**1.1. Conventional ceramic method**

The conventional solid-state reaction, starting from metal oxides or carbonates, is the oldest method for the synthesis of ceramics, since it is economic, efficient, and easily scalable. In fact, despite of some disadvantages, such as particle agglomeration and growth, it is still regularly used to synthesize novel materials for the first time, also for the widespread diffusion of the necessary equipment in academic laboratories.

experimental conditions. In these last years, this kind of synthesis has been mainly used to produce nanoparticles with peculiar magnetic properties, in particular superparamagnetism for biomedical application. The particle growth is controlled only by kinetic factors, so by controlling pH, temperature, ionic strength, salts nature or the Fe(II)/Fe(III) concentration ratio,

Raman Spectroscopy in Zinc Ferrites Nanoparticles http://dx.doi.org/10.5772/intechopen.72864 227

Recently, plant-based green syntheses of nanoparticles have attracted the attention of researchers. Various green resources, like micro-organisms and plants, are available for these syntheses. The extract of plants not only acts as reducing agent toward the metal ions in a short time with respect to micro-organisms or the classical organic/inorganic substances, but also provides high-yield nanosized particles. The preparation time of nanoparticles depends upon the variety of plants and the concentration of phyto-chemicals. Plant-based green syn-

Among the so-called physical methods, the most used to produce zinc ferrites are the following.

Ultrasonic cavitation chemistry is useful for synthesizing a variety of compounds at milder conditions. The major advantage of this method is that it affords a reliable and facile route for the control of both the synthetic process and nanostructure of advanced materials. This process also provides chemical homogeneity and reactivity through atomic level mixing and phase pure crystalline materials can be prepared by annealing at reduced temperatures. In addition, the use of additive components (stabilizers or surfactants, precipitants) and particu-

Thermal plasmas, such as direct current arcs and radio frequency (RF) plasmas, offer unique advantages for the synthesis of ceramic powders due to the easily achievable high temperatures and energy densities. In a RF thermal plasma flame, the gas temperatures may exceed 10<sup>4</sup> K independently of the gas composition. In addition, a high temperature gradient exists between the hot plasma flame and the surrounding gas phase. The resulting rapid quenching rate is favorable for producing fine particles with unstable structures in thermodynamic

The large variety of methods used to obtain zinc ferrites nanoparticles reflects on a very scattered scenery in terms of properties of the obtained materials. This is not simply due to the above-mentioned close correlation among functional parameters and morphology, gran size, intentional doping, cation distribution, and nanoparticle architecture. Indeed, it is extremely important to verify and control the magnetic, structural and chemical purity, and homogeneity of nanoparticles because even low amount of extrinsic phases or elements can alter the functional properties. In particular, it is very important to monitor the presence of unwanted iron oxides phases, possible source of extrinsic contribution to the functional properties of zinc

the shape and size of the nanoparticles can be customized [13].

thesis of magnetic nanoparticles is still under research [14, 15].

**1.7. Green synthesis**

**1.8. Ultrasonic cavitation method**

**1.9. Thermal plasma**

terms [17].

lar calcination requirements are avoided [16].
