BaTiO3-Based Lead-Free Electroceramics with Their Ferroelectric and Piezoelectric Properties Tuned by Ca2+, Sn4+ and Zr4+ Substitution Useful for Electrostrictive Device Application

Dense microstructure BaTiO₃ (BT) ceramic with c/a ~1.0144 and average grain size ~7.8 μmis developed by achieving the ferroelectric parameters Psat. = 24.13 μC/cm2 and Pr = 10.42 μC/cm2 with lower coercive field of Ec = 2.047 kV/cm. For BT ceramic, the “sprout” shape nature is observed for strain-electric field measurements with remnant strain ~ 0.212%, converse piezoelectric constant ~376.35 pm/V and electrostrictive coefficient Q33~ 0.03493 m4/C2. To tune the piezoelectric properties of BT ceramic, the substitutions of Ca2+ and Sn4+, Zr4+ are done for Ba2+ and Ti4+ sites respectively. The Ba0.7Ca0.3Ti1-xSnxO3 (x = 0.00, 0.025, 0.050, 0.075, and 0.1, BCST) system was studied with ferroelectric, piezoelectric and electrostrictive properties. The electrostrictive coefficient (Q33) ~ 0.0667 m4/C2 was observed for x = 0.075 and it is higher than the lead-based electrostrictive materials. Another (1-X) Ba0.95Ca0.05Ti0.92Sn0.08O3 (BCST) – (X) Ba0.95Ca0.05Ti0.92Zr0.08O3 (BCZT), ceramics (x = 0.00, 0.25, 0.50, 0.75, and 1) is studied. The BCST-BCZT ceramic system shows the increase of polymorphic phase transition temperatures toward the room temperature by Ca2+, Sn4+ and Zr4+ substitution. For BCST-BCZT system the composition x = 0.75 exhibits the d33, and Q33 values of 310 pC/N, 385 pm/V and 0.089 m4/C2 respectively which is greater than BT ceramics

Effect of nano-size on magnetostriction of BiFeO3 and exceptional magnetoelectric coupling properties of BiFeO3_P(VDF-TrFE) polymer composite films for magnetic field sensor application

The existence of magnetostriction in bulk BiFeO3 is still a matter of investigation and it is also an issue to investigate the magnetostriction effect in nano BiFeO3. Present work demonstrates the existence of magnetostrictive strain in superparamagnetic BiFeO3 nanoparticles at room temperature and the magnetoelectric coupling properties in composite form with P(VDFTrFE). Despite few reports on the magnetostriction effect in bulk BiFeO3 evidenced by the indirect method, the direct method (strain gauge) was employed in this work to examine the magnetostriction of superparamagnetic BiFeO3. In addition, a high magnetoelectric coupling coefficient was observed by the lock-in technique for optimized BiFeO3_P(VDF-TrFE) nanocomposite film. These nanocomposite films also exhibit room-temperature multiferroic properties. These results provide aspects of material with immense potential for practical applications in spintronics and magneto-electronics applications. We report a magnetoelectric sensor using superparamagnetic BiFeO3_P(VDF-TrFE) nanocomposite film for detection of ac magnetic field