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Comparing the electromechanical properties of CaTiO3- and BaZrO3-modified Bi0.5Na0.5TiO3–SrTiO3 ceramics

Published online by Cambridge University Press:  07 October 2020

Hoang Thien Khoi Nguyen ,
Trang An Duong ,
Sang Sub Lee ,
Chang Won Ahn ,
Hyoung-Su Han Open the ORCID record for Hyoung-Su Han [Opens in a new window]  and
Jae-Shin Lee Open the ORCID record for Jae-Shin Lee [Opens in a new window]
Hoang Thien Khoi Nguyen
Affiliation:
School of Materials Science and Engineering, University of Ulsan, 12, Techno saneop-ro55 beon-gil, Nam-gu, Ulsan44776, Republic of Korea
Trang An Duong
Affiliation:
School of Materials Science and Engineering, University of Ulsan, 12, Techno saneop-ro55 beon-gil, Nam-gu, Ulsan44776, Republic of Korea
Sang Sub Lee
Affiliation:
School of Materials Science and Engineering, University of Ulsan, 12, Techno saneop-ro55 beon-gil, Nam-gu, Ulsan44776, Republic of Korea
Chang Won Ahn
Affiliation:
Department of Physics and EHSRC, University of Ulsan, 93, Daehak-ro, Nam-gu, Ulsan44610, Republic of Korea
Hyoung-Su Han
Affiliation:
School of Materials Science and Engineering, University of Ulsan, 12, Techno saneop-ro55 beon-gil, Nam-gu, Ulsan44776, Republic of Korea
Jae-Shin Lee*
Affiliation:
School of Materials Science and Engineering, University of Ulsan, 12, Techno saneop-ro55 beon-gil, Nam-gu, Ulsan44776, Republic of Korea
*
a)Address all correspondence to this author. email: jslee@ulsan.ac.kr
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Abstract

The effects of CaTiO3 (CT) and BaZrO3 (BZ) modification upon the crystal structure and electromechanical properties of lead-free Bi0.5Na0.5TiO3–SrTiO3 piezoelectric ceramics were compared within a doping range of 0–4 mol%. The different effects of CT and BZ modification upon the phase transition are clearly observed in the polarization and strain hysteresis loops. The CT-modified specimens maintain strong ferroelectricity without any abnormal enhancement in the electric field-induced strain. However, the addition of as little as 1 mol% BZ induces a transition from a nonergodic relaxor phase to an ergodic relaxor phase, thus resulting in disruption of the ferroelectric order and the generation of a high field-induced strain. The present authors believe that the substitution of large ions (such as Zr4+) into the B-sites, rather than the A-sites, of the Bi0.5Na0.5TiO3-based ceramics plays a significant role in the phase transition behavior.

Keywords

ceramicpiezoelectricferroelectric
Type
Invited Feature Paper
Information
Journal of Materials Research , First View , pp. 1 - 10
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Copyright © The Author(s), 2020, published on behalf of Materials Research Society by Cambridge University Press

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References

Rödel, J., Jo, W., Seifert, K.T.P., Anton, E.M., Granzow, T., and Damjanovic, D.: Perspective on the development of lead-free piezoceramics. J. Am. Ceram. Soc. 92, 1153 (2009).CrossRefGoogle Scholar
