| Zdroj: |
Green, D C, Boston, R, Glatzel, S, Lees, M R, Wimbush, S C, Potticary, J, Ogasawara, W & Hall, S R 2015, ' On the Mechanism of Cuprate Crystal Growth : The Role of Mixed Metal Carbonates ', Advanced Functional Materials, vol. 25, no. 29, pp. 4700–4707 . https://doi.org/10.1002/adfm.201501058 |
| Popis: |
The mechanism of formation of the superconductor Bi2Sr2CaCu2O8+x (Bi-2212) has been an open question since its discovery in 1988. By controlling crystal growth through the use of biopolymers as multivalent cation chelating agents, it is demonstrated through X-ray diffraction and thermogravimetric analysis, that it is the formation of a mixed metal carbonate eutectic that promotes the formation of the target phase. X-ray diffraction experiments, supported by infrared spectroscopy, identify this phase as (Sr1−x Ca x )CO3. This knowledge allows to further reduce the eutectic melting point by the incorporation of a biopolymer rich in potassium ions, resulting in the scalable formation of Bi-2212 at a temperature 50 °C lower than has been achieved previously. |
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