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以硝酸、氨水、硝酸铵、商业氧化钇及草酸为初始原料,加入分散剂聚乙二醇(PEG2000)及表面活性剂十二烷基苯磺酸钠(SDBS),采用改进的草酸沉淀工艺成功制备氧化钇前驱体Y(NH_4)(C_2O_4)_2·H_2O及经随后的焙烧工艺获得最终产品Y_2O_3粉体。具体工艺中,将一定浓度的小体积Y(NO_3)_3溶液滴入大体积氨水-硝酸铵混合溶液中形成Y(OH)_3溶胶,整个滴入过程体系pH值保持稳定,然后将85℃温度下的饱和草酸溶液滴加入上述制备的Y(OH)_3溶胶中,进行沉淀转化以制备钇草酸盐前驱体Y(NH_4)(C_2O_4)_2·H_2O,继而经焙烧工艺成功制备Y_2O_3粉体。X射线衍射技术(XRD)和扫描电子显微镜(SEM)表征表明:前驱体Y(NH_4)(C_2O_4)_2·H_2O具有立方晶体结构,有轻微的团聚,经950℃焙烧2 h后,尽管失去了O,C和H,立方相Y_2O_3产品完整地保留了前驱体的形貌特征。进一步,主要通过调整表面活性剂SDBS/分散剂PEG2000质量比及改变草酸沉淀转化终点pH值来考察其对Y_2O_3产品尺寸及形貌的影响。不同条件下制备的Y_2O_3粉体扫描电子显微镜(SEM)表征表明:精确控制实验条件,特别是控制草酸沉淀转化过程终点pH值,可制备出形貌和尺寸可控的Y_2O_3粉体,当草酸沉淀转化过程中终点pH值小于1.8时,制备的Y_2O_3粉体粒径在1μm以下。另外,基于前驱体Y(NH_4)(C_2O_4)_2·H_2O在空气气氛下的差示-热重(TG-DSC)分析结果,其热分解过程应为:Y(NH_4)(C_2O_4)_2·H_2O→Y(NH_4)(C_2O_4)_2→Y_2O_2CO_3→Y_2O_3。
Using nitric acid, ammonia, ammonium nitrate, commercial yttria and oxalic acid as raw materials, polyethylene glycol (PEG2000) and surfactant sodium dodecyl benzene sulfonate (SDBS) were added as dispersants and the improved oxalic acid precipitation process was successfully used Preparation of yttrium oxide precursor Y (NH_4) (C_2O_4) _2 · H_2O and subsequent calcination process to obtain the final product Y_2O_3 powder. Specific process, a certain concentration of Y (NO_3) _3 solution was dropped into a large volume of ammonia - ammonium nitrate mixed solution to form Y (OH) _3 sol, the whole dropping system pH remained stable, and then 85 ℃ temperature (Y_2O_4) _2 · H_2O, which is a precursor of Y (OH_4) _2 · H_2O, was prepared by the method of precipitation and conversion. The Y_2O_3 powder was successfully prepared by calcination. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) characterization indicated that the precursor Y (NH 4) (C 2 O 4) 2 · H 2 O had a cubic crystal structure and slightly agglomerated. After being calcined at 950 ℃ for 2 h, O, C and H, the cubic phase Y_2O_3 product completely preserved the precursor morphology. Further, the influence of the mass ratio of surfactant SDBS / dispersant PEG2000 and the pH value of oxalic acid precipitation on the size and morphology of Y2O3 was investigated. The SEM results of Y_2O_3 powders prepared under different conditions show that the Y_2O_3 powder with morphology and size controllable can be prepared by precisely controlling the experimental conditions, especially controlling the pH value at the end of the oxalate precipitation process. When the oxalate precipitation When the final pH of the conversion process is less than 1.8, the particle size of Y_2O_3 powder is below 1μm. In addition, the thermal decomposition process of Y (NH 4) (C 2 O 4) 2 · H 2 O based on TG-DSC analysis in air is as follows: → Y (NH_4) (C_2O_4) _2 → Y_2O_2CO_3 → Y_2O_3.