Synthesis, Structure, and Physical Properties of <i>Ln</i>(Cu,Al,Ga)_{13–<i>x</i>} (<i>Ln</i> = La–Pr, and Eu) and Eu(Cu,Al)_{13–<i>x</i>}

<i>Ln</i>(Cu,Al,Ga)_{13–<i>x</i>} (<i>Ln</i> = La–Pr, and Eu; <i>x</i> ∼ 0.2) were synthesized by a combined Al/Ga flux. Single crystal X-ray and neutron diffraction experiments revealed that these compounds crystallize in the NaZn₁₃ structure-type (space group <i>Fm</i>3̅<i>c</i>) with lattice parameters of <i>a</i> ∼ 12 Å, <i>V</i> ∼ 1600 Å, and <i>Z</i> ∼ 8. Our final neutron models led us to conclude that Cu is occupationally disordered on the 8<i>b</i> Wyckoff site while Cu, Al, and Ga are substitutionally disordered on the 96<i>i</i> Wyckoff site of this well-known structure-type. The magnetic susceptibility data show that Ce­(Cu,Al,Ga)_{13–<i>x</i>} and Pr­(Cu,Al,Ga)_{13–<i>x</i>} exhibit paramagnetic behavior down to the lowest temperatures measured while Eu­(Cu,Al,Ga)_{13–<i>x</i>} displays ferromagnetic behavior below 6 K. Eu­(Cu,Al)_{13–<i>x</i>} was prepared via arc-melting and orders ferromagnetically below 8 K. The magnetocaloric properties of Eu­(Cu,Al,Ga)_{13–<i>x</i>} and Eu­(Cu,Al)_{13–<i>x</i>} were measured and compared. Additionally, an enhanced value of the Sommerfeld coefficient (γ = 356 mJ/mol-K²) was determined for Pr­(Cu,Al,Ga)_{13–<i>x</i>}. Herein, we present the synthesis, structural refinement details, and physical properties of <i>Ln</i>(Cu,Al,Ga)_{13–<i>x</i>} (<i>Ln</i> = La–Pr, and Eu) and Eu­(Cu,Al)<sub>13–<i>x</i>