Ionic conductivity in the Lu<Subscript>2</Subscript>O<Subscript>3</Subscript>-TiO<Subscript>2</Subscript> system

Nanocrystalline Lu₂O₃-TiO₂ (33.3–44 mol % Lu₂O₃) materials with a partially disordered pyrochlore structure, prepared via heat treatment in the range 1400–1750°C, are found to possess high oxygen ionic conductivity. Their 740°C conductivity is 10^-3 to 10^-2 S/cm, depending on the heat-treatment temperature and composition, which is comparable to that of the well-known fluorite solid electrolyte ZrO₂-9 mol % Y₂O₃.Translated from Neorganicheskie Materialy, Vol. 41, No. 3, 2005, pp. 324–331.Original Russian Text Copyright © 2005 by Shlyakhtina, Mosunov, Stefanovich, Knotko, Karyagina, Shcherbakova.This revised version was published online in April 2005 with a corrected cover date.This revised version was published online in April 2005 with a corrected cover date.     

Superionic Conductors in the Bi<Subscript>2</Subscript>WO<Subscript>6</Subscript>-Bi<Subscript>2</Subscript>VO<Subscript>5.5</Subscript> System

Bi₂V_xW_{1 − x} O_{6 − y} ceramics are synthesized, and their structure and electrical properties are studied. The results indicate that the Bi₂WO₆-Bi₂VO_5.5 system contains Bi₂WO₆- and Bi₂VO_5.5-based solid solutions in the ranges 0 < x ≤ 0.2 and 0.75 ≤ x < 1, respectively. Tungsten stabilizes the high-temperature, tetragonal phase γ-Bi₂VO_5.5, which persists down to room temperature at 0.75 ≤ x ≤ 0.84. In the range 350–550°C, the electrical conductivity of the bismuth-vanadate-based solid solutions exceeds that of Bi₂VO_5.5 by about one order of magnitude. The conductivity of the Bi₂WO₆-based solid solutions is also higher than that of the host phase.__________Translated from Neorganicheskie Materialy, Vol. 41, No. 7, 2005, pp. 866–870.Original Russian Text Copyright © 2005 by Voronkova, Yanovskii, Kharitonova, Rudnitskaya.     

Photoluminescence and Electrical Conductivity of As<Subscript>2</Subscript>S<Subscript>3</Subscript>〈Au〉 and As<Subscript>2</Subscript>S<Subscript>5</Subscript>〈Au〉 Glasses

The 77-K photoluminescence spectra of (As₂S₃)_{100 − x} Au_x and (As₂S₅)_{100 −x} Au_x (0 ≤ x ≤ 0.04) semiconducting glasses are measured for the first time. At low doping levels, the spectra of the (As₂S₅)_{100 − x} Au_x glasses are split into two components, one of which arises from the Au dopant. The temperature-dependent conductivity of the glasses shows two breaks at low Au concentrations and anomalous behavior in the range 300–360 K. Qualitative analysis of the conductivity data suggests that most of the impurity atoms have saturated valence bonds and form solid solutions with host atoms, changing the band gap of the material. A small fraction of the impurity atoms, those having unsaturated valence bonds, produce an electrically active level responsible for impurity conduction.__________Translated from Neorganicheskie Materialy, Vol. 41, No. 7, 2005, pp. 876–880.Original Russian Text Copyright © 2005 by Babaev, Kamilov, Sultanov, Askhabov, Terukov.     

Phase diagram of the TlGaSe<Subscript>2</Subscript>-CuGaSe<Subscript>2</Subscript> system

The phase equilibria in the TlGaSe₂-CuGaSe₂ system are studied for the first time over the entire composition range using differential thermal analysis, x-ray diffraction, and conductivity measurements. The system is shown to contain TlGaSe₂- and CuGaSe₂-based solid solutions extending to 2 mol % CuGaSe₂ and 1.5 mol % TlGaSe₂, respectively.Translated from Neorganicheskie Materialy, Vol. 41, No. 2, 2005, pp. 148–150.Original Russian Text Copyright © 2005 by Georgobiani, Matiev, Khamkhoev, Evloev.     

Luminescence Study of LiY<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Eu<Subscript>x</Subscript>(MoO<Subscript>4</Subscript>)<Subscript>2</Subscript>

The luminescence spectra of LiY_{1 − x} Eu_x(MoO₄)₂ (x = 0.0005, 0.001, 0.01, 0.05, 0.1, 0.5, 1) scheelite solid solutions are measured under laser excitation at 337.1 nm. The effect of Eu³⁺ concentration on the luminescence behavior of the solid solutions is examined. The highest integrated emission intensity is offered by LiY_0.5Eu_0.5(MoO₄)₂. Eu³⁺ substitution for Y³⁺ has no effect on the symmetry of the emission centers involved. Eu³⁺ is shown to occupy only one site in the structure of the solid solutions. X-ray diffraction and luminescence data indicate that all of the solid solutions have an undistorted scheelite structure.__________Translated from Neorganicheskie Materialy, Vol. 41, No. 7, 2005, pp. 871–875.Original Russian Text Copyright © 2005 by Zaushitsyn, Mikhailin, Romanenko, Khaikina, Basovich, Morozov, Lazoryak.     

Phase Relations and Transport Properties of Alloys in the Bi<Subscript>2</Subscript>Te<Subscript>3</Subscript>-TlGaTe<Subscript>2</Subscript> System

Using physicochemical analysis, the Bi₂Te₃-TlGaTe₂ system is shown to contain Bi₂Te³⁻ and TlGaTe₂-based restricted solid-solution series and a liquid-liquid miscibility gap in the composition range ≃12–30 mol % TlGaTe₂. The power factor α²σ of (Bi₂Te₃)_1−x (TlGaTe₂)_x solid solutions with 0.01 ≤ x ≤ 0.02 is suitable for thermoelectric applications.__________Translated from Neorganicheskie Materialy, Vol. 41, No. 7, 2005, pp. 785–786.Original Russian Text Copyright © 2005 by Abilov, Seidov.     

Preparation and Electrical Properties of Cd<Subscript>x</Subscript>Zn<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript> Te Crystals

Single-crystal ingots of Cd_xZn_1−x Te solid solutions are grown by the sublimation method. Samples with x = 0.95, 0.90, and 0.85 taken from the end portions of the ingots are chemically homogeneous and have p-type conductivity with a 300-K hole concentration below 10¹² cm⁻³. Temperature-dependent electrical conductivity measurements are used to evaluate the ionization energies of electrically active centers.__________Translated from Neorganicheskie Materialy, Vol. 41, No. 7, 2005, pp. 782–784.Original Russian Text Copyright © 2005 by Britan, Pigur, Popovich, Tsyutsyura.     

Electrical Conductivity of Bi<Subscript>2</Subscript>WO<Subscript>6</Subscript> Crystals Doped with Ca<Superscript>2+</Superscript>, Pb<Superscript>2+</Superscript>, Sr<Superscript>2+</Superscript>, and Ba<Superscript>2+</Superscript>

Single crystals of Bi₂WO₆ (a layered perovskite-like compound) doped with Ca²⁺, Pb²⁺, Sr²⁺, and Ba²⁺ on the Bi³⁺ site are grown, and their oxygen ionic conductivity is measured along the polar axis. The intrinsic conductivity of the doped crystals differs insignificantly from the conductivity of undoped Bi₂WO₆, indicating that the oxygen ions in the Bi₂O₂ layers contribute little to the oxygen ionic conductivity of the crystals. The sharp change in the activation energy for conduction at 600°C attests to a transition from one conduction mechanism to another in going from low to high temperatures.__________Translated from Neorganicheskie Materialy, Vol. 41, No. 7, 2005, pp. 863–865.Original Russian Text Copyright © 2005 by Kharitonova, Voronkova, Yanovskii.     

Ionic Conductivity of Ln<Subscript>2 + <Emphasis Type="Italic">x</Emphasis></Subscript>Zr<Subscript>2 − <Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>7 − <Emphasis Type="Italic">x</Emphasis>/2</Subscript> (Ln = Sm-Gd) Solid Solutions

The electrical conductivity of Ln_{2 + x} Zr_{2 − x} O_{7 − x/2} (Ln = Sm-Gd) solid solutions prepared from mechanically activated Ln₂O₃ and ZrO₂ is shown to correlate with their structural properties. In the three systems, the x-T regions are determined in which electrical transport is dominated by oxygen-ion conduction. In the Sm₂O₃-ZrO₂ system, ionic conductivities from 5 × 10⁻⁴ to 6 × 10⁻³ S/cm at 740°C are found in Sm_{2 + x} Zr_{2 − x} O_{7 − x/2} with 26.6, 33.3, 35.5, 37, and 40 mol % Sm₂O₃ prepared at 1450, 1530, and 1600°C. Eu_{2 + x} Zr_{2 − x} O_{7 − x/2} and Gd_{2 + x} Zr_{2 − x} O_{7 − x/2} containing 33.3 to 37 mol % Ln₂O₃ have 740°C ionic conductivities of 10⁻³ to ∼7.5 × 10⁻³ and 10⁻³ to 7 × 10⁻³ S/cm, respectively. The activation energy of conduction in Ln_{2 + x} Zr_{2 − x} O_{7 − x/2} (Ln = Sm-Gd), E _a = 0.84–1.04 eV, increases with the atomic number of Ln and x. The highest ionic conductivity is offered by the stoichiometric Ln₂Zr₂O₇ (Ln = Sm-Gd) pyrochlores prepared at 1600°C, owing to the optimal concentration of Ln_Zr + Zr_Ln antistructure pairs (∼5–22%). The grains in the ceramic samples studied range in size from 0.5 to 2 µm.__________Translated from Neorganicheskie Materialy, Vol. 41, No. 8, 2005, pp. 975–984.Original Russian Text Copyright © 2005 by Shlyakhtina, Kolbanev, Knotko, Boguslavskii, Stefanovich, Karyagina, Shcherbakova.     

Crystal-chemical aspect of formation of CdAs<Subscript>2</Subscript>-ZnAs<Subscript>2</Subscript> solid solutions

The initial stages of the formation of CdAs₂-ZnAs₂ solid solutions are analyzed in terms of crystalchemical energetics. Given that the bond enthalpies decrease in the order H (Zn-As)< H (Cd-As)< H (As-As), it is concluded that, most likely, CdAs₂-based solid solutions are substitutional and ZnAs₂-based solid solutions are interstitial, and that the thermochemical stability of the substitutional solid solutions is higher than that of CdAs₂ . The conclusions drawn from crystal-chemical analysis correlate with the reported x-ray diffraction, chemical analysis, resistivity, and Hall data for the solid solutions.Translated from Neorganicheskie Materialy, Vol. 41, No. 1, 2005, pp. 7–10. Original Russian Text Copyright © 2005 by Sanygin, Mikhailov, Palkina, Steblevskii, Kvardakov, Marenkin.     

Electrical Properties of Amorphous S<Subscript>0.60</Subscript>Ge<Subscript>0.40</Subscript>:H<Subscript>x</Subscript> Films

Amorphous Si_0.60Ge_0.40:H_x films containing 1.7, 3.9, 7.1, 12.1, and 17.3 at % H are prepared by magnetron sputtering at different hydrogen partial pressures, and their electrical conductivity is measured from 80 to 350 K. The conductivity of the films exhibits Arrhenius behavior in the range 250–350 K and satisfies the relation log(σT ^1/2) ∼ T^−1/4 between 80 and 250 K. The conductivity data are used to evaluate the electron localization radius, hop distance, and activation energy of hopping conduction at 80 K; the electron mobility at the Fermi level and in the conduction band; and the 300-K activation energy of conduction.__________Translated from Neorganicheskie Materialy, Vol. 41, No. 7, 2005, pp. 787–791.Original Russian Text Copyright © 2005 by Najafov, Isakov.     

Thermodynamic Properties of CaNdAlO<Subscript>4</Subscript>-SrNdAlO<Subscript>4</Subscript> Solid Solutions

The structural and thermodynamic properties of CaNdAlO₄-SrNdAlO₄ solid solutions are studied at 1673 K by x-ray diffraction and high-temperature calorimetry. The lattice parameters and unit-cell volume of the solid solutions are shown to vary linearly with composition. The measured heats of solid solution are used to evaluate the enthalpies of formation from the constituent oxides and constituent elements and the mixing enthalpies.__________Translated from Neorganicheskie Materialy, Vol. 41, No. 8, 2005, pp. 971–974.Original Russian Text Copyright © 2005 by Komissarova, Ryumin, Pushkina, Zimina, Novoselov, Pajaczkowska, Borik, Il’inskii.     

Mechanochemical Synthesis of Crystalline Compounds in the Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>–GeO<Subscript>2</Subscript> System

Crystalline mechanochemical synthesis products in the Bi₂O₃–GeO₂ system are studied by x-ray diffraction. The results indicate the formation of sillenite (Bi₁₂GeO₂₀), eulytite (Bi₄Ge₃O₁₂), and Aurivillius (Bi₂GeO₅) phases. The Aurivillius phase is shown to be in mechanochemical equilibrium with the sillenite phase in the 2Bi₂O₃ + GeO₂ system and with the eulytite phase in the Bi₂O 3 + GeO 2 system. The structural parameters of the synthesized metastable solid solutions are determined. The three phases contain high concen-trations of vacancies. In addition, the sillenite and Aurivillius phases are characterized by compositional disordering. Structural and ESR data point to partial reduction of the oxides, which accounts for the formation of the Aurivillius phase. According to x-ray photoelectron spectroscopy results, mechanical activation of bismuth oxide produces reduced binding energy states of Bi and O, which is tentatively attributed to clustering and the formation of complex radicals.__________Translated from Neorganicheskie Materialy, Vol. 41, No. 6, 2005, pp. 711–719.Original Russian Text Copyright © 2005 by Zyryanov, Smirnov, Ivanovskaya.     

High-temperature phase transition of Tm<Subscript>2</Subscript>Ti<Subscript>2</Subscript>O<Subscript>7</Subscript>

The high-temperature (>1600°C) order—disorder phase transition of Tm₂Ti₂O₇ is shown to be irreversible. The 740°C ionic conductivity of nanocrystalline Tm₂Ti₂O₇ ceramics synthesized at 1670°C is 2 × 10^-3 S/cm and remains unchanged upon heat treatment in air at 860°C for 240 h. The conductivity of the high-temperature (disordered pyrochlore) phase of Tm₂Ti₂O₇ is independent of grain size in the range 20–30 nm.Translated from Neorganicheskie Materialy, Vol. 40, No. 12, 2004, pp. 1495–1500.Original Russian Text Copyright © 2004 by Shlyakhtina, Knotko, Larina, Borichev, Shcherbakova.     

Ultrafine Cr-Doped Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Prepared by Detonation Synthesis

Data are presented on the phase composition, particle size distribution, EPR, and luminescence of ultrafine chromium-doped alumina powders prepared by detonation synthesis. The largest particles in the powders are shown to consist mainly of a Cr₂O₃ solid solution in α-Al₂O₃. The luminescence spectrum of fine particles shows, in addition to lines characteristic of ruby, extra lines which are tentatively attributed to Cr³⁺ ions incorporated substitutionally into θ-Al₂O₃.__________Translated from Neorganicheskie Materialy, Vol. 41, No. 8, 2005, pp. 948–954.Original Russian Text Copyright © 2005 by Lyamkina, Chiganova, Slabko, Vorotynov, Taranova.     

Phase equilibria in the TlInSe<Subscript>2</Subscript>-CuInSe<Subscript>2</Subscript> and TlInSe<Subscript>2</Subscript>-AgInSe<Subscript>2</Subscript> systems

The phase equilibria in the TlInSe₂-CuInSe₂ and TlInSe₂-AgInSe₂ systems are studied over the entire composition range using differential thermal analysis, x-ray diffraction, and conductivity and density measurements. The systems are shown to contain restricted solid-solution series extending at room temperature to 2.5 mol % CuInSe₂ and 1.5 mol % TlInSe₂ in the TlInSe₂-CuInSe₂ system and to 3 mol % AgInSe₂ and 2 mol % TlInSe₂ in the TlInSe₂-AgInSe₂ system.Translated from Neorganicheskie Materialy, Vol. 41, No. 3, 2005, pp. 281–285.Original Russian Text Copyright © 2005 by Georgobiani, Matiev, Khamkhoev, Evloev.This revised version was published online in April 2005 with a corrected cover date.This revised version was published online in April 2005 with a corrected cover date.     

Thermal conductivity of Sb<Subscript>2</Subscript>Te<Subscript>3</Subscript>-Gd<Subscript>2</Subscript>Te<Subscript>3</Subscript>-Bi<Subscript>2</Subscript>Te<Subscript>3</Subscript> solid solutions

We have measured the thermal conductivity of Bi₂Te₃-Sb₂Te₃-Gd₂Te₃ solid solutions at temperatures from ～80 to 300 K and have determined the electronic and lattice components of their total thermal conductivity and the contributions of Sb₂Te₃ and Gd₂Te₃ to their thermal resistance. The results indicate that heat in these materials is transported largely by phonons and that three-phonon processes play a key role in determining the lattice thermal conductivity of the solid solutions.     

Coprecipitation of Trace Amounts of <Superscript>137</Superscript>Cs and <Superscript>85</Superscript>Sr with [Na(18-Crown-6]BPh<Subscript>4</Subscript> from Neutral and Alkaline Solutions

Coprecipitation of ¹³⁷Cs and ⁸⁵Sr with [Na(18-crown-6]BPh₄ solid phase from aqueous, aqueous-ethanolic, and alkaline solutions is studied. ¹³⁷Cs and ⁸⁵Sr cocrystallize with [Na(18-crown-6]BPh₄ from aqueous and aqueous-ethanolic solutions. The cocrystallization coefficients D of ¹³⁷Cs and ⁸⁵Sr from aqueous solutions are 2.6±0.5 and 3.3±0.3, respectively. For aqueous-ethanolic solutions, the corresponding values are 4.4±0.5 and 3.4±0.4. In the alkaline solutions (0.1 and 1 M NaOH), 54–74% of ¹³⁷Cs and 37–51% of ⁸⁵Sr pass into the [Na(18-crown-6]BPh₄ solid phase, depending on the crown ether concentration in the system.__________Translated from Radiokhimiya, Vol. 47, No. 3, 2005, pp. 257–260.Original Russian Text Copyright © 2005 by Kulyukhin, Konovalova, Rumer, Kamenskaya, Mikheev.     

Optical and photoelectric properties of Cd<Subscript>1 - <Emphasis Type="Italic">x</Emphasis></Subscript>Zn<Subscript>x</Subscript>As<Subscript>2</Subscript> single crystals

The optical absorption, photoconductivity, and short-circuit photocurrent spectra of structurally perfect Cd_{1 - x} Zn_xAs₂ (x = 0.03, 0.05, 0.06) single crystals are studied for the first time near the intrinsic edge in the range 80–300 K. The results demonstrate that the intrinsic edge in the solid solutions is due to indirect transitions involving the formation of excitons for both the E c and E c polarizations. The indirect gaps _g ⁱ of the solid solutions are determined. In the range 80–300 K, the data for x = 0–0.06 and both polarizations are well fitted by _g ⁱ (x) = _g ⁱ (0) + 0.0866x + 2.35x ². The introduction of 6 mol % ZnAs₂ into CdAs₂ increases its _g ⁱ by 14 meV.Translated from Neorganicheskie Materialy, Vol. 41, No. 3, 2005, pp. 268–272.Original Russian Text Copyright © 2005 by Morozova, Marenkin, Mikhailov, Koshelev.This revised version was published online in April 2005 with a corrected cover date.This revised version was published online in April 2005 with a corrected cover date.     

Phase transition of the new ferromagnet Cd<Subscript>1 - <Emphasis Type="Italic">x</Emphasis></Subscript>Mn<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>GeAs<Subscript>2</Subscript> at high pressures (0.9–4.7 GPa)

Pressure-dependent resistivity and Hall effect measurements indicate that p - type Cd_{1 - x}Mn_x GeAs₂ solid solutions with x = 0.06 and 0.18 undergo a high-pressure semiconductor-metal transition. The characteristic points of the phase transition are located, and its dynamics is analyzed in terms of the theory of mixed-phase systems.Translated from Neorganicheskie Materialy, Vol. 41, No. 1, 2005, pp. 11–14. Original Russian Text Copyright © 2005 by Mollaev, Arslanov, Zalibekov, Marenkin, Novotortsev, Mikhailov, Molchanov.