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Fabrication and properties of PYN–PMN–PZT quaternary piezoelectric ceramics for high-power, high-temperature applications
Materials Letters 64 (2010) 654–656
Contents lists available at ScienceDirect
Materials Letters j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / m a t l e t
Fabrication and properties of PYN–PMN–PZT quaternary piezoelectric ceramics for high-power, high-temperature applications Haiyan Chen ⁎, Chunhua Fan Institute of Marine Materials Science and Engineering, Shanghai Maritime University, Shanghai, 201306, China
a r t i c l e
i n f o
Article history: Received 4 September 2009 Accepted 10 December 2009 Available online 16 December 2009 Keywords: PYN–PMN–PZT Piezoelectric materials High power High Curie temperature Electrical properties
a b s t r a c t xPb(Yb1/2Nb1/2)O3 – 0.05Pb(Mn1/3Nb2/3)O3 – (0.95 – x)Pb(Zr0.48Ti0.52)O3 (PYN–PMN–PZT) quaternary piezoelectric ceramics were prepared by a traditional ceramics process. The effects of Pb(Yb1/2Nb1/2)O3 (PYN) content on the phase structure, electrical properties and Curie temperature of the quaternary system were investigated in detail. The phase structure of PYN–PMN–PZT ceramics changed from tetragonal to rhombohedral with increasing PYN content. The piezoelectric coefficient (d33), the electromechanical coupling factor (Kp) and the dielectric constant (εT33/ε0) reach maximum values near the morphotropic phase boundary (MPB), whereas the mechanical quality factor (Qm) decreases. The sintered PYN–PMN–PZT ceramics exhibit high TC, and as the PYN content increases, TC decreases slightly. The MPB of the tetragonal and rhombohedral phase coexist and are located at a PYN composition of 0.12 ≤ x ≤ 0.14.The composition of PYN–PMN–PZT around the MPB showed high d33 (>300pC/N), Kp (> 0.50), Qm (>1000) and TC (>350 °C), meaning it is a very promising piezoelectric material for high-power and high-temperature applications. © 2009 Elsevier B.V. All rights reserved.
1. Introduction In recent years, the high-power characteristics of piezoelectric ceramics have been intensively investigated for device applications, such as piezoelectric transformers and ultrasonic motors. These highpower devices are usually driven at a high electrical field and a high vibration level, which are associated with significant heat generation. For use in high-power devices, it is desirable for piezoelectric ceramics to combine a high mechanical quality factor (Qm) with a high piezoelectric constant (d33) and a high electromechanical coupling factor (Kp) [1–4]. A high Curie temperature (TC) is also desired because this extends their range of operating temperatures, reduces temperature dependence and enhances the output power [5,6]. However, to simultaneously achieve high values of Qm, d33 and Kp in one material is against the conventional concept of “hard” and “soft” piezoelectric characteristics. The roles of several dopants, of either donor or acceptor type, added to piezoelectric ceramics have been clarified. Also, the properties of ternary or more complex solid solutions have been significantly improved. The compositions of all of these materials are close to the morphotropic phase boundary (MPB), and they consist of relaxor ferroelectric and normal ferroelectric PZT. The relaxor ferroelectric ceramics usually have lower TC, such as Pb(Ni1/3Nb2/3)O3 (−120 °C), Pb (Mg1/3Nb2/3)O3 (−8 °C), Pb(Mn1/3Nb2/3)O3 (20 °C) and Pb(Zn1/3Nb2/3)O3 (140 °C). Although xPbZrO3 −(1−x)PbTiO3 (x=0.50) binary systems
⁎ Corresponding author. Tel.: +86 21 38284804; fax: +86 21 38284800. E-mail address: [email protected] (H. Chen). 0167-577X/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2009.12.020
