Energy storage enhancement and bandgap narrowing of lanthanum and sodium co-substituted BaTiO₃ ceramics

Abstract

A novel lead-free Ba_(1-x)(La,Na)_xTiO₃ (BLNT), (0 ≤ x ≤ 0.08) ferroelectric ceramic with enhanced energy storage density was fabricated by the conventional solid-state method. With an increase in La^3+/Na⁺ content, the energy storage density, efficiency and power density were increased. The samples with (x = 0.08) show recoverable energy storage of (1.07 J/cm3), 3 times higher than that of pure BaTiO₃ ceramics, energy storage efficiency of (87.6%) and power density of 0.314 MW/cm³, 17 times greater than that of pure BaTiO₃ ceramics. Comparison with other lead-free ferroelectric ceramics confirmed the superiority potential of (BLNT-0.08) ceramics for the design of ceramics capacitors for energy storage applications. The effect of La³⁺/Na⁺ contents on the optical properties of BaTiO³ ceramics was studied via UV spectroscopy. The results revealed that the introduction of structure disorder by means of A-site vacancies leading to the creation of shallow defects resulting in narrowing the bandgap energy. This work may provide a simple and powerful method to develop inexpensive energy storage and photovoltaic devices based on ferroelectric ceramics.

Keywords:

• Co-substitution
• remnant polarization
• energy storage
• energy efficiency
• power density
• bandgap energy

Acknowledgments

The authors are greatly indebted to the Sao Paulo Research Foundation (FAPESP) (grant no# 2019/03110-8) for financial support.