Supplementary Information for

Textured Pb(Zr,Ti)O3-Pb[(Zn,Ni)1/3Nb2/3]O3 Multilayer

Ceramics and their Application to Piezoelectric

Actuators

Eun-Ji Kima,†, Tae-Gon Leeb,†, Dae Su Kima, Sun-Woo Kima, Yeon-Jeong Yee b, Seung Ho

Hanc, Hyung-Won Kangc, and Sahn Nahma,b,*

a Department of Materials Science and Engineering, Korea University, 145 Anam-ro,

Seongbuk-gu, Seoul, 02841, Republic of Korea

b Department of Nano Bio Information Technology, KU-KIST Graduate School of

Converging Science and Technology, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul,

02841, Republic of Korea

c Electronic Materials and Device Research Center, Korea Electronics Technology Institute,

25, Saenari-ro, Bundang-gu, Seongnam-si, Gyeonggi-do, 13509, Republic of Korea

† These authors contributed to this work equally.

Corresponding Author

*E-mail: snahm@korea.ac.kr

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1. Analysis of exp (– ( E/E 0) /t ) and constant t

Figure S1 shows the variations in the value of exp(– (E/E0)/t) with respect to the applied

electric field (E) for PZT-PZNN thick films with various BT contents. The t values, which are

used to calculate exp(– (E/E0)/t) of the PZT-PZNN thick films, are listed in Table 1 and

indicated in Fig. S1. The exp(– (E/E0)/t) values of all the thick-films are one at E = 0,

decrease with increasing E, and finally, approach zero at large applied electric fields. In

addition, the thick film with a large t value exhibits a large value of exp(– (E/E0)/t) at the

same applied electric field.

Fig. S1. Variation of exp(– (E/E0)/t) with respect to the applied electric field (E) for the PZT-

PZNN thick-films with various amounts of BT contents

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2. Calculation of strain change with a decrease in the electric field

The strain (SI) developed in the PZT-PZNN thick films with increasing electric field was

different from the strain (SD) developed in the thick films with decreasing electric field. This

difference (∆S = SD - SI) formed the S-E hysteresis curve and is related to the loss of the PZT-

PZNN thick film. Figures S2(a)–(c) depict the variation in ∆S with respect to the applied

electric field. All the thick films exhibited a similar shape of the curve. These curves can be

fitted by L × f(E), where L is a constant and the function f(E) is expressed by the following

equation:

f(E) = [(E/Emax)α-1×(1 – E/Emax)β-1] / [∫0

1

uα-1×(1 – u)β-1 du], (S1)

where f(E) is a probability density function of the beta distribution [1], Emax is the maximum

applied electric field, and α and β are constants. The values of α and β depend on the

materials and are 1.4 and 2.7, respectively, for PZT-PZNN thick films, indicating that all

PZT-PZNN thick films have the same f(E) function. Therefore, the magnitude of ∆S is

determined by the value of L, which is listed in Table 1 for the PZT-PZNN thick films with

various amounts of BT seeds. The L × f(E) curves are also illustrated in Fig. S2(a)–(c) as

yellow dot-dashed lines, and they are well matched with the measured ∆S. Moreover, the

measured S-E hysteresis curves are well fitted with the calculated S-E curves obtained using

Eqs. (1), (2), and (S1), as depicted in Fig. 4(d)–(f). Additionally, because the magnitude of ∆S

depends on the L value of the PZT-PZNN thick film, the size of the S-E hysteresis curve is

also determined by the L value; the PZT-PZNN thick film exhibits the largest S-E hysteresis

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curve because it has the largest L value.

Fig. S2. Variations in the measured and calculated ∆S values with respect to the applied

electric field (E) for the (a) PZT-PZNN thick film, (b) PZT-PZNN thick film with 5 vol% BT

seeds, and (c) PZT-PZNN thick film with 10 vol% BT seeds.

