Mechanistic understanding of the increased photoactivity of TiO2 nanosheets upon tantalum doping

Doping of Ta5+ into TiO2 replaces Ti4+ to decrease the recombination rate and elongate the electron lifetime due to the formation of shallow electron traps from Ti3+ defects. The elongated electron lifetime increases electron population and photocatalytic activity.

Nanocracks upon Fracture of Oligoclase

Abstract—The spectrum of fractoluminescence (FL) upon fracture of the surface of oligoclase is obtained. The analysis of the spectrum has shown that fracture of crystals leads to the formation of electronically excited free radicals ≡Si−O• and Fe3• ions as well as electron traps. FL consisted of a set of the signals with the intensities varying by an order of magnitude. The duration of the signals was ~50 ns and the time interval between them varied from ~0.1 to 1 μs. Each signal contained four maxima associated with the destruction of barriers preventing the motion of dislocations along the sliding planes. These breakthroughs cause the formation of the smallest (“primary”) cracks. All other, larger cracks are formed by the coalescence of the “primary” cracks. The sizes of “primary” cracks range from ~10 to 20 nm and the time of their formation is 16 ns. The distribution of cracks by size (surface areas of crack walls) is power law with the exponent –1.9.