Combined electrochemical and Mössbauer studies of the Sb3+/Sb5+ equilibrium in a silicate glass-forming melt

The antimony redox equilibrium in an oxide glass-forming melt has been studied quantitatively. Oxygen fugacities at various concentrations and temperatures have been measured electrochemically, and Sb3+/Sb5+ concentration ratios were determined by Mössbauer spectroscopy. Equilibrium constants K(T) and thermodynamie standard values are given for the redox reaction in the melt at temperatures between 1000 and 1500 °C. If K{T) is known, the progress of redox fining can be followed by measuring only the oxygen fugacity

Magnetic and Spectroscopic Properties of LiAuSn

The stannide LiAuSn was synthesized by reaction of the elements in a sealed tantalum tube. Magnetic susceptibility measurements reveal Pauli paramagnetism. LiAuSn shows a single 119 Sn Möss-bauer signal at an isomer shift of 2.12(3) mm/s subject to a quadrupole splitting of 1.51(2) mm/s. The 119 Sn MAS NMR spectrum reveals a strong Knight shift of 5183 ppm, The unique lithium site present in the crystal structure is reflected by a single 7 Li NMR signal at 9.8 ppm. While a significant shift of this resonance towards larger frequencies at higher temperature indicates that the s-spin density at the lithium sites increases with increasing temperatures, no motional narrowing occurs up to 470 K. This result indicates that the lithium ions are immobile on the NMR timescale within the temperature range observed

Chemical bonding in EuTGe (T=Ni, Pd, Pt) and physical properties of EuPdGe

International audienceEuPdGe was prepared from the elements by reaction in a sealed tantalum tube in a high-frequency furnace. Magnetic susceptibility measurements show Curie-Weiss behavior above 60 K with an experimental magnetic moment of 8.0(1)μB/Eu indicating divalent europium. At low external fields antiferromagnetic ordering is observed at TN=8.5(5) K. Magnetization measurements indicate a metamagnetic transition at a critical field of 1.5(2) T and a saturation magnetization of 6.4(1)μB/Eu at 5 K and 5.5 T. EuPdGe is a metallic conductor with a room-temperature value of 5000±500 μΩ cm for the specific resistivity. 151Eu Mössbauer spectroscopic experiments show a single europium site with an isomer shift of δ=−9.7(1) mm/s at 78 K. At 4.2 K full magnetic hyperfine field splitting with a hyperfine field of B=20.7(5) T is observed. Density functional calculations show the similarity of the electronic structures of EuPdGe and EuPtGe. T-Ge interactions (T=Pd, Pt) exist in both compounds. An ionic formula splitting Eu2+T0Ge2− seems more appropriate than Eu2+T2+Ge4− accounting for the bonding in both compounds. Geometry optimizations of EuTGe (T=Ni, Pt, Pd) show weak energy differences between the two structural types