Comprehensive study on Al3+ doped Ba0.9La0.1Fe12O19 hexaferrite: structural, morphological, and electrical properties

The present work conducted a comprehensive study on the structural, microstructural, and electrical properties of Ba_0.9La_0.1Fe₁₂O₁₉ hexaferrite doped with Al³⁺ ions. The Ba_0.9La_0.1Fe_12-xAl_xO₁₉ system, with x = 0.0; 0.1; 0.3; 0.5; 0.7; 1.0, and 1.3 were prepared by ball milling assisted solid-state reaction method. The Rietveld method was utilized to refine the crystal structure, revealing an isostructural phase similar to a hexagonal magneto-plumbite mineral within the P6₃mc centrosymmetric space group (No-186). The lattice parameters (a, c, and V) reach a minimum at x = 0.7 for Al³⁺ content, exhibiting similar behavior when considering the other space group P6₃/mmc. In addition, the crystalline size and microstrain, determined for the size-strain plot method (SSP), are 47.2 to 142 nm and 1.2 × 10^-3 to 3.9 × 10^-3, respectively. The micrographic images revealed clusters of particles with an average grain size ranging from 0.57 to 1.48 μm. The AC conductivity remains constant at low frequencies, indicating the movement of long-range carriers. Dispersion at high frequencies results from electron hopping. The dielectric loss presented a low-frequency dispersion of the Maxwell-Wagner-type and dielectric relaxation at high frequencies. The study is important because it demonstrates the variation in the physical properties of doped barium hexaferrite.