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3. EDS analysis on the PZT-PZNN MLCS with BT seeds

To identify the diffusion of the Ag ions, the PZT-PZNN layer of the MLC sintered at

950 °C for 10 h was analyzed by EDS. Figure S3(a) shows the EDS spectrum obtained from

the PZT-PZNN layer of the MLCs containing 5 vol% BT seeds. The inset shows an SEM

image of the area of which the EDS results were obtained. Table S1 lists the chemical

composition of the PZT-PZNN layer. The spectrum did not reveal the presence of Ag and Pd

ions, indicating that the diffusion of Ag (or Pd) ions from the 80Ag/20Pd electrode to the

PZT-PZNN layer is most likely negligible. An EDS analysis of the 80Ag/20Pd inner

electrode was also conducted, as shown in Fig. S3(b), and the inset shows the SEM image of

the area of which the EDS results were obtained. These results showed that the 80Ag/20Pd

inner electrode contained very small amounts of Pb, Zn, and Nb ions (< 1.0 atomic %), which

is smaller than the error range, as listed Table S2 below. They could have originated from the

PZT-PZNN layer because the thickness of the inner electrode is relatively small (~ 5 μm).

Therefore, the diffusion of ions from PZT-PZNN to the inner electrode is also considered to

be negligible. Pt is observed in the EDS spectrum because it was coated for the EDS analysis.

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Fig. S3. EDS spectra of the (a) PZT-PZNN layer and (b) 80Ag/20Pd inner electrode of MLCs containing 5 vol% of BT seeds. The inset in

each figure shows the SEM image of the area where the EDS spectrum was obtained.

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Table S1. Chemical composition of the PZT-PZNN ceramic layer.

Elements Mass concentration[wt.%]

Atomic concentration[at.%]

Pb 70.67 48.80

Zr 8.59 13.47

Ti 6.36 19.02

Zn 0.82 1.80

Ni 1.10 2.67

Nb 6.32 9.73

Ag 0.00 0.00

Pd 0.00 0.00

Pt (Coated) 6.14 4.51

Total 100.00 100.00

Table S2. Chemical composition of the 80Ag/20Pd inner electrode.

Elements Mass concentration[wt.%]

Atomic concentration[at.%]

Pb 1.65 0.89

Zr 0.00 0.00

Ti 0.00 0.00

Zn 0.07 0.11

Ni 0.00 0.00

Nb 0.24 0.29

Ag 71.43 73.74

Pd 20.56 21.52

Pt (Coated) 6.05 3.45

Total 100.00 100.00

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4. Microstructure of PZT-PZNN MLCs and PZT-PZNN MLCs with 10 vol% BT seeds

MLCs comprising five layers of PZT-PZNN thick films were sintered at 950 °C for 1 h,

and 80Ag/20Pd was used as the electrode for this MLC. Figure S4(a) depicts the SEM images

of the PZT-PZNN MLCs. The thicknesses of the PZT-PZNN layer and 80Ag/20Pd electrode

were approximately 95 μm and 5 μm, respectively. An enlarged SEM image of the interface

between the PZT-PZNN ceramic layer and the electrode is depicted in Fig. S4(b). A

continuous interface was formed between the ceramic thick film and electrode. Moreover, the

average grain size of the PZT-PZNN thick film was small (approximately 5 μm).

The microstructure of the MLCs comprising five layers of the PZT-PZNN thick films

with 10 vol% BT seeds was investigated, as depicted in Fig. S4(c). MLCs with five layers of

PZT-PZNN thick films were well-fabricated, and the thicknesses of the PZT-PZNN thick film

and 80Ag/20Pd electrodes were approximately 100 μm and 5 μm, respectively. Figure S4(d)

depicts an enlarged SEM image of the interface between the PZT-PZNN ceramic layer and

the 80Ag/20Pd electrode. The PZT-PZNN thick films were well-textured with an average

grain size of approximately 10 μm. The average size of the textured grains of the MLCs with

10 vol% BT seeds was smaller than that of the PZT-PZNN MLCs with 5 vol% BT seeds (~20

μm) probably because of the larger number of BT seeds.

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Fig. S4. SEM images of the (a) PZT-PZNN MLC and (b) the interface between the PZT-

PZNN layer and Ag/Pd electrode for MLCs with five layers of PZT-PZNN thick films. SEM

images of the (c) PZT-PZNN MLC and (d) the interface between the PZT-PZNN layer and

Ag/Pd electrode for MLCs with five layers of PZT-PZNN thick films containing 10 vol% BT

seeds. The textured grains with BT seeds are depicted in Fig. S4(d).

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5. XRD patterns of PZT-PZNN MLCs with various amounts of BT seeds

Figure S5(a) depicts the XRD pattern of the MLCs with five layers of PZT-PZNN thick

films. A normal perovskite structure with a high intensity of (110) reflection was observed in

the pure PZT-PZNN MLCs, and the reflections for the secondary phase were not observed.

