SiO2 xerogel

Figure 5. PLE (a, c) and PL (b, d) spectra measured at 1.53 pm from erbium-doped TiO2/SiO2 xerogels fabricated in PAA (a, b) and from bulk xerogels (c, d) 30 wt. % TiO2/70 wt. % SiO2 (upper spectra), 50 wt. % TiO2/50 wt. % SiO2 (middle spectra), 70 wt. % TiO2/30 wt. % SiO2 (lower spectra).

Comparison of the spectra described above allows for conclusion that synthesis of erbium-doped SiO2/TiO2 composites in matrices with the pores in mesoscopic range as well as in bulk xerogels give the appearance of the strong excitation band with the maximum at 360 nm in PLE spectra of erbium for the... 

Hydrolysis of a mixture of Si(OR>4 and Ti(OR)4 results in the immediate precipitation of titania, because Ti(OR)4 is much more reactive than Si(OR)4. When (R0)3Si(CH2)3C[C(Me)0]2Ti(0R)3 or (R0)3Si(CH2)3C[C(Me)0]2 2Ti(0R)2 is hydrolyzed under basic conditions, transparent and crack-free monolithic xerogels are formed instead. Mixed-oxide powdCTS with the nominal composition Ti02 SiO2 or Ti02-2Si02 and a low crystallization tendency are obtained when the organic groups were removed by calcination at 550 °C. 

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