Influence of the substituent LiNbO3 in the structural, ferroelectric, dielectric, optical and mechanical properties of K0.5Bi0.5TiO3

Eco-friendly, K0.5Bi0.5TiO3 based binary perovskite system with small amount of LiNbO3 was synthesised and its influence in the structural, ferroelectric, optical and mechanical properties is analyzed. The samples, (1-x) K0.5Bi0.5TiO3-xLiNbO3, named as KLN100x (x = 0.04-0.08) could be refined in both ideal cubic perovskite structure (space group Pm3m) and in the tetragonal P4mm structure. The tetragonality of all the samples is close to unity which is common for relaxor ferroelectric perovskites. KLN4, KLN5, KLN6 and KLN7 shows relaxor like polarization-electric field (P-E) loops while highly distorted P-E loop was observed for KLN8. Emergence of impurity phases at higher doping concentrations lead to distorted P-E loop limiting ferroelectric application for higher concentrations. The temperature dependent dielectric curve along with ln(1/& epsilon;r-1/& epsilon;m) Vs. ln(T-Tm) plot further confirms the relaxor behavior of the samples. The relaxor nature reduces the energy barrier required for dipole switching in ferroelectric materials resulting in low remanent polarization and enhance the energy storage properties. The recoverable energy density of 1.3 J/cm3 for KLN4 at a low electric field of 100 kV/cm makes it an appealing candidate in the energy storage domain.

Automated summary

An eco-friendly binary perovskite system based on K0.5Bi0.5TiO3 with a small amount of LiNbO3 was synthesized, and its influence on structural, ferroelectric, optical, and mechanical properties was analyzed. The samples, (1-x) K0.5Bi0.5TiO3-xLiNbO3, showed both the ideal cubic perovskite structure (space group Pm3m) and the tetragonal P4mm structure. The tetragonality of all samples was close to unity, indicating relaxor ferroelectric behavior. However, higher doping concentrations led to the emergence of impurity phases and distorted P-E loops, limiting the ferroelectric application. The relaxor nature of the samples resulted in low remanent polarization and enhanced energy storage properties, making KLN4 a promising candidate in the energy storage domain.