Mechanosynthesis of lanthanum manganite

Abstract

Lanthanum manganite LaMnO 3 was prepared using a high energy ball milling SPEX 8000 D mixer/mill. Powders of Mn 2O 3 and La 2O 3 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 LaMnO 3 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.