Pollucite structures present remarkable chemical stability and good corrosion resistance against the leaching medium, which renders them promising for the permanent disposal of radioactive ¹³⁷Cs. However, it is still challenging to prepare pollucite with dense structures and high immobilization performance at low temperature so far. Additionally, the fundamental understanding of the mechanism underlying the leaching behaviors of Cs⁺ from pollucite remains largely unexplored. In this paper, we realize the low-temperature production of pollucite by tailoring the nature of geopolymer precursors and employing B₂O₃ additives. It has been shown that the introduction of B₂O₃ not only significantly reduces the crystallization temperature of pollucite, but also improves the immobilization performance of Cs through encapsulation effect. Differential scanning calorimetry and X-ray diffraction confirm the formation of crystalline pollucite from amorphous geopolymer at ∼700 °C in the presence of 7.5 wt% B₂O₃. By further increasing the treatment temperature to 1000 °C, pollucite grains can be well-encapsulated by glass phase, exhibiting leaching rates ∼2 order lower than their unencapsulated counterparts. Moreover, distinct leaching mechanisms that govern the leaching behaviors of Cs⁺ from specimens being treated at different temperatures are unveiled. We anticipate that the proposed scheme facilitates the low-temperature production of high-quality pollucite structures with promising applications in the immobilization of hazardous wastes.

硅钙石结构具有出色的化学稳定性和对浸出介质的良好耐腐蚀性，这使其有希望永久性地处理放射性¹³⁷ Cs。然而，到目前为止，在低温下制备具有致密结构和高固定化性能的聚碳酸钙仍然是一个挑战。另外，对于从钙铝石中浸出Cs ^+的行为的机理的基本理解仍未得到开发。在本文中，我们通过调整地质聚合物前体的性质并使用B ₂ O ₃添加剂实现了低温生产方沸石。已经表明，引入了B ₂ O ₃不仅显着降低了钙长石的结晶温度，而且通过包封作用提高了铯的固定化性能。差示扫描量热法和X射线衍射证实在存在7.5wt％的B ₂ O ₃的情况下，在约700℃下由无定形地质聚合物形成了结晶的绿土。通过将处理温度进一步提高到1000°C，可以使玻璃态颗粒良好地包裹，与未包裹的相比，浸出率低约2个数量级。此外，控制Cs ⁺浸出行为的独特浸出机制揭开了在不同温度下处理过的标本的样本。我们预计，拟议的方案将有助于低温生产高质量的钙铝石结构，并在固定危险废物方面具有广阔的应用前景。