FLAME-inars
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24th March – Talk 22:

Unveiling the structural balance, phase transitions and the intermediate state at the AFE/FE phase boundary in PbZr1-xTixO3

Prof. Dr. Nan Zhang Electronic Materials Research Laboratory Xi'an Jiaotong University, China

Abstract

The importance of understanding the antiferroelectric perovskites, especially the classical PbZrO3 (PZO)-based systems, have been widely recognized in fundamental and applicational researches. Many aspects have also been discussed in previous seminars in this online event. The antiferroelectric PbZr1-xTixO3 (PZT) is especially interesting, not only because it is regarded as having similar structures of PZO but also because the AFE state becomes less stable by introducing the ferroelectric-active Ti ions into the system. This opens up more tunable structural parameters and functional applications. For example, it enlarges the temperature range of the intermediate state, reduces the AFE-FE transition field, and induces local disordering in the AFE domains. Therefore, we choose Zr-rich PZT as a candidate to perform dedicated studies on the complex structural changes as a function of temperature and in the AFE-FE phase transition process.

We carried out optical, scattering, and other experiments on a series of PZT compositions from the AFE end (x ~ 0.02) to the AFE-FE phase boundary (x ≤ 0.07). The results and analyses reveal several interesting characteristics and behaviours of PZT, especially when the AFE and FE states are in competition. In this talk, I will first introduce our proposed local structural model of the high-temperature intermediate state; then I will move to compositions with slightly higher Ti% to talk about the complex phase coexistence and a peculiar transition itinerary at the AFE / FE boundary; finally, I will talk about the interruption of long-range AFE ordering under pressure and electric field, and possible applications.

References

[1] Zheyi An, Hiroko Yokota, Nan Zhang, Marek Paściak, Jan Fábry, Miloš Kopecký, Jiří Kub, Guanjie Zhang, A. M. Glazer, T. R. Welberry, Wei Ren and Zuo-Guang Ye, Multiple structural components and their competition in the intermediate state of antiferroelectric Pb(Zr,Ti)O3, Phys. Rev. B 103, 054113 (2021);

[2] Zheyi An, Shanshan Xie, Nan Zhang, Jian Zhuang, A. M. Glazer, Wei Ren and Zuo-Guang Ye, Ferroelastic domain hierarchy in the intermediate state of PbZr0.98Ti0.02O3 single crystal, APL Materials 9, 030702 (2021).

Professor Nan Zhang received her DPhil degree in the research group of crystallography and ferroelectrics at the University of Oxford in 2009. She continued working as a post-doc in Oxford and then Simon Fraser University, mainly working on the average and local structures of PZT. She joined the Electrical Materials Research Laboratory at Xi'an Jiaotong University in 2015. Since 2017, she works as a professor at Xi'an Jiaotong University, focusing on the multi-scale-structures of ferroelectric / piezoelectric materials and the structure-property relationships.

She has won several awards, including the 2015 Spriggs Phase Equilibria Award from American Ceramics Society and Top 10 Scientific Advances of 2020 in China.

About the FLAME-inars

The FLAME-inars are organized by the collaborative project FLAME at TU Darmstadt, in which electronic-structure-property relationships are being developed and exploited to realize novel lead-free antiferroelectric compounds. The seminars will gather experts in processing, characterization and theory to discuss materials and applications, bulk and thin films, fundamental properties, electronic structure & defects, and related aspects.

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