Template-free synthesis of single-crystalline SmF3 rattle-structured sub-micropumpkins

Abstract

Single-crystalline SmF₃ sub-micropumpkins with a rattle-type structure have been successfully synthesized on a large scale by reaction of aqueous Sm³⁺ with ammonium fluoride in the presence of ethylenediaminetetraacetic acid (EDTA) at 110 °C for 16 h, which were confirmed by X-ray powder diffraction, energy dispersive X-ray analysis, transmission electron microscopy, and scanning electron microscopy. The reaction time and EDTA have been shown to play important roles in the formation of SmF₃ rattle-structured sub-microcrystals. A mechanism for the formation of the SmF₃ rattle-structured sub-micropumpkins via cooperation of an oriented aggregation process and Ostwald ripening has been proposed based on observations of time-dependent experiments. In addition, this crystal growth mode could be expanded to the synthesized Eu-doped SmF₃ rattle-structured sub-microcrystals. It is believed that the results of the present investigation may provide a versatile approach for designing and fabricating a wide range of nano/microcrystals.