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Synthesis and morphology of nanodisperse cerium oxide modified by gadolinium oxide
Journal of Sol-Gel Science and Technology ( IF 2.3 ) Pub Date : 2020-08-14 , DOI: 10.1007/s10971-020-05387-9
S. I. Niftaliev , I. V. Kuznetsova , Yu. N. Vlasov , L. V. Lygina , V. Yu. Tuneekov , C. S. Gadzhiyeva

Stable sols were obtained in the CeO2–Gd2O3 system using the stabilizing additive Hamulsion RUGLAP. The formation of phases in the CeO2–Gd2O3 system with Gd2O3 content of up to 0.07 mol occurs already at the stage of synthesis by the Krekke method. The electrokinetic potential is positive for all samples. A sharp increase in the electrokinetic potential (with Gd2O3 content of over 0.07 mol) is connected with a change in the nature of potential-determining ions of the electrical double layer and the diffusion of excess Gd3+ ions from the solid core of a colloidal particle into its surface. The absorption spectra were analyzed to determine the band gap of colloidal sol particles. With an increase in the cerium oxide content in the sol with the stabilizer (CeO2–Stab), the value of the band gap energy for direct and indirect transitions increases. An additional absorption band appears in the sol spectra based on the CeO2–Gd2O3–Stab system in the 265 ÷ 275 nm wavelength range, the value of the band gap energy for direct transitions 4.46–4.62 eV, presumably, corresponds to solid solutions of Ce1−yGdyO2 type. The suggested stabilizer, which contains silicon oxide, guar gum, and gelatin, is neutral with respect to positively charged sol particles. It is adsorbed on the surface of dispersed particles and isolates them from each other, without causing coagulation of the sol. When gadolinium oxide (0.01 mol) is added to the CeO2 sol, an average particle size decreases to 13 ± 2.8 nm. The nanoparticles are weakly agglomerated, if Gd2O3 content in the sol is up to 0.05 mol; with increasing gadolinium oxide content the size of agglomerates increases. The processes of sol dehydration proceed in the range of 65–90 °C. The activation energy of these processes is in the range of 51–54 kJ/mol. The values of activation energies indicate the presence of moisture in a bound state in the structure of the stabilizing additive Hamulsion RUGLAP.



中文翻译:

氧化g修饰的纳米分散二氧化铈的合成与形貌

使用稳定添加剂Hamulsion RUGLAP在CeO 2 -Gd 2 O 3系统中获得稳定的溶胶。在Cere 2 -Gd 2 O 3体系中,Gd 2 O 3含量高达0.07 mol的相的形成已经在通过Krekke方法进行的合成阶段发生。所有样品的电动势均为正。电动势的急剧增加(Gd 2 O 3的含量超过0.07 mol)与双电层的电势决定离子的性质变化以及过量Gd 3+的扩散有关离子从胶体颗粒的固体核进入其表面。分析吸收光谱以确定胶体溶胶颗粒的带隙。随着使用稳定剂(CeO 2 -Stab)的溶胶中二氧化铈含量的增加,用于直接和间接跃迁的带隙能量值增加。在265÷275 nm波长范围内,基于CeO 2 -Gd 2 O 3 -Stab系统的溶胶光谱中会出现一个附加吸收带,直接跃迁的带隙能量值为4.46-4.62 eV,可能对应于Ce 1- y Gd y O 2的固溶体类型。建议的稳定剂包含氧化硅,瓜尔豆胶和明胶,相对于带正电的溶胶颗粒为中性。它被吸附在分散颗粒的表面上并使它们彼此隔离,而不会引起溶胶的凝结。当将氧化((0.01摩尔)添加到CeO 2溶胶中时,平均粒径减小到13±2.8 nm。如果Gd 2 O 3,则纳米颗粒微团聚溶胶中的含量最高为0.05 mol;随着氧化oxide含量的增加,附聚物的尺寸增加。溶胶脱水过程在65–90°C的温度范围内进行。这些过程的活化能在51–54 kJ / mol的范围内。活化能的值表明在稳定添加剂Hamulsion RUGLAP的结构中以结合态存在水分。

更新日期:2020-08-14
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