Síntese por energia de micro-ondas de ferritas NI-ZN.

Abstract

The aim of this work is to obtain Ni-Zn ferrites powders by combustion reaction using the microwaves energy as heating source and to make the structural, morphologic and magnetic characterization the goal of this preparation is to obtain, crystalline, nanosize and monophase materials. The powders were prepared according to the concept of the propellants and explosive chemistry using a vitreous silica crucible and urea, glycine and the urea:glicyne (1:1) mixture, as fuel for synthesis. The characterizationhas done by XRD, EDX, N2 adsorption, particle size distribution, SEM and AGM. The XRD resulting show the formation of the inverse spinel phase of Ni-Zn ferrite for the urea powdes obtained. The using glycine and urea:glycine (1:1) powders mixture as fuel, besides the majority phase of spinel Ni-Zn ferrite, the outstanding presence of the Fe2O3 (hematite) and Ni (metallic nickel) and the powders obtained with the mixture urea:glycine (1:1), the presence of the second phase Ni (metallic nickel). The microwaves oven exposure time and power changed slightly the final powders characteristics. The exposure time increase was more preponderant than the increase of the power of the microwaves oven in the structural, morphologic and magnetic characteristics, for the powders obtained. In general, the powders synthesized by microwaves energy present a potencial to be use in several applications. The urea powders synthesized are promising for applications in catalysis, ferrofluids, and magnetic sensors, and to be submitted for sintering for devices production, seen the great probability of it obtains materials with elevated density and good properties in low sintering temperatures. The powders synthesized by glicina and mixture of the fuels are promising for application as electromagnetic radiation absorbers, due the elevated particle size and the good magnetic characteristics observed. Amount the synthesized samples the powders obtained with the fuel mixture, in the power of 900 W and exposure time at 10 min resulted in best magnetic characteristics.