissot and H. Schmid, ‘Pseudo-binary Pb(Mg

1/3

2/3

–PbO phase

diagram and crystal growth of Pb(Mg

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2/3

[PMN]’, Mat. Res. Bull., 25, 739–

748, (1990).

14. H. Luo, G. Shen, P. Wang, X. Le, and Z. Yin, ‘Study of new piezoelectric material–

relaxor ferroelectric single crystals’, J. Inorg. Mater., 12, 768 (1997).

15. G. Xu, H. Luo, G. Shen, Q. Le, W. Zhong, H. Xiu and Z. Yin, ‘Growth and properties

of tetragonal single crystal PMN–PT’, The Eleventh Chinese Conference on Crystal

Growth and Materials, Chang-Chuen, Applied Chemistry Institute, Chinese Academy

of Sciences, September 7–13, 1997.

16. P. Han, ‘Growth and characterization of large PMN–PT crystals’, US Navy Workshop

on Acoustic Transduction Materials and Devices, at State College, PA, April 13–15,

1999.

17. P.M. Bridenbaugh, J. Rottenberg and G. Ruland, ‘Single crystal growth of PMN–

PT’, US Navy Workshop on Acoustic Transduction Materials and Devices, at State

College, PA, April 13–15, 1999.

18. S.G. Lee, R. Monteiro, M.C. Custodio and R.S. Feigelson, ‘Growth of PMN and

PMN–PT by the vertical Bridgman method’, US Navy Workshop on Acoustic

Transduction Materials and Devices, at State College, PA, April 13–15, 1999.

19. K.T. Zawilski, M. Custodio, C. Claudia, R.C. DeMattei, S.G. Lee, R.G. Monteiro,

H. Odagawa and, R.S. Feigelson, ‘Segregation during the vertical Bridgman growth

of lead magnesium niobate–lead titanate single crystals’, J. Crystal Growth, 258,

353–367 (2003).

20. P. Han and J. Tian, ‘Progress in growth of 3-inch diameter PMN–PT crystals’, US

Navy Workshop on Acoustic Transduction Materials and Devices, The Penn State

Conference Center, State College, PA, 9–11 May, 2006.

21. J.S. Nordyke, Lead in the World of Ceramics, The American Ceramic Society, Inc.

Columbes, OH 43214. (1984).

22. W.G. Pfann, Zone Melting, 2nd edn, Wiley, New York (1966).

23. P. Han, ‘Hybrid Stockbarger zone-leveling melting method for directed crystallization

and growth of single crystals of lead magnesium niobate–lead titanate (PMN–PT)

solid solutions and related piezocrystals’, US Patent 6942730 B2 (Nov., 2001).

24. P. Han, Final Report (HCM0012, 1999), Contract No. N00014-98C-0414, Project

title: ‘Growth of large-sized relaxor ferroelectric single crystals’.

25. P. Han, ‘Recent development of fabrication of PMN–PT piezocrystals: crystal

manufacturing and domain engineering, US Navy Workshop on Acoustic Transduction

Materials and Devices, The Penn State Conference Center, State College, PA, 6–8

May, 2003.

26. P. Han, W. Yan, J. Tian, X. Huang and H. Pan, ‘Cut directions for the optimization

of piezoelectric coefficients of lead magnesium niobate–lead titanate ferroelectric

crystals’, Appl. Phys. Lett., 86, 052902 (2005).

27. X.Y. Zhao, B.J. Fang, H. Cao, Y.P. Guo and H.S. Luo, ‘Dielectric and piezoelectric

performance of PMN–PT single crystals with compositions around the MPB: influence

of composition, poling field and crystal orientation’, Mater. Sci. Engr. B Solid State

Mater. for Adv. Tech., 96, 254–262 (2002).

28. H. Cao, B.J. Fang, H.Q. Xu and H.S. Luo, ‘Effects of segregation on composition

and dielectric and piezoelectric properties of Pb(Mg

1/3

2/3

–38%PbTiO

single

crystal’, J. Inorg. Mater., 18, 50–56 (2003).

WPNL2204

Bridgman growth and properties 37

29. J. Tian, P. Han and D. Payne, ‘Measurements along the growth direction of PMN-PT

crystals: dielectric, piezoelectric, and elastic properties’, IEEE Trans. UFFC, vol 54,

no. 9, 1895–1902, September (2007).

30. A.J. Moulson and J.M. Herbert, Electroceramics, 2nd edn. Wiley, Hoboken, NJ

(2003).

