This work evaluates the structural evolution of silicate gel over time with mineral additives. A comparison between fresh and aged silicate gel synthesized from silica and potassium hydroxide was carried out using FTIR, Raman, and ²⁹Si MAS-NMR spectroscopies. Then, different additives, including NaOH, AlOOH, Li₂B₄O₇, and HCl, were incorporated into the silica solution. The effects of these additives on the aspect, transparency, Qⁿ polymerization, and stability of the silicate gels were studied. Structural studies showed that the quantification of Qⁿ species was difficult using FTIR and Raman spectroscopies because of the existence of several contributions in the same spectral region of silicate species. More precise information was provided by ²⁹Si NMR spectroscopy, which demonstrated the increase in Q³ species to the detriment of Q⁴, revealing the depolymerization of the structure over time. Further study of the effect of additives revealed that HCl, AlOOH, and Li₂B₄O₇ did not improve the stability of the gel due to the formation of several networks. However, promising stability and transparency results were obtained using NaOH with a silicate/modifier molar ratio of 2.52.

这项工作评估了含矿物添加剂的硅酸盐凝胶随时间的结构演变。使用FTIR，拉曼光谱和²⁹ Si MAS-NMR光谱对由二氧化硅和氢氧化钾合成的新鲜和老化的硅酸盐凝胶进行了比较。然后，将不同的添加剂，包括NaOH，AlOOH，Li ₂ B ₄ O ₇和HCl，掺入二氧化硅溶液中。研究了这些添加剂对硅酸盐凝胶的外观，透明性，Q ⁿ聚合和稳定性的影响。结构研究表明Q ⁿ的量化FTIR和拉曼光谱法很难对这些物种进行分析，因为在相同的硅酸盐物种光谱区域中存在多种贡献。²⁹ Si NMR光谱提供了更精确的信息，该信息表明Q ³物种的增加对Q ⁴有害，揭示了结构随时间的解聚。对添加剂效果的进一步研究表明，由于形成了多个网络，HCl，AlOOH和Li ₂ B ₄ O ₇并未改善凝胶的稳定性。但是，使用硅酸盐/改性剂摩尔比为2.52的NaOH获得了令人满意的稳定性和透明性结果。