Magnetization and Specific Absorption Rate Studies of Ball-Milled Iron Oxide Nanoparticles for Biomedicine

Table 3

Mössbauer hyperfine parameters for Fe₃O₄ nanoparticles measured at RT.

Sample	Particle diameter (nm)	Spectral component	δ (mm/s)	Δ𝐸𝑄 (mm/s)	𝐻hf (kOe)	D𝐻hf (kOe)	A (%)	Component identification	(A)/[B] site occupancy
Fe3O4; Bare	15	1; 2; 3; 4	0.33; 0.42; 0.36; 0.32	—; —; —; 0.61	470; 400; —; —	51; 166; —; —	18; 38; 39; 5	SR (A); SR [B]; IR; FR	0.47
Fe3O4; 5% OA	11	1; 2; 3; 4	0.34; 0.39; 0.37; 0.32	—; —; —; 0.59	480; 413; —; —	44; 143; —; —	18; 33; 47; 2	SR (A); SR [B]; IR; FR	0.55
Fe3O4; 10%	9	1; 2; 3; 4	0.32; 0.39; 0.36; 0.27	—; —; —; 0.62	479; 409; —; —	47; 155; —; —	18; 34; 45; 3	SR (A); SR [B]; IR; FR	0.53
Fe3O4; 20%	8	1; 2; 3; 4	0.30; 0.39; 0.41; 0.29	—; —; —; 0.62	474; 427; —; —	37; 90; —; —	14; 16; 68; 3	SR (A); SR [B]; IR; FR	0.87
*Bulk Fe3O4		1; 2	0.27; 0.66	—; —	491; 453	—; —	—; —	(A); [B]	0.5

Isomer shifts, δ: referenced to metallic iron at RT (error: ±0.03 mm/s), Δ𝐸_𝑄: quadrupole splitting (error: ±0.05 mm/s), 𝐻_hf: average magnetic hyperfine field (error: ±3 kOe), D𝐻_hf: FWHM of magnetic hyperfine field distribution, A: absorption area (error: ±5%), SR: slow relaxation; FR: fast relaxation, IR: intermediate relaxation, (A): tetrahedral spinel site, and [B]: octahedral spinel site.
*Source [24].