The shape of the liquid-liquid coexistence line in the phase diagram of a lithium-sodium system is determined using the gamma-ray attenuation technique. The measured coordinates of the critical point of the coexistence curve (critical temperature T_C = 576.8 ± 1.0 K; critical composition X_C= 35.9 ± 0.4 at. % Na) are in good agreement with the data in the literature. The critical exponent β for the coexistence curve is 0.34 ± 0.004 in the range 1 · 10⁻³ < (T_C—T)/T_C < 5 · 10⁻². Mutual diffusion in a Li-=Na melt of near-critical composition is studied at temperatures of 583 to 998 K using the same technique. The behaviour of the interdiffusion coefficient is found not to obey the Arrhenius law at temperatures below 700 K. Darken’s relation is used to estimate the temperature dependence of the long-wave limit S_CC(0) of the Bhatia-Thornton concentration-concentration correlation function.

中文翻译：

---

液态锂钠合金中的相平衡和相互扩散

锂钠系统相图中的液-液共存线的形状是使用伽马射线衰减技术确定的。共存曲线的临界点的测量坐标（临界温度T _C = 576.8±1.0 K；临界组成X _C = 35.9±0.4 at。％Na）与文献中的数据高度吻合。共存曲线的临界指数β为0.34±0.004，范围为1·10 ^-3 <（T _C -T）/ T _C <5·10 ^-2。使用相同的技术，在583至998 K的温度下研究了近临界组成的Li- = Na熔体中的相互扩散。发现在700 K以下温度下互扩散系数的行为不遵守阿伦尼乌斯定律。使用Darken关系来估算Bhatia-Thornton浓度-浓度相关函数的长波极限S _CC（0）的温度依赖性。