Neodymium is one of the most sought-after rare earth elements (REE), as it is an essential component in permanent magnets used in wind turbines and electric motors that are needed to address the issue of climate change. In nature, the enrichment of Nd and other REE is frequently attributed to their transport and deposition by hydrothermal fluids. Although numerous studies have investigated the complexation of Nd with chloride, sulfate, and fluoride in hydrothermal fluids, a major knowledge gap is its behavior in carbonate-bearing fluids at elevated temperatures, which hinders our ability to predict the mobility of Nd in ore-forming hydrothermal systems. In this contribution, we evaluate the speciation of Nd in carbonate-bearing fluids under acidic (pH_T 2–4) and alkaline (pH_T 7.8–9.8) conditions using the autoclave solubility method at temperatures between 175 and 250 °C with synthetic Nd-hydroxylbastnäsite as the reference phase. We demonstrate that the predominant aqueous complexes are NdCO₃⁺ and NdCO₃OH⁰ under acidic and alkaline conditions, respectively. Our findings predict that carbonate species have the potential to be capable ligands for REE mobilization in hydrothermal fluids.

钕是最受欢迎的稀土元素 (REE) 之一，因为它是解决气候变化问题所需的风力涡轮机和电动机中使用的永磁体的重要组成部分。在自然界中，钕和其他稀土元素的富集通常归因于它们在热液中的迁移和沉积。尽管许多研究已经研究了热液中 Nd 与氯化物、硫酸盐和氟化物的络合，但一个主要的知识空白是它在高温下在含碳酸盐流体中的行为，这阻碍了我们预测 Nd 在成矿过程中的迁移率的能力水热系统。在这篇文章中，我们评估了酸性（pH _T 2-4）和碱性（pH _T7.8–9.8) 条件下使用高压釜溶解法在 175 和 250 °C 之间的温度下使用合成的 Nd-羟基硅碳酸盐作为参考相。我们证明了在酸性和碱性条件下，主要的水性配合物分别是 NdCO ₃ ⁺和 NdCO ₃ OH ^{0 。}我们的研究结果预测，碳酸盐物种有可能成为热液中 REE 流动的配体。