Contrary to the dislocation-driven ‘smaller-is-stronger’ size-effect in nanocrystals, the size-dependence of strength in deformation twinning, another carrier of plasticity, still lacks universal understanding. Deformation twinning enables pseudoplastic strain of >5% in a shape memory ceramic (ZrHfO₄)${}_{\mathrm{x}}$ (YTaO₄)${}_{\mathrm{1-x}}$. We use diffraction methods, microstructure analysis, and in-situ nanomechanical experiments to uncover contributing factors to the competition between twinning and slip in these submicron-sized ionic crystals, revealing power-law scaling of strength with size for both mechanisms. The significant twinning size-dependence was found to follow a superimposed power-law with exponent of -1, identical to that in metals. These findings unveil the universality of the superimposed power-law size-effect for twinning in single-crystals and provide new insights on deformability of ceramics and microstructure-driven nano-plasticity.

与位错驱动的纳米晶体“小而强”的尺寸效应相反，变形孪晶（可塑性的另一个载体）中强度的尺寸依赖性仍然缺乏普遍的理解。变形孪生可在形状记忆陶瓷（ZrHfO ₄）中实现大于5％的假塑性应变${}_{\mathrm{X}}$ （YTaO ₄）${}_{\mathrm{1-x}}$。我们使用衍射方法，微观结构分析和原位纳米力学实验来揭示这些亚微米级离子晶体中孪晶和滑移之间竞争的影响因素，揭示两种机制的强度随大小的幂律定标。发现显着的孪晶尺寸相关性遵循指数为-1的叠加幂律，与金属中的幂律相同。这些发现揭示了单晶孪晶中叠加的幂律尺寸效应的普遍性，并为陶瓷的可变形性和微观结构驱动的纳米塑性提供了新的见解。