The influence of fluorine doping on transport properties in the novel proton conductors Ba4In2Zr2O11-0.5xFx with perovskite structure

The effect of fluorine doping on the transport properties of perovskite-related complex oxides based on oxygen-ion conductor Ba₄In₂Zr₂O₁₁ is analyzed. The effect of fluorine doping and air humidity on the cell volume is established. The introduction of fluorine into the oxygen sublattice leads to the decreasing in the cell volume. The hydration of samples leads to the lattice expansion for both undoped and doped samples in comparison with unhydrated samples. The amount of water uptake decreases with the increase in the fluorine concentration. It was shown that fluorine doping allows to increase the proton conductivity in the region of low fluorine concentrations. The determining factor is not the change in the concentration of the current carrier, but the increase in its mobility.     

Über das Oxoindat Ba4In2O7

On the Oxoindate Ba₄In₂O₇ Ba₄In₂O₇ was prepared for the first time by solid state reaction and investigated by X-ray methods. (Space group D_4h¹⁷–14/mmm, a = 4.175; c = 29.483 Å; Z = 2). It shows a close crystal chemical relationship to Ba₃In₂O₆ and La₂SrCu₂O₆. One of the oxygen point positions is occupied only by a half. This fact alleviates the understanding of the layer structure of Ba₄In₂O₇. The compound is compared with Sr₄Tl₂O₇ and a further discussion in respect to Ba₅In₂O₈ shows the probable identity of Ba₅In₂O₈ with Ba₄In₂O₇.     

Effect of F<Superscript>–</Superscript>-doping on the transport properties of perovskite-like complex oxides

The structural and electric characteristics of fluorine-substituted complex oxides obtained by anion doping based on Ba₂CaNbO_5.5 and Ba₂In₂O₅ matrices were compared. The mobility of ion charge carriers was found to depend on the concentration of the dopant anion and oxygen vacancies and the degree of disordering of the latter.     

Oxygen permeation and phase structure properties of partially A-site substituted BaCo0.7Fe0.225Ta0.075O3-δ perovskites

Ba_0.9R_0.1Co_0.7Fe_0.225Ta_0.075O_3-δ (BRCFT, R = Ca, La or Sr) membranes were synthesized by a solid-state reaction. Metal cation Ca²⁺, La³⁺ or Sr²⁺ doping on A-site partially substituted Ba²⁺ in BaCo_0.7Fe_0.225Ta_0.075O_3-δ oxides, and its subsequent effects on phase structure stability, oxygen permeability and oxygen desorption were systematically investigated by XRD, TG-DSC, H₂-TPR, O₂-TPD techniques and oxygen permeation experiments. The partial substitution with Ca²⁺, La³⁺ or Sr²⁺, whose ionic radii are smaller than that of Ba²⁺, succeeded in stabilizing the cubic perovskite structure without formation of impurity phases, as revealed by XRD analysis. Oxygen-involving experiments showed that BRCFT with A-site fully occupied by Ba²⁺ exhibited good oxygen permeation flux under He flow, reaching about 2.3 mL·min⁻¹ ·cm⁻² at 900 °C with 1 mm thickness. Of all the membranes, BLCFT membrane showed better chemical stability in CO₂, owing to the reduction in alkalinity of the mixed conductor oxide by La doping. In addition, we also found the stability of the perovskite structure under reducing atmospheres was strengthened by increasing the size of A-site cation (Ba²⁺>La³⁺>Sr²⁺>Ca²⁺).     

