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

Gd[Formula: see text]-substituted M-type hexaferrites with composition Ba[Formula: see text]Sr[Formula: see text]Ca[Formula: see text]Fe[Formula: see text]Al 2 Gd x O[Formula: see text] (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[Formula: see text]/Al[Formula: see text] 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 [Formula: see text] values, validating structural reliability. Lattice expansion with increasing Gd[Formula: see text] content is attributed to its larger ionic radius relative to Fe[Formula: see text], while the c/a ratio remained below 3.98, confirming structural stability. Crystallite size ranged from 54.58[Formula: see text]nm to 64.41[Formula: see text]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 [Formula: see text], while [Formula: see text]/[Formula: see text] confirmed single-domain behavior throughout. Enhanced magnetocrystalline anisotropy with Gd[Formula: see text] 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. These findings establish Gd[Formula: see text]/Al[Formula: see text] co-substituted BaSrCa hexaferrites as promising multifunctional candidates for microwave absorption, EMI shielding, radiation protection, and spintronic applications.