Cold sintering process (CSP) has attracted great interest due to its extremely low processing temperatures, fast processing times, and simplicity to allow for the densification of ceramics and composites. Understanding the detailed mechanisms underlying low temperature densification is crucial to develop advanced materials and facilitate sustainable and cost‐effective industrial implementation to come. Here, by taking BaTiO₃ powder and Sr(OH)₂·8H₂O transient chemical flux as a model system, chemical transformation at solid/flux interfaces driving the dissolution‐precipitation creep mechanism were investigated. We demonstrate that Sr(OH)₂·8H₂O acts both as a sintering flux and a solid solution doping additive, resulting in the formation of BaTiO₃ ‐ Ba_1‐xSr_xTiO₃ with lower Curie temperatures. Using strontium (Sr) as a tracer chemistry, transmission electron microscopy chemical mapping with energy‐dispersive X‐ray analysis indicates that there is a precipitation of a Ba_1‐xSr_xTiO₃ mainly at grain/grain interfaces, while grain cores remain undoped. In addition, the difference in the interfacial Sr concentration, which is influenced by the applied uniaxial pressure direction, was clearly observed. This successful visualization of compositional distribution after CSP underlines the significant role of the pressure solution creep in densification process.

中文翻译：

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BaTiO3的原位掺杂及助熔冷烧结压力溶液的可视化

冷烧结工艺（CSP）由于其极低的加工温度，快速的加工时间以及简化陶瓷和复合材料的致密性而引起了人们的极大兴趣。了解低温致密化的详细机制对于开发先进材料和促进可持续且具有成本效益的工业实施至关重要。在此，以BaTiO ₃粉末和Sr（OH）₂ ·8H ₂ O瞬态化学通量为模型系统，研究了固溶通量界面上的化学转化驱动溶解-沉淀蠕变机理。我们证明了Sr（OH）₂ ·8H ₂O既充当烧结助熔剂，又充当固溶体掺杂添加剂，从而在较低居里温度下形成BaTiO ₃ -Ba _{1 x} Sr _x TiO ₃。使用锶（Sr）作为示踪剂化学物质，透射电子显微镜化学图谱和能量色散X射线分析表明，Ba _{1 x x} Sr _x TiO ₃沉淀主要在晶粒/晶粒界面处，而晶粒核心保持未掺杂。另外，清楚地观察到界面Sr浓度的差异，该差异受所施加的单轴压力方向的影响。CSP后这种成分分布的成功可视化强调了压力溶液蠕变在致密化过程中的重要作用。