Numerous oxides possess interesting properties in fields such as electron conduction (ITO), gaseous detection (SnO2, In2O3, ZnO), luminescence (ZnO), or magnetic recording (ferrites). Since their properties are strictly related to the size of the particles, it is therefore also crucial to use reliable, high-performing synthesis methods. Among the methods used, certain consist of decorrelating the kinetic steps of nucleation and growth from the precipitation phenomenon. Others are aimed at limiting the growth of the object, with the help of complexing agents that play the role of inhibitors and stabilisers, and enable the surface/volume relationship to be controlled.
The idea of limiting the space offered to the growth of particles leads to very good results. Synthesis is therefore the most often drivren in multi-phased environments: the reactor is composed of micelles or vesicles formed in emulsions, microemulsions or in ion-exchange resins. The synthesis can also be carried out in homogenous but viscous environments (gels or polymer solutions): the reduction of the precursors' diffusion speed thus limits the size of the objects.
This type of approach is used for the synthesis of SnO2 nanoparticles, deposited on a silicon chip, a system that is currently used as sensitive layer for gas sensor applications.
We should also emphasize the synthesis of the 15 nm monodispersed Sn/SnOx core/shell nanoparticle composites, which is carried out using an organometallic/sol-gel composite mechanism. In the same way, ZnO nano-rods and nanowires for electronic or optic properties (varistors, nano-lasers) were prepared, starting with the thermal decomposition of the ZnCy2 precursor, followed by oxidation in the presence of a retarder (the HDA ligand).
Over and above their intrinsic properties, the importance of such materials resides in their extreme stability in an oxidizing atmosphere, unlike metallic nanoparticles. To these nanoparticles they confer their wide range of application possibilities and a easy implementation.