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首页> 外文期刊>Journal of Non-Crystalline Solids: A Journal Devoted to Oxide, Halide, Chalcogenide and Metallic Glasses, Amorphous Semiconductors, Non-Crystalline Films, Glass-Ceramics and Glassy Composites >Morey Award paper - What is so exciting about non-linear viscous flow in glass, molecular dynamics simulations of brittle fracture and semiconductor-glass quantum composites
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Morey Award paper - What is so exciting about non-linear viscous flow in glass, molecular dynamics simulations of brittle fracture and semiconductor-glass quantum composites

机译：莫雷奖论文-玻璃中的非线性粘性流动，脆性断裂的分子动力学模拟以及半导体-玻璃量子复合材料的令人兴奋之处

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Results of recent research are reported in the areas of: (1) non-linear viscous flow in glass, (2) molecular dynamics of brittle fracture and (3) optical properties of semiconductor-glass quantum composites. In all three areas, a fundamental understanding of the underlying behavior of materials has emerged from key experiments or computer simulations. These are described here: (1) The non-linear viscosity studies have established the behavior of viscosity at high strain rates in silicate glasses. Results of measurements show marked shear thinning associated with changes in the glass structure at high shear rates. A strain-rate-dependent (SRD) viscosity equation is presented which describes well the behavior of silicate glasses. (2) Molecular dynamics computer simulations of amorphous and crystalline silica have examined brittle fracture under applied uniaxial strain. Their results begin to reveal the underlying atomic processes that take part in free surface formation and fracture. For example, an examination of the atomic dynamics at the crack tip reveals that cracks form by the coalescence of pre-existing voids in the glass structure and that fracture surfaces are formed as silicon ions are shielded from the surface by oxygen ions resulting in a predominance of oxygen ions on the fracture surface. The results also suggest a mechanism for the formation of mirror, mist and hackle regions in the fractography of fractured surfaces. (3) Experimental studies of the optical properties of semiconductors formed in a glass matrix were conducted to examine the effect of size confinement on the electronic bandgap of the semiconductors. The results reveal differences in behavior between direct-gap semiconductors (CdS, CdSe and CdTe) and indirect-gap semiconductors (Si and Gel. An analysis of the data shows that the expected blue shift in bandgap energy of direct-gap semiconductors that results from reduced crystal sizes saturates at very small sizes due to the mixing of states between conduction band side valleys and the central valley. This effect does not appear to dominate indirect-gap semiconductors allowing their size-induced bandgap blue shift to cover the entire range of visible wavelengths. This effect suggests the use of quantum confined indirect-gap materials such as Si and Ge in stacks of films with different bandgaps to produce solar cells with increased theoretical efficiency. (C) 1998 Elsevier Science B.V. All rights reserved. [References: 44]
机译：最近的研究结果报告在以下领域：（1）玻璃中的非线性粘性流动，（2）脆性断裂的分子动力学和（3）半导体-玻璃量子复合材料的光学性质。在所有这三个领域中，从关键实验或计算机模拟中已经形成了对材料基本行为的基本理解。这里描述了这些：（1）非线性粘度研究已经确定了硅酸盐玻璃在高应变速率下的粘度行为。测量结果表明，在高剪切速率下，剪切变稀与玻璃结构的变化有关。提出了应变率相关（SRD）粘度方程，该方程很好地描述了硅酸盐玻璃的行为。 （2）非晶硅和结晶硅的分子动力学计算机模拟研究了在施加的单轴应变下的脆性断裂。他们的结果开始揭示参与自由表面形成和断裂的潜在原子过程。例如，对裂纹尖端的原子动力学的检查表明，裂纹是由玻璃结构中预先存在的空隙的聚结形成的，并且由于硅离子被氧离子从表面屏蔽而形成了断裂表面。断裂面上的氧离子。结果还提出了在断裂表面的形貌中形成镜面，薄雾和裂纹区域的机制。 （3）对玻璃基质中形成的半导体的光学特性进行了实验研究，以研究尺寸限制对半导体的电子带隙的影响。结果表明，直接间隙半导体（CdS，CdSe和CdTe）与间接间隙半导体（Si和Gel）之间的行为差​​异。数据分析表明，直接间隙半导体的带隙能量的预期蓝移是由减小的晶体尺寸由于导带侧谷和中心谷之间的混合状态而在非常小的尺寸处饱和，这种作用似乎并不能控制间接间隙半导体，从而使尺寸引起的带隙蓝移覆盖了整个可见光范围这种效应表明，在具有不同带隙的薄膜堆叠中使用诸如Si和Ge等量子限制的间接间隙材料，可以生产理论效率更高的太阳能电池（C）1998 Elsevier Science BV版权所有[参考文献：44 ]

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