Extraction of U(VI) and Th(IV) ions from nitric acid solutions with <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>′,<Emphasis Type="Italic">N</Emphasis>′-tetra-2-ethylhexylglutaramide

N,N,N′,N′-Tetra-2-ethylhexylglutaramide (TEHGA) was used as a new extractant for the extraction of U(VI) and Th(IV) from nitric acid solutions. Toluene was found to be the most suitable diluent for TEHGA. The extraction of nitric acid was also studied. The influence exerted on the distribution ratio (D) of U(VI) and Th(IV) by the concentrations of HNO₃, TEHGA, and LiNO₃ as salting-out agent, and also by the equilibration time, temperature, and kind of diluent was examined. Good U–Th separation can be achieved using 2–3 M HNO₃. The results obtained show that U(VI) and Th(IV) are mainly extracted as UO₂(NO₃)₂·2TEHGA and Th(NO₃)₄·TEHGA, respectively. The IR spectra of the extracted species were analyzed. The thermodynamic functions of the process were calculated. Back-extraction of U(VI) and Th(IV) from the organic phases was also studied.     

Thermal conductivity of Er<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Sn<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Se (<Emphasis Type="Italic">x</Emphasis> ≤ 0.025) solid solutions

The thermal conductivity of Er _x Sn_{1 ? x} Se solid solutions has been measured at temperatures from 80 to 360 K. The results have been used to evaluate the electronic and lattice components of thermal conductivity for elastic carrier scattering, parabolic bands, and arbitrary degeneracy. With increasing erbium content and temperature, both the electronic and lattice components decrease considerably. Long-term annealing increases both components. It follows from the present experimental data that heat conduction in Er _x Sn_{1 ? x} Se is mainly due to phonons and that the observed rise in thermal resistance with Er content is due to phonon-phonon and paramagnetic-ion scattering.     

Etching of Zn<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Cd<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Te by solutions of the HNO<Subscript>3</Subscript>-HBr-citric acid system

Chemical etching of CdTe single crystals and Zn _x Cd_1?x Te solid solutions by bromine-evolving etchants of the HNO₃-HBr-citric acid system is studied. Projections of the surfaces of equal dissolution rates are plotted; the kinetics of etching processes and the influence exerted on it by the composition of solid solutions and initial concentrations of citric acid are found. The concentration limits of solutions for chemicody-namical polishing of surfaces of the mentioned semiconductors are determined.     

Structural and magnetic properties of Cr<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>V<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Te (<Emphasis Type="Italic">x</Emphasis> = 0−0.4) solid solutions

Cr_1?x V _x Te solid solutions with a hexagonal structure (NiAs type) have been obtained in the composition range x = 0?0.4 by direct melting of elemental mixtures, followed by annealing and quenching. The 80-K magnetic moment is found to decrease from 2.4μ_B in CrTe to 1.52μ_B in Cr_0.6V_0.4Te. The Curie temperature varies from 342 K to 321 K, respectively.     

Synthesis and structural properties of AgCl<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Br<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> (<Emphasis Type="Italic">x</Emphasis> = 0.5–0.8) solid solutions

The properties of AgCl_{1 - x} Br_x ( x = 0.5-0.8) solid solutions prepared by the Bridgman-Stockbarger method are studied using a variety of techniques (x-ray diffraction, microstructural examination, chemical analysis, and x-ray microanalysis). The lattice parameter of the solid solutions is found to exhibit a negative deviation from additivity. The effects of composition and preparation conditions on the structural properties of the solid solutions are discussed. The structural characteristics of abrasively polished surfaces of the samples are shown to be influenced by the preparation conditions.Translated from Neorganicheskie Materialy, Vol. 41, No. 1, 2005, pp. 78–87. Original Russian Text Copyright © 2005 by Artjushenko, Baskov, Golovanov, Kuzmicheva, Lisitskii, Musina, Polyakova, Sakharov, Sakharova.     

Growth and properties of single crystals of Si<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Ge<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> (0 < <Emphasis Type="Italic">x</Emphasis> < 0.35) solid solutions

Single-crystalline Si_{1 − x} Ge _x ingots with a germanium content of up to 35 at. %, a diameter of 10mm, and a length of up to 10 cm were grown using the crucibleless float-zone melting technique. The ingots had a homogeneous distribution of germanium and a low density of dislocations. The material was characterized with respect to the structure and electrical properties. The resistivity and the carrier lifetime, mobility, and concentration in Si_{1 − x} Ge _x single crystals have been studied as functions of the germanium content.     

