Structural perspective on the anomalous weak-field piezoelectric response at the polymorphic phase boundaries of (Ba, Ca)(Ti, M)O-3 lead-free piezoelectrics (M = Zr, Sn, Hf)

Abebe, Mulualem and Brajesh, Kumar and Mishra, Anupam and Senyshyn, Anatoliy and Ranjan, Rajeev (2017) Structural perspective on the anomalous weak-field piezoelectric response at the polymorphic phase boundaries of (Ba, Ca)(Ti, M)O-3 lead-free piezoelectrics (M = Zr, Sn, Hf). In: PHYSICAL REVIEW B, 96 (1).

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Abstract

Although, as part of a general phenomenon, the piezoelectric response of Ba(Ti-1 M-y(y))O-3 (M = Zr, Sn, Hf) increases in the vicinity of the orthorhombic (Amm2)-tetragonal(P4mm) and orthorhombic (Amm2)-rhombohedral (R3m) polymorphic phase boundaries, experiments in the last few years have shown that the same phase boundaries show significantly enhanced weak-field piezoproperties in the Ca-modified variants of these ferroelectric alloys, i.e., (Ba, Ca)(Ti, M)O-3. So far there is a lack of clarity with regard to the unique feature(s) which Ca modification brings about that enables this significant enhancement. Here, we examine this issue from a structural standpoint with M = Sn as a case study. We carried out a comprehensive comparative structural, ferroelectric, and piezoelectric analysis of the Amm2 phase in the immediate vicinity of the P4mm-Amm2 phase boundaries of (i) Ca-modified Ba(Ti, Sn)O-3, as per the nominal formula (1-x)BaTi0.88Sn0.12O3-(x)Ba0.7Ca0.3TiO3 and (ii) without Ca modification, i.e., Ba(Ti1-ySny) O3. We found that the spontaneous lattice strain of the Amm2 phase is noticeably smaller in the Ca-modified counterpart. Interestingly, this happens along with an improved spontaneous polarization by enhancing the covalent character of the Ti-O bond. Our study suggests that the unique role of Ca modification lies in its ability to induce these seemingly contrasting features (reduction in spontaneous lattice strain but increase in polarization).

Item Type:	Journal Article
Publication:	PHYSICAL REVIEW B
Additional Information:	Copy right for this article belongs to the AMER PHYSICAL SOC, ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	12 Aug 2017 04:39
Last Modified:	12 Aug 2017 04:39
URI:	http://eprints.iisc.ac.in/id/eprint/57604

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