金刚石的低压金属助熔剂生长的热力学与动力学测试，及对立方氮化硼的拓展
Thermodynamic and Kinetic Tests for Low-Pressure Metal-Flux Growth of Diamond, with an Extension to Cubic Boron Nitride
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中文总结 AI 辅助
该研究探讨金刚石低压金属助熔剂生长的热力学与动力学条件，提出同位素分辨测试方法并拓展至立方氮化硼，为相关实验及模拟提供量化标准。
中文摘要 AI 辅助
金刚石可在近1大气压下从液态Ga-Fe-Ni-Si合金中生长，尽管在该条件下块状石墨在热力学上更稳定。本观点探讨了在这种亚稳 regime 中，金刚石生长前沿持续推进需满足的条件。我为特定界面事件定义了有限差传输自由能，确定了在扭折处完成单个碳原子附着是控制持续生长的可重复事件。在宏观极限下，表面项相互抵消，所需碳活度由金刚石的体自由能确定。在石墨归一化尺度上，1300K时金刚石平衡阈值约为2.0，而石墨饱和值为1。因此，金刚石生长需要在石墨阈值之上进行动力学选择，而非体相稳定性的逆转。该分析区分了热力学驱动力、动力学可达性、实验检测限及实验后残留的碳，提供了同位素分辨测试，用于区分持续金刚石生长与籽晶存活、瞬态碳附着或石墨未检测。13C富集的金刚石籽晶可对天然丰度气体或凝聚碳源进行测试：在原始籽晶外形成的结晶连续12C富集层，无需对每种进料进行同位素标记即可建立源自源的外延生长。相同的计算方法拓展至立方氮化硼，需分别考虑硼和氮的化学势，10B/11B及15N的对比可区分每种元素的储层供应与籽晶损失。所得标准使低压金属助熔剂生长的主张可量化测试，并为实验、热力学建模及原子模拟提供指导。
英文摘要
Diamond was grown from a liquid Ga-Fe-Ni-Si alloy near 1 atm, although bulk graphite is thermodynamically more stable under those conditions. This Perspective asks what must be true for a diamond growth front to continue advancing in such a metastable regime. I define a finite-difference transfer free energy for a specified interfacial event and identify the completed attachment of one carbon atom at a kink as the repeatable event that governs sustained growth. In the macroscopic limit, surface terms cancel, and the required carbon activity is fixed by the bulk free energy of diamond. On a graphite-normalized scale, the diamond equilibrium threshold is about 2.0 at 1300 K, whereas graphite saturation occurs at unity. Diamond growth therefore requires kinetic selection above the graphite threshold, not a reversal of bulk phase stability. The analysis distinguishes thermodynamic driving force, kinetic accessibility, experimental detection limits, and the carbon retained after an experiment. It gives isotope-resolved tests for distinguishing sustained diamond growth from seed survival, transient carbon attachment, or failure to detect graphite. A $^{13}\mathrm{C}$-enriched diamond seed provides a test of natural-abundance gas or condensed carbon sources: a registered, crystallographically continuous $^{12}\mathrm{C}$-rich layer outside the original seed can establish source-attributed overgrowth without isotopically labeling each feed. The same accounting is extended to cubic boron nitride. Separate boron and nitrogen chemical potentials are required, and $^{10}\mathrm{B}/^{11}\mathrm{B}$ and $^{15}\mathrm{N}$ contrasts could distinguish reservoir supply from seed loss for each element. The resulting criteria make low-pressure metal-flux growth claims quantitatively testable and guide experiments, thermodynamic modeling, and atomistic simulation.
