Phase transitional behavior and electric field-induced large strain in alkali niobate-modified Bi0.5(Na0.80K0.20) 0.5TiO3 lead-free piezoceramics

Jigong Hao, Bo Shen, Jiwei Zhai*, H. D. Chen

*Corresponding author for this work

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The effect of (KyNa1-y)NbO3 (KyNN) addition on the ferroelectric stability and consequent changes in the electrical properties of lead-free Bi0.5(Na 0.80K0.20)0.5TiO3 (BNKT20) piezoceramics were systematically studied. Results showed that the K yNN substitution into BNKT20 induces a phase transition from coexistence of ferroelectric tetragonal and rhombohedral to a relaxor pseudocubic with a significant disruption of the long-range ferroelectric order, and correspondingly adjusts the ferroelectric-relaxor transition point T F-R to room temperature. Accordingly, a large electric-field-induced strain of 0.33%-0.46% (Smax/Emax = 413-575 pm/V), which is derived from a reversible field-induced ergodic relaxor to ferroelectric phase transformation, was obtained in KyNN-modified compositions near the phase boundary. Moreover, a relationship between the position of the ferroelectric-relaxor phase boundary and the tolerance factor t of the end member KyNN was found in BNKT20-xKyNN system, which is expected to provide a guideline for searching the new ferroelectric-relaxor phase boundary where the strain response is consistently derivable in (Bi 0.5Na0.5)TiO3-based materials.

Original languageEnglish
Article number034101
JournalJournal of Applied Physics
Issue number3
StatePublished - 10 Feb 2014

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