Sesquioxides of rare earth elements crystalize into one or more of three crystal structures: hexagonal (type A, space group Pm1), monoclinic (type B, space group C2/m), or body-centered cubic (type C, space group Ia).
Sesquioxides of rare earth elements crystallize into one or more of three crystal structures: hexagonal (type A, space group P6125), monoclinic (type B, space group C2/c), or body-centered cubic (type C, space group Im3m).