还原剂浓度对化学还原法制备纳米锡银合金粉末颗粒生长的影响

Effect of reducing agent concentration on the growth of Sn-Ag nanoparticles synthesized by chemical co-reduction method

采用化学共还原法制备纳米级Sn-3.5Ag(质量分数,%)合金粉末,分析粉末的微观形貌、物相组成和熔化行为,着重研究还原剂溶液的浓度对粉末粒径的影响,探究液相中颗粒形核长大机制。结果表明:还原剂浓度控制液相中颗粒形核和长大的速率,粉末平均粒径随还原剂浓度降低而增大,还原剂溶液的浓度为0.25 mol/L时粉末平均半径达到最小值约为13 nm;粉末由β-Sn和Ag3Sn两相组成,熔点约为206℃;还原剂浓度升高,溶液中大量金属离子用于瞬间形核从而抑制纳米颗粒的后续长大;液相中Ag3Sn优先形核生长,随着溶液中银原子的饱和度下降,粉末的物相组成转由β-Sn占主导,最终形成由Ag3Sn相和β-Sn相组成的纳米合金粉末。

Sn-3.5%Ag(mass fraction,%)nanoparticles were synthesized by chemical co-reduction method and the morphology,phase composition and thermal behavior were studied.The effects of reducing agent concentration on nanoparticles size and the mechanism of nucleation and growth in the solution were studied.The results show that the concentration of reducing agent controls the rate of particle nucleation and growth in the solution,and the average particle size decreases with increasing the reducing agent concentration.The average radius of the nanoparticles reaches a minimum value of about13nm when the reducing agent concentration is0.25mol/L.The nanoparticles consist ofβ-Sn and Ag3Sn phases.The minimum melting point is about206℃.The increasing concentration of the reducing agent consumes a large amount of metal ions for instantaneous nucleation and inhibits further growth of the nanoparticles.Ag3Sn nucleates and grows in the solution preferentially.With the decrease of Ag atoms saturation in the solution,the composition of the nanoparticles is dominated byβ-Sn.Finally forms nano-alloy consisting of Ag3Sn andβ-Sn phases.