Jo, W., Dittmer, R., Acosta, M., Zang, J., Groh, C., Sapper, E., Wang, K., and Rödel, J.: Giant electric-field-induced strains in lead-free ceramics for actuator applications–status and perspective. J. Electroceram. 29, 71 (2012).CrossRefGoogle Scholar
Rödel, J., Webber, K.G., Dittmer, R., Jo, W., Kimura, M., and Damjanovic, D.: Transferring lead-free piezoelectric ceramics into application. J. Eur. Ceram. Soc. 35, 1659 (2015).CrossRefGoogle Scholar
Hao, J., Li, W., Zhai, J., and Chen, H.: Progress in high-strain perovskite piezoelectric ceramics. Mater. Sci. Eng., R 135, 1 (2019).CrossRefGoogle Scholar
Smolenskii, G.A.: New ferroelectrics of complex composition IV. Sov. Phys.-Solid State 2, 2651 (1961).Google Scholar
Zheng, T., Wu, J., Xiao, D., and Zhu, J.: Recent development in lead-free perovskite piezoelectric bulk materials. Prog. Mater. Sci. 98, 552 (2018).CrossRefGoogle Scholar
Hiruma, Y., Nagata, H., and Takenaka, T.: Thermal depoling process and piezoelectric properties of bismuth sodium titanate ceramics. J. Appl. Phys. 105, 084112 (2009).CrossRefGoogle Scholar
Hiruma, Y., Nagata, H., and Takenaka, T.: Detection of morphotropic phase boundary of (Bi1/2Na1/2)TiO3–Ba(Al1/2Sb1/2)O3 solid-solution ceramics. Appl. Phys. Lett. 95, 052903 (2009).CrossRefGoogle Scholar
Takenaka, T., Maruyama, K.I., and Sakata, K.: (Bi1/2Na1/2)TiO3-BaTiO3 system for lead-free piezoelectric ceramics. Jpn. J. Appl. Phys. 30, 2236 (1991).CrossRefGoogle Scholar
Sasaki, A., Chiba, T., Mamiya, Y., and Otsuki, E.: Dielectric and piezoelectric properties of (Bi0.5Na0.5)TiO3–(Bi0.5K0.5)TiO3 systems. Jpn. J. Appl. Phys. 38, 5564 (1999).CrossRefGoogle Scholar
Hong, C.H., Kim, H.P., Choi, B.Y., Han, H.S., Son, J.S., Ahn, C.W., and Jo, W.: Lead-free piezoceramics–Where to move on? J. Materiomics 2, 1 (2016).CrossRefGoogle Scholar
Cho, S.Y., Kim, E.Y., Kim, S.Y., Pham, T.L., Han, J.K., Song, D.S., Jung, H.K., Lee, J.S., An, K.S., Lim, J., and Bu, S.D.: Relaxor phase evolution of (Bi0.5Na0.5-xKx)TiO3 ceramics due to K ion substitution and their corresponding electrical properties. Energies 13, 455 (2020).CrossRefGoogle Scholar
Pham, K.N., Hussain, A., Ahn, C.W., Kim, W., Jeong, S.J., and Lee, J.S.: Giant strain in Nb-doped Bi0.5(Na0.82K0.18)0.5TiO3 lead-free electromechanical ceramics. Mater. Lett. 64, 2219 (2010).CrossRefGoogle Scholar
Jo, S., Hong, C.H., Kim, D.S., Kang, H.W., Ahn, C.W., Lee, H.G., Nahm, S., Jo, W., and Han, S.H.: Phase transition behavior and mechanical properties of (1- x)(Bi1/2Na1/2)TiO3-xSrTiO3 lead-free piezoelectric ceramics. Sens. Actuat. A 258, 201 (2017).CrossRefGoogle Scholar
Duong, T.A., Han, H.S., Hong, Y.H., Park, Y.S., Nguyen, H.T.K., Dinh, T.H., and Lee, J.S.: Dielectric and piezoelectric properties of Bi1/2Na1/2TiO3–SrTiO3 lead-free ceramics. J. Electroceram. 41, 73 (2018).CrossRefGoogle Scholar
Wang, G., Hong, Y.H., Nguyen, H.T.K., Kim, B.W., Ahn, C.W., Han, H.S., and Lee, J.-S.: High electromechanical strain properties in SrTiO-modified Bi1/2Na1/2TiO3‒KTaO3 lead-free piezoelectric ceramics under low electric field. Sens. Actuat. A 293, 1 (2019).CrossRefGoogle Scholar
