Chromium-induced structural distortion and magneto-dielectric tuning in Dy3Fe5-xCrxO12 nanoparticles

Abstract Chromium-substituted dysprosium iron garnet nanoparticles with nominal composition Dy 3 Fe 5-x Cr x O 12 (0.0 ≤ x ≤ 1.0) were synthesized via a sol–gel auto-combustion route to investigate the effect of Cr3 + substitution on the structural, vibrational, magnetic, and dielectric properties. X-ray diffraction confirmed the formation of single-phase cubic garnet for all compositions, with a systematic decrease in lattice parameter from 12.60 to 12.52 Å and a reduction in unit-cell volume from 2000 to 1963 Å 3 , indicating successful chromium incorporation into the host lattice. The crystallite size decreased overall from 47 to 37 nm, while intermediate compositions showed increased microstrain and dislocation density, revealing substitution-induced lattice distortion. FTIR and Raman analyses revealed shifts, broadening, and weakening of characteristic metal–oxygen vibrational modes, consistent with progressive local disorder and modification of FeO 6 /FeO 4 polyhedra at higher Cr content. Magnetic measurements showed soft ferrimagnetic behavior for all samples, with saturation magnetization decreasing from 6.5 to 3.75 emu/g as Cr content increased, reflecting magnetic dilution and weakening of Fe–O–Fe superexchange interactions. Dielectric studies indicated enhanced low-frequency dielectric response together with suppressed dielectric loss, suggesting reduced conduction loss and improved dielectric stability after chromium substitution. Overall, the results demonstrate that Cr substitution effectively tailors the structure–property relationships in DyIG nanoparticles and provides a viable route for designing magneto-dielectric and multifunctional materials for high-frequency device applications.