Figure 4.

TEM image of core–shell structure of apatite (Ap)-coated citric acid–stabilized cobalt ferrite (CFCA-Ap) in low (a) and high-resolution field (b), and SEM image of CFCA-Ap particles (c). EDS analysis of the samples at the CFCA-Ap surface: Ca/P = 1.47 (d). Core–shell structure of CFCA-Ap particles corresponding electron diffraction patterns of core structure (e) and shell structure (f). g is size distribution of core–shell structure of CFCA-Ap.