高压导致纳米TiO_(2)形变的电子显微研究

Electron microscopic study on high-pressure induced deformation of nano-TiO_(2)

α-PbO_(2)相TiO_(2)高压相具有适宜的带隙能和可见光范围的光催化能力,是一种适用于可见光、高效且环保的光催化材料.本文使用金刚石对顶压砧对锐钛矿纳米球进行加压-卸压处理得到了α-PbO_(2)相TiO_(2)高压相.利用透射电子显微镜对比初始样品和卸压样品,观察结果表明晶粒发生了明显形变,高分辨图显示其晶粒中存在大量[100]方向层错和形变孪晶,其中亚微米级晶粒中形成了透镜形片层结构的形变孪晶带;纳米级晶粒中形成了扇形多重形变孪晶.研究表明高压下锐钛矿TiO_(2)可以发生明显的形变,其形变的微观机制与金属类似,主要为形变孪晶和层错滑移,形变孪晶的形成存在明显的尺寸效应.这些结果为TiO_(2)高压相变的尺寸效应研究提供了一个新的切入点,同时还为制备孪晶α-PbO_(2)相TiO_(2)高压相提供了方法.

The high-pressureα-PbO_(2)phase of TiO_(2)has suitable band gap and photo catalytic capability in the visible light range,which is an environmentally friendly and efficient photocatalytic material.In this work,α-PbO_(2)phase of TiO_(2)is obtained by the pressure-relief treatment of anatase nanospheres through using diamond anvil cell,and transmission electron microscope(TEM)observation shows the obvious deformation of TiO_(2)nanospheres.High-esolution TEM shows that there are a large number of stacking faults along the[100]direction and deformation twins in the grain.Specifically,the deformation twin band with lens lamellar structure is formed in the submicron grain.The fan-shaped multiple deformation twins are formed in the nanocrystalline grains.This study shows that anatase TiO_(2)can be deformed under high pressure,and its micro mechanism of deformation is similar to metal’s,mainly including deformation twins and stacking fault slip.There is obvious size effect in the formation of deformation twins.These results provide a new breakthrough point for the study of the size effect of high-pressure phase transformation of TiO_(2),and also point out an experimental direction for preparing the twin high-pressureα-PbO_(2)phase.