Abstract: Effects of different heat treatment conditions on the structure and property of CeO2 nanocrystalline synthesized by precipitation method were studied with XRD method combining with measurement of relative density of CeO2 nanocrystalline powders. The results indicate that the grain size of CeO2 nanocrystallites increases sharply with the increase of calcination temperature; the crystal lattice distortion degree reduces obviously because of the crystalline grain growing up to integrity; the increase of compact degree of the structure makes the crystal lattice constant decrease, and the relative density increases remarkably with the rise of calcinations degree of the responding powders. At lower temperature (e.g. 300 ℃) , calcination time makes no obvious influence on the grain size of CeO2 nanocrystalline , and, the responding crystal lattice distortion degree, crystal lattice constant and relative density changes little. However, at higher temperature (e.g. 700 ℃), the grain of CeO2 nanocrystalline grows up with the prolonging calcination time, especially at initial stages of calcinations, then tends slower, while this makes the crystal lattice distortion degree reduce more and more, but crystal lattice constant has some increase and relative density decreases a little. It is thought that diffusion growth mechanic plays the main role in the different influence actions on the structure and property by calcination time at different calcination temperatures for CeO2 nanocrystalline grain growing up in the process of heating treatment.
Structure and property changes of CeO2 nanocrystalline in thermal treatment process
Abstract：
Effects of different heat treatment conditions on the structure and property of CeO2 nanocrystalline synthesized by precipitation method were studied with XRD method combining with measurement of relative density of CeO2 nanocrystalline powders. The results indicate that the grain size of CeO2 nanocrystallites increases sharply with the increase of calcination temperature; the crystal lattice distortion degree reduces obviously because of the crystalline grain growing up to integrity; the increase of compact degree of the structure makes the crystal lattice constant decrease, and the relative density increases remarkably with the rise of calcinations degree of the responding powders. At lower temperature (e.g. 300 ℃) , calcination time makes no obvious influence on the grain size of CeO2 nanocrystalline , and, the responding crystal lattice distortion degree, crystal lattice constant and relative density changes little. However, at higher temperature (e.g. 700 ℃), the grain of CeO2 nanocrystalline grows up with the prolonging calcination time, especially at initial stages of calcinations, then tends slower, while this makes the crystal lattice distortion degree reduce more and more, but crystal lattice constant has some increase and relative density decreases a little. It is thought that diffusion growth mechanic plays the main role in the different influence actions on the structure and property by calcination time at different calcination temperatures for CeO2 nanocrystalline grain growing up in the process of heating treatment.
图3 纳米CeO2晶粒尺寸和 晶格畸变度与焙烧温度之间的关系 Fig.3 Relation of grain size and lattice distortion degree of CeO2 nanocrystallites with different calcination temperatures
图4 纳米CeO2的晶格常数和相对密度与焙烧温度的关系 Fig.4 Relation of lattice constant and relative density of CeO2 nanocrystallites with calcination temperature
