Fig. (1).

TEM images of the Fe₃O₄ particles synthesized by using different volume ratios of ethylene glycol to diethylene glycol. (a) 20/0, 300 nm; (b) 10/10, 165 nm; (c) 5/15, 90 nm; and (d) 1/19, 18 nm (reproduced with permission from reference 34).