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Ce-doped HfO 2 nanoparticles were successfully prepared in molten chlorides. Nanoparticles were obtained at 380 °C during 1 h in a LiCl/KCl molten flux. The Ce-doped HfO 2 nanoparticles showed sizes below 7 nm and spherical shapes. Complete stabilization of cubic phase was achieved by adding 10 mol % of Ce. XRD, Raman and HRTEM techniques confirmed that the Ce-doped HfO 2 nanoparticles have a cubic structure. Furthermore, this simple, efficient and high yield (>95%) method represents an alternative route for the synthesis of fluorite-type cubic phases and should be useful for doping or co-doping HfO 2 with other cations. [ABSTRACT FROM AUTHOR]

HfO 2 nanoparticles were successfully synthesized by a green chemistry method, which consist of mechanically activated metathesis and molten salts, using LiCl/KCl. This methodology is useful to prepare cubic phase at low-temperature (380 °C) without using any doping element, which is an outstanding advantage over existing techniques. Following this green route easily allows obtaining HfO 2 nanoparticles; showing irregular and spherical like morphologies with a diameter in the range of 8–20 nm by TEM observations and crystallite size of 6.5 and 14.7 nm calculated from Scherer's equation for cubic and monoclinic phases respectively. The temperature and reaction time parameters played a very important role for obtaining monoclinic or cubic phase during molten salt stage. [ABSTRACT FROM AUTHOR]