Temperature-driven magnetic and structural transitions in multiferroic Lu(1-)Sc FeO3

Novel metastable hexagonal Lu(1-x)SxFeO3 compounds were prepared by an ethylene glycol-based small molecule sol-gel synthesis route. Samples were investigated by means of XRD, Raman spectroscopy, XPS, SEM and magnetometry techniques. Based on the obtained data several different phase composition regions were discovered at room temperature depending on the Sc content. Three dominant phases were observed and denoted as the orthorhombic Pnma, hexagonal P63cm, and cubic Ia-3 with the hexagonal phase being stable without any additional phases when 0.40 ≤ x < 0.65. Temperature dependent structural analysis allowed for the construction of the phase diagram which revealed that upon increasing Sc content the reversible polar to non-polar phase transition temperature can be decreased from above 1200 °C (when x = 0.15) to around 800 °C (x = 0.75). SEM analysis indicated a rapid reduction in particle size from ∼2.726 µm when x = 0 down to ∼0.962 µm when x = 0.75, however in the case when x = 1, an increase in particle size was observed. XPS analysis confirmed the elemental composition and its changes as well as the stability of the 3 + oxidation state of the iron ions. Magnetization measurements confirmed a non-zero room temperature magnetization as well as the spin reorientation transitions whose critical temperatures TN increases from 156 K (x = 0.25) to 170 K (x = 0.75).