offer good piezoelectricity and higher TC (∼390 °C), the PZT polynary systems listed above are limited to TC <330 °C [6]. Of the relaxor ferroelectric ceramics, Pb(Yb1/2Nb1/2)O3 (PYN) is antiferroelectric with a monoclinic perovskite structure and has a relatively high TC (300 °C) [7], and the (1 − x − y)Pb(Yb1/2Nb1/2) − xPbZrO3–yPbTiO3 (x = 0.42, y=0.48) ternary system shows a high TC (395 °C) and a high Kp (0.61) [8]. On the other hand, the Pb(Mn1/3Nb2/3)O3–PbZrO3–PbTiO3 ternary system exhibits a very high Qm and therefore is an excellent candidate for high-power application [9,10]. It is believed that Pb(Yb1/2Nb1/2)O3–Pb (Mn1/3Nb2/3)O3–PbZrO3–PbTiO3 (PYN–PMN–PZT) quaternary piezoelectric ceramics, obtained by combining Pb(Yb1/2Nb1/2)O3–PbZrO3–PbTiO3 with Pb(Mn1/3Nb2/3)O3–PbZrO3–PbTiO3, could exhibit many desirable properties. In this study, PYN–PMN–PZT quaternary piezoelectric ceramics were investigated in the vicinity of the MPB by varying the PYN content. The phase structure, piezoelectric and dielectric properties and the Curie temperature near the MPB of these materials were studied in detail. 2. Experimental 2.1. Sample preparation The compositions of the PYN–PMN–PZT systems were Pb0.98Sr0.02 (Yb1/2Nb1/2)x (Mn1/3Nb2/3)0.05(0.95 − x)Pb(Zr0.48Ti0.52)O3 + 0.25 wt.% CeO2 containing various PYN contents (0.06 ≤ x ≤ 0.16). PbTiO3 has a higher Curie temperature (TC = 490 °C) than PbZrO3 (TC = 230 °C), therefore a Ti-rich composition (Zr/Ti = 48/52) was chosen so that
H. Chen, C. Fan / Materials Letters 64 (2010) 654–656
Fig. 1. XRD patterns of PYN–PMN–PZT with different PYN contents.
655
Fig. 3. Dielectric properties of PYN–PMN–PZT as a function of PYN content (f = 1 KHz).
3. Results and discussion PYN–PMN–PZT would have a higher TC. The samples were prepared by the columbite precursor method. Commercially available PbO, SrCO3, Yb2O3, MnCO3, Nb2O5, ZrO2, TiO2 and CeO2 were used as the raw materials. Once synthesized, the PYN–PMN–PZT perovskite powders were mixed with 5 wt.% polyvinyl alcohol (PVA) solution, and then pressed into disks 12 mm in diameter at a pressure of 100 MPa. The samples were sintered at 1240 °C for 3 h in a covered alumina crucible. The pellets were polished to a thickness of 0.5 mm. Electrodes were made by applying a silver paste on the two major faces of the disks followed by heat treatment at 830 °C for 8 min, and subsequent poling in a DC electric field of 30–40 kV/cm in a silicon oil bath at 120 °C.
2.2. Measurements The sintered samples were ground and polished to remove the surface layer for X-ray diffraction (XRD, D/MAX-RB, Rigaku, Japan). Cu Kα radiation with a step of 0.02° was used. KP and Qm were calculated using the resonance–antiresonance method. d33 was measured (Model ZJ-2, China) using a quasi-static method. The capacitance and dielectric dissipation (tanδ) at 1 kHz were measured directly using an impedance analyzer (Agilent 4294A Precision Impedance Analyzer, Japan). The dielectric constant (εT33/ε0) was calculated using the capacitance and the dimensions of the samples.
Fig. 2. d33, KP, and Qm of PYN–PMN–PZT as a function of PYN content.
3.1. Phase structure Fig. 1 shows the XRD patterns of the sintered PYN–PMN–PZT samples with increasing PYN content. The content of the perovskite phase for all of the specimens is 100%. The tetragonal, rhombohedral and tetragonal–rhombohedral phases are identified by analysis of the peaks [002 (tetragonal), 200 (tetragonal), 200 (rhombohedral)] in the 2θ range of 43°–47°. A transition from the tetragonal to the rhombohedral phase is observed as the PYN content increases. Firstly, incorporation of Yb3+ and Nb5+ into B-sites of the perovskite structure for sample compositions near the MPB causes lattice variation, resulting in a small tolerance factor and stabilization of the rhombohedral phase compared with the tetragonal phase [11]. Secondly, increasing the PYN content shifts the MPB region towards higher proportions of PbZrO3. The compositions with 0.12 ≤x ≤ 0.14 were composed of a mixture of tetragonal and rhombohedral phases which are located near the MPB. 3.2. Piezoelectric and dielectric properties Fig. 2 shows d33, Kp, and Qm as a function of PYN content. PYN–PMN– PZT exhibits high d33 and Kp values around the MPB. The piezoelectricity achieves higher values around the MPB, while Qm shows the opposite trend and is lower around the MPB. In the MPB region, the piezoelectricity reaches its maximum value due to piezoelectric interactions among the five existing domains, two of which belong to the tetragonal phase (180° and 90°) and three to the rhombohedral
Fig. 4. Temperature dependence of εT33/ε0 of PYN–PMN–PZT with different PYN contents (f = 1 KHz).
