基于Rb的低熔点特点,提出了固/液转变+超声分散的纳米化策略,即：将熔化的液态Rb置于特定介质(甲苯)中进行超声乳化,进而冷却凝固形成固态纳米颗粒以实现其纳米化。通过这种策略,成功获得了分散在甲苯里的Rb纳米颗粒。这些Rb纳米颗粒呈近球形,平均粒径约为45 nm。金属Rb纳米颗粒的尺寸可通过调节超声功率进行控制。随着超声功率的降低,颗粒的平均粒径增加。当超声功率降至320和240 W时,平均粒径分别增加至55和70 nm。金属Rb纳米颗粒具有良好的点火作用,可实现有机物甲苯在显著低于其着火点的温度下(如120℃)快速引燃(点火时间小于1 s),且随着温度的升高,甲苯的点火时间变短。当温度为250℃时,可在0.25 s内点燃甲苯。本工作不仅为金属Rb的纳米化提供了新的途径,而且还可望为新型含能材料及点火器件的设计提供新思路与依据。

Metallic rubidium (Rb) has great potential in various fields, such as energy, catalysis, and medical treatment. Fragmenting bulk Rb to the nanoscale is essential for its efficient application in these fields. However, as an alkali metal with a high chemical activity, Rb reacts violently with trace water, oxygen, and others; thus, preparing nanosized Rb is challenging. This study proposes a sample solid-liquid transformation and ultrasonic dispersion method to prepare Rb nanoparticles (NPs) utilizing Rb's low melting point. This method uses the ultrasonic emulsification of liquid Rb in a specific liquid (toluene) to form a colloidal Rb solution. Typically prepared Rb NPs are nearly spherical with an average size of approximately 45 nm. Further, the average size increases with a decrease in ultrasonic power. When the ultrasonic power falls to 320 and 240 W, the average NP size rises to 55 and 70 nm, respectively, demonstrating good controllability of the proposed method. Further experiments demonstrated that Rb NPs can ignite toluene at relatively low temperatures (say 120^oC) within 1 s. When the temperature is up to 250^oC, toluene can be ignited in 0.25 s. This study not only provides a new method for synthesizing Rb NPs but also offers new opportunities for novel energy-containing materials and ignition devices.