Extremely consistent dielectric capacitors with excellent comprehensive dielectric permittivity characteristics using (Ba, Sr) (Ti, Zr) O3 lead-free ceramic-based relaxor ferroelectrics

Abstract

For decades, lead-free eco-friendly BaTiO3 ferroelectrics and their derivate have been established to be exceptional candidates for maintainable development and piezoelectric devices. In this work, the lead-free Ba0.8Sr0.2Ti0.75Zr0.25O3 system is prepared using a conventional solid-state reaction method. The incorporation of the Sr and Zr elements into the BaTiO3 matrix has broken the long-range ferroelectric polarization to announce the formation of Polar Nano-Regions (PNRs). The structural results have confirmed that the Ba0.8Sr0.2Ti0.75Zr0.25O3 reveals a single phase with a P4mm space group. The Raman analysis indicates the presence of active vibration Raman modes ҐR3c, Raman = 9A1 + 9E. Moreover, the X-ray diffraction (XRD) study and Raman results approve the absence of secondary phases. The temperature-dependent permittivity shows the presence of broad and frequency-dependent maximum dielectric pics. At 100 Hz, the maximum value of the relative permittivity ε′ ≈ 7000 is higher than that for conventional BaTiO3 perovskites (ε′ = 3000–6000). These results are due to the existence of domain boundary effects (PNRs) in Ba0.8Sr0.2Ti0.75Zr0.25O3 and the lattice distortion effects in high entropy systems. In addition, the observed elevated dielectric permittivity could be attributed to the dense microstructure of the ceramic with a large grain size of approximately 1.1 μm. The evolution of the characteristic frequency versus the maximum temperature is discussed in terms of the Vogel-Fulcher formula. Likewise, the characteristic diffuseness of the dielectric peak is described based on an empirical Lorenz-type relation. The deviation from the Curie-Weiss law (γ = 1.623) indicates that the lead-free Ba0.8Sr0.2Ti0.75Zr0.25O3 ferroelectric compound reveals a relaxor behavior. The encouraging dielectric properties of our solid solution (high relative permittivity of ε′ ≈ 7000 and very low dielectric losses of tan (δ) = 0.1) allow us to classify our Ba0.8Sr0.2Ti0.75Zr0.25O3 sample among the dielectric materials intended for energy storage in capacitors used in power electronic devices.