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H. Chen, C. Fan / Materials Letters 64 (2010) 654–656
phase (180°, 71° and 109°). It can be seen that d33 > 300 pC/N, Kp > 0.50 and Qm > 1000 around the MPB. The dielectric properties as a function of PYN content at room temperature are plotted in Fig. 3, as is a comparison between the fresh and poled samples. It can be seen that εT33/ε0 increases with increasing PYN content, achieving a maximum value at x = 0.12, and then decreases significantly as the PYN content increases further. The tanδ shows the same trend. Compared with the fresh samples, the εT33/ε0 of the poled samples is higher when x < 0.12, and then lower at higher PYN contents. The tanδ of the poled samples is consistently lower than that of the fresh samples. This is because the PYN contents lower than x = 0.12 contain more of the tetragonal phase, while more rhombohedral phase is present when the PYN content is greater than x = 0.12. There exist only 180° and 90° domains in the tetragonal phase perovskite structure. After poling, the formation and reversion of 180° domains do not increase the dielectric constant. The variation of the dielectric properties reflects the transition from the tetragonal phase to the rhombohedral phase. Upon poling, an inner field forms in PYN–PMN–PZT, which can restrain the movement of domain walls, therefore the tanδ decreases compared with the fresh samples. 3.3. Curie temperature Because the Curie temperature of PYN (TC = ∼ 300 °C) is lower than that of PZT (Zr/Ti = 1:1 TC = ∼ 390 °C), with increasing PYN content, the Curie temperature of PYN–PMN–PZT decreases. Consequently, the peak in the dielectric spectrum corresponding to the Curie temperature moves towards room temperature as shown in
Fig. 4. It can also be seen that TC decreases slightly with increasing PYN content and TC > 350 °C around the MPB, which is close to the maximum TC of 386 °C currently reported for polynary PZT-based high-power piezoelectric ceramics. 4. Conclusions These results reveal that the MPB of the tetragonal and rhombohedral phase coexist when PYN–PMN–PZT has a PYN composition of 0.12 ≤ x ≤ 0.14. PYN–PMN–PZT exhibits high d33 (>300 pC/N), Kp (>0.50), Qm (>1000) and TC (>350 °C) around the MPB. The dielectric constant also reaches a maximum value around the MPB. Acknowledgement This work was supported by the Shanghai Natural Science Foundation in China. References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11]
Hao H, Zhang SJ, Shrout TR. J Am Ceram Soc 2008;91:2232–5. Park SH, Ural S, Ahn CW, Nahm S, Uchino K. Jpn J Appl Phys 2006;45:2667–73. Abdullah A, Shahini M, Pak A. J Electroceram 2009;22:369–82. Uchino K, Zheng JH, Joshi A, Chen YH, Yoshikawa S, Hirose S, et al. J Electroceram 1998:33–40. Zhang SJ, Xia R, Lebrun L, Anderson D, Shrout TR. Mater Lett 2005;59:3471–5. Jeong DY, Ryu J, Park DS. Mater Sci Eng B 2009;163:88–92. Park KH, Choo WK. J Phys Condens Matter 1991;10:5995–6007. Ohuchi H, Tsukamoto S, Ishii M, Hayakawa H. J Eur Ceram Soc 1999;19:1191–6. Osamu I, Kaoru S, Yoichi M. Jpn J Appl Phys 1999;38:5531–4. Chen CY, Lin HL. Ceram Inter 2004;30:2075–9. Yamashita Y, Hosono Y, Harada K, Ichinose N. Jpn J Appl Phys 2000;39:5593–6.
