**4. Conclusion**

Different synthetic methods were used to prepare several perovskite type compounds. Phase-pure perovskites were obtained in all cases, irrespective of the method of synthesis and even when more than one method was used. It is to note that no differences in the overall crystal structure were observed in any of the cases when the method was changed. Moreover, changes in the crystal structure of the compounds within each series could be perfectly explained considering only compositional (and resulting structural) variables such as the mean A-site ionic radius or the A-site disorder, none of them being influenced by the synthesis route. This is true for the Ln1−xAxFeO3−δ series where changes from orthorhombic to cubic are consistent with the change in the doping level x and also for the Ln0.5A0.5FeO3 where the change was observed from rhombohedral to cubic symmetry when the mean Asite radius, <rA>, was varied.

At least in the present group of compounds this seems to indicate that, properly used, and with no other factors present (such as in the case of the growth of samples on crystallographycally oriented substrates), the structural characteristics can be studied and properly addressed without having into account the synthesis method.

It is no news that, compared with the solid state reaction, the glycine-nitrate route, sol-gel and freeze-drying techniques require lower calcination temperatures to yield pure crystals of perovskite phases, with the resulting energy saving (very important nowadays). The disadvantage is, however, the fact that they are more time consuming and require more controlled synthesis conditions. In the same way, it is clearly observed that the ceramic method always yields phases with higher particle sizes but this is not a disadvantage if the final compounds are not to be used in an application that requires high specific area. It is to note that in the case of the Nd0.8Sr0.2(Mn1-xCox)O3 , grain size was observed to change depending on the synthesis route. Although no significant differences were observed in the crystal structure, sol-gel method resulted in smaller grain sizes than the freeze drying method. In consequence, this seems to be a consequence of the preparative method which reinforces the idea that, if the microstructure of the sample is the key issue, the use of several synthesis methods is always worth trying.
