Structure and Properties of Yb3Ge5

Single crystals of Yb₃Ge₅, grown from pure gallium or indium metal flux and investigated by means of CCD four-circle diffractometry, were consistent with the Th₃Pd₅-type of structure, displaying full order of vacancies and germanium atoms. From magnetic susceptibility and electrical resistivity measurements, performed on single-crystalline specimens, Yb₃Ge₅ was found to be an intermediate valent systems.     

A constitutional diagram of the system VC0.88−HfC0.98−WC

The system VC_0.88–HfC_0.98–WC was investigated by means of melting point, differential-thermoanalytical, X-ray diffraction and metallographic techniques on hot pressed and heat treated as well as melted alloy specimens and a complete constitutional diagram from 1500°C through the melting range established.The phase behaviour within VC_0.88–HfC_0.98–WC is characterized by the presence of a large (binary) miscibility gap within VC–HfC (T _crit.,hypo.=3000°C). Additions of WC decrease the miscibility gap in the ternary. Interaction of the solvus (boundary of the cubic-B1 monocarbide solution) and the ternary miscibility gap was established at 2075°C and (VC)_0.17(HfC)_0.37(WC)_0.46: On cooling below 2075°C alloys of this composition enter a decomposition reaction into two isotypic cubic B1 phases and hexagonal WC.Solid state and melting behaviour was established within the isopleths VC_0.88–WC and VC_0.88–HfC_0.98 as well as within (V_0.8W_0.2)C–(Hf_0.8W_0.2)C and WC–(V_0.38Hf_0.62)C. The isopleth VC_0.88–HfC_0.98 intersects the four phase plane of the ternary V–Hf–C euctetic [2580±10°C, (VC)_0.78(HfC)_0.22]. Originating at the VC–HfC binary this eutetic trough proceeds into the VC–HfC–WC ternary with raising temperatures connecting the maximum critical point of the disappearing miscibility gap [(VC)_0.35(HfC)_0.51(WC)_0.14] by a limiting tie line (2830±20°C).Isothermal sections have been calculated assuming regular solutions.With 9 Figures     

Ternäre Komplexboride mit ThMoB4-Typ

Ternary complex borides of formulaMM′B₄ ^* have been prepared within the system Th—{V, Mo, W, Re}—B. The crystal structure of these compounds has been determined by means of single crystal photographs of the compounds ThMoB₄ and ThWB₄. ThVB₄, ThMoB₄, ThWB₄, ThReB₄ were found to be isotypic. The relationship to the crystal chemistry of boron layer structures such as AlB₂, YCrB₄, and Y₂ReB₆ will be discussed.     

Development and validation of a sandwich ELISA for the determination of potentially allergenic sesame (Sesamum indicum) in food

This paper presents a sandwich enzyme-linked immunosorbent assay (ELISA) that allows the determination of traces of sesame in food. Chicken anti-sesame antibodies, used as coating antibodies, and rabbit anti-sesame antibodies, used as secondary antibodies, were prepared by immunization with a protein extract of white, peeled sesame. The ELISA did not show any cross-reactivity with 19 food ingredients commonly found in sesame-containing foodstuffs such as seeds, nuts, and cereals. In whole grain bread, crisp toast, and snacks, the limit of detection (S/N = 3) was 0.5, 0.5, and 0.3 μg sesame protein/g, and the limit of quantification (S/N = 10) was 0.6, 0.8, and 1.4 μg sesame protein/g, respectively. The analysis of blank food matrices (whole grain bread, white bread, crisp toast, and snacks) spiked with sesame protein at four spike levels generally resulted in mean recoveries from 72% to 145%. In the case of spiking blank food matrices with sesame seeds, the ELISA proved to be more accurate for whole wheat cookies than for whole wheat bread.     

The clathrate Ba8CuxGe46−x−y□y: Phase equilibria and crystal structure

Phase relations at 700 °C, 800 °C and solidus temperatures have been derived for the clathrate system Ba₈Cu_xGe_46−x−y□_y via X-ray single crystal and powder diffractometry combined with electron probe micro analysis and differential thermal analysis. The ternary clathrate phase derives from binary Ba₈Ge₄₃□₃ and extends up to x=6. Structure investigations define cubic primitive symmetry with the space group type consistent with a clathrate type I structure throughout the entire homogeneity region 0<x?6 but defect-free Ba₈Cu_xGe_46−x exists for x?5.5.     

Radiation annealing studies in ion bombarded MgO

Abstract

The energy distributions of convoy electrons produced at glancing angle incidence of fast ions are studied with Classical Trajectory Monte Carlo (CTMC) calculations. The image potentials both of the ion and of the convoy electron are taken into account. For light ions, the acceleration of the convoy electron by the ion's image potential is depressed by the image potential of the convoy electron, while for heavy ions this effect is negligible.     

Skutterudites,a most promising group of thermoelectric materials

The current review summarizes and discusses the latest research activities (after 2014) on p- and n-type skutterudite thermoelectrics.     

Physical properties of skutterudites YbxM4Sb12, M = Fe, Co, Rh, Ir

A series of compounds , , were synthesised by reaction sintering. From Rietveld refinements isotypism was determined in all cases with the -(skutterudite)-type, space group - No. 204. These refinements also served to derive the Yb-content in the samples. There is a systematic trend for the Yb-occupancy in the parent lattice , revealing a gradual decrease of the Yb-content from x =0.8 (), x =0.5 (FeCo), x =0.2 (Co), x =0.1 (Rh) to (Ir). This dependency seems to correlate with the thermal stability of the ternary compounds: a true ternary compound forms for , whilst for stable binary skutterudite compounds already exist. Measurements of various bulk properties revealed the absence of any long range magnetic order in this series of compounds. While the samples rich in Yb behave metallic like, the Rh and Ir based skutterudites show a semiconducting-like resistivity which at lower temperatures is characterised by variable range hopping in the presence of strong Coulomb interaction. Although exhibits a Seebeck coefficient up to about 150 μV/K, figures of merit ZT generally are below 0.1 near room temperature, primarily due to the large resistivities of the sintered material. Received 15 July 1999