Contents lists available at ScienceDirect
Materials Letters j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / m a t l e t
Fabrication and properties of PYN–PMN–PZT quaternary piezoelectric ceramics for high-power, high-temperature applications Haiyan Chen ⁎, Chunhua Fan Institute of Marine Materials Science and Engineering, Shanghai Maritime University, Shanghai, 201306, China
a r t i c l e
i n f o
Article history: Received 4 September 2009 Accepted 10 December 2009 Available online 16 December 2009 Keywords: PYN–PMN–PZT Piezoelectric materials High power High Curie temperature Electrical properties
a b s t r a c t xPb(Yb1/2Nb1/2)O3 – 0.05Pb(Mn1/3Nb2/3)O3 – (0.95 – x)Pb(Zr0.48Ti0.52)O3 (PYN–PMN–PZT) quaternary piezoelectric ceramics were prepared by a traditional ceramics process. The effects of Pb(Yb1/2Nb1/2)O3 (PYN) content on the phase structure, electrical properties and Curie temperature of the quaternary system were investigated in detail. The phase structure of PYN–PMN–PZT ceramics changed from tetragonal to rhombohedral with increasing PYN content. The piezoelectric coefficient (d33), the electromechanical coupling factor (Kp) and the dielectric constant (εT33/ε0) reach maximum values near the morphotropic phase boundary (MPB), whereas the mechanical quality factor (Qm) decreases. The sintered PYN–PMN–PZT ceramics exhibit high TC, and as the PYN content increases, TC decreases slightly. The MPB of the tetragonal and rhombohedral phase coexist and are located at a PYN composition of 0.12 ≤ x ≤ 0.14.The composition of PYN–PMN–PZT around the MPB showed high d33 (>300pC/N), Kp (> 0.50), Qm (>1000) and TC (>350 °C), meaning it is a very promising piezoelectric material for high-power and high-temperature applications. © 2009 Elsevier B.V. All rights reserved.
1. Introduction In recent years, the high-power characteristics of piezoelectric ceramics have been intensively investigated for device applications, such as piezoelectric transformers and ultrasonic motors. These highpower devices are usually driven at a high electrical field and a high vibration level, which are associated with significant heat generation. For use in high-power devices, it is desirable for piezoelectric ceramics to combine a high mechanical quality factor (Qm) with a high piezoelectric constant (d33) and a high electromechanical coupling factor (Kp) [1–4]. A high Curie temperature (TC) is also desired because this extends their range of operating temperatures, reduces temperature dependence and enhances the output power [5,6]. However, to simultaneously achieve high values of Qm, d33 and Kp in one material is against the conventional concept of “hard” and “soft” piezoelectric characteristics. The roles of several dopants, of either donor or acceptor type, added to piezoelectric ceramics have been clarified. Also, the properties of ternary or more complex solid solutions have been significantly improved. The compositions of all of these materials are close to the morphotropic phase boundary (MPB), and they consist of relaxor ferroelectric and normal ferroelectric PZT. The relaxor ferroelectric ceramics usually have lower TC, such as Pb(Ni1/3Nb2/3)O3 (−120 °C), Pb (Mg1/3Nb2/3)O3 (−8 °C), Pb(Mn1/3Nb2/3)O3 (20 °C) and Pb(Zn1/3Nb2/3)O3 (140 °C). Although xPbZrO3 −(1−x)PbTiO3 (x=0.50) binary systems
⁎ Corresponding author. Tel.: +86 21 38284804; fax: +86 21 38284800. E-mail address: [email protected] (H. Chen). 0167-577X/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2009.12.020
