Charge transport and dielectric characteristics of Sm _x Bi_1−x FeO₃ thin films from the perspective of grain and grain boundary properties

Abstract

Samarium-substituted bismuth ferrite (SmxBi1-xFeO3) compositions comprise a system of important materials due to their combination of multiferroic properties. Several dielectric and charge transport reports in literature can be found in this system. However, as a typical polycrystalline electroceramic, their grains and grain boundaries (GBs) are expected to possess very different properties. To this date, these distinctions have not been performed on this system. In this work, through measurements via impedance spectroscopy on SmxBi1-xFeO3 thin films, we show that using a brick layer model allows the separation of the electrical properties of grains and GBs. Results indicate that grains have dielectric permittivity and electrical conductivity much higher than GBs. Their properties mostly control the characteristics observed in the studied thin films. The introduction of samarium reduces the electrical conductivity and increases the activation energies for charge transport in grains and GBs. In turn, dielectric permittivity is reduced in grains and subtly increased in GBs

Room temperature ferroelectricity and ferromagnetism in Ni-substituted Bi5Ti3FeO15

“…The (Bi 2 O 2 ) 2+ layers play key roles in both space-charge compensation and insulation, which are expected to reduce the leakage current. The BTF is considered to be a combination of ferroelectric Bi 4 Ti 3 O 12 and multiferroic BiFeO 3 , herein the Bi 4 Ti 3 O 12 is a typical ferroelectric compound and well-known fatigue-free ferroelectric material by lanthanide substitution at the A-site [14][15][16][17], whereas BiFeO 3 is the only well-studied single-phase multiferroic material that exhibits both ferroelectric and antiferromagnetic orders [18][19][20][21][22][23][24]. However, the intrinsic character of the antiferromagnetic state of the BTF along with a low Néel temperature (T N ) limits its application prospects [25][26][27], therefore; it is highly expected that both ferroelectric and ferromagnetic orders can coexist in the BTF.…”