Synthèse de nanoparticules photocatalytiques activables par rayons X pour la mise au point d'une nouvelle thérapie anti-cancéreuse par voie physique

PARIS-MINES ParisTech (751062310) / SudocSudocFranceF

Synthesis of hafnium germanate (HfGeO4) by co-precipitation routes

International audienc

Synthesis of hafnium germanate (HfGeO4) particles: Impact of crystallization route on X/UV conversion properties

International audienceThe crystallization route - calcination or hydrothermal ripening - of an amorphous hafnium and germanium oxide coprecipitate determines the X/UV conversion properties of the resulting hafnium germanate (HfGeO4). The calcination of the amorphous precipitate leads to micrometric aggregated particles exhibiting strong X/UV conversion whereas its hydrothermal crystallization resulted in well individualized nanoparticles with no X/UV conversion property. To explain these phenomena, the crystalline structure and chemical composition of the final products were investigated with X-ray diffraction (XRD) and inductively coupled plasma-mass spectrometry (ICP-MS). The key result is that germanium is partially solubilized from the amorphous precursor in hydrothermal conditions, resulting in the crystallization of a Ge deficient hafnium germanate possessing no X/UV conversion properties

Effect of hydrothermal ripening on the photoluminescence properties of pure and doped cerium oxide nanoparticles

International audienceWe synthesized and characterized a set of undoped and doped cerium oxide nanoparticles with the following chemical formula: Ce1−xMxO2−(x/2) (M: Y or Gd and x = 0 or 0.15) by different coprecipitation protocols at room temperature. Room temperature photoluminescence spectra were similar whatever the protocols and doping. After hydrothermal ripening at neutral pH, a moderate but significant particle growth was observed for doped particles whereas undoped ones remained the same. Simultaneously, the photoluminescence band at 400 nm was significantly red-shifted and practically vanished for doped particles whereas it was only slightly weaker and shifted for pure ceria. All other bands in the same region were much less affected: the bands at 363 and 378 nm became more intense, the shoulder at 420 nm remained roughly unchanged. These phenomena were observed systematically whatever the coprecipitation protocol. As a consequence, the band at 400 nm can be specifically attributed to surface defects that disappear during growth under hydrothermal conditions