Competition between structural and electronic factors in (Al/In) doped lanthanum manganites

X-ray structure parameters of La0.7Ca0.3Mn0.96(InxAl(1-x))0.04O3 perovskite manganites determined from the Rietveld analysis of the orthorhombic unit cell, space group Pbnm, showed strong dependence on x. Resistivity (ρ) and ac magnetic susceptibility (χ) measurements showed decrease in the metallic-to-semiconductor transition temperature Tρ and the ferromagnetic-to-paramagnetic Curie temperature TC as x increases. The large drop in Tρ and TC for x=0.0 and 1.0 is ascribed to the difference between the electronic configuration (E-factor) and ionic radius (structure factor) of the dopants and the Mn3+ ions. Decrease in Tρ and TC for samples (0.2<x<0.8) is mainly due to the size mismatch between the A and B sites (structure factor). -- Research highlights: → Tρ and TC decreased as In content increased in the (Al/In) doped LCMO manganites. → Drop in Tρ and TC for x=0 and 1 is ascribed to electronic and structure factors of (Al/In) and Mn3+ ions. → For x ranging from 0.2 to 0.8 the drop is mainly due to the size mismatch between the A and B sites.