Ceramic samples of LuFeO multiferroic were synthesized using solution chemical homogenization and subsequent annealing at 900–1100°C and at low oxygen pressure (10–10 atm), which was controlled by oxide getter mixtures FeO/FeO и FeO/LuFeO/LuO. Samples of LuFeO were obtained, differing in their non-stoichiometry and isotopic composition of the oxygen sublattice. The samples were studied using X-ray diffraction, elemental analysis, Raman spectroscopy, and magnetometry. It was shown that structural changes occurring with changes in the oxygen nonstoichiometry of LuFeO are manifested in the Raman scattering spectra and have a strong effect on the magnetic susceptibility of the samples. The developed technique of isotopic substitution of oxygen O with O in LuFeO made it possible to obtain samples with an O content of 44(1)%, showing a negative isotopic shift of the magnetic transition by 1.7–1.9 K, which indicates a noticeable electron–phonon interaction in the system.
M.N. Markelova (Thu,) studied this question.