掺CeO_2的MgO-CaO材料缺陷研究

Defect study of MgO-CaO material doped with CeO_2

以分析纯Ca(OH)2和Mg(OH)2为原料,CeO2为掺杂剂,利用行星球磨机混合后压制成型,经1650℃烧成,保温3h,制备了MgO-CaO材料。通过XRD和SEM对试样进行了分析表征。结果表明,随CeO2掺入量的增大,CaO的晶格常数先增大后减小,试样的体积密度不断增大,显气孔率减小,致密化程度增强;在烧结致密化过程中,MgO晶粒长大比CaO更为明显,试样晶粒间的气孔逐渐减少,但MgO晶粒中的气孔逐渐增多,而CaO晶粒中未有气孔出现;CeO2促进材料致密的实质是与CaO发生置换固溶,Ce4+进入CaO晶格内,增大了Ca2+空位浓度,有利于Ca2+的扩散。

MgO-CaO material was generated by using analytically pure Ca（OH）2 and Mg（OH）2 as me raw ma- terials, CeO2 as the dopant and sintered at 1650℃ for 3h with the mixing and pressing of planetary ball mill. Furthermore, XRD and SEM analysis of the sample characterization was performed. According to the results, with the additions of CeO2, the lattice constants of CaO increase and then decrease; bulk density of the samples increases and apparent porosity decreases, strengthening the densification of MgO-CaO materials. In the sinte- ring densification process, MgO grains grow more than CaO2; pores in MgO-CaO grains gradually decrease while pores in MgO grains gradually increase and no pores in CaO grains. The nature of CeO2 promoting densi- fication was to substitute and solutionize with CaO, Ce^4＋ approaching into CaO lattices, enlarging the vacancy concentration of Ca^2＋ and accelerating the diffusion of Ca^3＋.