Zhang, Y., Liang, G., Tang, S., Peng, B., Zhang, Q., Liu, L., and Sun, W.: Phase-transition induced optimization of electrostrain, electrocaloric refrigeration and energy storage of LiNbO3 doped BNT-BT ceramics. Ceram. Int. 46, 1343 (2020).CrossRefGoogle Scholar
Yin, J., Zhao, C., Zhang, Y., and Wu, J.: Ultrahigh strain in site engineering-independent Bi0.5Na0.5TiO3-based relaxor-ferroelectrics. Acta Mater. 147, 70 (2018).CrossRefGoogle Scholar
Acosta, M., Jo, W., and Rödel, J.: Temperature-and frequency-dependent properties of the 0.75Bi1/2Na1/2TiO3–0.25SrTiO3 lead-free incipient piezoceramic. J. Am. Ceram. Soc. 97, 1937 (2014).CrossRefGoogle Scholar
Li, H.L., Liu, Q., Zhou, J.J., Wang, K., Li, J.F., Liu, H., and Fang, J.Z.: Grain size dependent electrostrain in Bi1/2Na1/2TiO3-SrTiO3 incipient piezoceramics. J. Eur. Ceram. Soc. 36, 2849 (2016).CrossRefGoogle Scholar
He, H., Lu, X., Li, M., Wang, Y., Li, Z., Lu, Z., and Lu, L.: Thermal and compositional driven relaxor ferroelectric behaviours of lead-free Bi0.5Na0.5TiO3–SrTiO3 ceramics. J. Mater. Chem. C 8, 2411 (2020).CrossRefGoogle Scholar
Gupta, S.K., McQuade, R., Gibbons, B., Mardilovich, P., and Cann, D.P.: Electric field-induced strain in Sr(Hf0.5Zr0.5)O3-modified Bi0.5(Na0.8K0.2)0.5TiO3 piezoelectric ceramics. J. Appl. Phys. 127, 074104 (2020).CrossRefGoogle Scholar
Habib, M., Munir, M., Khan, S.A., Song, T.K., Kim, M.H., Iqbal, M.J., Qazi, I., and Hussain, A.: Evaluation of high strain response in lead-free BNBTFS-xNb ceramics by structure and ferroelectric characterizations. J. Phys. Chem. Solids 138, 109230 (2020).CrossRefGoogle Scholar
Cheng, R., Xu, Z., Chu, R., Hao, J., Du, J., and Li, G.: Electric field-induced ultrahigh strain and large piezoelectric effect in Bi1/2Na1/2TiO3-based lead-free piezoceramics. J. Eur. Ceram. Soc. 36, 489 (2016).CrossRefGoogle Scholar
Liu, X. and Tan, X.: Giant strains in non-textured (Bi1/2Na1/2)TiO3-based lead-free ceramics. Adv. Mater. 28, 574 (2016).CrossRefGoogle Scholar
Wang, C., Xia, T., and Lou, X.: Large strain response in Li/Nb co-doped Bi0.5(Na0.8K0.2)0.5TiO3 lead-free piezoceramics. Ceram. Int. 44, 7378 (2018).CrossRefGoogle Scholar
Yin, D.S., Zhao, Z.H., Dai, Y.J., Zhao, Z., Zhang, X.W., Wang, S.H., and Zhang, S.: Electrical properties and relaxor phase evolution of Li-modified BNT-BKT-BT lead-free ceramics. J. Am. Ceram. Soc. 99, 2354 (2016).CrossRefGoogle Scholar
Han, H.S., Do, N.B., Pham, K.N., Jang, H.D., Tran, V.D.N., Tai, W.P., and Lee, J.S.: Sintering behaviour and piezoelectric properties of CuO-added lead-free Bi(Na,K)TiO3 ceramics. Ferroelectrics 421, 88 (2011).CrossRefGoogle Scholar
Han, H.S., Ahn, C.W., Kim, I.W., Hussain, A., and Lee, J.S.: Destabilization of ferroelectric order in bismuth perovskite ceramics by A-site vacancies. Mater. Lett. 70, 98 (2012).CrossRefGoogle Scholar
Do, N.B., Lee, H.B., Yoon, C.H., Kang, J.K., Lee, J.S., and Kim, I.-W.: Effect of Ta-substitution on the ferroelectric and piezoelectric properties of Bi0.5(Na0.82K0.18)0.5TiO3 ceramics. Trans. Electron. Electron. Mater. 12, 64 (2011).CrossRefGoogle Scholar
