Multiple nano-sized a-Ni（OH）2was synthesized by ultrasonic-assisted precipitation under different conditions. The crystal structure and particle size distribution of the sample were characterized with X-ray diffraction（XRD）, infrared spectroscopy, and laser particle size analyzer（PSA）. The results show that the samples are anisotropic polycrystalline of a and b Ni（OH）2, and the ratio of a and b changes with the difference of nickel source, resulting in the largest ratio of a-Ni（OH）2using nickel nitrate as reactant. Larger amount of Na2CO3is conducive to the formation of a-Ni（OH）2; while the resultant phases are all b with the same conditions but no doping. The results of PSD indicate that the samples are about 100–120 nm in size, and the sample with nickel sulfate as nickel source has the minimum particle size. The three ions of nickel source appear in the absorption peaks in the Fourier transform infrared spectrum showing that the ions change the crystal structure of Ni（OH）2. EDS testing shows that Y and anion distribute in the lattice of aNi（OH）2uniformly.
Qing-Sheng XuYan-Juan ZhuLiang-Guo HuangJie LuoZhong-Ju ZhangCheng-Cheng MiaoHu Ye
The nano-nickel hydroxide samples were prepared by means of ultrasonic-assisted precipitation and the impact of source/doping element/buffer on the structure of Ni（OH）： was studied. The results of XRD, IR and TEM testing clearly revealed that larger anionic radius of the nickel sources or the buffer solution was conducive to the formation of α-Ni（OH）2. The proportion of α-Ni（OH）： samples doped with two elements was larger than that doped with single element. Additionally, speciation, valence as well as the radius of doping ions can directly affect the phase of Ni（OH）2.
