Relationship between variation of Bi and O valence states in perovskite bismuthates Ba_1-xK_xBiO₃ (BKBO), grown in modified synthesis conditions, and their superconducting state properties is presented. Chemical composition, crystal structure and phase purity of BKBO was determined via micro X-ray fluorescence ($\mu$XRF), energy-dispersive X-ray spectroscopy (EDS) and X-ray powder diffraction technique (XRD). X-ray photoemission spectroscopy (XPS) and SQUID magnetometry showed variations of electronic structure and superconducting state properties, i.e., lower and upper critical fields, and transition temperature for the samples synthesized at various conditions. We report that, multiple valencies of bismuth, observed already in BKBO systems and assigned to disproportionation of bismuth valence states, lead in fact to deterioration of superconducting state properties.

提出了在改进的合成条件下生长的钙钛矿型铋酸盐Ba _1-x K _x BiO ₃（BKBO）中Bi和O价态变化之间的关系，以及它们的超导状态性质。BKBO的化学组成，晶体结构和相纯度通过微X射线荧光测定（$\mu$XRF），能量色散X射线光谱仪（EDS）和X射线粉末衍射技术（XRD）。X射线光电子能谱（XPS）和SQUID磁力仪显示了在各种条件下合成的样品的电子结构和超导状态特性（即上下临界场）和转变温度的变化。我们报告说，铋的多个价态已经在BKBO系统中观察到，并被分配给铋价态的歧化，实际上导致超导态性质的恶化。