“…Despite the fact that nanocrystalline GdFeO 3 has been successfully synthesized by various methods, including co-precipitation, 19,20 hydrothermal method, 21,22 solution combustion, 23,24 sol–gel, 25,26 microwave method, 27 sonochemical method, 28 and employing heterobimetallic precursors 29 and metal–organic precursors, 30 these methods do not always make it possible to obtain GdFeO 3 nanoparticles with the required particle size. In our previous works, 31–33 we favored the co-precipitation method, as it allows the synthesis of GdFeO 3 nanoparticles with isometric morphology and minimal chemical impurities, but we took different approaches to minimize the size of the resulting particles and the degree of their aggregation, including the co-precipitation at low temperature 31,32 and the use of free impinging-jets microreactors. 31,33 In this paper, we propose an ultrasound-assisted co-precipitation method for the synthesis of superparamagnetic GdFeO 3 nanoparticles.…”