Electromagnetic Wave Absorption Properties of Co-Ti Substituted Ba M-Type Ferrite Produced by a Modified Chemical Coprecipitation

In this paper, the electromagnetic wave absorption properties of Co-Ti substituted Ba M-type hexagonal ferrite (BaFe9:5(Co1� yTiy)2:5O19 (y ¼ 0:4 � 0:8)) produced by a modified coprecipitation method were investigated. This modified chemical coprecipitation method was the combination of the coprecipitation and the synthesis from a salt melt. The sample, Ba9:5(Co0:5Ti0:5)2:5O19 sintered at 1423 K for 5 h, whose powder was produced by the modified coprecipitation method, exhibited high permeability (� r 00 max ¼ 11) and reflection loss (R.L.) around � 10 dB at a relatively wide frequency range (0:8 � 9 GHz) comparable to the Ultra Wide Band (UWB). In order to enhance the sintering, the addition of Bi2O3 was carried out. The Ba9:5(Co0:4Ti0:6)2:5O19 sample sintered at 1423 K for 5 h with a Bi2O3 content of 2 mass%, exhibited high permeability (� 00 max ¼ 25 and � 00 at 1 GHz ¼ 10). This sample also showed good microwave absorption properties (reflection loss: