Abstract: A battery includes: an electrode group including an air electrode and a negative electrode that are stacked with a separator interposed therebetween; and a container housing the electrode group together with an alkaline electrolyte liquid. The air electrode includes a catalyst for an air secondary battery, and this catalyst for an air secondary battery includes a pyrochlore bismuth-ruthenium composite oxide having a full width at half maximum of a diffraction peak corresponding to a (222) face obtained by a powder X-ray diffraction method using CuK? rays as X-rays, of 0.350 deg or larger and 0.713 deg or smaller.

Abstract: A battery includes: an electrode group including an air electrode and a negative electrode that are stacked with a separator interposed therebetween; and a container housing the electrode group together with an alkaline electrolyte liquid. The air electrode includes a catalyst for an air electrode. This catalyst for an air electrode is a catalyst for an air electrode including an oxide containing at least bismuth (Bi), ruthenium (Ru), sodium (Na), and oxygen, and Na/(Ru+Bi+Na) representing an atomic ratio of the sodium to a sum of the bismuth, the ruthenium, and the sodium is 0.126 or more and 0.145 or less.

Abstract: A sliding component having excellent lubricity and a high recovery rate of a sealed fluid is provided. In a mechanical seal as a sliding component in which a plurality of spiral grooves serving as a plurality of dynamic pressure generation grooves extending from a low pressure side to a high pressure side are formed on a sliding surface of a stationary seal ring serving as any one sliding member in the mechanical seal, the sliding surface is provided with an annular groove serving as a recessed portion extending in a circumferential direction and opened to the low pressure side and the annular groove communicates with the spiral groove.