31. Piezoelectric and Ferroelectric Crystals Committee, ‘IRE Standards on Piezoelectric

Crystals: Measurements of Piezoelectric Ceramics, 1961’, Proc. IRE, 1161–1169

(1961).

32. Standards Committee of the IEEE Ultrasonics, Ferroelectrics, and Frequency Control

Society, ‘IEEE Standard on Piezoelectricity’, IEEE, New York, 1–66 (1987).

33. Y. Li, Z. Qin, and Z. Zhou, Measurement of Piezoelectric and Ferroelectric Materials,

1st edn, Science Press, Beijing (1984).

34. IEEE, ‘IRE Standards on Piezoelectric Crystals: Determination of the Elastic,

Piezoelectric, and Dielectric Constants – The Electromechanical Coupling Factor,

1958’, Proc. IRE, 764–778 (1958).

35. T.R. Shrout, Z.P. Chang, N.C. Kim, and S. Markgraf, ‘Dielectric behavior of single-

crystals near the (1 – x)Pb(Mg

1/3

2/3

–xPbTiO

morphotropic phase-boundary’,

Ferroelectrics Lett. Sect., 12, 63–69 (1990).

36. D. Zekria, V.A. Shuvaeva and A.M. Glazer, ‘Birefringence imaging measurements

on the phase diagram of Pb(Mg

1/3

2/3

–PbTiO

’, J. Phys. -Condensed Matter,

17, 1593–1600 (2005).

37. J. Tian, ‘Measurements along the growth direction for PMN–PT crystals: dielectric,

piezoelectric, and mechanical properties’, MS Thesis, University of Illinois at Urbana-

Champaign, Urbana (2006).

38. D. Viehland, J.F. Li, E. McLaughlin, J. Powers, R. Janus and H. Robinson, ‘Effect

of uniaxial stress on the large-signal electromechanical properties of electrostrictive

and piezoelectric lead magnesium niobate lead titanate ceramics’, J. Appl. Phys., 95,

1969–1972 (2004).

39. A.A. Bokov and Z.G. Ye, ‘Universal relaxor polarization in Pb(Mg

1/3

2/3

and

related materials’, Phys. Rev. B, 66, 064103 1–9 (2002).

40. D. Viehland and J.F. Li, ‘Young’s modulus and hysteretic losses of 0.7Pb(Mg

1/3

2/3

)

–0.3PbTiO

: single versus polycrystalline forms’, J. Appl. Phys, 94, 7719–7722

(2003).

41. W.G. Cady, Piezoelectricity, McGraw-Hill, New York (1946).

42. J.F. Nye, Physical Properties of Crystals, Clarendon Press, Oxford (1957).

43. H. Goldstein, Classical Mechanics, 2nd edn, Addison-Wesley, Reading, MA, (1980).

44. R. Zhang, B. Jiang and W. Cao, ‘Orientation dependence of piezoelectric properties

of single domain 0.67Pb(Mg

1/3

2/3

– 0.33PbTiO

crystals’, Appl. Phys. Lett.,

82, 3737–3739 (2003).

45. M. Sugimoto, ‘Magnetic spinel single crystals by Bridgman technique’, Crystals,

Growth, Properties and Applications, ed (C.J.M. Rooijmans) Springer-Verlag, Berlin,

Heidelberg, New York (1978).

46. J. Tian and P. Han, ‘Growth and property characterization of lead magnesium niobate–

lead titanate based single crystals’, US Navy Workshop on Acoustic Transduction

Materials and Devices, The Penn State Conference Center, State College, PA, 15–17

May, 2007.

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2.1 Introduction

Relaxor single crystals, notably single crystals of solid solutions of

Pb(Zn

1/3

2/3

–PbTiO

(PZN–PT) and Pb(Mg

1/3

2/3

–PbTiO

(PMN–

PT), have been studied extensively in recent years due to their extremely

high dielectric and piezoelectric constants compared with state-of-the-art

lead zirconate titanate (PZT) ceramics. They are candidate materials for new

high-performance piezo-devices such as medical ultrasound imaging probes

(Saitoh et al., 1994, 1999; Lopath et al., 1996; Gururaja et al., 1999; Ritter

et al., 2000; Oakley and Zipparo, 2000; Rhim et al., 2002, 2005; Michau

et al., 2002; Cheng et al., 2003; Marin-Franch et al., 2004; Chen and Panda,

2005), sonars for underwater communications (Powers et al., 2000; Tressler

and Howarth, 2000, 2003; Park and Hackenberger, 2002; Marin-Franch et al.,

2004), high-authority sensors and actuators (Wlodkowski et al., 2000, 2001;

Park and Hackenberger, 2002; Shipps and Deng, 2003), etc.

