Structural analysis of novel antiferromagnetic material CeRu₂Al₁₀ and its related compounds under pressure

We performed synchrotron X-ray studies of orthorhombic CeRu₂Al₁₀ and its related compounds CeT₂Al₁₀ (T = Fe, Os) and RRu₂Al₁₀ (R = La, Yb, Lu). The results of the X-ray studies indicate that all of the compounds retain their orthorhombic crystal structures and that their lattice parameters all monotonically decrease with pressure; that is, no structural changes or distortions occur below 10 GPa within the experimental accuracy of this study. In addition, we evaluated the bulk moduli of the compounds, which are mainly affected by the transition metal in RT₂Al₁₀ systems. All of the compounds exhibited crystal structures that were harder along the b-axis than along the a- or c-axes. Furthermore, anisotropic shrinkage induced a difference between the physical pressure of CeRu₂Al₁₀ and the chemical pressure of Ce(Ru_1-xFe_x)₂Al₁₀ (0 ≤ x ≤ 1). Thus, the physical properties of CeRu₂Al₁₀ under pressure were observed to be strongly affected by crystal structure shrinkage along the a- and c-axes. (author)