Abrupt Change in Electronic States under Pressure in New Compound EuPt₃Al₅

Synthesis, magnetic and NMR spectroscopic properties of the MAl5Pt3 series (M = Ca, Y, La–Nd, Sm–Er)

“…All samples were prepared with the nominal composition of MAl 5 Pt 3 (M = Ca, Y, La–Nd, Sm–Er) in analogy to SrAl 5 Pt 3 , 39 EuAl 5 Pt 3 , 41 and CeAl 5 Pt 3 . 40 The powder X-ray diffraction patterns clearly indicate the formation of the title compounds as well as them being isostructural to their Sr/Eu/Ce analogues.…”

“…All members of the MAl 5 Pt 3 series crystallizes in the orthorhombic crystal system with space group Pnma ( oP 36, c 9 ) and are isostructural with the aluminum representatives CeAl 5 Pt 3 , EuAl 5 Pt 3 and SrAl 5 Pt 3 . 39–41 Besides the aluminum compounds also several gallium compounds MGa 5 Pt 3 (M = Ca–Ba, Eu) 44,45 have been reported, having the corresponding composition. These compounds, however, should not be considered isostructural to the prototypic YNi 5 Si 3 structure, 61 but rather isopointal.…”

“…The europium compound shows antiferromagnetic ordering and an interesting change in electronic states under pressure. 41 Since three compounds are known to crystallize in the same structure type, the question arose if other rare-earth or alkaline-earth members can be synthesized. Here we report that the series could be extended to Ca, Y and La–Nd as well as Sm–Er.…”

On the Ytterbium Valence and the Physical Properties in Selected Intermetallic Phases

“…48 A similar close relationship is known for Eu 2+ (117 pm) and Sr 2+ (118 pm). 43 Some examples are EuAl 2 Pt and SrAl 2 Pt (MgCuAl 2 type, space group Cmcm), 49 EuAl 5 Pt 3 50 and SrAl 5 Pt 3 51 (YNi 5 Si 3 type, space group Pnma), SrAu 3 Al 2 52 and EuAu 3 group C2/c), EuRh 2 In 8 58 and SrRh 2 In 8 59 (CeFe 2 Al 8 type, space group Pbam), EuPtSi and SrPtSi (LaIrSi type, space group Pnma), 60 or finally EuPt 2 Si 2 and SrPt 2 Si 2 (ThCr 2 Si 2 type, space group I4/mmm). 61 Besides the direct comparisons Sr 2+ /Eu 2+ and Ca 2+ /Yb 2+ , it is not always possible to directly compare an Eu(II) example and an Yb(II) example within one series of compounds, since (i) the structure type is not formed with both cations or (ii) the given ytterbium is trivalent.…”