Effects of quenching on phase transformations and ferroelectric properties of 0.35BCZT-0.65KBT ceramics

Abstract

Solid solutions of 0.35(Ba,Ca)(Zr,Ti)O3-0.65(K0.5Bi0.5)TiO3 (BCZT-KBT) having various Ca and Zr contents were synthesized by solid state reaction. The sintered ceramics exhibited interesting features comprising core-shell type microstructures and relaxor ferroelectric behaviour. The influence of air-quenching on structure and electrical properties has been systematically investigated. The results indicate that the compositional heterogeneity in the shell regions, for the slow-cooled state, was reduced by air quenching. Improvements are evident in ferroelectric tetragonal phase content, accompanied by increased polarisation values and depolarisation temperatures. Comparing the results obtained for two BCZT compositions, it was demonstrated that the stability of the ferroelectric tetragonal phase in slow-cooled BCZT-KBT samples was improved for the ceramic with lower Ca and Zr concentrations, denoted x=0.06, comparing with that for higher levels, denoted x=0.15. Furthermore, the electric field-induced ferroelectric state in the quenched ceramic with x=0.06 was found to be more stable during heating, yielding an enhanced depolarisation temperature.

Quenching‐circumvented ergodicity in relaxor Na1/2Bi1/2TiO3‐BaTiO3‐K0.5Na0.5NbO3

“…This then entails an increased correlation between the existing PNRs apart from providing means of tailoring ergodicity as an alternative to new solid solutions or chemical doping. A similar increase in the correlation length of PNRs was facilitated in ergodic relaxor (Ba, Ca)(Ti, Zr)O 3 ‐K 1/2 Bi 1/2 TiO 3 by quenching; although driven by chemical heterogeneity (unlike the present study), the quenched samples exhibited enhanced non‐cubic (tetragonal) phase fraction as opposed to the slow‐cooled specimens 41 …”

“…A similar increase in the correlation length of PNRs was facilitated in ergodic relaxor (Ba, Ca)(Ti, Zr)O 3 -K 1/2 Bi 1/2 TiO 3 by quenching; although driven by chemical heterogeneity (unlike the present study), the quenched samples exhibited enhanced non-cubic (tetragonal) phase fraction as opposed to the slowcooled specimens. 41 In NBT-6BT, it has been demonstrated that Bi-O and Bi-Ti bond distances feature an abrupt change at T m but not at T F-R , indicating the transformation from rhombohedral to tetragonal phase to occur gradually. However, a recent report indicated that quenching results in enhanced Bi 3+ offcentering as opposed to furnace-cooled specimens, 32 which can alter the local structure.…”

Effect of sintering temperature on the depolarization behavior of (Bi0.5Na0.5)TiO3‐based ceramics

“…This is because that the polarization are nonsaturated at 6 kV/mm, and appropriate high temperature can promote the movement of domain walls and thus favor the polarization reversal. 38,39 However, with further increase in temperature, the depolarization behavior becomes dominant and the long-range FE order diminishes into polar nano regions (PNRs), reducing the polarization. 32 In addition, the temperature at which the maximum P r appears increases with the increase in T s , which is 90°C, 100°C, and 120°C for the samples sintered at T s = 1100°C, 1140°C, and 1180°C, respectively.…”

Enhancement of electrical properties in the ternary PMN–PT–PZ through compositional variation, crystallographic texture, and quenching

“…In another lead‐free family, the Na 0.5 Bi 0.5 TiO 3 ‐based piezoceramics, quenching from the sintering temperature was used to defer the ferroelectric‐relaxor transition temperature ( T F‐R ) to higher values, thereby improving the thermal stability of ferro/piezoelectric properties . In the solid solutions of 0.35(Ba,Ca)(Zr,Ti)O 3 –0.65(K 0.5 Bi 0.5 )TiO 3 , the quenching process was again used to enhance polarization and increase thermal stability of the ceramics …”

“…14,15 In the solid solutions of 0.35(Ba,Ca)(Zr,Ti)O 3 -0.65(K 0.5 Bi 0.5 ) TiO 3 , the quenching process was again used to enhance polarization and increase thermal stability of the ceramics. 16 In the current study, Pb(Mg 1/3 Nb 2/3 )O 3 -PbZrO 3 -PbTiO 3 (PMN-PZT) ternary system was chosen and investigated to improve the soft piezoelectric properties through a compositional variation and development of crystallographic texture, as an initial focus. PMN is a relaxor ferroelectric with high dielectric properties at room temperature, whereas PZT is a normal ferroelectric with higher piezoelectric and ferroelectric properties.…”