Magnetic susceptibility of nanostructural manganite LaMnO$_{3+\delta}$ produced by mechanochemistry method

The mechanochemical method is shown to be a relatively simple method for producing nanostructural manganites LaMnO$_{3+\delta}$ with crystallite size $D\ge$ 10 nm. An increase in the treatment duration in a planetary mill from 1 to 13 h decreases the size $D$ and increases microstrains. The Curie temperature of the nanostructural manganites decreases insignificantly and the phase transition is smeared as $D$ decreases. A decrease in the unit-cell volume and the temperature dependences of the inverse magnetic susceptibility $1/\chi(T)$ indicate an increase in the Mn$^{4+}$ ion concentration with the milling duration. The variation of the magnetic properties of LaMnO$_{3+\delta}$ nanostructural powders is explained by the competition of a number factors, such as variations of the composition, the cation-sublattice defect structure, the size effect, and the microstrain level.