Therefore, it can be suggested that a homogeneous perovskite phase was well-formed in this

MLC without any secondary phase. Figures S5(b) and (c) depict the XRD patterns of the

MLCs with five layers of PZT-PZNN thick films containing 5 vol% and 10 vol% BT seeds,

respectively. These XRD patterns exhibited intense (100) and (200) reflections; however, the

intensity of the (110) reflection was extremely low, indicating that these MLCs were textured

along the [001] direction. The Lotgering factor of the MLCs with 5 vol% BT seeds was 93%

and that of MLCs with 10 vol% BT seeds was 90%. Therefore, MLCs with 5 vol% BT seeds

were considered to have the maximum degree of texture.

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Fig. S5. XRD patterns of PZT-PZNN MLCs with various amounts of BT seeds; (a) 0 vol%,

(b) 5 vol%, and (c) 10 vol%.

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6. EBSD images and fatigue properties of PZT-PZNN MLC layer with BT seeds

Figures S6(a) and (b) depict the SEM and EBSD images of the PZT-PZNN thick films

containing 10 vol% BT seeds. Most grains were aligned along the [100] direction (green

colored area) and [001] direction (red colored area). However, some grains, indicated by the

arrows in Fig. S6(a), were not completely textured. Therefore, it is considered that the PZT-

PZNN thick films with 5 vol% BT seeds exhibit the maximum degree of texturing.

The S-E curves of the PZT-PZNN MLCs containing various amounts of BT seeds were

recorded, as shown in Fig. S6(c). The MLCs without BT seeds exhibited a small strain of

0.16% at 4 kV/mm. On the other hand, the largest strain of 0.28% at 4 kV/mm was

obtained for the MLCs with 5 vol% BT seeds and slightly decreased strain of 0.26% at 4

kV/mm was observed for the MLC with 10 vol% BT seeds. In addition, the strain of the

MLCs was slightly less than those of the PZT-PZNN thick films. The strain of the PZT-

PZNN MLCs containing 5 vol% BT seeds was measured after various electric field cycles

to evaluate the fatigue performance of the MLCs. Figure S6(d) shows the unipolar S–E

curves of these MLCs measured after the application of various electric field cycles. The

applied electric field is indicated in the inset of Fig. S6(d); the frequency of the applied

electric field was 100 Hz with a maximum electric field of 1 kV/mm. This electric field was

continuously applied to the specimen. The fatigue test requires an electric field

corresponding to at least 90% of the EC value to be applied to the specimen [2]. This is the

minimum electric field that must be applied to the specimen for the fatigue test. If the

specimen retains good piezoelectric properties after the fatigue test, which is conducted

with an applied electric field larger than the minimum electric field, the specimen has

excellent fatigue properties. The EC of the PZT-PZNN thick films was approximately 0.6

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kV/mm (Fig. 3(d), indicating that the minimum electric field for the fatigue test of this

specimen is 0.54 kV/mm. However, a large electric field of 1 kV/mm, which is much

larger than the minimum electric field (0.54 kV/mm), was used for the fatigue test of the

PZT-PZNN MLCs to show that the PZT-PZNN MLCs developed in this study have

excellent fatigue properties. The strain of these MLCs was approximately 0.28 % after the

first cycle and remained unchanged after 106 cycles. These results suggest that the PZT-

PZNN MLCs exhibit good fatigue properties. Based on these results, one could assume that

the PZT-PZNN MLC actuators might also have good fatigue performance.

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Fig. S6. (a) SEM and (b) EBSD images of the PZT-PZNN MLCs layer with 10 vol% BT seeds. (c) S-E curves of PZT-PZNN MLCs

containing various amounts of BT seeds. (d) S-E curves after the application of various electric field cycles for the PZT-PZNN MLCS

containing 5 vol% BT seeds .

