Andriy V. Tkachuk

Electric transport and magnetic properties of TiCo1−xNixSb solid solution

Abstract The carrier transport properties of the new TiCo1−xNixSb solid solution were studied. This continuous substitutional solid solution ranges over the whole concentration region with the cubic MgAgAs crystal structure type. Semiconductor–semimetal transitions were observed in these samples with small Ni substitution (x≥0.01). The band gap parameter calculated from resistivity measurements for the annealed TiCoSb compound is 0.19 eV. Homogenized TiCoSb has a relatively high linearly dependent thermopower in the temperature range 77–380 K. The magnetic properties of pure and slightly doped TiCoSb are strongly dependent on the preliminary heat treatment.

Crystal structure and physical properties of (Ti,Sc)NiSn and (Zr,Sc)NiSn solid solutions

Crystal structure, electrotransport and magnetic properties for Ti1−xScxNiSn and Zr1−yScyNiSn solid solutions were studied. Stability ranges of the limited solubility for these phases were established. All alloys of these solid solutions crystallize with the MgAgAs structure type. A gradual semiconductor–semimetal transition was observed in the resistivity when increasing the Sc content for these substitutional series of alloys. The samples with small Sc content have quite a high positive thermopower value at elevated temperatures. The room temperature magnetic susceptibility of the (Ti,Sc)NiSn solid solution samples shows enhanced paramagnetism, while the (Zr,Sc)NiSn ones are characterized by weak Pauli paramagnetism.

-interaction between components in the Ti-Mn-Sb system at 870 K and the physical properties of Ti5Mn0.45Sb2.55

Abstract The isothermal section of the phase diagram at 870 K of the ternary Ti–Mn–Sb system was investigated. The existence of a new ternary compound, Ti 5 Mn 0.45 Sb 2.45 , was revealed crystallizing in the W 5 Si 3 -type tetragonal structure (space group I4/mcm ) with lattice parameters a =1.0462(1) nm and c =0.52776(3) nm. This compound has been characterized by measurements of the electrical resistivity, thermopower, and magnetic susceptibility over a wide temperature range and the EPR spectrum at room temperature.

Synthesis, crystal structure and physical properties of ZrNiSn semiconductor doped with Mn

The resistivity, thermopower, dc magnetic susceptibility and electron paramagnetic resonance (EPR) spectra of ZrNi, x Mn x Sn solid solution with low (0.001≤x≤0.05) Mn concentration were investigated in the 78-400 K temperature range. Polycrystalline samples of the ZrNi x Mn x Sn compounds were prepared by arc-melting of the pure metals. Quantitative atomic emission spectroscopy confirmed the appropriate Mn contents in all alloys. The lattice parameters of the ZrNi 1-x Mn x Sn compounds with different Mn concentration are almost unchanged. Magnetic susceptibility shows the linear dependence versus inverse magnetic field for all samples, what is evidence for the magnetic interactions in the ZrNi 1-x Mn x Sn compounds The temperature dependence of magnetic susceptibility for the compounds with 0.005≤x≤0.05 can be described approximately by a Curie-Weiss law. The results of static magnetic measurements were confirmed by EPR technique. The broad line of I type belongs to Mn 2+ ions in the Ni-sites in crystal lattice coupled by magnetic dipolar interaction. The narrow line of II type is interpreted as an EPR spectrum of exchange-coupled pairs or clusters of more than two Mn 2+ ions. The unusual magnetic properties and the features of dipolar and exchange interaction of the Mn 2 ions in the lattice of ZrNi 1-x Mn x Sn solid solution are discussed.

V–Mn–{Sn,Sb} ternary systems

Abstract The isothermal section of the phase diagrams of ternary V–Mn–Sn and V–Mn–Sb systems has been investigated at 770 and 870 K, respectively. No ternary compounds were observed. The systems are characterised by the existence of solid solutions based on the binary compounds. The temperature dependence of the electrical resistivity and differential thermopower for (V,Mn)3Sb solid solution has been measured.

Low- and high-temperature structures of YbCuBi

Abstract A variable temperature single-crystal X-ray diffraction study was undertaken on the intermetallic compound YbCuBi, which undergoes a phase transition at ∼375 K. At low temperatures (T = 193 K, a = 4.5821(3) Å, c = 7.8107(8) Å; T = 295 K, a = 4.5825(6) Å, c = 7.8597(10) Å), YbCuBi adopts the LiGaGe-type (ordered CaIn2-type) structure (Pearson symbol hP6, space group P63mc, Z = 2). At high temperatures (T = 393 K, a = 4.5885(14) Å, c = 7.913(2) Å; T = 473 K, a = 4.594(4) Å, c = 7.928(6) Å), YbCuBi adopts the ZrBeSi-type (ordered Ni2In-type) structure (Pearson symbol hP6, space group P63/mmc, Z = 2). The structure consists of Yb atoms separating hexagonal ∞2[CuBi] nets, which are buckled at low temperatures but planar at high temperatures.

Isothermal section of the Ti–Mn–Sn system and crystal structure of the TiMnSn4 compound

Abstract The isothermal section of the phase diagram of ternary Ti–Mn–Sn system has been investigated at 770 K. The existence of new TiMnSn 4 ternary compound was established and its crystal structure was determined. TiMnSn 4 stannide crystallizes in the Mg 2 Ni structure type (space group P6 2 22 , a =0.55537(1) nm, c =1.40326(2) nm). For the given compound the temperature dependences of electrical resistivity, differential thermopower and magnetic susceptibility were investigated. On the basis of binary Mn 3 Sn, Ti 6 Sn 5 and Ti 3 Sn compounds the solid solutions were formed.

In search of the elusive amalgam SrHg8: a mercury-rich intermetallic compound with augmented pentagonal prisms

In confirmation of its predicted existence in the Sr-Hg phase diagram, the mercury-rich intermetallic compound SrHg(8) has been prepared by reaction of the elements at 200 degrees C. Single-crystal X-ray diffraction analysis revealed that it adopts a new structure type (Pearson symbol oP72, space group Pnma, a = 13.328(1) A, b = 4.9128(5) A, c = 26.446(3) A). The Sr atoms are centred within two types of 18-vertex Hg polyhedra formed by augmenting pentagonal prisms with octagonal waists. The condensation of these Sr@Hg(18) clusters is associated with the formation of a complex anionic Hg-Hg bonding network, as supported by electronic structure calculations which reveal strong mixing of Hg 6s and 6p states in highly delocalized bands superimposed with a narrower 5d band below the Fermi level.

Lanthanum iron trigermanide, LaFeGe3

Lanthanum iron trigermanide, LaFeGe3, adopts the BaNiSn3-type structure, which consists of square nets of Ge atoms, with Fe and Ge atoms positioned alternately above or below each square. Between these layers reside the La atoms.

Cerium cadmium diantimonide, CeCd0.660Sb2

Cerium cadmium diantimonide, CeCd0.660 (4)Sb2, adopts the HfCuSi2-type structure and is confirmed to have defects in the Cd site. Layers of condensed CdSb4/4 tetrahedra and square nets of Sb atoms are separated by Ce atoms.