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Lead-based ferroelectric materials dominate the electronic industry due to their possible applications in sensors, actuators, advanced storage materials, microwave devices, and MEMS. Due to the toxicity of lead, there is a need for the development of environmentally compatible alternatives. Lead-free ternary solid solutions of (1−2x)K0.5Bi0.5TiO3-xBaTiO3-xLiNbO3 (KBLN100x) with x = 0.03, 0.05, 0.07, and 0.09 are synthesized using a standard solid-state reaction method. X-ray diffraction studies confirm the pseudocubic structure of the samples. Structural, Raman, dielectric and piezoelctric studies indicate that a normal to relaxor ferroelectric transition occurs as dopant concentration increases, and it is attributed to the increase in charge fluctuation and site disorder that resulted in the reduction in correlation lengths of the inbuilt dipole moments. A recoverable energy density of 1.3 J/cm3 was achieved for the KBLN7 sample, making it an attractive candidate in the energy storage realm. A strain value of 0.17% with Smax/Emax of 218 pm/V is observed for KBLN3 sample, indicating that K0.5Bi0.5TiO3 (KBT)-based systems can be used for actuator applications on further improvement. The normal-relaxor crossover of KBT with appropriate dopants indicates that KBT-based systems are efficient for both actuator and energy storage applications on improvising and tuning as required.

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Bismuth-based piezoelectric ceramics are presently of immense interest to researchers as they are believed to be Pb-free alternatives to well-known lead zirconate titanate-based piezoceramics. Herein, the author reports a lead-free ternary solid solution (1−2x)Na0.5Bi0.5TiO3-xBaTiO3-xBa0.7Ca0.3TiO3 (x = 0.01, 0.03, 0.05, 0.07, and 0.09: BNT-BT-BCT) synthesized through a standard solid state reaction route. All the samples crystallized to a complete perovskite structure studied through the powder x-ray diffraction analysis. Rietveld analysis of x-ray diffraction data revealed a structural transformation from monoclinic (Cc) to tetragonal phase (p4mm) with the co-existence of monoclinic (Cc) and tetragonal (p4mm) phases in the samples of x ≥ 0.03. The temperature-dependent dielectric analysis of (x = 0.03 and x = 0.05) systems suggests relaxor characteristics near ferroelectric–antiferroelectric phase transition temperature (Td). A changeover from relaxor to a near normal ferroelectric character was realized for x ≥ 0.07. Furthermore, the existence of polar nano-regions (PNRs) was studied through HR-TEM. Interestingly, a low electric field (±25 kV/cm) driven enhanced piezoelectric [(with 0.22% of strain; Smax/Emax = 850 pm/V for x = 0.03) and (with 0.17% strain and Smax/Emax of 714 pm/V for x = 0.07)] and an electrostrictive [with 0.20% of strain; Smax/Emax = 820 pm/V for x = 0.05] was achieved around Td. This can be attributed to the combined effects of phase boundary, ferroelectric–antiferroelectric transition, and the existence of PNRs.