12434-24-1Relevant articles and documents
Hydrogen induced structure and property changes in Eu3Si4
Ek, Gustav,Nedumkandathil, Reji,Johansson, Robert,Montero, Jorge,Zlotea, Claudia,Andersson, Mikael S.,Nordblad, Per,Tang, Chiu,Sahlberg, Martin,H?ussermann, Ulrich
, p. 37 - 45 (2019)
Hydrides Eu3Si4H2+x were obtained by exposing the Zintl phase Eu3Si4 to a hydrogen atmosphere at a pressure of 30 bar and temperatures from 25 to 300 °C. Structural analysis using powder X-ray diffraction (PXRD)data suggested that hydrogenations in a temperature range 25–200 °C afford a uniform hydride phase with an orthorhombic structure (Immm, a ≈ 4.40 ?, b ≈ 3.97 ?, c ≈ 19.8 ?), whereas at 300 °C mixtures of two orthorhombic phases with c ≈ 19.86 and ≈ 19.58 ? were obtained. The assignment of a composition Eu3Si4H2+x is based on first principles DFT calculations, which indicated a distinct crystallographic site for H in the Eu3Si4 structure. In this position, H atoms are coordinated in a tetrahedral fashion by Eu atoms. The resulting hydride Eu3Si4H2 is stable by ?0.46 eV/H atom with respect to Eu3Si4 and gaseous H2. Deviations between the lattice parameters of the DFT optimized Eu3Si4H2 structure and the ones extracted from PXRD patterns pointed to the presence of additional H in interstitials also involving Si atoms. Subsequent DFT modeling of compositions Eu3Si4H3 and Eu3Si4H4 showed considerably better agreement to the experimental unit cell volumes. It was then concluded that the hydrides of Eu3Si4 have a composition Eu3Si4H2+x (x 2Eu3 interstitials. Eu3Si4 is a ferromagnet with a TC at about 120 K. Ferromagnetism is effectively quenched in Eu3Si4H2+x. The effective magnetic moment for both materials is 7.5 μB which is typical for compounds containing Eu2+ 4f7 ions.
The Zintl phase Eu2Si
Mishra, Ratikanta,Hoffmann, Rolf-Dieter,Poettgen, Rainer,Trill, Henning,Mosel, Bernd D.
, p. 741 - 744 (2002)
The Zintl phase Eu2Si was synthesized from elemental europium and silicon in a sealed tantalum tube in a high-frequency furnace at 1270 K and subsequent annealing at 970 K. Investigation of the sample by X-ray powder and single crystal techniques revealed: Co2Si (anti-PbCl2) type, space group Pnma, a = 783.0(1), b = 504.71(9), c = 937.8(1) pm, wR2 = 0.1193, 459 F2 values and 20 variables. The structure contains two europium and one silicon site. 151Eu Moessbauer spectroscopic data show a single signal at an isomer shift of -9.63(3) mm/s, compatible with divalent europium. Within the Zintl concept electron counting can be written as (2Eu2+)4+Si4-, in agreement with the absence of Si-Si bonding. Each silicon atom has nine europium neighbors in the form of a tri-capped trigonal prism. The silicon coordinations of the Zintl phases Eu2Si, Eu5Si3, EuSi, and EuSi2 are compared.
Structure-composition sensitivity in "Metallic" Zintl phases: A study of Eu(Ga1-xTtx)2 (Tt=Si, Ge, 0≤x≤1)
You, Tae-Soo,Zhao, Jing-Tai,Poettgen, Rainer,Schnelle, Walter,Burkhardt, Ulrich,Grin, Yuri,Miller, Gordon J.
, p. 2430 - 2442 (2009)
Two isoelectronic series, Eu(Ga1-xTtx)2 (Tt=Si, Ge, 0≤x≤1), have been synthesized and characterized by powder and single-crystal X-ray diffraction, physical property measurements, and electronic structure calculations. In
Interaction of the components in the systems Ce-Ag-Si at 500 °c and Eu-Ag-Si at 400 °c
Belan,Bodak,Gladyshevskii,Soroka,Kuzhel,Protsyk,Stets
, p. 212 - 216 (2008/10/09)
Isothermal sections of the phase diagrams of the systems Ce-Ag-Si and Eu-Ag-Si were built at 500 and 400 °C, respectively. Three intermetallic compounds were found in the former system, two in the latter and their crystal structures and homogeneity region
