Structure and Properties of Silica Glass Densified in Cold Compression and Hot Compression.
Structure and Properties of Silica Glass Densified in Cold Compression and Hot Compression.
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DOI：
10.1038/srep15343
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发表时间：
2015-10-15
影响因子：
4.6
通讯作者：
Huang L
中科院分区：
文献类型：
--
作者：
Guerette M;Ackerson MR;Thomas J;Yuan F;Bruce Watson E;Walker D;Huang L
二氧化硅玻璃在许多研究中显示出具有在不同温度下在压力下永久致密化以形成高密度无定形（HDA）二氧化硅的显著能力。然而，在室温下冷压缩和热压缩中导致二氧化硅玻璃不可逆致密化的过程（例如，接近玻璃化转变温度）在自然界中是常见的。在这项工作中，使用热压技术从高温（1100 °C）和高压（高达8 GPa）条件下淬火石英玻璃，这导致相对于环境条件下原始石英玻璃的密度增加约25%，杨氏模量增加约71%。我们的实验和分子动力学（MD）模拟提供了坚实的证据，热压缩HDA二氧化硅的中程有序是不同的，在室温下冷压缩的对应物。这解释了前者比后者在加热和压缩时具有更高的热稳定性和机械稳定性，正如我们在原位布里渊光散射（BLS）实验中所揭示的那样。我们的研究证明了所得密度作为多晶结构指标的局限性，并指出了压缩过程中温度的重要性，以便从根本上了解HDA二氧化硅。
Silica glass has been shown in numerous studies to possess significant capacity for permanent densification under pressure at different temperatures to form high density amorphous (HDA) silica. However, it is unknown to what extent the processes leading to irreversible densification of silica glass in cold-compression at room temperature and in hot-compression (e.g., near glass transition temperature) are common in nature. In this work, a hot-compression technique was used to quench silica glass from high temperature (1100 °C) and high pressure (up to 8 GPa) conditions, which leads to density increase of ~25% and Young’s modulus increase of ~71% relative to that of pristine silica glass at ambient conditions. Our experiments and molecular dynamics (MD) simulations provide solid evidences that the intermediate-range order of the hot-compressed HDA silica is distinct from that of the counterpart cold-compressed at room temperature. This explains the much higher thermal and mechanical stability of the former than the latter upon heating and compression as revealed in our in-situ Brillouin light scattering (BLS) experiments. Our studies demonstrate the limitation of the resulting density as a structural indicator of polyamorphism, and point out the importance of temperature during compression in order to fundamentally understand HDA silica.