New transition metal-rich rare-earth palladium/platinum aluminides with RET5Al2 composition: structure, magnetism and 27Al NMR spectroscopy

REPd5Al2 compounds with RE = Ce–Gd as well as Y and Lu have been previously synthesized. Although some compounds with the small lanthanides also exist, the compounds with intermediate-sized rare-earth elements (RE = Tb–Yb) had not been prepared. We report on the missing members of the REPd5Al2 (RE = Tb–Yb) series as well as on the new REPt5Al2 (RE = Y, Gd–Tm, Lu) series, which we have synthesized and structurally as well as magnetically characterized. All members crystallize isostructurally in the ZrNi2Al5 type with an anti-arrangement of the T = Pd/Pt and Al atoms. YPd5Al2 and LuPd5Al2, as well as the respective platinum homologs, YPt5Al2 and LuPt5Al2, have been characterized also by 27Al magic-angle spinning nuclear magnetic resonance spectroscopy. Consistent with the XRD analysis, the spectra indicate the existence of only one distinct Al site in the structure.