High-pressure structural investigation on lead-free piezoelectric 0.5Ba(Ti0.8Zr0.2)O3 - 0.5(Ba0.7Ca0.3)TiO3 |
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| Authors: | Anshuman Mondal Pinku Saha Bishnupada Ghosh Mrinmay Sahu Goutam Dev Mukherjee Rajeev Ranjan Kumar Brajesh |
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| Affiliation: | 1. Department of Physical Sciences, Indian Institute of Science Education and Research Kolkata, Nadia, India;2. Department of Materials Engineering, Indian Institute of Science, Bengaluru, India;3. Department of Material science and Engineering, Indian Institute of Technology Kanpur, Kanpur, India |
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| Abstract: | The solid solution 0.5Ba(Ti0.8Zr0.2)O3 − 0.5(Ba0.7Ca0.3)T iO3 (BCZT) has become a promising member of the lead-free piezoelectric materials because of its exceptionally high piezoelectric properties. In this study, we focus on studying pressure-dependent Raman spectroscopy, powder x-ray diffraction, and dielectric constant measurements on BCZT. The data show several structural transitions are present, where the system from ambient mixed phase (tetragonal P4mm + orthorhombic Amm2) transforms into single phase (P4mm) at 0.3 GPa, then converts into cubic phase (Pm3m) at 4.8 GPa followed by another possible structural re-ordering around 10 GPa. Although there have been a lot of unanimity with the ambient crystallographic state of BCZT, our analysis justifies the presence of an intermediate orthorhombic phase in the Morphological Phase Boundary (MPB) of BCZT phase diagram. The transformation tetragonal to cubic is indicated by the Raman mode softening, unit cell volume change, and the (Ti/Zr)O6 octahedra distortion, which coincides with the well-known ferroelectric-paraelectric transition of the system. The sudden drop in the dielectric constant value at 4.7 GPa also confirms the loss of ferroelectric nature of the BCZT ceramic. |
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