Ti离子辐照诱发焦绿石Gd_2Zr_2O_7相变的电子显微研究

Ti-ion-irradiation-induced phase transition of Gd_2Zr_2O_7 pyrochlore

通过高分辨和剖面电子显微技术研究了离子注入在单晶焦绿石Gd2Zr2O7中的产生的结构相变。在单晶Gd2Zr2O7中注入200keVTi+离子,注量为1×1017ions/cm2,注入温度为常温。电子显微研究表明,1×1017ions/cm2的Ti+离子注入没有使样品非晶化,而是诱发了单晶Gd2Zr2O7从焦绿石结构转变成萤石结构。从高分辨像和选区电子衍射花样发现Gd3+和Zr3+发生了阳离子无序。重离子入射产生的级联碰撞致使阳离子无序被认为是相变发生的物理机制。

Ion-irradiation-induced transition of single crystal Gd_2Zr_2O_7 pyrochlore was studied by cross-sectional transmission electron microscopy (TEM) and high-resolution TEM (HRTEM). The implantation of 200keV Ti ions with a dose of 1×10^(17)ions/cm^2 was conducted at room temperature. No amorphization was observed, but a phase transition from an isometric pyrochlore structure-type to the fluorite structure occurred. The cation disordering of Gd^(3+) and Zr^(3+) was revealed by HRTEM image and the selected area electron diffraction patterns (SAEDP). The physical mechanism of the transition was attributed to cation disordering produced by the cascade collision of ion irradiation.