Expansion of the hexagonal phase-forming region of Lu1-xScxFeO3 by containerless processing.

Hexagonal Lu1-xScxFeO3 (0 ≤ x ≤ 0.8) was directly solidified from an undercooled melt by containerless processing with an aerodynamic levitation furnace. The hexagonal phase-forming region was considerably extended compared to that of the conventional solid-state reaction (x ∼ 0.5). Synchrotron X-ray diffraction measurements revealed that the crystal structure of the hexagonal phase was isomorphous to hexagonal ferroelectric RMnO3 (R = a rare earth ion) with a polar space group of P63cm. As x increased, the a-axis lattice constant decreased linearly, strengthening the antiferromagnetic interaction between the Fe(3+) ions on the a-b plane. Accordingly, the weak ferromagnetic transition temperature increased from 150 K for x = 0 to 175 K for x = 0.7. These transition temperatures were much higher than those of hexagonal Lu1-xScxMnO3. The results indicate that hexagonal Lu1-xScxFeO3 is a suitable alternative magnetic dielectric for use at higher temperatures.