采用化学还原法,在水相中,以硼氢化钠为还原剂,月桂酸为分散剂,通过还原银氨络合物溶液制备了纳米银胶体,之后通过调节胶体的pH值,分离出了纳米银颗粒.TEM和XRD分析表明,该纳米银颗粒的平均粒径大约为17 nm,集中分布于5～30 nm,且无明显的团聚现象；红外光谱分析表明该纳米银颗粒表面包覆有月桂酸,紫外光谱表明制得的纳米银胶体在397 nm处有较强的吸收峰.将分离出的“湿”纳米银颗粒作为功能相,加入预先配制的载体相中,运用机械搅拌和超声分散等手段,制得了纳米银导电浆料.热重分析表明该浆料含有约67%(质量分数)的金属银,在220℃下烧结2h后,其电阻率为4.2 ×10-5 Ω·cm.经微细笔直写后,其线条的分辨率可以达到60μm.%In water phase, silver nano - colloid was prepared by chemical reduction method with sodium borohydride as reductant, lauric acid as dispersant, and silver - ammonia complex as main salt. Then, by adding phosphoric acid to adjust pH value of the colloidal system, silver nanoparticles were precipitated and separated. Transmission electron microscopy (TEM) and X -ray diffraction (XRD) analyses showed that the prepared Ag nanoparticles have an average diameter of about 17 nm with the distribution of 5 -30 nm, and had no agglomeration. FT - IR spectrum indicated that the nanoparticles are capsulated by lauric acid, and UV - Vis spectrum revealed that the Ag nano - colloid has a strong absorption peak at 397 nm. Using the prepared wet Ag nanoparticles as functional phase, a conductive nano - silver paste was formulated with an organic vehicle by dispersion methods of mechanical stirring and ultrasonic vibration. Ther-mogravimetry analysis ( TGA) showed that the paste contains 67 wt% Ag. Its electrical resistivity is up to 4. 2 × 10-5Ω ? Cm after sintering at 220t for 2 h. Upon direct - writing by micro - pen, an array pattern with the resolution of 60 jxm is achieved.Paste
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