2017/07/08 by Bharat G. Baraskar, Rahul C. Kambale, A. R. James +6
Materials Science · Engineering · #Ferroelectric and Piezoelectric Materials #Microwave Dielectric Ceramics Synthesis #Multiferroics and related materials
paper · doi:10.1111/jace.15073
Lead‐free Ba 0.7 Ca 0.3 Ti 1− x Sn x O 3 ( x =0.00, 0.025, 0.050, 0.075, and 0.1, abbreviated as BCST) electroceramic system was prepared by the solid‐state reaction method and its ferroelectric, piezoelectric, and electrostrictive properties were investigated. X‐ray diffraction shows that the compositions with x ≤0.05 exhibit a tetragonal crystal structure having P4mm symmetry; while the compositions x =0.075 and 0.1 exhibit a mixed P4mm+Amm2 phase coexistence of tetragonal and orthorhombic and P4mm+Pm m pseudo‐cubic lattice symmetries, respectively, at room temperature. The dense microstructure having relative density ~90%‐92% and average grain size in the range ~2.36 μm to 8.56 μm was observed for BCST ceramics. Temperature‐dependent dielectric measurements support the presence of phase coexistence and show the decrease in Curie temperature ( T C ) with Sn 4+ substitution. The dielectric loss (tan δ) values in the temperature range (−100°C to 150°C) was observed to be <4%, for all BCST ceramics. The BCST compositions exhibit typical polarization‐electric field (P‐E) hysteresis and electric field induced strain (S‐E) butterfly loop, which confirms the ferroelectric and piezoelectric character. The compositions x =0.025, 0.05 and 0.075 show the peaking behavior of displacement current density ( ) to an applied electric field ( ) (J‐E) which implies the saturation state of polarization. The maximum electrostrictive coefficient ( Q 33 ) value of 0.0667 m 4 /C 2 was observed for x =0.075 and it is higher than some of the significant lead‐based electrostrictive materials. The compositions x =0.05 and 0.075 exhibit the notable electrostrictive properties that may be useful for piezoelectric Ac device applications. The observed results are discussed and correlated with the structure‐property‐composition.