The combination of ultrasonic technique with synchrotron X-ray diffraction and radiography in a multi-anvil apparatus was utilized to measure the elastic wave velocities of sodium aluminosilicate glass and melt with the partially depolymerized composition of NaAlSiO (NAS). The measurements were conducted at pressure and temperature of up to 7.3 GPa and at ambient temperature for glass and up to 4.3 GPa and 2120 K for melt, respectively. The compressional wave velocity () of the NAS glass remained mostly constant up to 4 GPa; subsequently, it increased with increasing pressure. Additionally, the NAS glass exhibited a minimum shear wave velocity () at 4–5 GPa. Alternatively, the of the NAS melt was smaller than that of the NAS glass, showing a velocity minimum at ∼2 GPa. The negative pressure dependence of of the NAS melt is completely different from the depolymerized diopside (Di) melt, which shows a monotonic increase in with pressure. The contrasting behavior of the NAS and Di melts is caused by the difference in their structure, characterized by their degree of polymerization. Natural magma found in the interior of the Earth, such as basalt, has a partially depolymerized composition. This study indicates that the magma can exhibit elastic properties with negative pressure dependence, similar to the NAS melt.

中文翻译：

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高压高温下铝硅酸钠玻璃和熔体的弹性波速测量

利用超声波技术与同步加速器 X 射线衍射和多砧装置中的射线照相相结合，测量了部分解聚的 NaAlSiO (NAS) 成分的铝硅酸钠玻璃和熔体的弹性波速度。玻璃的测量压力和温度分别高达 7.3 GPa 和环境温度，熔体的测量压力和温度分别高达 4.3 GPa 和 2120 K。 NAS 玻璃的压缩波速 () 在高达 4 GPa 时基本保持恒定；随后，它随着压力的增加而增加。此外，NAS 玻璃的最小剪切波速度 () 为 4-5 GPa。或者，NAS 熔体的速度小于 NAS 玻璃的速度，显示速度最小值为 ~2 GPa。 NAS 熔体的负压依赖性与解聚透辉石 (Di) 熔体完全不同，后者表现出随压力单调增加。 NAS 和 Di 熔体的对比行为是由它们的结构差异引起的，其特征在于它们的聚合度。地球内部发现的天然岩浆（例如玄武岩）具有部分解聚的成分。这项研究表明，岩浆可以表现出与负压相关的弹性特性，类似于 NAS 熔体。