Merce Segarra

In this work, magnetic copper ferrite nanoparticles are synthesized by polymer-assisted sol–gel and coprecipitation methods. The obtained purity and particle size reach values of 96% and 94 nm, respectively. Evident differences in the crystal structure have been found in the synthesized nanoparticles. A tetragonal structure is formed by the sol–gel method, while the cubic form is obtained when the coprecipitation approach is used. This work provides experimental evidence of the formation of both phases by using the same reactants and thermal conditions and only modifying the technical procedure. The formation and stability of each phase are analyzed by temperature-dependent measurements, and the observed crystal structure differences are used to propose a potential fundamental explanation to our observations based on differences in the cations’ distribution and Jahn–Teller distortion. Moreover, different copper ferrite purities and particle sizes are found when using each of the methods. The spherical shape of the particles and their tendency to sinter, forming micrometric clusters, are observed by electron microscopy. Finally, the divergence in magnetization between the samples prepared by each method supports our argument about the different cations’ distribution and opens the door to a wide range of different technological applications for these materials.

Magnetic ferrites are used in a wide range of technological applications, such as biomedicine, electronics, or energy. They also present interesting magnetic properties, especially for high-frequency applications. These materials have been prepared by a large variety of methods, from basic solid-state reaction to advanced wet chemical methods. However, most of these approaches are complex and have low production rates. In this work, a deep analysis of an easy polymer-assisted sol–gel synthesis of copper ferrite (CuFe₂O₄) nanoparticles is done. A multivariate analysis, by means of the design of experiments approach, is carried out to account for two variables at a time. Moreover, a wide experimental domain is explored, and the impact of each variable on the chemical composition and magnetic properties is determined. This work results in an optimization of the synthesis method to obtain high-purity nanoparticles (∼96%).