This study explored the impact of sintering time and temperature on the synthesis and formation of high-entropy rare earth oxides(HEOs).By systematically varying the sintering conditions,a series of Lu_(2)Yb_(2)Tm_(2)...This study explored the impact of sintering time and temperature on the synthesis and formation of high-entropy rare earth oxides(HEOs).By systematically varying the sintering conditions,a series of Lu_(2)Yb_(2)Tm_(2)Er_(2)O_(12) samples was synthesized and their structural and chemical properties were analyzed using scanning electron microscopy(SEM)with energy-dispersive X-ray spectroscopy(EDS)elemental mapping,X-ray diffraction(XRD),high-resolution transmission electron microscopy(HRTEM),and X-ray photoelectron spectroscopy(XPS).According to XRD patterns,a single-phase cubic C-type structure is easier to form at higher sintering temperatures(1400-1500℃),with sharper peaks signifying better crystallinity.With longer sintering times improving grain development and homogeneity,SEM research reveals a change in morphology from spherical grains at lower temperatures(1100-1200℃)to blocky grains at higher temperatures(1300-1500℃).HRTEM pictures verified the nanoparticles'strong crystallinity,and at higher temperatures,the lattice fringes widen and become more distinct,indicating better atomic ordering and diffusion.Stable and uniform high-entropy oxide production is indicated by the XPS spectra,which shows uniform elemental distribution and consistent chemical states of the constituent elements with very slight variations in the oxygen peaks.The findings highlight how important the sintering temperature is for reaching the intended high-entropy phase,with higher temperatures promoting improved atomic diffusion and compositional homogeneity.The results open the door for the use of high-entropy rare earth oxides in sophisticated functional materials by offering insightful information on how to best synthesize them.展开更多
喷雾热解法是制备纳米CeO_(2)粉体的途径之一,但液滴在高速高温气流中发生的蒸发、破碎和热解行为影响了最终产品的性能和品质。本文基于VOF(Volume of fluid)蒸发传质模型与有限速率化学反应模型的耦合方法,研究了热解中液滴形貌以及...喷雾热解法是制备纳米CeO_(2)粉体的途径之一,但液滴在高速高温气流中发生的蒸发、破碎和热解行为影响了最终产品的性能和品质。本文基于VOF(Volume of fluid)蒸发传质模型与有限速率化学反应模型的耦合方法,研究了热解中液滴形貌以及流场的变化和产物分布随时间的全过程。结果表明:当入口气流速度为60 m/s、温度为650℃时,液滴在破碎前的形貌发生了变化,即液滴表面先出现波纹状起伏,然后加剧为褶皱状起伏,最后转变为沟壑状起伏;液滴迎风面与背风面存在压力差,流场中局部(液滴边缘)气流速度最大为67 m/s;子液滴数量沿X轴正方向不断减少且周围有产物CeO_(2)生成,计算域内产物CeO_(2)含量随时间的延长而逐渐增大;产物CeO_(2)主要生成于气相与氧化剂的交界面处,而非直接附着在液滴表面。展开更多
基金Project supported by Natural Science Foundation of Zhejiang Province(LD21E080001)Zhejiang Provincial Ten Thousand Talent Program(ZJWR0302055)。
文摘This study explored the impact of sintering time and temperature on the synthesis and formation of high-entropy rare earth oxides(HEOs).By systematically varying the sintering conditions,a series of Lu_(2)Yb_(2)Tm_(2)Er_(2)O_(12) samples was synthesized and their structural and chemical properties were analyzed using scanning electron microscopy(SEM)with energy-dispersive X-ray spectroscopy(EDS)elemental mapping,X-ray diffraction(XRD),high-resolution transmission electron microscopy(HRTEM),and X-ray photoelectron spectroscopy(XPS).According to XRD patterns,a single-phase cubic C-type structure is easier to form at higher sintering temperatures(1400-1500℃),with sharper peaks signifying better crystallinity.With longer sintering times improving grain development and homogeneity,SEM research reveals a change in morphology from spherical grains at lower temperatures(1100-1200℃)to blocky grains at higher temperatures(1300-1500℃).HRTEM pictures verified the nanoparticles'strong crystallinity,and at higher temperatures,the lattice fringes widen and become more distinct,indicating better atomic ordering and diffusion.Stable and uniform high-entropy oxide production is indicated by the XPS spectra,which shows uniform elemental distribution and consistent chemical states of the constituent elements with very slight variations in the oxygen peaks.The findings highlight how important the sintering temperature is for reaching the intended high-entropy phase,with higher temperatures promoting improved atomic diffusion and compositional homogeneity.The results open the door for the use of high-entropy rare earth oxides in sophisticated functional materials by offering insightful information on how to best synthesize them.
文摘喷雾热解法是制备纳米CeO_(2)粉体的途径之一,但液滴在高速高温气流中发生的蒸发、破碎和热解行为影响了最终产品的性能和品质。本文基于VOF(Volume of fluid)蒸发传质模型与有限速率化学反应模型的耦合方法,研究了热解中液滴形貌以及流场的变化和产物分布随时间的全过程。结果表明:当入口气流速度为60 m/s、温度为650℃时,液滴在破碎前的形貌发生了变化,即液滴表面先出现波纹状起伏,然后加剧为褶皱状起伏,最后转变为沟壑状起伏;液滴迎风面与背风面存在压力差,流场中局部(液滴边缘)气流速度最大为67 m/s;子液滴数量沿X轴正方向不断减少且周围有产物CeO_(2)生成,计算域内产物CeO_(2)含量随时间的延长而逐渐增大;产物CeO_(2)主要生成于气相与氧化剂的交界面处,而非直接附着在液滴表面。
