溶胶—凝胶法合成超微LaNiO_3及电性质研究

Study on the Synthesis and Electrical Properties of UItrafine LaNiO_3 by Sol-Gel Method

用溶胶—凝胶法在低温（６５０ ℃） 合成了ＬａＮｉＯ３ 超微粉末。ＸＲＤ 分析表明所合成的ＬａＮｉＯ３ 为单相的钙钛矿型微晶， 属于三方晶系， 空间群为Ｒ３Ｍ。ＳＥＭ 分析表明， 所合成的ＬａＮｉＯ３ 粒子呈球形， 平均粒径小于０－１μｍ 。计算表明， ＬａＮｉＯ３ 的平均晶粒度随焙烧温度的升高而增大， 而平均晶格畸变率随焙烧温度的升高而减小。室温电阻率测量表明， 超微ＬａＮｉＯ３ 的电阻率比相应的氧化镧、氧化镍混合物的低， 而高于金属镍的电阻率， 具有半金属性。

LaNiO 3 ultrafine powders were prepared at low temperature by sol-gel method.XRD patterns showed that the prepared LaNiO 3 was single-plase perovskite in structure,they are rhombohedral system with space group R3M.SEM photos indicated that LaNiO 3 particles were spherical in shape,and the mean particle size of LaNiO 3 was smaller than 0.1μm.Calculation showed that the average crystallite size of LaNiO 3 increased with the increasing in calcination temperatures,but the crystal lattice distortion rate decreased with the increase of calcining temperatures.Measurement of electrical resistivity at room temperature revealed that the electrical resistivity of ultrafine LaNiO 3 was lower than that of the mixture of La 2O 3 and NiO,but higher than that of metallic Ni,and therefore, LaNiO 3 exhibited the properties of semimetal.