EuPtAl has been prepared from the elements via arc-melting and subsequent temperature treatment; the structure was refined from single crystal X-ray diffraction data. The compound crystallizes in an orthorhombic (3 + 1)D commensurately modulated structure (ScPtAl type) with space group Cmcm(α,0,0)0 s0 (α = 2/3). Full ordering of the Pt and Al atoms within the [PtAl] polyanion was observed. Magnetic measurements revealed an anomaly in the susceptibility data at T = 41.6(1) K, which was also observed as λ-type anomaly in heat capacity measurements ( T = 40.7(1) K). Temperature dependent powder X-ray diffraction experiments indicated a drastic shortening of the c axis (-18 pm, -1.1%) around 45 K, while the a axis nearly remains the same (-1 pm, -0.2%). Measurements of the electrical resistivity verified the anomaly, indicating a clear change in the electronic structure of the material. The observed anomalies in the physical measurements can be explained by a temperature driven first order valence change from Eu at higher temperatures (>55 K) to Eu at low temperatures. This valence change was proven by temperature dependent Eu Mössbauer spectroscopic investigations. Isostructural EuPtGa was prepared in comparison, and it shows divalent Eu atoms down to 2.5 K along with antiferromagnetic ordering at T = 13.1(1) K.

Structural and property investigations of the five Zintl phases Eu5In2Pn6 and Eu3MAs3 (Pn = As–Bi; M = Al, Ga) including magnetic and 121Sb and 151Eu Mössbauer spectroscopic measurements.

The new equiatomic scandium transition metal aluminides ScTAl for T = Cr, Ru, Ag, Re, Pt, and Au were obtained by arc-melting of the elements followed by subsequent annealing for crystal growth. The samples were studied by powder and single crystal X-ray diffraction. The structures of three compounds were refined from single crystal X-ray diffractometer data: ScCrAl, MgZn2 type, P63/mmc, a = 525.77(3), c = 858.68(5) pm, R1 = 0.0188, wR2 = 0.0485, 204 F2 values, 13 variables, ScPtAl, TiNiSi type, Pnma, a = 642.83(4), b = 428.96(2), c = 754.54(5) pm, R1 = 0.0326, wR2 = 0.0458, 448 F2 values, 20 variables and ScAuAl, HfRhSn type, P6̅2c, a = 722.88(4), c = 724.15(4) pm, R1 = 0.0316, wR2 = 0.0653, 512 F2 values, 18 variables. Phase pure samples of all compounds were furthermore investigated by magnetic susceptibility measurements, and Pauli-paramagnetism but no superconductivity was observed down to 2.1 K for all of them. The local structural features and disordering phenomena have been characterized by 27Al and 45Sc magic angle spinning (MAS) and static NMR spectroscopic investigations.

Structural and property investigation of the new Zintl phase Eu5Al2Sb6including121Sb and151Eu Mössbauer spectroscopy and theoretical calculations.

The five ternary intermetallic compounds