A brownmillerite electronic material LiBiFe2O5: structural, dielectric, electrical, and ferroelectric properties for device application

A lead-free brownmillerite ferroelectric material LiBiFe2O5 (LBFO) has been synthesized via a solid-state reaction technique. Using the procedure of N-TREOR method of X-ray diffraction, the crystal structure of the prepared sample is found to be monoclinic with lattice parameters: a = 13.6726 angstrom, b = 4.1560 angstrom, c = 8.5317 angstrom, and beta = 102.89. Based on analysis of electrical data, the existence of Koop's and Maxwell-Wagner relaxation phenomena and dielectric relaxation in the material has been confirmed. This analysis has also shown a high impact of the dielectric permittivity (epsilon(r)) and low tangent loss (tan delta) on using the material in some electronic devices. A detailed study of the frequency-temperature-dependent ac conductivity has suggested the presence of Jonscher's universal power law in the material. As the material has thermistor constant (beta) values of 4019.26, 11535.75, and 484.36 in different temperature ranges indicating high-temperature NTC thermistor application.