Gradient nanostructured metallic materials with a gradual change of grain boundary and dislocation density display unprecedent mechanical properties. Herein, we uncover a gradient of point defects concentration and concomitant gradient bandgap (E _g) narrowing in metal oxide nanoparticles processed by a combination of severe shearing and frictional sliding deformation. Using the valence electron-energy loss spectroscopy technique, we find a gradual decrease of E _g from 2.93 eV in the interior to 2.43 eV at the edge of the high-pressure torsion processed ZnO flake-shaped particle. This work paves the way to strain engineering of gradient-structured metal oxide semiconductors for unique functional properties.

具有逐渐改变的晶界和位错密度的梯度纳米结构金属材料显示出前所未有的机械性能。在这里，我们发现了由严重剪切和摩擦滑动变形共同作用的金属氧化物纳米粒子中的点缺陷浓度梯度和伴随的梯度带隙（E _g）变窄。使用价电子能量损失谱技术，我们发现E _g从高压扭转处理的ZnO薄片状颗粒的内部逐渐从内部的2.93 eV下降到边缘的2.43 eV。这项工作为梯度结构的金属氧化物半导体的独特工程性能铺平了道路。