Structure of hybrid (organic/inorganic) TiO2-SiO2 xerogels II: Thermal behavior as monitored by temperature-programmed techniques and spectroscopy

Gustavo Larsen, Melissa Buechler-Skoda, Chao Nguyen, David Vu, Edgar Lotero

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

Titanium-containing xerogels made by acid pre-hydrolysis of tetraethylorthosilicate (TEOS) and dimethyl-dimethoxysilane (SiMe2(OMe)2), followed by reaction with dichloro-diisopropyl titanium (TiCl2(i-OPr)2) were characterized by means of several techniques. The decomposition patterns of these xerogels, both in the presence and in the absence of oxygen are discussed in terms of the gaseous products' evolution under temperature-programmed (TP) reaction conditions, and diffuse reflectance infrared spectroscopy (DRIFTS). The primary decomposition routes of residual alkoxide groups are: (i) auto-redox (CO, CO2) and dehydration (to olefins) under pyrolysis conditions; (ii) oxidative (CO, CO2) under flowing air. The decomposition of the Si-C bond upon heating, as monitored by all three techniques, follows a pattern independent of that of (CH) species from -OR groups. The 29Si MAS/NMR of these materials is dominated by the so-called D2 (Me2Si(OX)2), Q3 ((OR)Si(OX)3) and Q4 (Si(OX)4) resonances. Fairly homogeneous proton envelopes around Si centers are evident from the NMR spectra of these materials in the proton cross-polarization mode.

Original languageEnglish (US)
Pages (from-to)161-168
Number of pages8
JournalJournal of Non-Crystalline Solids
Volume279
Issue number2-3
DOIs
StatePublished - Feb 2001

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Materials Chemistry

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