**2.5 Characterization**

Room temperature X-ray powder diffraction data were collected in the 18≤2≤110° range with an integration time of 10 s/0.02° step. A Bruker D8 Advance diffractometer equipped with a Cu tube, a Ge (111) incident beam monochromator (λ = 1.5406 Å) and a Sol-X energy

Synthetic Methods for Perovskite Materials – Structure and Morphology 499

oxidises from Fe3+ to Fe4+, with smaller radius (<rFe>, rFe3+=0.645 Å and rFe4+ =0.585 Å)

The increase of the <A-O> distances and <Fe-O-Fe> bond angles with increasing doping level (x) can be explained due to the structural transition produced with x: when passing from orthorhombic (*Pnma,* LPS20) to a mixture of rhombohedral and cubic (*R-3c* + *Pm-3m,* LSC80) the octahedra that compose the perovskite structure reduce its cooperative

These results are in nice agreement with other structural studies of related perovskites in which similar structural transitions with doping level were observed (Blasco et al., 2008;

Fig. 2. (a) X-ray diffraction patterns for the series Ln1−xAxFeO3−δ with x=0.2 to x=0.8, all obtained by the ceramic route. Rietveld fits to the X-ray diffraction data for samples LPS20

(Shannon, 1976). Details of these effects are given elsewhere (Vidal et al., 2007).

tilting and the structure "expands".

Dann et al., 1994; Tai et al., 1995).

(b), LPSC50 (c) and LSC80 (d).

dispersive detector were used for the samples obtained by glycine-nitrate route and LSSB-ss. A Philips X'Pert-MPD X-ray diffractometer with secondary beam graphite monochromated Cu–Kα radiation was used for the samples obtained by ceramic solid-state, sol-gel and freeze-drying techniques.

All samples were single phase without detectable impurities. The crystal structure was refined by the Rietveld method (Rietveld, 1959) from X-ray powder diffraction data using GSAS software package (Larson & Von Dreele, 1994).

Microstructural analysis was carried out in a JEOL JSM 6400 scanning electron microscope (SEM) using a secondary electron detector at 30 kV and 1.10−10 A for the LPS20, LNSC30, LPSC40, LPSC50, LPSC60, LPSC70 samples and a JEOL JSM-7000F at 3 kV and 11.10-12 A for the rest of samples.
