Organic-inorganic Hybrid Gels of Diol-TEOS Type. Synthesis and Study on the Chemical Interaction.

Hybrid inorganic-organic materials, silica - diol, were prepared by the sol-gel process from mixtures of tetraethyl orthosilicate (TEOS) and two diols (1,2-propanediol and 1,4-butanediol), using different molar ratios TEOS: diol, in acidic catalysis. The resulted materials were studied by thermal analysis, FT-IR spectroscopy, 29Si-NMR and nitrogen adsorption measurements. The thermal analysis of the gels, in air and nitrogen, has clearly evidenced the chemical bonding of the studied diols with the Si-OH groups resulting from the hydrolysis of TEOS, forming hybrid gels.

The Effect of Temperature and Fe3+ Concentration on the Formation of γ-Fe2O3 Nanoparticles Embedded in Silica Matrix.

The paper presents a study on the formation and thermal stability of γ-Fe2O3 nanoparticles within the silica matrix depending on the Fe(III) carboxylate-type precursors, their annealing temperature and the concentration of Fe3+. Obtaining of the precursors, within the pores of the gel, bases on the redox reaction between Fe(NO3)3 and diols: ethylene glycol (EG) and 1,4 buthane diol (1,4 BG), respectively. Thus, we have prepared gels with different Fe2O3/SiO2 ratios (20, 30, 50, 70 wt% Fe2O3) which were annealed in the temperature range 573-1273 K.