**2. Methods of synthesis**

There are different methods of synthesis used in the field of Solid State Chemistry. Among them, one of the most used is that known as ceramic method. The ceramic method consists

of the grinding of the stoichiometric quantities of the corresponding starting compounds and subsequent heating by using furnaces at relatively high temperatures. However, it is not the most efficient method many times.

The sol-gel method and, used more and more every day, the freeze-drying method, seem to offer purer materials by reducing the heating time and working at not so high temperatures. Besides, other methods complete the list of synthesis processes of solid materials.
