Abstract Densification of ZnO-PTFE (polytetrafluoroethylene) composites is permitted by the Cold Sintering Process, having no effect on the stability of both materials. Highly dense samples can be obtained by this technique at extremely low temperatures in just a few minutes. Interestingly, the obtained samples show an anisotropy impacting: crystalline, microstructural and electrical properties. While the Wurztite ZnO crystals show a preferential growth along (00l) direction, microstructure observations show a grain growth along the in-plane (perpendicular to pressure application direction) up to 240%. Electrical conductivity is also influenced and is related to microstructure. In this situation, the addition of PTFE insulating phase allows to increase the conductivity in plane compared to the pure cold sintered ZnO sample. A mechanism is proposed to explain this phenomenon which involves PTFE transient distribution competing with the transient liquid driving densification and grain growth associated with cold sintering. This is further confirmed by the observation of a curvature of microstructure direction while approaching die edges. These observations offer a large variety of designs for further orientation driven properties.

中文翻译：

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ZnO-PTFE 的冷烧结：利用聚合物相促进陶瓷各向异性晶粒生长

摘要 冷烧结工艺允许 ZnO-PTFE（聚四氟乙烯）复合材料致密化，这对两种材料的稳定性没有影响。通过这种技术，只需几分钟即可在极低的温度下获得高密度样品。有趣的是，获得的样品显示出各向异性影响：结晶、微观结构和电性能。虽然纤锌矿 ZnO 晶体显示出沿 (00l) 方向的优先生长，但微观结构观察显示沿面内（垂直于压力施加方向）的晶粒生长高达 240%。电导率也受到影响并且与微观结构有关。在这种情况下，与纯冷烧结 ZnO 样品相比，添加 PTFE 绝缘相可以提高平面电导率。提出了一种机制来解释这种现象，它涉及 PTFE 瞬态分布与瞬态液体驱动致密化和与冷烧结相关的晶粒生长竞争。通过在接近模具边缘时观察微观结构方向的曲率进一步证实了这一点。这些观察结果为进一步的定向驱动特性提供了多种设计。