Ce4Ag3Ge4O0.5 - chains of oxygen-centered OCe2Ce2/2] tetrahedra embedded in a CeAg3Ge4] intermetallic matrix

The oxidation of an intermetallic phase under high-pressure/high-temperature conditions led to the synthesis of Ce4Ag3Ge4O0.5 exhibiting OCe2Ce2/2] tetrahedral chains, in which the oxygen atoms statistically occupy the tetrahedral centres. Starting from a 1 : 1 : 1 CeAgGe precursor (NdPtSb type), a multianvil high-pressure/high-temperature experiment at 11.5 GPa and 1250-1300 degrees C revealed Ce4Ag3Ge4O0.5, crystallizing in the space group Pnma with the following lattice parameters: a = 2087.3(4), b = 439.9(1), and c = 1113.8(2) pm. Magnetic measurements showed Curie-Weiss behavior above 100 K with an experimental magnetic moment of 2.42 mu B per Ce atom, close to the value for the free Ce3+ ion, clearly indicating trivalent cerium in Ce4Ag3Ge4O0.5. Full potential GGA+U band structure calculations resulted in metallic properties and a magnetic ground state with one unpaired 4f-electron per cerium in agreement with the experiments

Structure and chemical bonding of PrRuSn

The new ternary stannide PrRuSn was synthesized from the elements via arc-melting. PrRuSn is isopointal to the orthorhombic TiNiSi-type structure, space group Pnma. The structure was characterized by X-ray powder and single crystal diffraction: a = 761.7(2), b = 483.9(2) and c = 730.3(3) pm, wR2 = 0.0386, 433 F2 values, 20 variables. The ruthenium and tin atoms in PrRuSn build up a three-dimensional [RuSn] polyanionic network with Ru–Sn distances in the range 268 – 274 pm. The praseodymium atoms fill channels within the polyanion. They bind to the network via short Pr–Ru distances of301 and 302 pm. Electronic structure calculations on PrRuSn and isopointal PrPdSn underline these features and reveal strong T–Sn (T = Ru, Pd) interactions within both solid state structures

Structure and chemical bonding of PrRuSn

The new ternary stannide PrRuSn was synthesized from the elements via arc-melting. PrRuSn is isopointal to the orthorhombic TiNiSi-type structure, space group Pnma. The structure was characterized by X-ray powder and single crystal diffraction: a = 761.7(2), b = 483.9(2) and c = 730.3(3) pm, wR2 = 0.0386, 433 F2 values, 20 variables. The ruthenium and tin atoms in PrRuSn build up a three-dimensional [RuSn] polyanionic network with Ru–Sn distances in the range 268 – 274 pm. The praseodymium atoms fill channels within the polyanion. They bind to the network via short Pr–Ru distances of301 and 302 pm. Electronic structure calculations on PrRuSn and isopointal PrPdSn underline these features and reveal strong T–Sn (T = Ru, Pd) interactions within both solid state structures

Cerium valence change in the solid solutions Ce(Rh1−xRux)Sn

The solid solutions Ce(Rh1−xRux)Sn were investigated by means of susceptibility measurements, specific heat, electrical resistivity, X-ray absorption spectroscopy (XAS), and 119Sn Mössbauer spectroscopy. Magnetic measurements as well as XAS data show a cerium valence change in dependence on the ruthenium content. Higher ruthenium content causes an increase from 3.22 to 3.45 at 300 K. Furthermore χ and χ−1 data indicate valence fluctuation for cerium as a function of temperature. For example, Ce(Rh0.8Ru0.2)Sn exhibits valence fluctuations between 3.42 and 3.32 in the temperature range of 10 to 300 K. This could be proven by using the interconfiguration fluctuation (ICF) model introduced by Sales and Wohlleben. Cerium valence change does not influence the tin atoms as proven by 119Sn Mössbauer spectroscopy, but it influences the electrical properties. Ce(Rh0.9Ru0.1)Sn behaves like a typical valence fluctuating compound, and higher ruthenium content causes an increase of the metallic behavior

Trivalent-intermediate valent cerium ordering in CeRuSn - A static intermediate valent cerium compound with a superstructure of the CeCoAl type

New equiatomic stannide CeRuSn was synthesized from the elements by arc-melting. CeRuSn was investigated by X-ray powder and single crystal diffraction..