Properties of YBaCuFe<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Ni<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>5</Subscript> (0 < <Emphasis Type="Italic">x</Emphasis> ≤ 0.3) solid solutions

YBaCuFe_{1 – x}Ni_xO₅ solid solutions are shown to exist for x 0.3. Data are presented on the lattice parameters, thermal stability, thermal expansion, electrical conductivity, thermoelectric power, magnetic susceptibility, and dielectric properties of the solid solutions. Ni substitution for Fe notably increases the electrical conductivity of the solid solutions, reduces their thermoelectric power and thermal expansion, and shifts the antiferromagnetic—paramagnetic phase transition and dielectric anomalies in YBaCuFe_{1 – x}Ni_xO₅ to lower temperatures.Translated from Neorganicheskie Materialy, Vol. 40, No. 12, 2004, pp. 1515–1519.Original Russian Text Copyright © 2004 by Chizhova, Klyndyuk, Bashkirov, Petrov, Makhnach.     

Hydrochemical synthesis of AgCl<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Br<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript> solid solutions

A phase-component model is proposed for the hydrochemical conversion of silver chloride to AgCl _x Br_{1 − x} solid solutions, and the corresponding quantitative relations are derived. Experimental data are used to obtain a relation between the equilibrium composition of solid solutions and that of the liquid phase at different temperatures. The possible mechanisms of solid-solution formation are considered.     

Lattice parameter of PbTe<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Cl<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> solid solutions

The lattice parameter of PbTe_1?x Cl _x solid solutions is shown to be a nonmonotonic function of chlorine content, with a minimum at x = 0.005. The results are interpreted in terms of a self-compensation model.     

Synthesis and properties of SrFe<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>M<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>3 − <Emphasis Type="Italic">z</Emphasis></Subscript> (M = Mo,W) perovskites

We have synthesized SrFe_{1 ? x} M _x O_{3 ? z} (M = Mo, W; 0 < x ≤ 0.5) solid solutions. Our results indicate that the introduction of stable MO₆ octahedra narrows the range of oxygen stoichiometries of the material and suppresses the perovskite-brownmillerite structural phase transition at low temperatures and oxygen partial pressures. We have studied the thermal stability of the synthesized materials in a reducing atmosphere and the effect of oxygen stoichiometry on their electronic and oxygen-ionic conductivity and phase transformations.     

Phase diagram of the Pb-NiSb system and properties of (NiSb)<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Pb<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> solid solutions

The phase diagram of the Pb-NiSb system is presented. The system is pseudobinary, with a limited series of NiSb-based solid solutions: ≃1 mol % Pb at 300 K. In the temperature range ≃520–670 K, the system contains un unstable compound, Ni₃Pb₂Sb₃. At 1320 K, a monotectic transformation occurs (≃15–71 mol % NiSb). Electrical and thermal conductivity measurements reveal an additional contribution to the lattice thermal resistivity of the (NiSb)_{1 − x} Pb _x solid solutions and show that electrons and phonons in these materials are scattered elastically.     

Low-temperature heat capacity of Li<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Ni<Subscript>2 − <Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>2</Subscript> solid solutions

The heat capacity of Li _x Ni_{2 − x} O₂ (x = 0.40–0.76) oxides has been measured using an adiabatic calorimeter, and their thermodynamic functions have been determined. The results indicate that the lithium nickelate solid-solution series contains a two-phase region and that near-stoichiometric LiNiO₂ has a layered structure, in accordance with earlier results.     

Thermal conductivity of TlIn<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Dy<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Te<Subscript>2</Subscript> solid solutions

The thermal conductivity of TlIn_{1 ? x} Dy _x Te₂ solid solutions, based on the compound semiconductor TlInTe₂, has been measured as a function of temperature (80–350 K). The results have been used to assess the effects of phonon-phonon and impurity scattering on the thermal conductivity of the solid solutions. Phonon scattering by the isovalent impurity Dy is shown to be significant above the Debye characteristic temperature of the materials.     

Heat capacity of Li<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Ni<Subscript>2 − <Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>2</Subscript> solid solutions

We have synthesized Li _x Ni_{2 − x} O₂ oxides in the range x = 0.1–0.84 and showed that the solid-solution system contains a two-phase region. The heat capacity of Li _x Ni_{2 − x} O₂ has been determined by differential scanning calorimetry.     

A model for calculating the composition of GaAs<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>P<Subscript>1–<Emphasis Type="Italic">x</Emphasis></Subscript> solid solutions under metalorganic vapor phase epitaxy conditions

A model is proposed for calculating the composition of GaAs _x P_1–x solid solutions, based on the iterative determination of the equilibrium partial pressures of the pyrolysis products of the starting reagents, followed by calculation of the composition of the solid solution in an adsorption–desorption model. The proposed model ensures good agreement between calculation results and experimental data.     

