Huang Jinhua, Ran Guang, Lin Jianxin, Shen Qiang, Lei Penghui, Wang Xina, Li Ning
College of Energy, Xiamen University, Xiamen 361102, China.
Materials (Basel). 2016 Dec 28;10(1):19. doi: 10.3390/ma10010019.
The microstructural evolution of Dy₂O₃-TiO₂ powder mixtures during ball milling and post-milled annealing was investigated using XRD, SEM, TEM, and DSC. At high ball-milling rotation speeds, the mixtures were fined, homogenized, nanocrystallized, and later completely amorphized, and the transformation of Dy₂O₃ from the cubic to the monoclinic crystal structure was observed. The amorphous transformation resulted from monoclinic Dy₂O₃, not from cubic Dy₂O₃. However, at low ball-milling rotation speeds, the mixtures were only fined and homogenized. An intermediate phase with a similar crystal structure to that of cubic Dy₂TiO₅ was detected in the amorphous mixtures annealed from 800 to 1000 °C, which was a metastable phase that transformed to orthorhombic Dy₂TiO₅ when the annealing temperature was above 1050 °C. However, at the same annealing temperatures, pyrochlore Dy₂Ti₂O₇ initially formed and subsequently reacted with the remaining Dy₂O₃ to form orthorhombic Dy₂TiO₅ in the homogenous mixtures. The evolutionary mechanism of powder mixtures during ball milling and subsequent annealing was analyzed.
采用X射线衍射仪（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）和差示扫描量热仪（DSC）研究了Dy₂O₃ - TiO₂粉末混合物在球磨及球磨后退火过程中的微观结构演变。在高球磨转速下，混合物被细化、均匀化、纳米晶化，随后完全非晶化，并且观察到Dy₂O₃从立方晶体结构转变为单斜晶体结构。非晶化转变是由单斜Dy₂O₃引起的，而非立方Dy₂O₃。然而，在低球磨转速下，混合物仅被细化和均匀化。在800至1000℃退火的非晶混合物中检测到一种晶体结构与立方Dy₂TiO₅相似的中间相，这是一种亚稳相，当退火温度高于1050℃时会转变为正交Dy₂TiO₅。然而，在相同的退火温度下，烧绿石Dy₂Ti₂O₇最初形成，随后与剩余的Dy₂O₃反应，在均匀混合物中形成正交Dy₂TiO₅。分析了粉末混合物在球磨及后续退火过程中的演变机制。
