Ferroelectric, piezoelectric and electrostrictive properties of Sn⁴⁺‐modified Ba_0.7Ca_0.3TiO₃ lead‐free electroceramics

Abstract

Lead‐free Ba0.7Ca0.3Ti1−xSnxO3 (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+Pmtrue3false¯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 (TC) with Sn4+ 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 (trueJ→) to an applied electric field (trueE→) (J‐E) which implies the saturation state of polarization. The maximum electrostrictive coefficient (Q33) value of 0.0667 m4/C2 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.

Multifunctional barium titanate ceramics via chemical modification tuning phase structure

“…The highest Q 33 of ~0.02 m 4 /C 2 for lead‐based ceramics is much inferior to the lead‐free counterparts on the whole. Through chemical modification, lead‐free ST‐, BFO‐, KNN‐, BNT‐, and NN‐based ceramics can achieve the optimized Q 33 up to 0.02, 0.029, 0.034, 0.02‐0.047, and 0.04‐0.046 m 4 /C 2 , respectively 124‐131 . Pure BT exhibits strong electrostrictive effect with a high Q 33 of ~0.035 m 4 /C 2 , 124 and its Q 33 can be improved to ~0.04 to 0.055 m 4 /C 2 via chemical modification.…”

“…Pure BT exhibits strong electrostrictive effect with a high Q 33 of ~0.035 m 4 /C 2 , 124 and its Q 33 can be improved to ~0.04 to 0.055 m 4 /C 2 via chemical modification. If oxygen octahedron space is tuned by A‐sites engineering, Q 33 can soar to ~0.06 to 0.07 m 4 /C 2 66,118,119,122‐129 . The outstanding electrostrictive effect may contribute to the superior electro‐strain property of BT‐based ceramics that is higher than lead‐based and other lead‐free systems.…”

“…BNT‐based ceramics can obtain giant strain of ~0.3% to 0.8%, whereas is accompanied by large hysteresis of more than 50% 18,19,34‐38,130,131 . A similar strain ceiling of ~0.25% presents in KNN‐, BFO‐, and BT‐based ceramics when the driving electric field is less than ~100 kV/cm 21,26,29,30,41,54,68,70,72,83,91,101‐104,110,118‐129,133,134 . In this situation, BT‐based systems possess much smaller hysteresis (basically <10%), making it foremost available for high‐precise piezo‐actuator applications.…”

“…A, Comparison of Q 33 for lead‐based ceramics 66,110 and lead‐free systems including SrTiO 3 (ST)‐, 132 BiFeO 3 (BFO)‐, 133 (K, Na)NbO 3 (KNN)‐, 134 (Bi 0.5 Na 0.5 )TiO 3 (BNT)‐, 130,131 NaNbO 3 (NN)‐, 135‐137 and BT‐based ceramics 66,118,119,122‐129 . B, Comparison of room‐temperature strain and hysteresis for lead‐based and lead‐free ceramics 18,19,21,26,29,30,34‐38,41,54,66,68,70,72,83,91,100‐104,110,118‐137 …”

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

“…P4mm + Amm2. However, the composition x = 0.10 shows the combination P4mm (60%) and cubic Pm ¯ 3 m (40%) (ICSD# 99736) lattice symmetries which is called the pseudo-cubic (PC) lattice symmetry [26]. Thus, to invoke the improved ferroelectric and piezoelectric behavior of the material system an attempt to be made to achieve phase coexistence of noncentrosymmetric lattice symmetries near room temperature.…”