Goldschmidt, V.M.: Geochemische verteilungsgesetze der elemente. Skrifter norske videnskaps Akad.(Oslo), I. Math.-Naturwiss. Kl 8, 5 (1926).Google Scholar
Nguyen, V.Q., Han, H.S., Kim, K.J., Dang, D.D., Ahn, K.K., and Lee, J.S.: Strain enhancement in Bi1/2(Na0.82K0.18)1/2TiO3 lead-free electromechanical ceramics by co-doping with Li and Ta. J. Alloys Compd. 511, 237 (2012).CrossRefGoogle Scholar
Hong, I.K., Han, H.S., Yoon, C.H., Ji, H.N., Tai, W.P., and Lee, J.S.: Strain enhancement in lead-free Bi0.5(Na0.78K0.22)0.5TiO3 ceramics by CaZrO3 substitution. J. Intell. Mater. Syst. Struct. 24, 1343 (2012).CrossRefGoogle Scholar
Shannon, R.D.: Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Crystallogr. A 32, 751 (1976).CrossRefGoogle Scholar
Tai, C.W., Choy, S.H., and Chan, H.L.W.: Ferroelectric domain morphology evolution and octahedral tilting in lead-free (Bi1/2Na1/2)TiO3-(Bi1/2K1/2)TiO3-(Bi1/2Li1/2)TiO3-BaTiO3 ceramics at different temperatures. J. Am. Ceram. Soc. 91, 3335 (2008).CrossRefGoogle Scholar
Ciomaga, C., Viviani, M., Buscaglia, M.T., Buscaglia, V., Mitoseriu, L., Stancu, A., and Nanni, P.: Preparation and characterisation of the Ba(Zr,Ti)O3 ceramics with relaxor properties. J. Eur. Ceram. Soc. 27, 4061 (2007).CrossRefGoogle Scholar
Zixiong, S., Yongping, P., and Yuwen, L.: Effect of Zr4+ content on the grain growth, dielectric relaxation behavior, and ferroelectric properties of Ba0.4Sr0.6Ti1−xZrxO3 nano-ceramics prepared by different methods assisted by fast microwave sintering. J. Electron. Mater. 43, 1466 (2014).CrossRefGoogle Scholar
Badapanda, T., Rout, S.K., Cavalcante, L.S., Sczancoski, J.C., Panigrahi, S., Sinha, T.P., and Longo, E.: Structural and dielectric relaxor properties of Yttrium-doped Ba(Zr0.25Ti0.75)O3 ceramics. Mater. Chem. Phys. 121, 147 (2010).CrossRefGoogle Scholar
Guo, F., Cai, W., Gao, R., Fu, C., Chen, G., Deng, X., Wang, Z., and Zhang, Q.: Microstructure, enhanced relaxor-like behavior and electric properties of (Ba0.85Ca0.15)(Zr0.1−xHfxTi0.9)O3 ceramics. J. Electron. Mater. 48, 3239 (2019).CrossRefGoogle Scholar
Du, H.L., Du, X., and Li, H.L.: Phase structure and electrical properties of lead-free Na0.5Bi0.5TiO3–CaTiO3 ceramics. Adv. Appl. Ceram. 112, 277 (2013).CrossRefGoogle Scholar
Rahman, J.U., Hussain, A., Maqbool, A., Song, T.K., Kim, W.J., Kim, S.S., and Kim, M.H.: Dielectric, ferroelectric and field-induced strain response of lead-free BaZrO3-modified Bi0.5Na0.5TiO3 ceramics. Curr. Appl. Phys. 14, 331 (2014).CrossRefGoogle Scholar
Gao, L., Huang, Y., Hu, Y., and Du, H.: Dielectric and ferroelectric properties of (1−x)BaTiO3–xBi0.5Na0.5TiO3 ceramics. Ceram. Int. 33, 1041 (2007).CrossRefGoogle Scholar
Rahman, J.U., Hussain, A., Maqbool, A., Ryu, G.H., Song, T.K., Kim, W.-J., and Kim, M.H.: Field induced strain response of lead-free BaZrO3-modified Bi0.5Na0.5TiO3–BaTiO3 ceramics. J. Alloys Compd. 593, 97 (2014).CrossRefGoogle Scholar
