Abstract The data collected in the present work extend the measured phase diagram for palladium hydride and palladium deuteride to a region that has been sparsely reported in open literature. Absorption isotherms were measured using a 2.5-g bed of palladium powder at temperatures between 130 and 393 K and pressures less than 1.3 × 105 Pa. Such low-pressure and low-temperature measurements are useful for characterizing palladium beds used for tritium pumping and storage. For tritium storage, pressures are kept below a few millibars for safety reasons. Low temperatures increase the tritium storage capacity of palladium. The measured absorption isotherms show the well-documented, two-phase behavior for this system: two solubility regions and a mixed, hydride-forming region. The isotherms show that an increased quantity of hydride is formed at lower temperatures, as marked by an increase in the hydride-forming region. This region exceeds hydrogen-to-metal ratios of 0.75 for T ≤ 273 K. Equilibrium pressures in the mixed region decrease with decreasing temperatures until a critical temperature is reached for each isotope. Below these critical temperatures, the rate of pressure decrease with decreasing temperature is significantly reduced. This change in trend suggests hydrogen isotopes are adsorbed onto the palladium surface, rather than forming a hydride. Using the equilibrium pressures recorded at temperatures between 236 and 393 K for protium and between 211 and 354 K for deuterium, the van’t Hoff constants were calculated to be A = −36 ± 1 kJ/mol and B = 88 ± 3 J/K for protium and A = −32 ± 2 kJ/mol and B = 88 ± 9 J/K for deuterium. These constants agree favorably with literature in the range where the temperatures of the measured isotherms overlap.

中文翻译：

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测量 130 K 和 393 K 之间的氢化钯和氘化钯等温线

摘要 目前工作中收集的数据将氢化钯和氘化钯的测量相图扩展到公开文献中很少报道的区域。吸收等温线是使用 2.5 克钯粉床在 130 到 393 K 和小于 1.3 × 105 Pa 的压力下测量的。这种低压和低温测量对于表征用于氚泵和储存的钯床很有用. 对于氚储存，出于安全原因，压力保持在几毫巴以下。低温会增加钯的氚储存能力。测得的吸收等温线显示了该系统有据可查的两相行为：两个溶解区域和一个混合的氢化物形成区域。等温线表明在较低温度下形成的氢化物数量增加，这表现为氢化物形成区域的增加。对于 T ≤ 273 K，该区域超过了 0.75 的氢金属比。混合区域中的平衡压力随着温度的降低而降低，直到每个同位素达到临界温度。低于这些临界温度，压力随温度降低而降低的速率显着降低。这种趋势变化表明氢同位素吸附在钯表面上，而不是形成氢化物。使用在 236 到 393 K 之间的温度和 211 到 354 K 之间的氘和平衡压力记录的平衡压力，van't Hoff 常数计算为 A = -36 ± 1 kJ/mol 和 B = 88 ± 3 J/K（对于 protium）和 A = -32 ± 2 kJ/mol 和 B = 88 ± 9 J/K 对于氘。在测量的等温线的温度重叠的范围内，这些常数与文献一致。