Self-assembly of 1D FeSe2 chains and Fe(dien)2 complexes for ferrimagnetic inorganic-organic hybrid cuboids

Abstract Challenges still remain in producing room-temperature ferromagnetism/ferrimagnetism in inorganic–organic hybrid compounds. Here, we report the Fe vacancy-doped inorganic–organic (FexSe2)2Fe(dien)2 (dien = diethylenetriamine, x  = 0.86) hybrid cuboids by self-assemble of finite one-dimensional (1D) FeSe2 chains and Fe(dien)2 complexes. A growth model is proposed by kinetically controllable syntheses of novel Fe2x+1Se4(dien)2 hybrids. The Rietveld refinement reveals that Fe vacancies in the Fe2.71Se4(dien)2 hybrid cuboids induce large distortions of the FeSe2 chains and the room-temperature lattice parameters are a = 9.225(4) A, b = 18.021(8) A and c = 11.609(6) A. Magnetic measurements and electron spin resonance spectra of the Fe2.71Se4(dien)2 hybrid cuboids show the ferrimagnetism with the Curie temperature (TC) of 600 K and the spin glass state with the freezing temperature (Tf) of 108 K. Impressive room-temperature ferrimagnetic properties of the Fe2.71Se4(dien)2 hybrid cuboids were ascribed to the high concentration of Fe3+ vacancies (0.29 per cell) in the hybrid cuboids, which is supported by the 57Fe Mossbauer spectrum fitting based on the ferrimagnetic model.