Preparation and magnetic properties of Al-modified acicular α-Fe particles

Al ions ranging from 0 to 24 wt% were introduced in α-FeOOH when α-Fe particles were produced through the neutralization of FeCl2 to Fe(OH)2, air oxidation of Fe(OH)2 to α-FeOOH, dehydration of α-FeOOH to α-Fe2O3, and finally reduction of α-Fe2O3 to α-Fe. The effects of Al ion on α-Fe particle are as follows: (1) it increases the dehyration temperature of α-FeOOH particle; (2) it effectively prevents the acicular particles from inter-particle sintering and spherization; (3) it impedes the hydrogen reduction reaction of Fe2O3; (4) it reduces the σ value of Fe particles; (5) it increases the 1Hc and squareness of Fe particles; and (6) it increase the stability of α-Fe toward environmental resistance.