Ultrafine Na-Sr-Si precursor powder for sealing glass via sol-gel route

摘要

Sealing glasses have been widely used as insulating and sealing materials in the electronics industry. In this study, ultrafine Na-Sr-Si precursor powder was synthesized from sodium nitrate (NaNO _3), strontium nitrate Sr(NO _3)2, and tetraethoxy orthosilicate (TEOS) via the sol-gel method. Nitric acid (HNO _3) or ammonia (NH _4OH) was used as acid or base catalysts, respectively, to achieve miniaturization of particles. The products were characterized by X-ray diffraction, scanning electron microscope, and thermogravimetric/differential thermal analyzer. The results showed that the mean particle size for acid-catalyzed Na-Sr-Si glass precursor powder was approximately 100-700 nm, and appeared to be smaller than that for base-catalyzed Na-Sr-Si glass precursor powder. This glass precursor powder synthesized by sol-gel process has a low processing temperature of about 850-900°C compared with the processing temperature of ~1400°C for traditional glass precursor powder. Furthermore, the coefficient of thermal expansion of this sealing glass was in the range 6.575×10 ~(-6)- 9.136×10 ~(-6)°C ~(-1), measured by the thermal mechanical analyzer.