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Structure-property relationships in the lead-free piezoceramic system K0.5Bi0.5TiO3 - BiMg0.5Ti0.5O3

DOI: 10.1016/j.actamat.2019.02.011 DOI Help

Authors: Aurang Zeb (University of Leeds; Islamia College Peshawar) , David Hall (University of Manchester) , Zabeada Aslam (University of Manchester) , Jennifer Forrester (University of Leeds) , Jing-Feng Li (Tsinghua University) , Yizhe L. Li (University of Manchester) , Chiu C. Tang (Diamond Light Source) , Ge Wang (University of Manchester) , Fangyuan Zhu (Shanghai Institute of Applied Physics, Chinese Academy of Science) , Steven J. Milne (University of Leeds)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Acta Materialia

State: Published (Approved)
Published: February 2019
Diamond Proposal Number(s): 14322

Abstract: Distinctive structure-property relationships are revealed in the relaxor ferroelectric ceramic solid solution, (1-x)K0.5Bi0.5TiO3 - xBiMg0.5Ti0.5O3: 0.02 < x < 0.08. The constructed phase diagram and results of in-situ synchrotron X-ray diffraction provide explanations for temperature and electric field dependent anomalies in dielectric, ferroelectric and electromechanical properties. At room temperature a mixed phase tetragonal and pseudocubic phase field occurs for compositions 0 > x ≤ 0.07. As temperature rises to ≥ 150 °C, the ferroelectric tetragonal relaxor phase changes to a pseudocubic ergodic relaxor phase; this change in length scale of polar order is responsible for an inflection in relative permittivity - temperature plots. The transition is reversed by a sufficient electric field, thereby explaining the constricted form of polarisation-electric field loops measured at >150°C. It is also responsible for a change in slope of the strain-electric field (S-E) plots which are relatively linear in the ferroelectric regime i.e. at temperatures up to 150 °C, giving unipolar strains of 0.11 % at 20 °C and 0.14% at 150 °C (50 kV cm-1 field). The additional contribution from the effect of the field-induced pseudocubic to tetragonal transition, generates strains of ∼ 0.2 % at 185 °C. Unusual for a piezoelectric solid solution, the maximum strains and charge coefficients (d33 =150 pC N-1, 20 °C) do not coincide with a morphotropic or polymorphic phase boundary.

Subject Areas: Materials

Instruments: I11-High Resolution Powder Diffraction , I15-Extreme Conditions

Added On: 19/02/2019 12:19

Discipline Tags:

Ceramics Materials Science

Technical Tags:

Diffraction X-ray Powder Diffraction