钝化线是描述裂纹试样在钝化过程中J积分与伸张区宽度(stretch zone width,SZW)间关系的一条直线,在J积分测试中,有效数据区的左右界限线以及确定延性断裂韧度JⅠC的偏置线都是建立在钝化线基础上的,因而钝化线在J积分测试中至关重要。...钝化线是描述裂纹试样在钝化过程中J积分与伸张区宽度(stretch zone width,SZW)间关系的一条直线,在J积分测试中,有效数据区的左右界限线以及确定延性断裂韧度JⅠC的偏置线都是建立在钝化线基础上的,因而钝化线在J积分测试中至关重要。通过对裂尖钝化过程的分析,基于D-B模型和J积分的路径无关性原理推导出一种钝化线方程。与现行标准中的钝化线相比,此方程与试验结果吻合得更好。展开更多
Surface passivation is one valuable approach to tune the properties of nanomaterials.The piezoelectric properties of hexagonal[001]ZnO nanowires with four kinds of surface passivations were investigated using the firs...Surface passivation is one valuable approach to tune the properties of nanomaterials.The piezoelectric properties of hexagonal[001]ZnO nanowires with four kinds of surface passivations were investigated using the first-principles calculations.It is found that in the 50%H(O)and 50%Cl(Zn),50%H(O)and 50%F(Zn)passivations,the volume and surface effects both enhance the piezoelectric coefficient.This differs from the unpassivated cases where the surface effect was the sole source of piezoelectric enhancement.In the 100%H,100%Cl passivations,the piezoelectric enhancement is not possible since the surface effect is screened by surface charge with weak polarization.The study reveals that the competition between the volume effect and surface effect influences the identification of the diameter-dependence phenomenon of piezoelectric coefficients for ZnO nanowires in experiments.Moreover,the results suggest that one effective means of improving piezoelectricity of ZnO nanowires is shrinking axial lattice or increasing surface polarization through passivation.展开更多
文摘钝化线是描述裂纹试样在钝化过程中J积分与伸张区宽度(stretch zone width,SZW)间关系的一条直线,在J积分测试中,有效数据区的左右界限线以及确定延性断裂韧度JⅠC的偏置线都是建立在钝化线基础上的,因而钝化线在J积分测试中至关重要。通过对裂尖钝化过程的分析,基于D-B模型和J积分的路径无关性原理推导出一种钝化线方程。与现行标准中的钝化线相比,此方程与试验结果吻合得更好。
文摘Surface passivation is one valuable approach to tune the properties of nanomaterials.The piezoelectric properties of hexagonal[001]ZnO nanowires with four kinds of surface passivations were investigated using the first-principles calculations.It is found that in the 50%H(O)and 50%Cl(Zn),50%H(O)and 50%F(Zn)passivations,the volume and surface effects both enhance the piezoelectric coefficient.This differs from the unpassivated cases where the surface effect was the sole source of piezoelectric enhancement.In the 100%H,100%Cl passivations,the piezoelectric enhancement is not possible since the surface effect is screened by surface charge with weak polarization.The study reveals that the competition between the volume effect and surface effect influences the identification of the diameter-dependence phenomenon of piezoelectric coefficients for ZnO nanowires in experiments.Moreover,the results suggest that one effective means of improving piezoelectricity of ZnO nanowires is shrinking axial lattice or increasing surface polarization through passivation.
