Effects of milling-induced disorder on the lattice parameters and magnetic properties of hematite

摘要: Abstract A ball-milling treatment in air for 30 min is enough to reduce anhydrous bulk hematite (α-Fe 2 O 3 ) grains nanometric sizes. For milling times, t m , of 15, 30 min, 1 and 2 h, the crystals suffer an anisotropic lattice dilation, which more pronounced smaller average grain sizes attained. Mossbauer susceptibility results show that process alters effective Morin temperatures, T M . The transition occurs less sharply than non-milled material spreads over a maximum extent 50 K =30 min. data indicate fraction undergoes shifts toward values not lower 235 K. =10 h suppressed down 12 K. Our do allow distinguishing from surface regions grains. In addition, disorder brought about by reduces magnetic response weak ferromagnetic state α-Fe modification seems depend mainly on dilation unit cell affects whole it related achieved.