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Magnesium-rich intermetallic compounds RE 3Ag4Mg12 (RE = Y, La–Nd, Sm–Dy, Yb) and AE 3Ag4Mg12 (AE = Ca, Sr)
Zeitschrift für Kristallographie - Crystalline Materials ( IF 1.2 ) Pub Date : 2022-09-16 , DOI: 10.1515/zkri-2022-0048 Maximilian Kai Reimann 1 , Steffen Klenner 1 , Josef Maximilian Gerdes 2 , Michael Ryan Hansen 2 , Rainer Pöttgen 1
Zeitschrift für Kristallographie - Crystalline Materials ( IF 1.2 ) Pub Date : 2022-09-16 , DOI: 10.1515/zkri-2022-0048 Maximilian Kai Reimann 1 , Steffen Klenner 1 , Josef Maximilian Gerdes 2 , Michael Ryan Hansen 2 , Rainer Pöttgen 1
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The magnesium-rich intermetallic compounds RE 3 Ag4 Mg12 (RE = Y, La–Nd, Sm–Dy, Yb) and AE 3 Ag4 Mg12 (AE = Ca, Sr) were synthesized from the elements in sealed tantalum ampoules through heat treatment in an induction furnace. X-ray powder diffraction studies confirm the hexagonal Gd3 Ru4 Al12 type structure, space group P 63 /mmc . Three structures were refined from single crystal X-ray diffractometer data: a = 973.47(5), c = 1037.19(5) pm, wR 2 = 0.0296, 660 F 2 values, 30 variables for Gd3 Ag3.82(1) Mg12.18(1) , a = 985.27(9), c = 1047.34(9) pm, wR 2 = 0.0367, 716 F 2 values, 29 variables for Yb3 Ag3.73(1) Mg12.27(1) and a = 992.41(8), c = 1050.41(8) pm, wR 2 = 0.0373, 347 F 2 values, 28 variables for Ca3 Ag3.63(1) Mg12.37(1) . Refinements of the occupancy parameters revealed substantial Ag/Mg mixing within the silver-magnesium substructure, a consequence of the Ag@Mg8 coordination. The alkaline earth and rare earth atoms build Kagome networks. Temperature dependent magnetic susceptibility measurements indicate diamagnetism/Pauli paramagnetism for the compounds with Ca, Sr, Y and YbII , while the others with the trivalent rare earth elements are Curie-Weiss paramagnets. Most compounds order antiferromagnetically at T N = 4.4(1) K (RE = Pr), 34.6(1) K (RE = Gd) and 23.5(1) K (RE = Tb) while Eu3 Ag4 Mg12 is a ferromagnet (T C = 19.1(1) K). 151 Eu Mössbauer spectra confirm divalent europium (δ = −9.88(1) mm s−1 ). Full magnetic hyperfine field splitting (18.4(1) T ) is observed at 6 K. Yb3 Ag4 Mg12 shows a single resonance in its 171 Yb solid state NMR spectrum at 6991 ppm at 300 K indicating a strong, positive Knight shift.
更新日期:2022-09-16