中文摘要：

采用液-液掺杂方式将仲钼酸铵、硝酸镧以及柠檬酸溶液混合,采用溶胶-凝胶法制备纳米稀土镧掺杂钼粉。研究初始溶液pH值和柠檬酸添加量对成胶效果的影响,讨论干凝胶的除胶工艺,分析稀土镧在掺杂钼粉中的存在形式。结果表明：当初始溶液的pH值为1且柠檬酸的添加量为仲钼酸铵质量的1.5倍时,可制备出疏松多孔、网状结构、成胶效果良好的干凝胶。采用直接烧结法在560℃焙烧可将胶体很好地除去,两段还原后得到颗粒为球形且十分均匀的纳米掺杂Mo粉。在掺杂MoO3粉中,镧以La2O3或La-Mo复合氧化物形式存在,稀土颗粒粘附在MoO3颗粒表面。在MoO3的还原过程中La-Mo复合氧化物分解,镧以La2O3的形式存在于Mo粉中。钼粉颗粒尺寸在500 nm左右,掺杂La2O3的尺寸约100 nm。

英文摘要：

After mixed the secondary ammonium molybdate,lanthanum nitrate and citric acid solution,the nano molybdenum powder doped with rare earth（RE） element lanthanum has been prepared by means of liquid-liquid doped method and sol-gel method.The effects of the initial solution pH value and citric acid addition on the gel forming characterization were investigated.The desizing processes of the xerogel were discussed.And the existing forms of the RE element in the doping molybdenum powder were analyzed.The results show that,the optimum process to prepare the xerogel with loosen,porous and net-like structure is that the pH value for the precursor solution is 1,and the mass ration of the citric acid to the lanthanum nitrate is 1.5,the optimum desizing process is the direct sintering method at 560 ℃.After two-step hydrogen reduction,the spherical and homogeneous doped molybdenum powder can be obtained.The existing form for the lanthanum element in the doped MoO3 powder is La2O3 or La-Mo composite oxides which adhere to the surface of the MoO3 particles.However,for the doped molybdenum powder,the La-Mo composite oxides are decomposed in the reduction process,the existing form is La2O3.The particle size of the doped RE-Mo powder and the La2O3 particles are about 500 nm and 100 nm,respectively.