O.L. Sologub

Bio: O.L. Sologub is an academic researcher from Moscow State University. The author has contributed to research in topics: Crystal structure & Tetragonal crystal system. The author has an hindex of 5, co-authored 8 publications receiving 73 citations.

Chapter 173 Ternary rare-earth-germanium systems

Abstract: Publisher Summary This chapter reviews the current knowledge concerning the phase diagrams and crystal structures of ternary metal germanides with the R elements. It describes the isothermal sections and crystallographic characteristics of ternary compounds and outlines the experimental methods that have been utilized. While no phase diagram is available for the Ce–Ga–Ge system, the X-ray phase analysis of 180 ternary alloys indicated the formation of four ternary compounds in the Ce–Ga–Ge system. No phase diagram has been constructed for the ternary Ho–A1–Ge system; however, data on the formation and crystal structure of three compounds exist because of the independent investigations of research groups from L’viv University and Geneva University.

Unique Magnetic Phases in an Antiferromagnet CeCoGe3

Abstract: We report on the magnetic properties of CeCoGe 3 by measuring the electrical resistivity, magnetic susceptibility, magnetization and specific heat, together with the magnetic properties of a reference compound LaCoGe 3 . The measurements were performed on a single crystal grown from a high-temperature solution using a third element, bismuth as flux. From the magnetic susceptibility and magnetization measurements, CeCoGe 3 is an antiferromagnet with a Neel temperature T N1 =21 K and undergoes two successive transitions T N2 =12 K and T N3 =8 K. The magnetization for H ∥[001] indicated a metamagnetic transition with three steps. We constructed a magnetic phase diagram from the magnetization measurements, which is very complex and is roughly similar to the previous result performed on a polycrystalline grain-aligned sample.

Low-Temperature Magnetic Properties of Several Compounds in Ce-Pd-X (X=Si, Ge and Al) Ternary Systems

Abstract: We have investigated several ternary compounds of cerium in the Ce-Pd-X (X=Si, Ge and Al) systems and their La counterparts by measuring the magnetic susceptibility, electrical resistivity and specific heat. The Ce ions in these compounds are in the nearly trivalent state and most of them show magnetic order of either long-range or spin-glass type at low temperatures. None of them distinctly exhibits the heavy fermion behavior, although it may be obscured by atomic disorder in some compounds. The relation between several isostructural ternary compounds of Ce-Pd-(Si and Ge) or Ce-Pd-(Al and Ga) system is qualitatively discussed in the framework of the Doniach phase diagram. The variation of the unit cell volume suggests that the former group is consistent with this phase diagram but the latter is not seemingly so. We found that LaPdSi 3 and LaPd 0.6 Ge 1.4 among the La counterparts are superconducting below 2.6 and 2.8 K, respectively.

Chapter 174 Crystal structures and crystal chemistry of ternary rare-earth germanides

Abstract: Publisher Summary This chapter reviews ternary R–M–Ge systems that have been studied over the entire concentration region but only partly investigated. The character of interaction in these systems varies, and major differences are seen in the number of ternary germanides observed within the investigated concentration range. The chapter describes the structure types and the crystal chemistry of the ternary (quaternary) germanides of the rare-earth metals. The known structures of the germanides belong to 135 structure types. As R and Ge are components with much different crystallochemical properties, the deciding factor that affects the formation, composition, and structure is the nature of the third component in the systems. The main reason for the formation of a large number of ternary compounds in the R–M–Ge systems (M = s or d element) is the presence of components with significantly different crystallochemical properties.

Polar-Covalent Bonding Beyond the Zintl Picture in Intermetallic Rare-Earth Germanides.

Abstract: A comparative chemical bonding analysis for the germanides La2 MGe6 (M=Li, Mg, Al, Zn, Cu, Ag, Pd) and Y2 PdGe6 is presented, together with the crystal structure determination for M=Li, Mg, Cu, Ag. The studied compounds adopt the two closely related structure types oS72-Ce2 (Ga0.1 Ge0.9 )7 and mS36-La2 AlGe6 , containing zigzag chains and corrugated layers of Ge atoms bridged by M species, with La/Y atoms located in the biggest cavities. Chemical bonding was studied by means of the quantum chemical position-space techniques QTAIM (quantum theory of atoms in molecules), ELI-D (electron localizability indicator), and their basin intersections. The new penultimate shell correction (PSC0) method was introduced to adapt the ELI-D valence electron count to that expected from the periodic table of the elements. It plays a decisive role to balance the Ge-La polar-covalent interactions against the Ge-M ones. In spite of covalently bonded Ge partial structures formally obeying the Zintl electron count for M=Mg2+ , Zn2+ , all the compounds reveal noticeable deviations from the conceptual 8-N picture due to significant polar-covalent interactions of Ge with La and M ≠ Li, Mg atoms. For M=Li, Mg a formulation as a germanolanthanate M[La2 Ge6 ] is appropriate. Moreover, the relative Laplacian of ELI-D was discovered to reveal a chemically useful fine structure of the ELI-D distribution being related to polyatomic bonding features. With the aid of this new tool, a consistent picture of La/Y-M interactions for the title compounds was extracted.

Chapter 173 Ternary rare-earth-germanium systems

Abstract: Publisher Summary This chapter reviews the current knowledge concerning the phase diagrams and crystal structures of ternary metal germanides with the R elements. It describes the isothermal sections and crystallographic characteristics of ternary compounds and outlines the experimental methods that have been utilized. While no phase diagram is available for the Ce–Ga–Ge system, the X-ray phase analysis of 180 ternary alloys indicated the formation of four ternary compounds in the Ce–Ga–Ge system. No phase diagram has been constructed for the ternary Ho–A1–Ge system; however, data on the formation and crystal structure of three compounds exist because of the independent investigations of research groups from L’viv University and Geneva University.