金属醇盐法制备Ta2O5气凝胶
Preparation of Ta2O5 aerogel with metal alkoxide method
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摘要: 以乙醇钽为前驱物，采用金属醇盐溶胶-凝胶技术，获得了Ta2O5湿凝胶，分析了不同条件下的溶胶-凝胶过程，并初步探讨了凝胶过程机理。Ta2O5的溶胶-凝胶过程主要受到水量、催化剂用量及钽源浓度等因素的影响：体系在强酸性条件下凝胶，且随着酸性的增强，体系凝胶时间明显缩短；当水量较少时，凝胶时间随水量的增加而增加，但当水量增加到一定程度时，体系凝胶时间基本不变；实验证明，通过增大溶剂用量，体系凝胶时间延长，气凝胶理论密度降低。通过对溶胶-凝胶过程的控制，结合超临界干燥技术，获得了密度低至44 mg/cm3的Ta2O5气凝胶样品。Abstract: With metal alkoxide as precursor, Ta2O5 aerogels were prepared by sol-gel technique. The sol-gel process is found to be affected by water amount, catalyst amount and concentration of Ta(OC2H5)5. The gelation can only happen in the presence of strong acid as catalyst, and with the increase of acid strength, the gelation time is obviously decreased. With the continuous increase of water, the gelation time lengthens and then tends to be constant. Additionally, the gelation time increases and the theoretical density of Ta2O5aerogel decreases as the solvent amount increases. Through sol-gel process control along with supercritical drying technique, the Ta2O5 aerogel with a low density of 44 mg/cm3 was prepared.
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Key words:
- metal-alkoxide method /
- ta2o5 aerogel /
- sol-gel /
- hydrolytic-polymeric /
- gelation time
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