Cockburn James, Boston Rebecca
Materials Science and Engineering, Sir Robert Hadfield Building, University of Sheffield Sheffield UK
RSC Adv. 2019 Dec 11;9(70):40917-40923. doi: 10.1039/c9ra08744c. eCollection 2019 Dec 9.
Cold sintering is a sintering technique which enables ceramic powders to be densified at greatly reduced temperatures compared to traditional solid state techniques, which often require temperatures in excess of 1000 °C. These temperatures often preclude the exploitation of size or orientational effects in ceramics as these are lost during heating. One such effect is the orientation of the crystallographic axis in YBaCuO (YBCO) which can be controlled through applied pressure. This effect is of interest for increasing critical current density which is highly dependent on the orientation of the - (CuO) planes within the ceramic. Using cold sintering, we demonstrate that dense YBCO can be created at 180 °C ( 1000 °C using solid state) and demonstrate that the likely sintering mechanism is mediated by the cracking which occurs in YBCO when exposed to water. In addition, the ceramics produced show and retain the orientational effect, representing a unique opportunity to study the effect on critical current density. We show that the intergranular critical current when the - planes are parallel to the applied field is around 15% higher than when perpendicular.
冷烧结是一种烧结技术，与传统固态技术相比，它能使陶瓷粉末在大幅降低的温度下致密化，传统固态技术通常需要超过1000℃的温度。这些温度常常排除了对陶瓷中尺寸或取向效应的利用，因为这些效应在加热过程中会丧失。其中一种效应是YBaCuO（YBCO）中晶轴的取向，它可以通过施加压力来控制。这种效应对于提高临界电流密度很有意义，临界电流密度高度依赖于陶瓷内部 - （CuO）平面的取向。通过冷烧结，我们证明了可以在180℃下制备致密的YBCO（固态法需要1000℃），并证明了可能的烧结机制是由YBCO暴露于水时发生的开裂介导的。此外，所制备的陶瓷显示并保留了取向效应，这为研究其对临界电流密度的影响提供了独特的机会。我们表明，当 - 平面与外加磁场平行时，晶间临界电流比垂直时高出约15%。
