Site engineering: A Tool to enhance functional properties in high-temperature lead-free relaxors prepared via air quenching

Abstract

With employing judicious chemical modifications, two new isovalently substituted lead-free binary solid-solutions of 0.67BiFe0.97-xGa0.03ScxO3-0.33BaTiO3 and 0.67 (Bi1-xLayFe0.97Ga0.03O3)-0.33 (BaTiO3) abbreviated as BFSBT-x and BLFBT-y respectively where x, y ≤ 0.07 were synthesized via site engineering, using solid-state route employing air quenching sintering technique. Site engineering is used to introduce the functionality by substituting A/B sites in respective solid solutions of these perovskites (general formula ABO3). To better understand its effect, crystal structural, dielectric, optical, and ferroelectric properties were characterized and compared for different compositions. The X-ray diffraction pattern suggests the formation of pure perovskite structure with pseudocubic phase as the major phase present in both BFSBT-x and BLFBT-y series. The direct band gap energy of 1.97 eV and 2.14 eV lying in visible range was obtained for x=0.03 and y=0.03 composition, respectively. The temperature-dependent dielectric studies reveal frequency-dependent dielectric anomalies in permittivity corresponding to diffuse phase transitions stipulating relaxor-like behavior, which was further confirmed by modified Curie-Weiss law fitting. The enhanced temperature stability, good dielectric properties, and lower band gap suggest that site engineering is an efficient way to enhance the functional properties of BiFeO3-BaTiO3 based samples for high-temperature applications. © 2023 IEEE.