碳热还原协同溶胶-凝胶法合成纳米ZrB2粉末

利用ZrO2-B2O3-C反应体系碳热还原的基本原理，分别使用正丙醇锆（Zr（Oc3H7）4）、硼酸（H3BO3）和蔗糖（C12H22O11）为原料，采用溶胶-凝胶-碳热还原法合成了二硼化锆（ZrB2）纳米粉末。我们首先使用络合剂醋酸（AcOH）修饰Zr（OC3H7）4，以防止Zr（OC3H7）4的快速水解；其次，选用蔗糖作为碳源，是考虑到蔗糖热解时可以完全分解为碳，这样可以准确计算热解过程碳的生成量。此外，研究了凝胶温度对ZrB2纳米粉末形貌的影响。结果表明：当起始原料B／Zr（mol）=2．3、热解温度为1550℃时，通过碳热还原协同溶胶-凝胶法成功合成了单相ZrB2纳米粉末；当凝胶温度分别为65、75和85℃时，ZrB2纳米粉末形貌从球状演变为链状，最后生长为棒状，生长机理为定向吸附。

Carbothermal Reduction Acted Synergistically with Sol.Gel Method to Synthesize ZrB2 Nanoparticles

Carbothermal reduction acted synergistically with sol-gel method to synthesize zirconium diboride （ZrB2 ） Nanoparticles was conducted using zirconium n-propoxide （Zr（OPr） 4）, boric acid （H3 BO3 ）, sucrose （C12 H22 O11 ）, and acetic acid （AcOH）. Here, CI2H22O11 was selected since it can be completely decomposed to carbon. Thus, carbon might be accounted precisely for the carbothermal reduction reaction. We investigated the influence of the gelation temper- ature on the morphology of ZrB2 particles. Increasing the gelation temperature, the particle shapes changed from sphere-like particles at 65 ℃ to particles chains at 75 ℃, and then rod-like particles at 85 ℃. An in-depth HRTEM observation revealed that the nanoparticles of ZrB2 were gradually fused together to evolve into a particle chain, finally ：into a rod-like shape. These morphologies related to the gelation temperature and obeyed the ＂oriented attachment mechanism＂ of crystallography.