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7. Simulated actuating properties of cantilever-type actuators

Figure S7(a) depicts the variations in the simulated acceleration as a function of the

frequency of the PZT-PZNN cantilever-type actuator. The PZT-PZNN thick films used to

produce this actuator did not contain BT seeds. The unipolar sinusoidal function with the

maximum voltage of 50 V, used for the measurement of the acceleration of this actuator, was

also utilized for the simulation. The maximum acceleration of this actuator was

approximately 32.5 G at a resonance frequency of 47.7 Hz, and the capacitance was

approximately 120 nF, revealing that the simulated acceleration, resonance frequency, and

capacitance are extremely similar to the measured values (Fig. 8(a-i)). The displacement of

this cantilever-type PZT-PZNN actuator was also simulated, and Fig. S7(b) depicts the

variations in the simulated displacements with respect to the applied voltage obtained at

different maximum applied voltages under a resonance frequency of 47.7 Hz. The

displacement of the actuator increased with increasing applied voltage, and the maximum

displacement of 6.93 mm was obtained at 50 V, indicating that the simulated displacement is

also similar to the measured displacement (6.9 mm), as depicted in Fig. 8(a-ii). Therefore, it

can be suggested that the simulated actuating properties agree well with the measured

actuating properties for the PZT-PZNN cantilever-type actuator.

Variations in the acceleration with respect to frequency for the PZT-PZNN cantilever-

type actuator are illustrated in Fig. S7(c). PZT-PZNN thick films with 5 vol% BT seeds were

used for the synthesis of this actuator. The input signal with a unipolar sinusoidal function

was used for this simulation with a maximum applied voltage of 50 V, which was the same as

the experimental input signal. The maximum acceleration of this actuator was large (44.5 G)

at a resonance frequency of 47.6 Hz. Moreover, this actuator exhibited a capacitance of 109

15

nF. Therefore, the simulated acceleration of this actuator was found to be extremely similar to

the experimentally measured acceleration (Fig. 8(b-i)). The displacement of this actuator was

also simulated, as depicted in Fig. S7(d). The displacement of the actuator increased with

increasing applied voltage. Moreover, this actuator exhibited a considerably large simulated

displacement of 9.76 mm at 50 V, indicating that the simulated displacement was similar to

the measured displacement (Fig. 8(b-ii)). Therefore, it can be concluded that the simulated

and measured actuating properties agreed well with each other for cantilever-type PZT-PZNN

actuators containing 5 vol% BT seeds.

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Fig. S7. Variations in the simulated (a) acceleration with respect to frequency at 50 V and (b)

displacement with respect to the applied voltage at different maximum voltages for the

cantilever-type PZT-PZNN actuator without BT seeds. Variations in the simulated (c)

acceleration with respect to frequency at 50 V and (d) displacement with respect to the

applied voltage at different maximum voltages for cantilever-type PZT-PZNN actuators with

5 vol% BT seeds.

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8. Actuating characteristics of the cantilever-type actuator with 10 vol% BT seeds

Variations in the acceleration with respect to frequency for the PZT-PZNN cantilever-

type actuator are depicted in Fig. S8(a). The PZT-PZNN layer of this actuator comprised 10

vol% BT seeds. The input signal with a unipolar sinusoidal function was used for this

measurement with a maximum applied voltage of 50 V. The maximum acceleration of this

actuator was approximately 39.9 G at a resonance frequency of 48 Hz. Because the maximum

acceleration of the pure PZT-PZNN actuator was 32.6 G, the force of this actuator was larger

than that of the PZT-PZNN actuator without BT seeds. Moreover, the power consumption of

this actuator was lower than that of the PZT-PZNN actuator without BT seeds because the

capacitance of this actuator (100 nF) was less than that of the actuator without BT seeds (120

nF).

Displacements of the cantilever-type PZT-PZNN actuator with 10 vol% BT seeds were

also measured at various applied voltages, as depicted in Fig. S8(b). Displacements of this

actuator increased with increasing applied voltage, and this actuator exhibited the largest

displacement of 8.8 mm at 50 V. The displacement of the PZT-PZNN actuator with 10 vol%

BT seeds was considerably larger than that of the PZT-PZNN actuator without BT seeds

because the textured MLCs with 10 vol% BT seeds exhibited larger strain in comparison with

the untextured MLCs. However, the maximum displacement (8.75 mm) and acceleration

(39.9 G) of the actuator with 10 vol% of BT seeds were smaller than the maximum

displacement (10.55 mm) and acceleration (46.9 G) of the actuator with 5 vol% BT seeds.

Therefore, it can be concluded that the actuator with 5 vol% BT seeds exhibited the best

actuating properties.

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Fig. S8. Variations in the (a) acceleration with respect to frequency and (b) displacement with

respect to applied voltage for PZT-PZNN cantilever-type actuators with 10 vol% BT seeds.

The unipolar sinusoidal function was applied to obtain the actuating properties of this

cantilever-type actuator.

