One-step synthesis of yttrium orthoferrite nanocrystals via sol–gel auto-combustion and their structural and magnetic characteristics

Single phase yttrium orthoferrite (YFeO3) nanocrystals have been one-step synthesized by a sol–gel auto-combustion method using nitrates of iron and yttrium as raw materials, citrate acid (CA) and ethylene glycol (EG) as chelating agents and nitrate ammonium as oxidant. The effects of CA/M and the pH value of the solutions on the concentrations of yttrium– and iron–citrate complex species were quantitatively studied to ensure the formation of chemically homogenous gels. The auto-combustion of the dried gels and the microstructural features and magnetic properties of as-synthesized YFeO3 nanocrystals were characterized and investigated by using XRD, FT-IR, TG-DTA, FESEM and VSM. It has been shown that a hexagonal YFeO3 can be formed during the auto-combustion of gels with CA/M = 1.5, EG/CA = 1.5, pH = 6.0 and Q = 35%, the molar ratio of the oxygen available from nitrates image to the oxygen required for complete oxidation of fuels to CO2, H2O and N2, while single phase orthorhombic YFeO3 nanocrystals of ∼90 nm in average diameter may be one-step synthesized from the gels with Q = 80%, and show an enhanced weak ferromagnetism characterized with a RT magnetization of 0.45 emu g−1 at the magnetic field 0.35T, a paramagnetism with the susceptibility χ = 2.27 × 10−5 emu g−1 Oe−1, and an extremely low coercive field of 245 Oe.