Synthetic Investigations in Borates, Borate Germanates, Gallium Oxonitrides, and Intermetallic Phases at Extreme Conditions

Multianvil Hochdruck-/Hochtemperatur Untersuchungen an Seltenerd Boraten, Borat Germanaten, Gallium Oxonitriden und Intermetallischen Phasen. Im Speziellen werden die neuen Borate alpha-Nd2B4O9, beta-Nd(BO2)3, delta-La,Ce(BO2)3 und Pr4B10O21 vorgestellt. Die Erweiterung des Systems durch Germanium führte zum neuen Borat Germanat Ce6(BO4)2Ge9O22. Im Bereich der Gallium Oxonitride konnte eine Spinell-Phase realisiert werden. Hochdruck-/Hochtemperatur Untersuchungen zeigten Phasenumwandlungen vom TiNiSi- und NdPtSb-Typ in den ZrNiAl-Typ bei Drücken von 7-14 GPa und 1000-1400 °C

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

An organometallic chimie douce approach to new Re(x)W(1-x)O3 phases

Re(x)W(1-x)O3.H2O and Re(x)W(1-x)O3 phases are prepared by a new organometallic chimie douce concept employing the organometallic precursor methyltrioxorhenium.Comment: 3 pages, 6 figures, submitted to Chem. Com

Single-Crystal Structure of HP-Sc₂TeO₆ Prepared by High-Pressure/High-Temperature Synthesis

The first high-pressure scandium tellurate HP-Sc2TeO6 was synthesized from an NP-Sc2TeO6 normal-pressure precursor at 12 GPa and 1173 K using a multianvil apparatus (1000 t press, Walker-type module). The compound crystallizes in the monoclinic space group P2/c (no. 13) with a = 729.43(3), b = 512.52(2), c = 1095.02(4) pm and β = 103.88(1)°. The structure was refined from X-ray single-crystal diffractometer data: R1 = 0.0261, wR2 = 0.0344, 568 F2 values and 84 variables. HP-Sc2TeO6 is isostructural to Yb2WO6 and is built up from TeO6 octahedra, typical for tellurate(VI) compounds. During synthesis, a reconstructive transition from P321 (normal-pressure modification) to P2/c (high-pressure modification) takes place and the scandium–oxygen distances as well as the coordination number of scandium increase. However, the coordination sphere around the Te6+ cations gets only slightly distorted. High-temperature powder XRD investigations revealed a back-transformation of HP-Sc2TeO6 to the ambient-pressure modification above 973 K

Single-Crystal Structure of HP-Sc2TeO6 Prepared by High-Pressure/High-Temperature Synthesis

The first high-pressure scandium tellurate HP-Sc2TeO6 was synthesized from an NP-Sc2TeO6 normal-pressure precursor at 12 GPa and 1173 K using a multianvil apparatus (1000 t press, Walker-type module). The compound crystallizes in the monoclinic space group P2/c (no. 13) with a = 729.43(3), b = 512.52(2), c = 1095.02(4) pm and β = 103.88(1)°. The structure was refined from X-ray single-crystal diffractometer data: R1 = 0.0261, wR2 = 0.0344, 568 F2 values and 84 variables. HP-Sc2TeO6 is isostructural to Yb2WO6 and is built up from TeO6 octahedra, typical for tellurate(VI) compounds. During synthesis, a reconstructive transition from P321 (normal-pressure modification) to P2/c (high-pressure modification) takes place and the scandium–oxygen distances as well as the coordination number of scandium increase. However, the coordination sphere around the Te6+ cations gets only slightly distorted. High-temperature powder XRD investigations revealed a back-transformation of HP-Sc2TeO6 to the ambient-pressure modification above 973 K

Trendbericht Festkörperchemie

Fein abgestimmte Elektrodenkomposite für Feststoffbatterien, Phosphidosilicate als Natriumionenleiter, Erbsenzählerei mit Nanopartikeln, hierarchische Kohlenstoffmaterialien aus metallorganischen Gerüststrukturen, phosphoreszierende Materialien und Neues aus der Hochdruckchemie

High-pressure/high-temperature synthesis of the new boron-rich terbium hydroxyborate Tb3B12O19(OH)7

Monoclinic Tb3B12O19(OH)7 was obtained by multianvil high-pressure/high-temperature syntheses at 6 GPa and 650 °C. The crystal structure was investigated by single-crystal X-ray diffraction methods and space group C2 (no. 5) with the unit cell parameters a = 24.2299(5) Å, b = 4.4667(1) Å, c = 7.0964(2) Å, β = 94.58(1)°, and two formula units per cell were revealed. Powder X-ray diffraction, infrared spectroscopy and the investigation of its second harmonic generation properties support the proposed structural model

Serendipitous formation and characterization of K-2[Pd(NO3)(4)]center dot 2HNO(3)

A potassium tetranitratopalladate(II) with the composition K-2[Pd(NO3)(4)]center dot 2HNO(3) was synthesized by a simple solvothermal process in a glass ampoule. The new compound crystallizes in the monoclinic space group P2(1)/c (no. 14) with the lattice parameters a = 1017.15(4), b = 892.94(3), c = 880.55(3) angstrom, and beta = 98.13(1)degrees (Z = 2). The crystal structure of K-2[Pd(NO3)(4)]center dot 2HNO(3) reveals isolated complex [Pd(NO3)(4)](2-) anions, which are surrounded by eight potassium cations and four HNO3 molecules. The complex anions and the cations are associated in layers which are separated by HNO3 molecules. K-2[Pd(NO3)(4)]center dot 2HNO(3) can thus be regarded as a HNO3 intercalation variant of beta-K-2[Pd(NO3)(4)]. The characterization is based on single-crystal X-ray and powder X-ray diffraction