Evidence and role of excessive iron in the lattice of M-type barium hexaferraite synthesized by one-step spark plasma sintering method

M-type barium hexaferrite (BaM) compounds with excessive iron, BaFe(12+x)O(19+1.5x) (0 <= x <= 0.4), have been synthesized. by spark plasma sintering method. The grains crystallized in plate-like form. The lattice parameters increased and the grain sizes decreased with increasing values of x. Specific saturation magnetization of 74.53-77.76 emu g(-1) is greater than the theoretical value of BaM single crystal. Coercivity of 694.30-1146.58 Oe is far lower than that measured the BaM materials prepared by available methods. (c) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.