Nowotny chimney ladder compounds in Nd1+EFe4−xCoxB4

Structural investigations on Nd_1+EFe_4−xCo_xB₄ show the presence of distinct new phases with multiplicative c axis extensions (ladder compounds) and limited homogeneous range. We also report on compoundsR_1+EFe₄B₄ (R = rare earth) for which several new representatives (e.g., with R = La and Lu) are described. The ladder compounds in both substitutional series appear related and a common sequence as a function of composition is suggested. As an example the first new ladder type Nd_1.06Fe_1.5Co_2.5B₄ to develop out of NdCo₄B₄ is similar to La_1.06Fe₄B₄ and the third namely Nd_1.09Fe₃CoB₄ resembles Pr_1.10Fe₄B₄.