Mechanism of AC charge transport in TlSb<Subscript>1–<Emphasis Type="Italic">x</Emphasis></Subscript>Ga<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>S<Subscript>2</Subscript> (<Emphasis Type="Italic">x</Emphasis> = 0 and 0.03)

The dielectric properties and ac electrical conductivity of TlSb_1–xGa _x S₂ (x = 0, 0.03) single-crystals have been measured in the frequency range 5 × 10⁴ to 3.5 × 10⁷ Hz. Experimental data on the frequency dispersion of the dielectric coefficients and electrical conductivity of the TlSb_1–xGa _x S₂ (x = 0, 0.03) single crystals have allowed us to identify the nature of the dielectric loss and the mechanism of charge transport and evaluate parameters of localized states in the band gap. The incorporation of gallium atoms into the crystal lattice of TlSbS₂ crystals has been shown to lead to an increase in the Fermi-level density of states and mean hop time and distance.     

Optical and transport properties of Fe-doped Cd<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Hg<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Se (<Emphasis Type="Italic">x</Emphasis> = 0.35)

The optical and transport properties of Fe²⁺-doped Cd _x Hg_1?x Se crystals with a midgap Fe²⁺ level have been studied. The results demonstrate that Fe²⁺ ions influence both the optical and transport properties of Cd _x Hg_1?x Se〈Fe²⁺〉. The observed optical absorption bands are due to a donor Fe²⁺ level in the band gap, with a depth E _Fe = 0.21 eV, and to band-band transitions. Thermal anneals in Hg and Se vapors have different effects on the carrier concentration and mobility in the crystals. The effect of annealing on the transport properties of the Fe²⁺-doped crystals differs from that for undoped crystals and is governed by the state of point defects.     

Magnetocaloric effect in La<Subscript>1–<Emphasis Type="Italic">x</Emphasis></Subscript>Ca<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>MnO<Subscript>3</Subscript> for <Emphasis Type="Italic">x</Emphasis> = 0.3, 0.35, and 0.4

We present systematic studies of the magnetocaloric properties of the polycrystalline La_1−x Ca _x MnO₃ system for x = 0.3, 0.35, and 0.4 near a second-order phase transition from a ferromagnetic to a paramagnetic state. The crystal structure of the studied manganites was shown to be in good agreement with previous reports. The value of the magnetocaloric effect has been determined from the measurement of magnetization as a function of temperature and external magnetic field. The maximum entropy change detected in La_0.7Ca_0.3MnO₃ at a field of 2 T reaches 8 J/kg K which exceeds that of gadolinium. In all studied samples, the paramagnetic–ferromagnetic transition is very narrow but no hysteresis is observed and the transitions are identified as second-order ones. The phase transition in La_0.7Ca_0.3MnO₃ appears to be almost of first-order.     

PbTe-VTe<Subscript>2</Subscript> phase diagram and properties of (PbTe)<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>(VTe<Subscript>2</Subscript>)<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> solid solutions

The T-x phase diagram along the PbTe-VTe₂ join of the Pb-V-Te system has been studied. Vanadium-doped lead telluride crystals have been grown, and the longitudinal vanadium and carrier profiles in the crystals have been investigated. The temperature dependences of resistivity for the crystals lend support to the conclusion drawn earlier that PbTe〈V〉 is in a semi-insulating state at low temperatures. The crystals offer a high 20-K electron mobility, on the order of 10⁵ cm²/(V s), which attests to high electrical homogeneity of the material and stabilization of the Fermi level.     

Structure and Superconductivity of (MgB<Subscript>2−<Emphasis Type="Italic">x</Emphasis></Subscript>C<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>)<Subscript>0.97</Subscript>Cu<Subscript>0.03</Subscript>

A series of samples of (MgB_2−x C _x )_0.97Cu_0.03 (x=0.00, 0.05, 0.10, 0.15, 0.20, 0.25) and MgB₂ were synthesized by a solid state reaction method. The structure, superconducting transition temperature and transport properties of the samples were studied by means of X-ray diffraction (XRD) and resistivity measurements. It is found that the c-axis of the lattice remains unchanged with increasing C doping, while the a-axis shows a small decrease. The T _c of the samples steadily decreases with increasing C doping. It is suggested that the chemical pressure effect plays a more important role influencing the normal state transport and T _c than the change of carrier concentration.