Effect of divalent ion of strontium substitution on the structural, optical, magnetic and blood compatibility studies in cobalt ferrite

This study investigates the effects of Sr 2+ substitution on the structural, morphological, and magnetic properties of magnetic cobalt ferrite (CoFe 2 O 4 ). Through sol–gel auto-combustion synthesis, Sr 2+ was substituted into Co-spinel ferrites (Co 1-x Sr x Fe 2 O 4 , where x = 0.0, 0.25, 0.5, 0.75, 1.0). SEM analysis revealed spherical grains with an average size of 54.4 nm. XRD analysis indicated systematic changes in crystallographic parameters and the formation of secondary phases with Sr-substitution. While the crystal size for CoFe 2 O 4 was calculated as 262 nm, this value was determined as 18 nm for Co 0.25 Sr 0.75 Fe 2 O 4 . FT-IR results suggested increased force constants of octahedral and tetrahedral bonds with higher Sr content, with main vibration bands at 423.6 and 606 cm −1 . M-H curves exhibited S -shaped behavior, indicating drastic magnetic property changes with Sr 2+ substitution. Coercivity field ( Hc ), saturation magnetization ( M S ), and remanent magnetization ( M r ) values ranged from 1447.8–545.4 Oe, 58.8-14 emu g −1 , and 36.8-7.6 emu g −1 , respectively. Blood compatibility experiments highlighted Co 0.75 Sr 0.25 Fe 2 O 4 nanoparticles with significantly low hemolysis rates compared to other concentrations.