T. Onimaru et al., Neutron powder diffraction on (CeB2C2)-B-11 and (NdB2C2)-B-11: A new modelfor the tetragonal crystal structure, J PHYS JPN, 68(7), 1999, pp. 2287-2291
Crystal structures of CeB2C2 and NdB2C2 were investigated by means of neutr
on powder diffraction using B-11 enriched samples. Diffraction patterns of
(CeB2C2)-B-11 and (NdB2C2)-B-11 are very similar to each other, and Rietvel
d 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/m
bm and P (4) over bar 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 s
quares and octagons.