Mechanosynthesis of lanthanum manganite

Mat. Sci. Eng. A 454-455(2007) 69-74, 2007.


Lanthanum manganite LaMnO3 was prepared using a high energy ball milling SPEX 8000 D mixer/mill. Powders of Mn2O3 and La2O3 were mixed in stoichiometric proportion for obtaining this manganite. Mechanosynthesis processing (MCP) was carried out at room temperature in air, in hardened-steel vials with balls using a weight ratio of balls to powder of 10:1. X-ray diffraction (XRD) was used to evaluate phase transformation as function of milling time. Morphology and grain size of the LaMnO3 were characterized by means of scanning electron microscopy (SEM). Particle size was measured by means of a zeta size analyzer. Selected area electron diffraction (SAED) patterns in a transmission electron microscopy (TEM) were indexed to identify this phase in the obtained sample. Found compounds exhibited orthorhombic structure, and it was confirmed that lanthanum manganite was produced after 4.5 h of milling. Evolution of the phase transformation showed that increasing the milling time produced an exponential decreasing in particle size, up to 480 nm after 6 h of milling, while milling times longer than 20 h produce an important reduction in the powder size, although higher iron contamination from the vials and balls is also greater.