Maryam Choudhary Hexagonal ferrites are named with letters like M, Y, W, Z, X, and U based on their block stacking sequences within the hexagonal crystal lattice. The letter designation corresponds to a specific arrangement of structural "blocks" (denoted R, S, T, M, Y) that build up the unit cell.

The U in U-type hexaferrite specifically denotes its unique crystal stacking—composed of two M‑blocks plus one Y‑block (i.e., U = 2M + Y)—hence the letter assignment based on its structural sequence

The “U” in U-type hexaferrite refers to its unique crystallographic structure, specifically how structural blocks are stacked in the unit cell. Letters like U, M, W, etc., were chosen to systematically classify different hexaferrite structures — not randomly, and not based on alphabet sequence or chemistry.

you means U refers unique,it is not a satisfied answer

how the stacking sequance of 2M and 1Y represents the U?