A facile one-pot synthetic approach, using oleic acid and oleylamine as composite stabilizers combined with high-temperature treatment in 1-octadecene, has been developed for the preparation of monodisperse and uniform lanthanum phosphate and europium-doped lanthanum phosphate nanocrystals. In particular, with the present synthetic approach, the size of the resulting nanocrystals could be tuned precisely and continuously from 3.5 to 6.5 nm by seed-mediated epitaxial growth. The as-obtained uniform nanocrystals with hydrophobic surfaces, which show efficient photoluminescence, could be easily dispersed in nonpolar solvents. More importantly, these nanocrystals can also be easily modified to water-dispersed ones with hydrophilic surfaces for potential use in in vitro imaging in bioanalysis. In addition, a synthetic mechanism for these monodisperse nanocrystals is presented and discussed.

In this paper, we report a facile route, the tin vapor treatment method, to prepare tin oxide containing mesoporous silica composites (TOMS), which display room-temperature photoluminescence (RT-PL). Among them, TOMS-1 and TOMS-2 were synthesized from mesoporous silica SBA-15 and KIT-6, respectively. They are composed of amorphous SiO2 and tin oxide species and they display strong emission near ultraviolet (UV) when excited by UV light. By increasing the preparation temperature, their Sn content can be increased and subsequently their photoluminescence (PL) intensities can be greatly enhanced. Besides, their PL properties are revealed to be closely related to 2-fold-coordinated tin oxygen-deficient centers.