Development of Complex Lead Free Perovskite Materials for Device Application

Abstract

The race of power expenditure of the present generation envisages the use of multifunctional materials. The energy consumption and loss of energy can be avoided by using smart materials for portable electronic applications (like energy storage devices, batteries, ceramic capacitors, supercapacitors, etc.). Lead based perovskites have been successfully used in piezoelectric devices, ferroelectric random access memory devices, solar cells etc. in the recent past by the electronic industries. However, the toxic effects of lead on the environment and human health is a matter of great concern. newlineHence there is a challenge to develop lead-free materials which can replace traditional lead zirconates (PZTs). So the selection of materials is focused on lead-free perovskite materials like BaTiO3 (BT), BiFeO3 (BF or BFO), and BaFe0.5Nb0.5O3 (BFN) in modified form. The different ionic radii, valences, and electro-negativity of cations induce vacancies, charge fluctuation, and local disorder to form small piezoelectric nano-clusters called polar nano regions (PNRs). The ferroelectric transition temperature (Curie temperature or TC) of a material can be tuned by the suitable substitution of cations. Freezing of PNRs generates a relaxor nature whereas TC is defined over a broad temperature range. The development of the relaxor ferroelectricity improves several characteristics, such as electrostrictive (sensitive to frequency or vibration), piezoelectric, and electromechanical coupling coefficients. Relaxor property is believed to suppress the leakage current and the energy dissipation of the studied materials. It has been verified through the slimmer hysteresis loops. Consequently, the recoverable energy of the materials is enhanced. High energy efficiency and electric breakdown strength, tuning of TC, dielectric parameters, and recoverable energy in a compound are required for the application purposes. The concepts of diffused phase transition (where the dielectric constant remains high over a wide range of temperatures) and rel