Melting properties and ultrasonic velocity of nitrogen to 20 kbar
Melting properties and ultrasonic velocity of nitrogen to 20 kbar
复制标题
氮气至 20 kbar 的熔化特性和超声波速度
DOI：
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发表时间：
1975
期刊：
影响因子：
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通讯作者：
J. Bronson
中科院分区：
文献类型：
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作者：
R. L. Mills;D. Liebenberg;J. Bronson
在活塞缸装置中，对压力高达20kbar的冷冻氮气进行了纵向声速和相对体积的同时测量。流体相和固相的结果与文献中较低压力下的数据相结合，得出了氮气在高压下熔化特性的方程。在整个实验范围内，与流体平衡的固体明显为β - N2 （hcp）。对高压下β - N2中的横向声速进行了估计。对熔融过程中总熵变化的分析表明，在整个熔化曲线上，由固态氮到液态氮的分子失序引起的熵分量具有一个相当恒定的值，约为ln1.7。没有迹象表明熔化曲线会在临界点处终止。
Simultaneous measurements of the longitudinal sound velocity and relative volume were made on freezing nitrogen at pressures up to 20 kbar in a piston–cylinder apparatus. Results in both the fluid and solid phases were combined with data at lower pressures from the literature to derive equations giving the melting properties of nitrogen at high pressure. The solid in equilibrium with the fluid is apparently β‐N2 (hcp) throughout the experimental range. An estimate was made of the transverse sound velocity in β‐N2 at high pressure. Analysis of the total entropy change on melting shows that the entropy component due to disordering of the molecules from solid to fluid nitrogen has a fairly constant value of about ln1.7 along the entire melting curve. There is no indication that the melting curve will terminate in a critical point.