Similar doubled structures have been found in B 12 P 2 and in B 6 O , and have been named ʻnanotwinsʼ. (Fig. ) and ABA stacking (Fig. ). The AB 1 CD 1 AB 1 CD 1 structure is the result of shifting the even planes B and D in opposite <110> directions in the a 1 ,b 1 ,c 1 coordinates. The FFT image corresponding to the AB 1 CD 1 AB 1 CD 1 structure (Fig. ) is identified in the a 1 ,b 1 ,c 1 coordinates. The ABAB structure shown in Fig. corresponds to a double-spaced orthorhombic lattice with unit cell parameters: a = 1.005 nm, b = 0.529 nm, c = 0.948 nm for B 6 S and a = 1.025 nm, b = 0.534 nm, c=0.968 nm for B 6 Se (Fig. ).