offer good piezoelectricity and higher TC (∼390 °C), the PZT polynary systems listed above are limited to TC <330 °C [6]. Of the relaxor ferroelectric ceramics, Pb(Yb1/2Nb1/2)O3 (PYN) is antiferroelectric with a monoclinic perovskite structure and has a relatively high TC (300 °C) [7], and the (1 − x − y)Pb(Yb1/2Nb1/2) − xPbZrO3–yPbTiO3 (x = 0.42, y=0.48) ternary system shows a high TC (395 °C) and a high Kp (0.61) [8]. On the other hand, the Pb(Mn1/3Nb2/3)O3–PbZrO3–PbTiO3 ternary system exhibits a very high Qm and therefore is an excellent candidate for high-power application [9,10]. It is believed that Pb(Yb1/2Nb1/2)O3–Pb (Mn1/3Nb2/3)O3–PbZrO3–PbTiO3 (PYN–PMN–PZT) quaternary piezoelectric ceramics, obtained by combining Pb(Yb1/2Nb1/2)O3–PbZrO3–PbTiO3 with Pb(Mn1/3Nb2/3)O3–PbZrO3–PbTiO3, could exhibit many desirable properties. In this study, PYN–PMN–PZT quaternary piezoelectric ceramics were investigated in the vicinity of the MPB by varying the PYN content. The phase structure, piezoelectric and dielectric properties and the Curie temperature near the MPB of these materials were studied in detail. 2. Experimental 2.1. Sample preparation The compositions of the PYN–PMN–PZT systems were Pb0.98Sr0.02 (Yb1/2Nb1/2)x (Mn1/3Nb2/3)0.05(0.95 − x)Pb(Zr0.48Ti0.52)O3 + 0.25 wt.% CeO2 containing various PYN contents (0.06 ≤ x ≤ 0.16). PbTiO3 has a higher Curie temperature (TC = 490 °C) than PbZrO3 (TC = 230 °C), therefore a Ti-rich composition (Zr/Ti = 48/52) was chosen so that
H. Chen, C. Fan / Materials Letters 64 (2010) 654–656
Fig. 1. XRD patterns of PYN–PMN–PZT with different PYN contents.
655
Fig. 3. Dielectric properties of PYN–PMN–PZT as a function of PYN content (f = 1 KHz).
3. Results and discussion PYN–PMN–PZT would have a higher TC. The samples were prepared by the columbite precursor method. Commercially available PbO, SrCO3, Yb2O3, MnCO3, Nb2O5, ZrO2, TiO2 and CeO2 were used as the raw materials. Once synthesized, the PYN–PMN–PZT perovskite powders were mixed with 5 wt.% polyvinyl alcohol (PVA) solution, and then pressed into disks 12 mm in diameter at a pressure of 100 MPa. The samples were sintered at 1240 °C for 3 h in a covered alumina crucible. The pellets were polished to a thickness of 0.5 mm. Electrodes were made by applying a silver paste on the two major faces of the disks followed by heat treatment at 830 °C for 8 min, and subsequent poling in a DC electric field of 30–40 kV/cm in a silicon oil bath at 120 °C.
2.2. Measurements The sintered samples were ground and polished to remove the surface layer for X-ray diffraction (XRD, D/MAX-RB, Rigaku, Japan). Cu Kα radiation with a step of 0.02° was used. KP and Qm were calculated using the resonance–antiresonance method. d33 was measured (Model ZJ-2, China) using a quasi-static method. The capacitance and dielectric dissipation (tanδ) at 1 kHz were measured directly using an impedance analyzer (Agilent 4294A Precision Impedance Analyzer, Japan). The dielectric constant (εT33/ε0) was calculated using the capacitance and the dimensions of the samples.
Fig. 2. d33, KP, and Qm of PYN–PMN–PZT as a function of PYN content.
3.1. Phase structure Fig. 1 shows the XRD patterns of the sintered PYN–PMN–PZT samples with increasing PYN content. The content of the perovskite phase for all of the specimens is 100%. The tetragonal, rhombohedral and tetragonal–rhombohedral phases are identified by analysis of the peaks [002 (tetragonal), 200 (tetragonal), 200 (rhombohedral)] in the 2θ range of 43°–47°. A transition from the tetragonal to the rhombohedral phase is observed as the PYN content increases. Firstly, incorporation of Yb3+ and Nb5+ into B-sites of the perovskite structure for sample compositions near the MPB causes lattice variation, resulting in a small tolerance factor and stabilization of the rhombohedral phase compared with the tetragonal phase [11]. Secondly, increasing the PYN content shifts the MPB region towards higher proportions of PbZrO3. The compositions with 0.12 ≤x ≤ 0.14 were composed of a mixture of tetragonal and rhombohedral phases which are located near the MPB. 3.2. Piezoelectric and dielectric properties Fig. 2 shows d33, Kp, and Qm as a function of PYN content. PYN–PMN– PZT exhibits high d33 and Kp values around the MPB. The piezoelectricity achieves higher values around the MPB, while Qm shows the opposite trend and is lower around the MPB. In the MPB region, the piezoelectricity reaches its maximum value due to piezoelectric interactions among the five existing domains, two of which belong to the tetragonal phase (180° and 90°) and three to the rhombohedral
Fig. 4. Temperature dependence of εT33/ε0 of PYN–PMN–PZT with different PYN contents (f = 1 KHz).
