Development of a novel combustion synthesis method for synthesizing of ceramic oxide powders

A novel combustion synthesis method has been developed to prepare electronic ceramic oxide powders—Ni 0.5Zn 0.5Fe 2O 4, ZnO, LiCoO 2, BaFe 12O 19 and YBa 2Cu 3O 7− x ( x≦0.25). Organic compounds (e.g., glycine, urea, citric acid, alanine, or carbohydrazide) to be mixed directly with metal nitrates without adding water, is the key technique of this method. Metal nitrates acting as oxidants were also used as cation sources, whereas an organic compound was employed as fuel. By directly mixing and thoroughly dehydrated, the reactant mixture having appropriate stoichiometric ratio of metal nitrates to organic fuel would transform into a flammable precursor. Once ignited in the air at room temperature, the precursor underwent a combustion process and yielded voluminous loose powders. Judging from experimental results, the feasibility of the proposed combustion synthesis method was proved to be efficient, quick and simple in becoming one of the suitable methods for mass production of ceramic oxide powder. Furthermore, a relatively low sintering temperature of 950 °C for 2 h is sufficient to sinter the as-synthesized Ni–Zn ferrite powders up to about 97% of theoretical density due to their size in nano-scale. The as-sintered Ni–Zn ferrite showed good magnetic properties as characterized by using VSM and impedance analyzer.