Structural and Magnetic Characterization of Mechanically Alloyed (FeO)(AlO) Solid Solutions via Pulsed Neutron Powder Diffraction.

Neutron powder diffraction experiments were carried out to characterize mechanochemically synthesized (FeO)(AlO) solid solutions with corundum-type structure, focusing on their lattice and magnetic structures with varying temperature and composition. The neutron diffraction experiments for (FeO)(AlO) in the temperature range between 4 K and 300 K reveal that no significant structural phase transition occurred. The behavior of temperature variation of lattice parameters is different from α-FeO and α-AlO and reveals the thermal expansion coefficients of α = 5.76(2) × 10 K and α = 6.19(5) × 10 K between 200 K and 300 K. The room temperature neutron diffraction of (FeO)(AlO) shows a linear decrease in lattice parameters with the aluminum substitution, following Vegard's law, along with a decrease in the magnetic moment, indicating the dilution effect on spin interactions. With the increase in the aluminum substitution from x = 0 to 0.5, the deduced magnetic moment decreases from 2.224 to 0.862 .