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H. Chen, C. Fan / Materials Letters 64 (2010) 654–656
phase (180°, 71° and 109°). It can be seen that d33 > 300 pC/N, Kp > 0.50 and Qm > 1000 around the MPB. The dielectric properties as a function of PYN content at room temperature are plotted in Fig. 3, as is a comparison between the fresh and poled samples. It can be seen that εT33/ε0 increases with increasing PYN content, achieving a maximum value at x = 0.12, and then decreases significantly as the PYN content increases further. The tanδ shows the same trend. Compared with the fresh samples, the εT33/ε0 of the poled samples is higher when x < 0.12, and then lower at higher PYN contents. The tanδ of the poled samples is consistently lower than that of the fresh samples. This is because the PYN contents lower than x = 0.12 contain more of the tetragonal phase, while more rhombohedral phase is present when the PYN content is greater than x = 0.12. There exist only 180° and 90° domains in the tetragonal phase perovskite structure. After poling, the formation and reversion of 180° domains do not increase the dielectric constant. The variation of the dielectric properties reflects the transition from the tetragonal phase to the rhombohedral phase. Upon poling, an inner field forms in PYN–PMN–PZT, which can restrain the movement of domain walls, therefore the tanδ decreases compared with the fresh samples. 3.3. Curie temperature Because the Curie temperature of PYN (TC = ∼ 300 °C) is lower than that of PZT (Zr/Ti = 1:1 TC = ∼ 390 °C), with increasing PYN content, the Curie temperature of PYN–PMN–PZT decreases. Consequently, the peak in the dielectric spectrum corresponding to the Curie temperature moves towards room temperature as shown in
Fig. 4. It can also be seen that TC decreases slightly with increasing PYN content and TC > 350 °C around the MPB, which is close to the maximum TC of 386 °C currently reported for polynary PZT-based high-power piezoelectric ceramics. 4. Conclusions These results reveal that the MPB of the tetragonal and rhombohedral phase coexist when PYN–PMN–PZT has a PYN composition of 0.12 ≤ x ≤ 0.14. PYN–PMN–PZT exhibits high d33 (>300 pC/N), Kp (>0.50), Qm (>1000) and TC (>350 °C) around the MPB. The dielectric constant also reaches a maximum value around the MPB. Acknowledgement This work was supported by the Shanghai Natural Science Foundation in China. References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11]
Hao H, Zhang SJ, Shrout TR. J Am Ceram Soc 2008;91:2232–5. Park SH, Ural S, Ahn CW, Nahm S, Uchino K. Jpn J Appl Phys 2006;45:2667–73. Abdullah A, Shahini M, Pak A. J Electroceram 2009;22:369–82. Uchino K, Zheng JH, Joshi A, Chen YH, Yoshikawa S, Hirose S, et al. J Electroceram 1998:33–40. Zhang SJ, Xia R, Lebrun L, Anderson D, Shrout TR. Mater Lett 2005;59:3471–5. Jeong DY, Ryu J, Park DS. Mater Sci Eng B 2009;163:88–92. Park KH, Choo WK. J Phys Condens Matter 1991;10:5995–6007. Ohuchi H, Tsukamoto S, Ishii M, Hayakawa H. J Eur Ceram Soc 1999;19:1191–6. Osamu I, Kaoru S, Yoichi M. Jpn J Appl Phys 1999;38:5531–4. Chen CY, Lin HL. Ceram Inter 2004;30:2075–9. Yamashita Y, Hosono Y, Harada K, Ichinose N. Jpn J Appl Phys 2000;39:5593–6.