In the present work we report the synthesis of La1-xMgxMnO3 (with x=0.10, 0.25, and 0.50) polycrystalline samples based on LaMnO3 (LMO) antiferromagnetic with low Neel temperature and insulating behavior. Structure was analyzed by Rietveld fitting of XRD patterns at room temperature by FullProf software, these show that La1-xMgxMnO3 (x=0.10, 0.25, 0.50) samples crystallize in the space group R-3c. Magnetic and electrical measurements exhibits ferromagnetic and semiconductor like behavior. A decreases of T-c is observed when x doping value increases. (C) 2017 Brazilian Metallurgical, Materials and Mining Association. Published by Elsevier Editora Ltda.

In order to improve the photocatalytic effect of Nb₂O₅, manganese from 1% to 10% was added by the polymeric precursor’s method. The samples obtained were subjected to different calcination temperatures from 400 to 700 °C. Characterization of the synthesized materials was performed by XRD, IR, Raman and Diffuse Reflectance Spectroscopy (DRS) spectroscopy, FE-SEM, Brunauer–Emmett–Teller (BET) method, Photoluminescence (PL) and Dynamic Light Scattering (DLS). Photocatalytic performance for degradation of Rhodamine B was also evaluated. The Rietveld refined X-Ray Diffraction (XRD) pattern of Nb₂O₅:Mn 1.0 wt.% (700 °C) sample was similar to that of the un-doped oxide, therefore indicating that Nb was replaced by Mn and, consequently, there are not significant variations in the oxide structure. The Nb₂O₅:Mn 10.0 wt.% (700 °C) sample has the lowest band gap energy. The specific surface area (SBET) PL value increased as manganese concentration increased. The Nb₂O₅:Mn 5.0 wt.% (700 °C) sample has an Eg of 3.15 eV and morphological and surface characteristics that made it an appropriate photocatalyst in the Rhodamine B degradation. The novelty of this work relies on the use of a small quantity of Mn ions as dopants leading to Nb₂O₅:Mn nanostructured particles without using any surfactant or other additives.

Yttrium-substituted Bi_1-xY_xFeO₃ (x=0, 0.03, 0.07, 0.15, 0.2 and 0.5) samples were prepared by solid state reaction technique. Morphological analysis was obtained by Scanning Electron Microscopy (SEM) technique indicating mainly granular behaviour. In addition, the substitution of yttrium promotes smaller particle size of BiFeO₃. The obtained samples were also studied by X-ray diffraction (XRD). The crystal structure and the lattice parameters were confirmed by XRD. Rietveld refinement of experimental X-ray diffraction patterns showed that substituted BiFeO₃ compounds crystallize in a R3c type structure and the lattice parameters decrease as Y concentration increases.