dc.contributor.author Zhang, L en dc.contributor.author Ren, X en dc.contributor.author Carpenter, Michael en dc.date.accessioned 2017-04-06T12:28:56Z dc.date.available 2017-04-06T12:28:56Z dc.date.issued 2017-02-21 en dc.identifier.issn 2469-9950 dc.identifier.uri https://www.repository.cam.ac.uk/handle/1810/263484 dc.description.abstract Dielectric and mechanical spectroscopies have been used to investigate ferroelectric transitions and twin wall dynamics in the lead-free ceramic 0.5Ba(Zr$_{0.2}$Ti$_{0.8}$)O$_{3}$−0.5(Ba$_{0.7}$Ca$_{0.3}$)TiO$_{3}$ (abbreviated as BZT-50BCT), which is known to have a high piezoelectric coefficient (d$_{33}$>545pC/N). Results from dynamical mechanical analysis in the frequency range 0.2-20 Hz and resonant ultrasound spectroscopy in the frequency range ∼0.1-1.2MHz confirm the existence of three phase transitions with falling temperature, at ∼360K (cubic-tetragonal), ∼304K (tetragonal-orthorhombic), and ∼273K (orthorhombic-rhombohedral). In comparison with BaTiO$_{3}$, however, the transitions are marked by rounded rather than sharp minima in the shear modulus. The pattern of acoustic loss is also quite different from that shown by BaTiO$_{3}$ in having a broad interval of high loss at low temperatures, consistent with a spectrum of relaxation times for interactions of ferroelastic twin walls. Differences in the dielectric properties also suggest more relaxor like characteristics for BZT-50BCT. It is proposed that the overall pattern of behavior is significantly influenced by strain heterogeneity at a local length scale in the perovskite structure due to the substitution of cations with different ionic radii. The existence of this strain heterogeneity and its influence on the elastic behavior near the transition points could be contributory factors to the development of adaptive nanoscale microstructures and enhanced piezoelectric properties. dc.description.sponsorship The authors gratefully acknowledge the funding support of the China Scholarship Council (Grant No. 201506280034), the National Basic Research Program of China (Grant No. 2012CB619401), National Natural Science Foundation of China (Grants No. 51431007, No. 51372195, No. 51321003, No. 51231008, and No. 51320105014), as well as the Project of the Chinese Academy of Engineering Physics (Grant No. YK2015-0602006). Resonant ultrasound spectroscopy facilities in Cambridge have been funded by the Natural Environment Research Council and the Engineering and Physical Sciences Research Council of Great Britain (Grants No. NE/B505738/1, No. NE/F017081/1, and No. EP/I036079/1). dc.language eng en dc.language.iso en en dc.publisher American Physical Society dc.title Influence of local strain heterogeneity on high piezoelectricity in 0.5Ba(Zr$_{0.2}$Ti$_{0.8}$)O$_{3}$−0.5(Ba$_{0.7}$Ca$_{0.3}$)TiO$_{3}$ ceramics en dc.type Article prism.issueIdentifier 5 en prism.number 054116 en prism.publicationDate 2017 en prism.publicationName Physical Review B en prism.volume 95 en dc.identifier.doi 10.17863/CAM.8828 dcterms.dateAccepted 2017-01-21 en rioxxterms.versionofrecord 10.1103/PhysRevB.95.054116 en rioxxterms.version AM en rioxxterms.licenseref.uri http://www.rioxx.net/licenses/all-rights-reserved en rioxxterms.licenseref.startdate 2017-02-21 en dc.identifier.eissn 2469-9969 rioxxterms.type Journal Article/Review en pubs.funder-project-id EPSRC (EP/P024904/1) pubs.funder-project-id EPSRC (EP/I036079/1) pubs.funder-project-id NERC (NE/F017081/1)
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