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9. Actuating characteristics of the PZT-PZNN bridge-type actuator with various

amounts of BT seeds

The actuating properties of the bridge-type PZT-PZNN actuators were also investigated,

and a unipolar sinusoidal function was employed as the input voltage to study the actuating

properties of these actuators. Figure S9(a-i) exhibits variations in the acceleration of the

bridge-type PZT-PZNN actuator with respect to the frequency, measured under a maximum

applied voltage of 100 V. The MLCs used for this actuator did not contain BT seeds. The

maximum acceleration of this actuator was 115 G at a resonance frequency of 217.5 Hz with

a capacitance of 120 nF. Notably, the shape of the acceleration curve was not symmetric with

respect to frequency. It can be explained that the presence of nonlinear deflection of the

actuator originated from the stretching strain [3]. Similar results were also observed in

previous studies [3]. Displacements of this bridge-type actuator were also measured at the

resonance frequency under various applied voltages, as depicted Fig. S9(a-ii). The

displacement increased with increasing voltage and the maximum displacement of 1.18 mm

was obtained at 100 V.

Figure S9(b-i) depicts the variation in the acceleration with respect to frequency for the

bridge-type PZT-PZNN actuators with 5 vol% BT seeds. Acceleration was measured at 100

V, and an input signal with a unipolar sinusoidal function was used. The maximum

acceleration was large (210.9 G) at a resonance frequency of 247.5 Hz, and this bridge-type

actuator exhibited a capacitance of 109 nF. The acceleration of this actuator (210.9 G) was

considerably larger than that of actuators without BT seeds (115.0 G), indicating that the

force of this actuator was larger than that of the actuators without BT seeds. The displacement

of this bridge-type actuator was measured as a function of the applied voltage, as depicted in

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Fig. S9(b-ii), at resonance frequency. The unipolar sinusoidal function was also applied to the

actuator to obtain these results. This actuator exhibited a large free stroke of 2 mm at the

applied voltage of 100 V. This displacement was much larger than that of PZT-PZNN

actuators synthesized without BT seeds (1.18 mm). Therefore, it can be concluded that the

textured PZT-PZNN MLCs also considerably improved the actuating properties of the bridge-

type actuator, such as the force and displacement of the actuator.

Figure S9(c-i) depicts the variation in the acceleration with respect to frequency for

bridge-type PZT-PZNN actuators with 10 vol% of BT seeds. Acceleration was measured at

100 V, and the unipolar sinusoidal function was used as the input signal of this actuator. The

maximum acceleration was 167.8 G at a resonance frequency of 215 Hz with a capacitance of

100 nF. The acceleration of this actuator (167.8 G) was larger than that of the actuators

without BT seeds (115.0 G), indicating that the force of this actuator was larger than that of

the PZT-PZNN actuators without BT seeds. The displacement of this actuator was measured

with respect to the applied voltage, as depicted in Fig. S9(c-ii), at a resonance frequency of

215 Hz. This actuator exhibited a large displacement of 1.84 mm at an applied voltage of 100

V. This displacement was larger than that of the PZT-PZNN actuators without BT seeds (1.18

mm). Therefore, this result confirmed that the textured PZT-PZNN MLCs considerably

improved the actuating properties, such as force and displacement of the bridge-type PZT-

PZNN actuator. Additionally, the acceleration and displacement of this actuator were smaller

than those of the actuator with 5 vol% BT seeds. Therefore, it can be also concluded that the

bridge-type PZT-PZNN actuator with 5 vol% BT seeds exhibited the best actuating

properties.

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Fig. S9. Variations in the (a-i) acceleration with respect to frequency and (a-ii) displacement

with respect to applied voltage for PZT-PZNN bridge-type actuators without BT seeds.

Variations in the (b-i) acceleration with respect to frequency and (b-ii) displacement with

respect to applied voltage for PZT-PZNN bridge-type actuators with 5.0 vol% BT seeds.

Variations in the (c-i) acceleration with respect to frequency and (c-ii) displacement with

respect to applied voltage for PZT-PZNN bridge-type actuators with 10.0 vol% of BT seeds.

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due to electric loading in ferroelectric ceramics, J. Eur. Ceram. Soc. 19 (1999) 1333-

1337.

[3] G. Gafforelli, A. Corigliano, R. Xu, S.-G. Kim, Experimental verification of a bridge-

shaped, nonlinear vibration energy harvester, Appl. Phys. Lett. 105 (2014) 203901.

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