Exploring gadolinium doped BaSrCa and Al-based ferrite nanoparticles for structural, mechanical, magnetic and radiation shielding applications

Gd 3+ -substituted M-type hexaferrites with composition Ba 0.25 Sr 0.25 Ca 0.5 Fe 10-x Al 2 Gd x O 19 (x = 0.0, 0.03, 0.05, 0.07) were synthesized via sol-gel auto-combustion method. The aim was to investigate the synergistic effects of Gd 3+ /Al 3+ co-substitution on structural, mechanical, magnetic, and gamma-ray shielding properties, a combination unreported in prior literature. XRD confirmed single-phase hexaferrite formation with no secondary phases; Celref refinement yielded low χ 2 values, validating structural reliability. Lattice expansion with increasing Gd 3+ content is attributed to its larger ionic radius relative to Fe 3+ , while the c/a ratio remained below 3.98, confirming structural stability. Crystallite size ranged from 54.58 to 64.41 nm, and SEM revealed well-defined grains with grain growth at higher substitution levels. Magnetically, coercivity increased consistently across all compositions, reaching a maximum of 2072 Oe at x = 0.07, while Mr/Ms > 0.5 confirmed single-domain behavior throughout. Enhanced magnetocrystalline anisotropy with Gd 3+ doping confirms its role as an effective magnetic hardener. Radiation shielding evaluation showed half-value layers lower than conventional concrete at low-to-intermediate photon energies, indicating superior attenuation performance.