Synthesis, magnetic and NMR spectroscopic properties of the MAl 5 Pt 3 series (M = Ca, Y, La-Nd, Sm-Er)

Following recent investigation in the ternary system Sr-Al-Pt led to the discovery of SrAl Pt which crystallizes in the orthorhombic YNi Si type ( ) structure. Interestingly, only two more aluminum representatives, CeAl Pt and EuAl Pt , have been reported to adopt this structure type. Therefore, we decided to investigate the existence range of compounds adopting the YNi Si type structure. Besides the already known Sr, Ce and Eu members, the series could be extended to Ca, Y and La-Nd as well as Sm-Er. All compounds were synthesized from the elements and characterized by powder X-ray diffraction. While for CaAl Pt and LaAl Pt also the respective M Al Pt members were observed, the other compounds could be obtained either as X-ray pure materials or with small amounts of Al Pt as a side phase. The structure of ErAl Pt could be refined from single crystal data, verifying that also the small rare-earth elements adopt the YNi Si type structure. Selected members of the series were furthermore characterized by magnetization and susceptibility measurements. Since YAl Pt could be obtained as a phase pure material and exhibits no paramagnetic behaviour it was investigated by Al MAS NMR investigations. Also, XPS measurements were conducted on this compound to gain an insight into the charge distribution. Finally, quantum-chemical calculations supported the NMR measurements and gave an insight into the chemical bonding and the charge distribution.