Hussain, A., Rahman, J.U., Zaman, A., Malik, R.A., Kim, J.S., Song, T.K., Kim, W.J., and Kim, M.H.: Field-induced strain and polarization response in lead-free Bi1/2(Na0.80K0.20)1/2TiO3–SrZrO3 ceramics. Mater. Chem. Phys. 143, 1282 (2014).CrossRefGoogle Scholar
Maqbool, A., Hussain, A., Ur Rahman, J., Kwon Song, T., Kim, W.-J., Lee, J., and Kim, M.-H.: Enhanced electric field-induced strain and ferroelectric behavior of (Bi0.5Na0.5)TiO3–BaTiO3–SrZrO3 lead-free ceramics. Ceram. Int. 40, 11905 (2014).CrossRefGoogle Scholar
Li, F., Zuo, R., Zheng, D., Li, L., and Viehland, D.: Phase-composition-dependent piezoelectric and electromechanical strain properties in (Bi1/2Na1/2)TiO3-Ba(Ni1/2Nb1/2)O3 lead-free ceramics. J. Am. Ceram. Soc. 98, 811 (2015).CrossRefGoogle Scholar
Huband, S. and Thomas, P.A.: Depolarisation of Na0.5Bi0.5TiO3-based relaxors and the resultant double hysteresis loops. J. Appl. Phys. 121, 184105 (2017).CrossRefGoogle Scholar
Zhu, Y., Zhang, Y., Xie, B., Fan, P., Marwat, M.A., Ma, W., Wang, C., Yang, B., Xiao, J., and Zhang, H.: Large electric field-induced strain in AgNbO3-modified 0.76Bi0.5Na0.5TiO3-0.24SrTiO3 lead-free piezoceramics. Ceram. Int. 44, 7851 (2018).CrossRefGoogle Scholar
Hong, Y.H., Han, H.S., Jeong, G.H., Park, Y.S., Dinh, T.H., Ahn, C.W., and Lee, J.S.: High electromechanical strain properties by the existence of nonergodicity in LiNbO3–modified Bi1/2Na1/2TiO3–SrTiO3 relaxor ceramics. Ceram. Int. 44, 21138 (2018).CrossRefGoogle Scholar
Ullah, M., Ullah Khan, H., Ullah, A., Ullah, A., Kim, I.W., Qazi, I., and Ahmad, I.: Dielectric, ferroelectric and piezoelectric properties of (1-x)(Bi0.5Na0.5)0.935Ba0.065Ti-x(LiSbO3) solid solutions. Ceram. Int. 44, 556 (2018).CrossRefGoogle Scholar
Jo, W., Granzow, T., Aulbach, E., Rödel, J., and Damjanovic, D.: Origin of the large strain response in (K0.5Na0.5)NbO3-modified (Bi0.5Na0.5)TiO3–BaTiO3 lead-free piezoceramics. J. Appl. Phys. 105, 094102 (2009).CrossRefGoogle Scholar
Han, H.S., Jo, W., Kang, J.K., Ahn, C.W., Kim, I.W., Ahn, K.K., and Lee, J.S.: Incipient piezoelectrics and electrostriction behavior in Sn-doped Bi1/2(Na0.82K0.18)1/2TiO3 lead-free ceramics. J. Appl. Phys. 113, 154102 (2013).CrossRefGoogle Scholar
Dinh, T.H., Tran, V.D.N., Nguyen, T.T., Hoang, Q.T.N., Han, H.S., and Lee, J.S.: The reduced reversible phase transition field of lead-free Bi-based ceramic composites by adding nonergodic relaxor. Ceram. Int. 43, 17160 (2017).CrossRefGoogle Scholar
Mostovych, N., Won, S.S., Kim, I.W., Kim, S.H., and Kingon, A.I.: Understanding the large strain behavior in the lead-free doped Bi1/2(Na0.78K0.22)1/2TiO3–BiMg1/2Ti1/2O3 (BNKT-BMT) piezoelectric system. AIP Adv. 10, 045033 (2020).CrossRefGoogle Scholar
Bai, W., Chen, D., Zheng, P., Shen, B., Zhai, J., and Ji, Z.: Composition- and temperature-driven phase transition characteristics and associated electromechanical properties in Bi0.5Na0.5TiO3-based lead-free ceramics. Dalton Trans. 45, 8573 (2016).CrossRefGoogle ScholarPubMed
Ullah Khan, N., Ullah, A., Ullah, A., Khan, M.Y., Kim, T.H., Kim, I.W., and Ahn, C.W.: Boosting electrostriction and strain performance in bismuth sodium titanate-based ceramics via introducing low tolerance factor chemical modifier. Sens. Actuat. A 291, 156 (2019).CrossRefGoogle Scholar
