Effect of anionic substitution on the structural and magneto-electrical properties of La-Ca-Mn-O perovskite manganites

The role of anion substitution of oxygen by fluorine in La0.7Ca0.3MnO3−δFx (x=0.0 and 0.6) system has been investigated by means of X-ray powder diffraction, electrical resistivity and magnetization measurements. The oxygen content of the samples, estimated by a redox back titration method, decreases with doping while the lattice parameters and unit cell volume increase slightly. The Curie temperature and the metal-insulator transition temperatures of the samples are also found to increase with doping. The deduced magnetoresistance is slightly higher for the doped sample.