Influence of non-magnetic Ti4+ ion doping at Mn site on structural and magnetic properties of La0.67Ba0.33MnO3

We have investigated the effect of titanium substitution on the structure and the magnetic properties of manganites with La0.67Ba0.33Mn1-xTixO3 (0 <= x <= 0.3) nominal composition. The polycrystalline samples have been produced by the conventional ceramic method at 1523 K. The morphology, grain size and phase identification studies were carried out by scanning electron microscopy, diffraction techniques (neutron and x-ray) and the chemical compositions were precisely determined by the inductively coupled plasma atomic emission spectroscopy technique. The structural refinement at room temperature by the Rietveld method revealed that for x >= 0.1 the compounds are almost a single phase manganite crystallizing in a rhombohedral (R (3) over barc) perovskite structure (LaAlO3 type). The more salient structural feature is an increase in cell parameter and inter-ionic distances with increasing Ti content. For x = 0 and x = 0.05 the samples exhibit two manganite phases with orthorhombic (Imma) and rhombohedral (R (3) over bar 3c) space groups. Compounds with x <= 0.1 are ferromagnetic with a Curie temperature decreasing with increasing x. More complicated magnetic behaviour is observed for larger Ti content.