Influence of oxygen vacancies on core‐shell formation in solid solutions of (Na,Bi)TiO₃ and SrTiO₃

Abstract

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High energy storage performance of lead‐free Nb‐modified (Bi0.2Na0.2Ca0.2Ba0.2Sr0.2)TiO3 high‐entropy ceramics

“…Obviously, all samples present a well‐crystallized perovskite structure and no second phase can be observed, implying that Nb 5+ ions successfully dissolved into the BNBCST lattice to form a uniform solid solution. From Figure 2B, comparing the diffraction data of x = 0.15 composition with those of (Na 0.5 Bi 0.5 )TiO 3 (PDF#: 70−4760), BaTiO 3 (PDF#: 74–1963), SrTiO 3 (PDF#: 35−0734), and CaTiO 3 (PDF#: 75−2100) standard JCPDS cards, the BNBSCT‐0.15Nb displays a single pseudo‐cubic structure, which is consistent with other Nb‐doped perovskite ferroelectrics 28,29 . From the enlarged image at around 46° in Figure 2A, the (200) peak slightly moves to low angles with the Nb content increasing from 0.01 to 0.25, which indicates that Nb doping can lead to the expansion of unit cells.…”

Modulation of phase boundary and domain structures to engineer strain properties in BNT-based ferroelectrics

“…Unfortunately, the negative strain (Sneg) and low positive strain in the BNT systems are not favorable to the application of precise actuators [3][4][5][6][7]. To solve these problems, many strategies were proposed to improve the strain performances, including core-shell structure, grain size engineering, defect modulation, and texturing techniques [8][9][10][11][12][13][14][15][16][17][18][19]. For instance, Steiner.…”

“…For instance, Steiner. et al constructed the core-shell structures in SrTiO3-modified BNT ceramics, and found that the oxygen vacancies could enhance the Sr 2+ ions diffused into the core region and transformed the ferroelectric behavior to ergodic relaxor states, which effectively promoted the strain response of d33 * [13]. By introducing plate-like NaNbO3 templates into the BNT-ST system, the grain orientation growth was successfully induced and the relaxor ergodicity was enhanced, and a high strain of ~0.39% was achieved in the <001>-oriented ceramics at the electric field of 60•kV/cm [14].…”

Influence of defect chemistry on the electromechanical strain properties of BNT–ST‐based ternary systems

“…Koch et al 19 reported a delicate interplay of defect complex formation, phase transitions, and phase coexistence using the temperature dependence of ionic conductivity in acceptor-doped BNT-based ceramics. Steiner et al 27 mentioned that oxygen vacancies play a crucial role in the chemical homogeneity and electric properties of NBT-ST-based ceramics. Jia et al 28 discussed the effect of defect dipoles (formed from oxygen vacancies due to B-site doping) on relaxor FE BNT-BT ceramics after poling.…”