离子交换法在钠钙硅酸盐玻璃中原位合成银纳米颗粒的研究

IN SITU SYNTHESIS OF SILVER NANOPARTICLES IN SODA-LIME SILICATE GLASS BY ION-EXCHANGE METHOD

采用离子交换结合热处理法,在商用钠钙硅酸盐平板玻璃中原位形成2～7 nm的银纳米颗粒.利用电子探针、X射线吸收近边结构谱、透射电子显微镜和高分辨透射电子显微镜研究了银离子在玻璃中的扩散、还原和生长机理.结果表明:玻璃中同时存在2价和3价铁离子,2价铁离子的存在有利于银离子被还原成中性银原子.银原子在玻璃中成核并生长成纳米颗粒.银纳米颗粒可以在离子交换时形成.提高热处理温度比延长热处理时间更有利于颗粒长大.特别当热处理温度高于玻璃转变温度时,出现Ostwald生长,导致银颗粒迅速长大,密度降低.大部分银纳米颗粒为十四面体单晶,少量为孪晶结构.

Ag nanoparticies embedded in soda- lime silicate glass with a mean size of 2-7 nm were synthesized by an ion exchange and subsequent thermal treatment method. Electron probing, X-ray absorption near-edge structure, transmission electron microscopy and high-resolution transmission electron microscopy were used to study the diffusion, redox and growth processes of the Ag ions in the glass matrix. The results indicate that Fe ions in the soda - lime glass exist in the form of hi-and tri-valences, and the Fez＋ induce Ag^4 into neutral Ag atoms. The Ag atoms nucleate and grow into nanoparticles. The Ag nanoparticles are formed in the ion exchange process. Particles grow faster by increasing the thermal treatment temperature than by extending the heating time. Specifically, Ostwald ripening happens when the treatment temperature is higher than the transformation temperature of soda - lime glass. The majority of the Ag nanoparticles are single crystals with a nearly cuboctahedral shape, others have a twined structure.