Gunawidjaja P N, Holland M A, Mountjoy G, Pickup D M, Newport R J, Smith M E
Department of Physics, University of Warwick, Coventry CV4 7AL, UK.
Solid State Nucl Magn Reson. 2003 Feb-Mar;23(1-2):88-106. doi: 10.1016/S0926-2040(02)00019-X.
The effects of different heat treatment schemes (i.e. successively or directly heated to particular temperatures) and atmospheres (air or nitrogen) on the solid-state NMR spectra obtained from (TiO(2))(0.15)(ZrO(2))(0.05)(SiO(2))(0.80) sol-gel materials are investigated. A combination of 1H, 13C, 17O and 29Si NMR is used. 29Si MAS NMR indicates that the extent of condensation of the silica-based network strongly depends on the maximum temperature the sample has experienced, but the condensation is largely independent of the details of the heat treatment scheme and atmosphere used. For sol-gel produced silicate-based materials the results show that the equilibrium structure at each temperature is reached rapidly compared to the time (2h) spent at that temperature. The 17O NMR results confirm that a nitrogen atmosphere does significantly reduce loss of 17O from the structure but care must be taken since there could be differential loss of 17O from the regions having different local structural characteristics.
研究了不同热处理方案（即依次或直接加热至特定温度）和气氛（空气或氮气）对由（TiO₂）₀.₁₅（ZrO₂）₀.₀₅（SiO₂）₀.₈₀溶胶-凝胶材料获得的固态核磁共振谱的影响。使用了¹H、¹³C、¹⁷O和²⁹Si核磁共振的组合。²⁹Si魔角旋转核磁共振表明，硅基网络的缩合程度强烈依赖于样品经历的最高温度，但缩合在很大程度上与所用热处理方案和气氛的细节无关。对于溶胶-凝胶法制备的硅酸盐基材料，结果表明，与在该温度下花费的时间（2小时）相比，每个温度下的平衡结构能迅速达到。¹⁷O核磁共振结果证实，氮气气氛确实能显著减少结构中¹⁷O的损失，但必须注意，因为具有不同局部结构特征的区域可能存在¹⁷O的差异损失。