Si, Y., Li, Y., Li, L., Li, H., Zhao, Z., and Dai, Y.: Giant electro-strain in textured Li-doped 0.852BNT–0.11BKT–0.038BT ternary lead-free piezoelectric ceramics. J. Am. Ceram. Soc. 103, 1765 (2019).CrossRefGoogle Scholar
Tran, V.D.N., Hussain, A., Han, H.S., Dinh, T.H., Lee, J.S., Ahn, C.W., and Kim, I.W.: Comparison of ferroelectric and strain properties between BaTiO3- and BaZrO3-modified Bi1/2(Na0.82K0.18)1/2TiO3 ceramics. Jpn. J. Appl. Phys. 51, 09MD02 (2012).CrossRefGoogle Scholar
Hao, K., Ge, W., Ren, Z., Liu, X., Luo, L., Li, X., Luo, H., and Viehland, D.: Combining effects of TiO6 octahedron rotations and random electric fields on structural and properties in Na0.5Bi0.5TiO3. J. Am. Ceram. Soc. 103, 3349 (2020).CrossRefGoogle Scholar
Ahn, C.W., Hong, C.H., Choi, B.Y., Kim, H.P., Han, H.S., Hwang, Y., Jo, W., Wang, K., Li, J.F., and Lee, J.S.: A brief review on relaxor ferroelectrics and selected issues in lead-free relaxors. J. Korean Phys. Soc. 68, 1481 (2016).CrossRefGoogle Scholar
Laulhé, C., Pasturel, A., Hippert, F., and Kreisel, J.: Random local strain effects in homovalent-substituted relaxor ferroelectrics: A first-principles study of BaTi0.74Zr0.26O3. Phys. Rev. B 82, 132102 (2010).CrossRefGoogle Scholar
Jeong, I.K., Park, C.Y., Ahn, J.S., Park, S., and Kim, D.J.: Ferroelectric-relaxor crossover in Ba(Ti1−xZrx)O3 studied using neutron total scattering measurements and reverse Monte Carlo modeling. Phys. Rev. B 81, 214119 (2010).CrossRefGoogle Scholar
Shen, M., Li, W., Li, M.Y., Liu, H., Xu, J., Qiu, S., Zhang, G., Lu, Z., Li, H., and Jiang, S.: High room-temperature pyroelectric property in lead-free BNT-BZT ferroelectric ceramics for thermal energy harvesting. J. Eur. Ceram. Soc. 39, 1810 (2019).CrossRefGoogle Scholar
Glaum, J., Simons, H., Acosta, M., Hoffman, M., and Feteira, A.: Tailoring the piezoelectric and relaxor properties of (Bi1/2Na1/2)TiO3-BaTiO3 via zirconium doping. J. Am. Ceram. Soc. 96, 2881 (2013).CrossRefGoogle Scholar
Chen, P.-Y., Chen, C.-S., Tu, C.-S., and Chang, T.-L.: Large E-field induced strain and polar evolution in lead-free Zr-doped 92.5%(Bi0.5Na0.5)TiO3–7.5%BaTiO3 ceramics. J. Eur. Ceram. Soc. 34, 4223 (2014).CrossRefGoogle Scholar
Glaum, J., Zakhozheva, M., Acosta, M., Aksel, E., Kleebe, H.-J., Hoffman, M., Schmitt, L.A., and Jo, W.: Influence of B-site disorder on the properties of unpoled Bi1/2Na1/2TiO3-0.06Ba(ZrxTi1-x)O3 piezoceramics. J. Am. Ceram. Soc. 99, 2801 (2016).CrossRefGoogle Scholar
Ullah, A., Ullah, M., Ullah, A., Ullah, A., Saddiq, G., Ullah, B., Zeb, A., Ullah Jan, S., and Kim, I.W.: Dielectric and electromechanical properties of Zr-doped BNT-ST lead-free piezoelectric ceramics. J. Korean Phys. Soc. 74, 589 (2019).CrossRefGoogle Scholar
Groszewicz, P.B., Breitzke, H., Jo, W., Rödel, J., and Buntkowsky, G.: Local structure of the B-site in BNT-xBT investigated by 47,49Ti NMR: Effect of barium content. J. Appl. Phys. 121, 114104 (2017).CrossRefGoogle Scholar