Unlike PZT materials, PZN–PT and PMN–PT single crystals can be grown

with relative ease from either high-temperature solution and/or congruent

melt. The growth of relaxor single crystals was pioneered by the Russian

scientists in the late 1950s, who successfully synthesized monocrystals of

Pb(Ni

1/3

2/3

(PNiT), Pb(Mg

1/3

2/3

(PMT), Pb(Co

1/3

2/3

(PCoN)

and Pb(Zn

1/3

2/3

(PZN) by the solution growth technique with PbO flux

(Myl’nikova and Bokov, 1959, 1962; Bokov and Myl’nikova, 1961). In the

late 1960s, Nomura and co-workers (Nomura et al., 1969; Yokomizo et al.,

1970) succeeded in growing single crystals of PZN–PT solid solution of the

entire composition range. Since then, there have been only a few reports on

the growth of PMN single crystals using the same flux (Bonner and Van

Uitert, 1967; Afanas’ev et al., 1977; Setter and Cross,1980; Petrovskii et al.,

1984).

In the early 1980s, Kuwata et al. (1981, 1982) performed a series of

measurements and found that PZN–9%PT samples poled along the [001]

crystal axis exhibited anomalously large piezoelectric coefficients and

Flux growth and characterization of PZN–PT

and PMN–PT single crystals

L-C LIM, National University of Singapore and Microfine

Materials Technologies Pte Ltd, Singapore

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Flux-growth and characterization of PZN–PT and PMN–PT 39

electromechanical coupling factors (d

= 1500 pC/N and k

= 0.92). There

followed a period of little research activity in this area. In 1990, Ye et al.

(1990) reported a systematic study on the growth of PMN single crystal with

PbO flux, who also noted that addition of 5 wt% B

promoted the formation

of the pyrochlore phase. On the other hand, Shrout et al. (1990) reported the

successful synthesis of PMN–PT single crystal with PbO + B

complex

fluxes.

In the mid-1990s, systematic studies of flux growth of PZN–PT single

crystals using the high-temperature flux technique have been carried out by

two separate groups in Pennsylvania State University and Toshiba Research

Center, respectively (Mulvihill et al., 1996; Park et al., 1996, 1997; Kobayashi

et al., 1997, 1998; Saitoh et al., 1999). By then, the size of the crystals

obtained was sufficiently large to enable a detailed property evaluation of

the materials and for device exploitation. In 1994, Saitoh et al. published the

first patent of medical ultrasonic probe made of PZN–PT single crystal of

improved sensitivity and bandwidth. In 1996 and 1997, Park and Shrout

(1997a, b, c) published a series of papers confirming the superior dielectric

and piezoelectric properties of single crystals of PZN–PT and PMN–PT

systems. Their works have created a renewed interest worldwide in growing

large-size relaxor–PT single crystals and in their applications in various

piezo devices and systems. More recent works related to flux growth of

PZN–PT single crystal include that of Gentil et al. (2000), Kumar et al.

(2000), Zhang et al. (2000), Santailler et al. (2002), Xiao et al. (2002),

Dabkowski et al. (2004), Lim and Rajan (2004), Benayad et al. (2004) and

Babu et al. (2006), while similar studies but for PMN–PT crystals were

performed by Park et al. (1998), Dong and Ye (1999), Jiang et al. (2001),

Fan et al. (2003), Lim et al. (2005) and Kania et al. (2005).

The size of PZN–PT and PMN–PT single crystals produced by the

conventional flux growth technique remained relatively small, being <20

mm typically. In order to growth large PZN–PT single crystals, other flux

growth techniques have been explored. These include the solution Bridgman

growth technique by Shimanuki et al. (1998), Harada et al. (1998, 2001),

Matsushita et al. (2002), Fang et al. (2002), Xu et al. (2002, 2003, 2005) and

Babu et al. (2006). In addition, the top-seeded solution growth technique has

also been attempted (Bonner and Van Uitert, 1967; Park et al., 1998; Chen

and Ye, 2001a,b; Karaki et al., 2002a; Bertram et al., 2003; Benayad et al.,

2004), while Fang et al. (2001) reported the growth of PZN–9%PT single

crystal directly from melt. At the time of writing, the largest flux-grown

PZN–PT single crystals measure about 3 inches (76.2mm) in diameter, and

were produced by the solution Bridgman growth method with a bottom-

supported Pt crucible (Matsushita et al., 2002).

As for PMN–PT, the growth of this crystal from congruent melts has been

experimented by contemporary researchers and crystal growers recently.

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