Abstract
Crystal structures of CeB2C2 and NdB2C2 were investigated by means of neutron powder diffraction using 11B enriched samples. Diffraction patterns of Ce11B2C2 and Nd11B2C2 are very similar to each other, and Rietveld analyses reveal that the crystal structure belongs to a symmetry group of tetragonal P4/mbm, where the rare earth atoms occupy 2(a) sites and the B and C atoms occupy two 4(h) sites with different positional parameters. The newly determined structure differs from previously reported ones with P4/mbm and P{&overline; 4}2c mainly in the site positions occupied by the B and C atoms. The B and C atoms form network planes consisting of non-regular squares and octagons.
