A new insight into structural complexity in ferroelectric ceramics

Weidong Zeng,Changlai Yuan,Guohua Chen,Jiwen Xu,Qingning Li,Changrong Zhou

doi:10.1007/s40145-017-0237-1

Weidong Zeng, Changlai Yuan + Show 4 more

Open Access

https://doi.org/10.1007/s40145-017-0237-1

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Abstract

The structure of the ferroelectrics has been widely studied in order to pursuing the origin of high electromechanical responses. However, some experiments on structure of ferroelectrics have yielded different results. Here, we report that the controversial phase structure is due to the adaptive diffraction of nanodomains which hides the natural crystal structure, and the electric-field-induced phase transition is that the natural crystal structure reappears due to the coalescent nanodomains or ordering nanodomains by applying a high electric field. The temperature dependence of dielectric constant with different measurement frequencies and X-ray diffraction (XRD) patterns of unpoled, poled, and annealing after poled ceramics in Bi0.5Na0.5TiO3–BaTiO3 (BNT–BT) ceramics authenticate the statement. These results provide a new insight into the origin of structural complexity in ferroelectric ceramics, which is related to the key role of nanodomains.

Highlights

Perovskite ferroelectric (FE) materials with excellent electromechanical and dielectric properties are widely used as sensors, actuators, generators, and ultrasound transducers [1,2,3]
Knowledge of the natural crystal structure distortions in ferroelectric is a fundamental issue to understanding the physical and structural origin of enormous electromechanical and high piezoelectric responses under a high electric field that has remained elusive for decades [4,5,6]
Most of the studies demonstrate that the ferroelectric solid solutions of Pb(ZrxTi1 x)O3 (PZT), Pb(Mg1/3Nb2/3)xTi1 xO3 (PMNT), Pb(Zn1/3Nb2/3)xTi1 xO3 (PZNT), (1–x)Bi0.5Na0.5TiO3– xBaTiO3 (BNT–BT), and (K,Na)NbO3 (KNN) in the vicinity of morphotropic phase boundary (MPB)

Summary

Introduction

Perovskite ferroelectric (FE) materials with excellent electromechanical and dielectric properties are widely used as sensors, actuators, generators, and ultrasound transducers [1,2,3]. It came to be generally accepted that the so-called MPB in PZT and BNT–BT is a region of coexistence between the tetragonal (T) and rhombohedral (R) phases. A new low-symmetry bridging monoclinic phase at the MPB was reported based on X-ray diffraction experiment [17,18]. X-ray coherent diffraction of nanodomains hides the natural structure of nanodomain materials, and nanodomain rearrangement driven by electrical field would recur to the natural crystal structure, which was generally inappropriately accepted as electric-field-induced irreversible phase transition. Our results naturally explain the controversial phase structure of BNT–BT systems in the MPB region and will provide a new insight into the interplay between giant dielectric, strain, ultrahigh piezoelectric responses, and microstructure in ferroelectrics

Experimental procedure

Results and discussion

Conclusions