Microwave Assisted Combustion Synthesis and Characterization of Nanocrystalline Nickel-doped Cobalt Ferrites

Abstract

)] were prepared by the microwave combustion synthesis, using a stoichiometric mixture of metal nitrates and urea as the oxidizer and fuel to drive the reaction. The effect of microwave irradiation on the phase composition was favorable to promote the formation of fluffy foams and nanoparticles sizes. The fast internal heating with microwaves leads to a reduction in synthesis time, to only 2 min. The structural, chemical and magnetic properties of the nickel-doped cobalt ferrites were analyzed by XRD, TEM, SEM and BET. The XRD results confirmed the formation of pure and single-phase spinel structure. The crystallite size of the nanoparticles was in the range of 38 -50 nm. SEM images show nanoparticles with spherical shape and homogenous morphology. The TEM analysis shows necked near-spherical particles with an average size of ~30 -50 nm, reflecting the highly crystalline nature of these nanoparticles. The magnetic measurements of all the samples were recorded using vibrating sample magnetometer (VSM) at room temperature in 10 kOe. Increasing the nickel content directly affects the structural characteristics of the particles, causing a reduction in the coercive field.

Mechanochemical synthesis and characterization of nanocrystalline Ni1-xCoxFe2O4 (0 ≤ x ≤ 1) ferrites

“…The inset shows the almost linear variation of saturation magnetization with heating temperature.Coercivity also shows a similar tendency with T, increasing about 50% between 600 and 800ºC. As shown in Table2, the obtained values of Ms and Hc for sample NCF-0.5-800 agree with those previously reported for Ni 0.5 Co 0.5 Fe 2 O 4 synthesized by other methods[28,[52][53][54][55][56][57]. It is important to remark that from the vast existing literature on this mixed ferrite, only reports dealing with materials with similar particle size and heating temperatures were selected for the comparison.…”

“…This is in agreement with the analysis derived from Raman results. It is known that Ni 2+ ions have a preference for octahedral sites, while Co 2+ and Fe 3+ ions can occupy both octahedral and tetrahedral sites [54]. Fe 3+ ions tend to occupy tetrahedral sites when the Co 2+ concentration increases, as deduced from the comparison of the fraction of Fe 3+ in tetrahedral sites relative to those in octahedral sites (f A /(f B + f B1 ) in Table 4) for the mixed substituted samples.…”

Effect depositions parameters on the characteristics of Ni0.5Co0.5Fe2O4 nanocomposite films prepared by DC reactive magnetron Co-Sputtering technique

“…86-2267, Fd-3m) while the samples prepared using mixing ratios of 75:25 and 80:20, there was no evidence on the formation of spinel structure except CoF 2 O 4 , which was observed in the sample prepared using mixing ratio of 75:25 without the formation of NiF 2 O 4 . This can be attributed to the fact that the Ni 2+ ion (radius of 0.78Å) is smaller than Co 2+ ion (radius of 0.82Å) [27]. On the other hand, the samples prepared at inter-electrode distance of 5 cm with mixing ratios of 50:50, 55:45, 60:40, and 65:35 showed all peaks assigned to the formation of spinel α-ferrite, in addition to the NiCoF 2 O 4 as singlephase cubic spinel structure, especially for mixing ratio of 65:35, as confirmed by JCPDS card .…”

Nb2O5 nanoparticles obtained by microwave assisted combustion synthesis under different conditions

“…The combustion synthesis is a redox reaction that involves an oxidant (normally nitrates) and an organic fuel (such as urea and citric acid) in solution. The highly exothermic and self-sustaining reaction quickly produces crystalline, nanosized, pure and homogeneous powders, without the need for further steps [14][15][16][17]. Some parameters of the synthesis, such as oxidant and fuel content, fuel type, and heating environment, will influence the final characteristics of the product [17,18].…”