Crystal structure data of the high-pressure polymorph were determined at 2.98(6) and 4.88(6) GPa. The monoclinic α-phase (space group C 2/ c ) undergoes a second-order ferroelastic phase transition at P c = 2.40(3) GPa to a triclinic β-phase (space group P 1 ‾ $‾ $ ).
#3d world magazine 113 pdf full
In the magnetically ordered state Eu 3 Pt 4 Zn 12 shows full magnetic hyperfine field splitting (23.0(1) T). The divalent ground state of Eu 3 Pt 4 Zn 12 is further confirmed by 151 Eu Mössbauer spectroscopy with an isomer shift of −9.66(2) mm s −1 at 78 K. The 3 K magnetization isotherms tend toward Brillouin type behavior with increasing europium dilution. The europium containing samples of the solid solution Eu 3− x Sr x Pt 4 Zn 12 are Curie–Weiss paramagnets and the experimental magnetic moments manifest stable divalent europium. Besides the Eu/Sr mixing within the solid solution, the structure refinements indicated small homogeneity ranges induced by Pt/Zn mixing. The striking building units in these phases are the kagome networks occupied by the europium and strontium atoms and 8 and 8 distorted cubes. The new compounds are isotypic with Gd 3 Ru 4 Al 12, space group P 6 3 / mmc. All samples were characterized by powder X-ray diffraction and the structures of Sr 3 Pt 3.93 Zn 12.07, Eu 1.80 Sr 1.20 Pt 4 Zn 12 and Eu 3 Pt 3.68 Zn 12.32 were refined from single crystal X-ray diffractometer data. Samples with x = 0, 0.5, 1, 1.5, 2, 2.5 and 3 were synthesized from the elements in sealed tantalum ampoules in an induction furnace.
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The 151 Eu isomer shifts show a linear correlation with the valence electron count for the whole series of Eu T Mg 2, Eu T Cd 2, Eu T In 2 and Eu T Sn 2 phases.Įu 3 Pt 4 Zn 12 and Sr 3 Pt 4 Zn 12 form a complete solid solution Eu 3− x Sr x Pt 4 Zn 12. The stable antiferromagnetic ground states are substantiated by metamagnetic transitions. Antiferromagnetic ordering sets in at 20.2 (EuIrMg 2 ), 22.3 (EuPdMg 2 ), 21.3 (EuAgMg 2 ), 10.9 (EuPdCd 2 ) and 15.5 K (EuPtCd 2 ), respectively. Temperature dependent magnetic susceptibility and 151 Eu Mössbauer spectroscopic measurements indicate stable divalent europium.
The striking crystal chemical motif of both series of compounds are networks of puckered Mg(Cd) hexagons in ABAB stacking sequence that derive from the aristotype AlB 2 however, with different tiling. Eu T Mg 2 ( T = Pd, Ag, Pt, Au) and Eu T Cd 2 ( T = Pd, Pt, Au) crystallize with the MgCuAl 2 type, space group Cmcm, while EuRhMg 2, EuIrMg 2 and CaRhMg 2 adopt the YSiPd 2 type, space group Pnma. The samples were characterized by powder X-ray diffraction and the structures were refined from single crystal X-ray diffractometer data.
The magnesium- and cadmium-rich intermetallic phases Eu T Mg 2 ( T = Rh, Pd, Ag, Ir, Pt, Au), Eu T Cd 2 ( T = Pd, Pt, Au) and CaRhMg 2 were synthesized from the elements in sealed niobium or tantalum ampoules and with heat treatments in muffle or induction furnaces.
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