Morphological and magnetic study of CaMnO3−x oxides obtained from different routes

The CaMnO_3−x (x=0 and 0.02) mixed oxide was synthesized from both thermal treatment of the CaMn(C₃H₂O₄)₂(H₂O)₄] metallo-organic precursor and ceramic method. In the case of the latter method, temperatures of 1350 °C and 50 h were necessary; however, lower temperatures, 800 °C, and shorter reaction times, 15 h, were utilized in the attainment of the mixed oxide from the precursor. As a consequence, the morphology of the different products is clearly different. The samples exhibit three-dimensional antiferromagnetic ordering with T_N near 120 K, and a low-dimensional antiferromagnetic ordering at high temperatures. The presence of a ferromagnetic component above T_N was also observed in both compounds, it is slightly stronger in the phase prepared by the ceramic route.