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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 >About diffusion mechanism in silica liquid under pressure
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About diffusion mechanism in silica liquid under pressure

机译：关于压力下二氧化硅液体中的扩散机理

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We perform a molecular dynamic simulation to study the diffusion mechanism in silica liquid under pressure up to 25 GPa and at temperature of 3000 K. We find that total O - Si - O angle distribution can be expressed by a simple relation between partial O - Si - O angle distribution and fractions of units SiO _x. Specifically, we demonstrate that these liquids consist of identical units SiO _4, SiO _5 and SiO _6 and have common partial O - Si - O angle distribution. We also show that each particle undergoes a series of stages where the particle locates in unchanged unit SiO _x, x = 3, 4,... 7 or OSi _y, y = 1, 2, 3, 4. The diffusivity strongly depends on the rate of transitions Si ~ξ → Si ~(ξ ± 1) and O ~ζ → O ~(ζ ± 1) which is significantly different between low- and high-pressure samples. For low-pressure sample the transitions Si ~4 → Si ~5, Si ~5 → Si ~4, O ~2 → O ~3 and O ~3 → O ~2 are dominant, meanwhile for high-pressure sample there are transitions Si ~ξ → Si ~(ξ ± 1) with ξ = 4, 5, 6 and O ~ζ → O ~(ζ ± 1) with ζ = 2, 3, 4. This finding may be common for diffusion in all network-forming liquids. The simulation also reveals the spatially heterogeneous dynamics in low-pressure liquid where a large cluster of immobile particle exists for the time that a number of particles move over several inter-particle distances.
机译：我们进行了分子动力学模拟，研究了在高达25 GPa的压力和3000 K的温度下在二氧化硅液体中的扩散机理。我们发现，总O-Si-O角分布可以通过部分O-Si之间的简单关系来表示。 -O角分布和SiO_x单位的分数。具体而言，我们证明了这些液体由相同的单元SiO _4，SiO _5和SiO _6组成，并具有共同的部分O-Si-O角分布。我们还表明，每个粒子都经历了一系列阶段，其中粒子位于不变的单位SiO _x，x = 3、4，... 7或OSi _y，y = 1、2、3、4。扩散率强烈取决于Si〜ξ→Si〜（ξ±1）和O〜ζ→O〜（ζ±1）的转变速率在低压和高压样品之间有显着差异。对于低压样品，转变为Si〜4→Si〜5，Si〜5→Si〜4，O〜2→O〜3和O〜3→O〜2为主导，而对于高压样品则有转变Si〜ξ→Si〜（ξ±1）且ξ= 4、5、6，O〜ζ→O〜（ζ±1）且ζ= 2、3、4。这一发现对于在所有网络中的扩散可能是共同的形成液体。该模拟还揭示了低压液体中的空间异质动力学，在该液体中存在大量不可移动的粒子簇，此时许多粒子在多个粒子间距离上移动。

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