熔盐法制备氧化锆纳米棒

采用非水解溶胶-凝胶工艺合成氧化锆干凝胶粉，然后将干凝胶粉与熔盐混合制备氧化锆纳米棒。借助DTA-TG、XRD、FE-SEM、TEM等测试手段研究了氧化锆的物相转变过程，探讨了熔盐种类与用量、氟化物的添加等工艺参数对制备氧化锆纳米棒的影响。结果表明：以NaVO₃为熔盐，用量为1：1（熔盐与干凝胶的质量比），并且在添加氟化钠的条件下能够制备产率高，且沿010] 方向择优生长的单斜氧化锆纳米棒；氟离子一方面加速了熔盐中Zr⁴⁺离子的传质，促使氧化锆干凝胶粉的溶解，另一方面吸附在氧化锆的高能晶面上抑制该晶面的生长，两者的共同作用促进了大量氧化锆纳米棒的形成。

Preparation of Zirconia Nanorods by Molten Salt Method

Zirconia nanorods were prepared via molten salt route, using zirconia dry gel powder as precursor synthesized by non-hydrolytic sol-gel (NHSG) method. Thermogravimetric analysis and differential thermal analysis (TG-DTA), X-ray diffraction analysis (XRD), transmission electron microscope (TEM) and field emission scanning electron microscopy (FE-SEM) were employed to characterize the phase transformation process of zirconia, the influences of the type, amount of molten salt and the role of fluoride on the formation of zirconia nanorods. The results show that the optimized molten salt type and dosage are NaVO₃ and 1:1 (m_{molten salt}:m_xerogel mass ratio), respectively, and the monoclinic zirconia nanorods grow preferentially along the 010] direction in the presence of sodium fluoride. It is found that the F^- in the flux plays a vital role in formation of zirconia nanorods: on one hand, the fluoride ions accelerate the mass transfer of Zr⁴⁺ ions and the dissolution of zirconia xerogel in molten salt system; on the other hand, fluoride ions adsorb on high-energy facets of the zirconia to block the growth along these facets. The interaction of two aspects promotes the formation of zirconia nanorods in large scale.