2𝑑 sin 𝜃 = 𝑛𝜆 (4) The layered crystals are connected to each other, and percolation of ZrP is formed. Table gives EDS results of the cross-section of the ZrP membrane, indicating that about 40 wt.% of the membrane is composed of O, P, and Zr atoms in the range of the image. In addition, the molar ratio of P and Zr is almost the same.