Evolution of the crystal structure and magnetic properties of Sm-doped BiFeO3 ceramics across the phase boundary region

TL;DR

This study investigates how samarium doping influences the crystal structure and magnetic properties of BiFeO3 ceramics, revealing phase transitions and magnetic behavior changes across different doping levels using advanced characterization techniques.

Contribution

It provides new insights into the structural and magnetic evolution of Sm-doped BiFeO3 ceramics prepared via sol-gel synthesis, highlighting phase coexistence and magnetic property variations.

Findings

Structural transitions from rhombohedral to orthorhombic phases with increased Sm doping.

Identification of phase coexistence regions at specific doping levels.

Single-phase rhombohedral ceramics show reduced remnant magnetization.

Abstract

Samarium doped BiFeO3 compounds having nano-size crystallites were prepared by the ethylene glycol assisted sol-gel synthesis method. X-ray diffraction and SEM measurements as well as Raman spectroscopy and FTIR experiments were used to clarify the evolution of the crystal structure on microscopic and local scale levels in the compounds having formula Bi1-xSmxFeO3, where x equals from 0 to 1. Magnetization measurements along with the structural data were used to determine a correlation between magnetic properties and crystal structure of the compounds. The compounds with from x 0.1-0.2 are characterized by the sequence of the structural transitions driven by the dopant increase, from the polar rhombohedral phase to the non-polar orthorhombic phase via two-phase regions characterized by the presence of the anti-polar orthorhombic phase. The concentration regions ascribed to a coexistence of the rhombohedral and the anti-polar orthorhombic phases as well as theanti-polar orthorhombic and the non-polar orthorhombic phases are observed in the ranges from 0.12 to 0.15 and from 0.15 to 0.18 respectively. The compounds having single-phase rhombohedral structure are characterized by a release of remnant magnetization as compared to ceramics with similar chemical compositions but synthesized by the solid-state reaction method and having microscopic size crystallites. A correlation between the type of structural distortion, morphology of crystallites and an onset of remnant magnetization is discussed highlighting a difference in the evolution of crystal structure and magnetization observed for the Sm-doped ceramics prepared by modified sol-gel method and conventional solid-state reaction technique.