La0.7Ca0.3Mn0.95M0.05O3 manganites (M = Al, Ga, Fe, Mn, and In):: Local structure and electron configuration effect on Curie temperature and magnetization

X-ray diffraction and magnetization measurements have been carried out in La0.7Ca0.3Mn0.95M0.05O3 manganites (M = Al, Ga, Fe, Mn, and In). It was found that the samples belong to orthorhombic phase and lattice parameters increase with increasing ionic radius of the dopants. Curie temperature, T-C, changes with doping due to a difference between the electron configuration (E-factor) and ionic radius (S-factor) of the dopants and manganese trivalent ion. The E-factor affects the T-C stronger than the S-factor and causes the T-C decrease. The S-factor can cause both positive and negative change in Delta T-C. The Delta T-C change, caused by the S-factor, is positive if ionic radius of the dopant is less than that of Mn3+ ion, and negative in opposite case, if dopant ionic radius is larger than that of Mn3+ ion. Saturation magnetization of the manganites decreases continuously with increasing ionic radius of the substituents and almost independent of magnetic nature of the dopants. (c) 2006 Elsevier B.V. All rights reserved.