Hydrothermal synthesis of superconductors Ba1−xKxBiO3 and double perovskites Ba1−xKxBi1−yNayO3

Superconducting Double Perovskite Bismuth Oxide Prepared by a Low‐Temperature Hydrothermal Reaction

“…[10] For this report, no description of the bismuth valence in the product was reported. However, previous reports on the preparation of double perovskite compounds, Ba 1-x K x Bi 1-y Na y O 3 , by a hydrothermal reaction at 180 8C did not show any superconductivity.…”

“…There is another report on the hydrothermal synthesis of a double perovskite with the structure Ba 1-x K x Bi 1y Na y O 3 . [10] However, no crystal structural refinement was performed; it also does not show any superconducting transition, even at temperatures as low as 2 K. Therefore, detailed investigation is necessary to understand the effect of the synthesis conditions and crystal structures on the emergence of superconductivity in Bi-based double perovskite oxides.…”

“…Thus, we cannot deny the possibility that Na and/or K occupy not only the A site, but also the B site, especially for synthesized products from higher Ba/Bi molar ratios. [10] In addition, the iodometric titration results suggest that both Bi 5+ and Bi 3+ are present in the synthesized compounds. The average Bi valence increases from 4.35 to 4.70 with an increase in the Ba/Bi molar ratio of the starting materials.…”

“…[3,[17][18][19] On the other hand, the double perovskite structure was formed by hydrothermal synthesis using Na in the starting materials. [9,10] These reported double perovskites contain either H 2 O or Na in the structure, which is consistent with our experimental results; Na was present in the starting materials and detected in the final products. The formation of double perovskite structures may be related to the different ionic and molecular radii of the components.…”

(Li1−xFex)OHFeSe Superconductors: Crystal Growth, Structure, and Electromagnetic Properties

“…This method is available for preparing novel SCs, such as Ba1−xKxBiO3 [79], Ba1−xKxBi1−yNayO3 [79], BaPd1−xBixO3 [80], and La2CuO4+y [81]. Recently, the hydrothermal growth of (Li1−xFex)OHFeSe single crystals has been reported [53].…”