Copper-ruby monoliths by the sol-gel process

Preparation and properties of uniformly dispersed Cu metal nanoclusters embedded in bulk silica an described. Clear gels were prepared from Cu(NO3)(2), H2N(CH2)(2)NH(CH2)(3)Si(OCH3)(3) (DAMO), and acid hydrolyzed Si(OC2H5)(4) (TEOS). The role of DAMO to immobilize Cu2+ in silica network is studied. The appearance of a strong surface plasmon band of Cu colloids at 562 nm was observed after heat treatment of the gels at 900 degrees C in 5%H-2-95%N-2 gas atmosphere. At this stage very uniform ruby-red color of the sample was established due to the formation of copper nanocrystals of mean diameter 15 nm, as confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM).