Phase composition, electroconductivity, oxygen ion transport number, and microhardness of Ln1 ? xSrxGa0.5 ? y/2Al0.5 ? y/2MgyO3 ? δ (Ln = La, Pr, Nd; x, y = 0.10, 0.15)

Phase composition, electroconductivity, oxygen ion transport number, and microhardness of samples of Ln_{1 − x} Sr_xGa_{0.5 − y/2}Al_{0.5 − y/2}Mg_yO_{3 − δ} (Ln = La, Pr, Nd; x, y = 0.10, 0.15) synthesized by a ceramic methods are studied. Methods of x-ray diffraction analysis and scanning electron microscopy reveal the La-containing samples to be homogeneous and have a perovskite structure. Magnesium does not dissolve in Pr-and Nd-containing systems but forms an individual phase based on magnesium oxide. Apart from magnesium oxide, in these systems there form extrinsic phases, specifically, LnSrGa₃O₇ and an unknown phase. The electroconductivity of La_{1 − x} Sr_xGa_{1 − y} Mg_yO_{3 − δ} decreases after substituting Al for Ga. Ceramic La_{1 − x} Sr_xGa_{0.5 − y/2}Al_{0.5 − y/2}Mg_yO_3−δ is a purely ionic conductor in the temperature interval 500 to 1000°C; Nd_xSr_xGa_{0.5 − y/2}Al_{0.5 − y/2}Mg_yO_{3 − δ} has predominantly ionic conduction; and the predominant type of conduction in Pr_{1 − x} Sr_xGa_{0.5 − y/2}Al_{0.5 − y/2}Mg_yO_{3 − δ} is electronic below 700–800°C, with the contribution of ionic conduction increasing at higher temperatures. Substituting Al for Ga raises the hardness of ceramics under study. Among the compositions studied, La_0.85Sr_0.15Ga_0.45Al_0.45Mg_0.10O_{3 − δ} and La_0.85Sr_0.15Ga_0.425Al_0.425Mg_0.15O_{3 − δ} exhibit a combination of electroconductivity and hardness that is optimal for application as electrolyte at reduced temperatures (600–800°C). The Pr_{1 − x} Sr_xGa_{0.5 − y/2}Al_{0.5 − y/2}Mg_yO_{3 − δ} system possesses mixed ionic-electronic conduction and high hardness, which makes it appealing for application as oxygen-penetrable membranes. Original Russian Text ? Yu.V. Danilov, A.D. Neuimin, L.A. Dunyushkina, L.A. Kuz’mina, N.S. Zybko, Z.S. Martem’yanova, A.A. Pankratov, 2007, published in Elektrokhimiya, 2007, Vol. 43, No. 1, pp. 57–65.     

Study of anionic conductors R1 ? y Sr y F3 ? y (R = Ce, Pr, Gd) and M1 ? x Y x O2 ? x /2 (M = Zr, Hf) using four-electrode method

The anionic conductivity parameters are determined for R_{1 − y} Sr _y F_{3 − y} (R = Ce, Pr, Gd), Zr_0.88Y_0.12O_1.94 single crystals and Zr_0.88Y_0.12O_1.94|M_0.88Y_0.12O_1.94 (M = Zr, Hf) bicrystals using an ac (5 Hz to 100 kHz) four-electrode method. The obtained conductometric data are compared with the results of studying these crystals using a two-electrode method. It is shown that physical parameters of R_{1 − y} Sr _y F_{3 − y} fluoride crystals with the tysonite (LaF₃) structure are stable at heating in air up to the temperatures of 200–300°C, which is important for their practical application. Original Russian Text ? N.I. Sorokin, B.P. Sobolev, 2008, published in Elektrokhimiya, 2008, Vol. 44, No. 9, pp. 1111–1115.     

Chemical interaction of CdTe and Cd1? x Zn x single crystals with aqueous H2O2 + HBr + Citric acid solutions

The chemical etching of single crystals of CdTe and Cd_1−x Zn _x Te solid solutions in bromine-evolving aqueous H₂O₂ + HBr + citric acid solutions is considered. Simplex design of experiments is used to construct the projections of etching rate isosurfaces and to map the polishing and nonpolishing composition regions. Dissolution in the polishing etchants is diffusion-controlled. As the zinc content of Cd_1−x Zn _x Te is raised, the etching rate increases; the boundaries of the polishing region do not change to any significant extent. The polish composition and the dynamic chemical polishing conditions are optimized for the semiconductors examined. Original Russian Text ? Z.F. Tomashik, I.I. Gnativ, V.N. Tomashik, I.B. Stratiichuk, 2007, published in Zhurnal Neorganicheskoi Khimii, 2007, Vol. 52, No. 7, pp. 1234–1238.     

Physicochemical properties of the surface of the (Y,La0.1)Ce x Zr1? x O2?δ( x = 0.1–0.7) and Y0.1Pr0.3Zr0.6O2?δ complex oxide systems

The physicochemical properties of the surface of the Y_0.1Ce _x Zr_1−x O_2−δ, La_0.1Ce _x Zr_1−x O_2−δ (x=0.1–0.7), and Y_0.1Pr_0.3Zr_0.6O_2−δ. complex oxide systems were studied using IR and X-ray photoelectron spectroscopies. An appreciable enrichment of the surface of the solids in rare-earth-metal cations (cerium or praseodymium) during the synthesis was revealed. While cations are uniformly spread over the surface of cerium-zirconium solid solutions, the Y_0.1Pr_0.3Zr_0.6O_2−δ surface is covered by the clusters or even a phase of praseodymia. Reductive treatment in hydrogen with subsequent reoxidation results in the segregation of cerium ions on the Y_0.1Ce_0.3Zr_0.6O_2−δ surface at a temperature as low as 770 K. Original Russian Text ? A.N. Kharlanov, L.N. Ikryannikova, V.V. Lunin, A. Yu. Stakheev, 2007, published in Zhurnal Fizicheskoi Khimii, 2007, Vol. 81, No. 7, pp. 1271–1277.     

Regions of stability of variable-composition perovskite phases La1?xSrxMn1?yMyO3 (M = Ti, Ni)

The formation of the orthorhombic solid solution series LaMn_1−y Ti _y O₃ with 0.0 ≤ y ≤ 0.15 and LaMn_1−y Ni _y O₃ with 0.0 ≤ y ≤ 0.4 was observed. The stability boundaries of the La_1−x Sr _x Mn_1−y M _y O₃ (M = Ti, Ni) perovskite phases were determined. Fragments of isobaric-isothermal sections of the phase diagrams of the La₂O₃-SrO-Mn₃O₄-TiO₂ and La₂O₃-SrO-Mn₃O₄-NiO systems in air at 1100°C were suggested. Original Russian Text ? E.A. Filonova, A.N. Demina, A.N. Petrov, 2007, published in Zhurnal Fizicheskoi Khimii, 2007, Vol. 81, No. 10, pp. 1787–1790.     

Oxygen deficiency and phase transitions in SrCo1– x – y Fe x Cr y O3–δ ( x =0.10–0.40, y =0–0.05)

Oxygen-deficient phases based on perovskite-like strontium cobaltites-ferrites are promising mixed conductors for high-temperature electrochemical applications. The p(O₂)-T-δ diagrams for the oxide systems SrCo_{1– x – y} Fe _x Cr _y O_{3– δ} (x=0.10–0.40; y=0–0.05) were studied at 500–1000 °C in the oxygen pressure range from 10^–5 to 0.21 atm using the coulometric titration technique and thermogravimetric analysis. Stability limits of the cubic perovskite phases having a high oxygen ionic conductivity were evaluated as functions of temperature, oxygen partial pressure and oxygen nonstoichiometry. It was found that doping with chromium and increasing the iron content in SrCo(Fe,Cr)O_{3– δ} both lead to a considerable enlargement of the cubic perovskite phase existence domain towards lower temperatures and reduced oxygen pressures. Electronic Publication     

Electroconduction and linear expansion of solid electrolytes Ce1? x Sm x O2?δ ( x = 0.10?0.30)

A complex investigation of solid electrolytes Ce_1−x Sm _x O_2−δ (x = 0.10−0.30) is performed in a broad temperature interval by methods of x-ray diffraction analysis, electroconduction, dilatometry, differential scanning calorimetry, and thermogravimetry. Ceramic technology is used for the synthesis. The density of the obtained specimens is no lower than 95%. The dilatometry measurements reveal the presence of singularities in the curves obtained at temperatures in the region of 180–230°C, which may be ascribed to a phase transition of the type order-disorder of hypothetical phase Ce₇SmO_15.5. The electroconduction and dilatometry methods also point to the presence of singularities in the temperature dependences in the temperature interval extending from 800 to 870°C. Original Russian Text ? E.G. Vaganov, V.P. Gorelov, N.M. Bogdanovich, I.V. Korzun, V.A. Kazantsev, 2007, published in Elektrokhimiya, 2007, Vol. 43, No. 6, pp. 695–698. Based on the report delivered at the 8th International Meeting on Fundamental Problems of Solid-State Ionics, Chernogolovka (Russia), 2006.     

Heteropoly Complexes Na0.5Cs2 ? x[H0.5 ? xM

Crystals of novel heterepoly complexes (HPC) Na_0.5Cs_{2 − x} [H_{0.5 − x} M _x ^II X^III(OH)₆Mo₆O₁₈] · 7−8H₂O (M^II = Fe, Mn; X^III = Cr, Al) are synthesized. Crystal structures of the complexes Na_0.5Cs_{2 − x} [H_{0.5 − x} Fe_xCr(OH)₆Mo₆O₁₈] · 7H₂O (I) (x = 0.19) and Na_0.5Cs_{2 − x} [H_{0.5 − x} Mn_xAl(OH)₆Mo₆O₁₈] · 8H₂O (II) (x = 0.22) are determined (space group Pbcn, Z = 8, a = 23.023(4) Å, b = 22.064(4) Å, c = 11.606(3) Å, V = 5895.66 ų for I and a = 22.972(9) Å, b = 22.002(8) Å, c = 11.543(5) Å, V = 5834.18 ų for II, respectively). The [X^III(OH)₆Mo₆O₁₈]³⁻ ligands were found to be coordinated in monodentate fashion to M atoms due to the participation of a terminal O atom of the cis-MoO₂ group in coordination with the Fe and Mn atoms, which was confirmed by IR data. __________ Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 9, 2005, pp. 663–676. Original Russian Text Copyright ? 2005 by Gavrilova, Molchanov.     

磷化镍修饰磷掺杂氧化镓可见光催化水分解产氢

以Ga₂O₃半导体为前驱体,用浸渍加低温磷化法制备了P掺杂Ga₂O₃表面修饰Ni₂P光催化剂(x-Ni₂P/Ga₂O₃-P_y,x代表Ni²⁺和Ga₂O₃的物质的量之比,y代表NaH₂PO·H₂O与Ga₂O₃的物质的量之比)。5%-Ni₂P/Ga₂O₃-P₆催化剂展现出在纯水中光催化析氢的高活性,在430 nm光照下的光量子效率为0.22%。机理研究结果表明Ni₂P修饰和P掺杂扩展了催化剂的光响应范围,同时提升了载流子分离迁移效率,其长周期光催化反应稳定性明显优于未磷化催化剂。     

Thermodynamic calculations of phase equilibria in the neodymium-barium-copper-oxygen system: A model of the Nd1 + x Ba2 ? x Cu3O6 + z phase

A thermodynamic model of the Nd_{1 + x} Ba_{2 − x} Cu₃O_{6 + z} phase is suggested. The model allows the properties and boundaries of the regions of various phase polymorphs to be described within the framework of a unified solid solution. Analytic equations for the Gibbs energy and chemical potentials of the components and the other thermodynamic functions of Nd_{1 + x} Ba_{2 − x} Cu₃O_{6 + z} were obtained. Original Russian Text ? V.A. Lysenko, 2007, published in Zhurnal Fizicheskoi Khimii, 2007, Vol. 81, No. 8, pp. 1358–1363.