Crystal structure and magnetic property correlations in Ba1−x Sr x Fe12O19 (0 ≤ x ≤ 1) hexaferrites

Abstract

This paper reports a comprehensive study on the structure-property correlations in strontium-substituted barium hexaferrite and their suitability for possible applications at room temperature. A series of samples, Ba1−x Sr x Fe12O19 (0 ≤ x ≤ 1) synthesized by citrate-based sol-gel auto-combustion technique, were characterized by various physicochemical characterization techniques. The x-ray diffraction data of these samples ensure the single-phase formation and the variation of crystallographic parameters as a function of strontium substitution was discussed. The decrease in lattice parameters with increasing strontium (x) substitution ensures the applicability of Vegard’s law for the present system. The scanning electron micrographs reveal some of the grains in hexagonal shape in these samples. Raman data revealed the interconnection between magnetic ion site occupancies and the corresponding magnetization contributions, thereby ensuring the structure-property correlations in these samples. As these hexaferrites consist of layers of (ferro- and antiferro-) magnetic domains, the sub-lattice magnetic contributions were estimated by fitting the magnetic hysteresis loops (M − H) data using theoretical models. The magnetization versus temperature (M − T) graphs confirmed the above room-temperature ferromagnetic behavior. This study clearly reveals that proper tuning of their structural properties can result in optimal magnetic properties, making them suitable for permanent magnet and room-temperature magnetic device applications.