We report low- and high-temperature Raman spectroscopy of pressure-induced amorphous boron carbide (a-B4C). Coarsening of carbon clusters in a-B4C was characterized during heating, whereas unusual temperature coefficients of a-B4C Raman peak shifts were observed during cooling. These results experimentally evidence that the amorphization of B4C is associated with the destruction of the C–B–C chains and a-B4C is composed of sp2 carbon aromatic rings and boron clusters. This disordered structure with relatively weak carbon sp2 bonds is believed to be responsible for the loss of B4C shear strength at high pressures.

Titanium-silica hollow spheres (TSHS) with a mesoporous shell were synthesized using an inverse multiple oil-water-oil (O/W/ O) emulsion. These novel materials show interesting potential for catalysis. Excellent catalytic performance was found in the epoxidation of cyclohexene with tert-butylhydroperoxide. The investigation of the titanium environment by UV-vis, Raman and FTIR spectroscopy showed that at low Ti loading only isolated species are present and catalytic measurements demonstrated that these species are the active sites for this reaction. At higher loading Ti-O-Ti microdomains are present and they do not exhibit any significant catalytic activity.