Zur Kristallchemie von Ba3In2Zn5O11. Ein tOxoindat/zinkatsol;zinkat mit Zn10O20- und In4O16-Makropolyedern und erstmals O2− in tetraedrischer Koordination durch Zn2+

On the Crystal Structure of Ba₃In₂Zn₅O₁₁. An Oxoindate/zincatesol;zincate with Zn₁₀O₂₀ and In₄O₁₆ Macropolyhedra with Zn²⁺ in Tetrahedral Coordination by O^2? Ba₃In₂Zn₅O₁₁ was prepared for the first time by a flux technique and investigated by single crystal X-ray work. It crystallizes with cubic symmetry, space group T-F4 3m, a = 13.3588 Å, Z = 8. Zn²⁺ show tetrahedral coordination by O^2?, forming Zn₁₀O₂₀ macropolyhedra. In addition the nZn/Osol;O part of the crystal structure is made up of Zn₁₀O₂₀ parts. Edge connection of four InO₆ octahedra results in In₄O₁₆ groups. The crystal structure will be shown and discussed.     

Synthesis,hydration, and electric properties of chlorine-substituted brownmillerite Ba<Subscript>1.95</Subscript>In<Subscript>2</Subscript>O<Subscript>4.9</Subscript>Cl<Subscript>0.1</Subscript>

Chlorine-substituted brownmillerite Ba_1.95In₂O_4.9C_l0.1 was obtained from barium indate Ba₂In₂O₅ by solid-phase synthesis. The ability to absorb water from the gas phase was confirmed by thermogravimetric studies. The transport properties were studied while varying the thermodynamic parameters of the external environment (T, pO₂, pH₂O). The chloride ions in the oxygen sublattice of barium indate Ba₂In₂O₅ were found to affect the ion conductivity. In a humid atmosphere, the sample exhibited proton conductivity (E _a = 0.54 eV), whose contribution became dominant below 300°C.     

Zur Kristallstruktur von Ba3In2O6

About the Crystal Structure of Ba₃In₂O₆ Single crystals of Ba₃In₂O₆ could be prepared by recrystallization of a flux and by solid state reaction in closed platinium tubes, respectively. Ba₃In₂O₆ crystallizes with tetragonal symmetry (space group 14/mmm, a = 4.1868; c = 21.7041 Å, Z = 2). Single crystal X-ray work lead to a crystal structure like La_2-xSr_1+xCu₂O_6-δ therefor Ba₃In₂O₆ is a modified member of the Sr₃Ti₂O₇-Type. The coordinations of Ba²⁺ and In³⁺ are described and the relations to the Sr₃Ti₂O₇-type are discussed.     

Structure,microstructure and physicochemical properties of BaW<Subscript>1−x</Subscript>Nb<Subscript>x</Subscript>O<Subscript>4−δ</Subscript> materials

Nb-doped BaWO₄ with the assumed formula BaW_1?xNb_xO_4?δ (x = 0, 0.005, 0.01, 0.02 and 0.05) were prepared by solid-state reaction method. Crystal structure and phase composition were determined by X-ray diffraction method. Scanning electron microscopy (SEM) coupled with energy-dispersive spectrometry (EDS) was used to describe microstructure and chemical composition of synthesised materials. It was found that solubility limit of niobium in the BaWO₄ structure is the range 0.5–1 mol%, as formation of second phase—Ba₅Nb₄O₁₅—was observed for samples with higher dopant content. For evaluation of the chemical stability of synthesized materials, the comparative CO₂/H₂O exposure test was performed. Samples were exposed to carbon dioxide- and water vapour-rich atmosphere (7% CO₂ in air, 100% RH) at 298 K for 700 h. During this exposition, the chemical reactions between the samples and the surrounding gaseous atmosphere resulting in formation of barium hydroxide and/or barium carbonate can process. Thermogravimetry (TG) method was used for chemical stability evaluation. The comparison of samples before and after the CO₂/H₂O exposure test was performed. To support the interpretation of TG results, the analysis of gaseous products evolved during thermal treatment of the samples was done using mass spectrometer. The effect of dopant on the BaWO₄ chemical stability improvement was observed. In order to determine the electrical properties of obtained materials, the DC resistance measurements in synthetic air atmosphere were taken. It was shown that niobium doping and the presence of second phase—Ba₅Nb₄O₁₅—leads to an increase in the total conductivity of synthesised materials.     

The Crystal Structures, Microstructure and Ionic Conductivity of Ba2In2O5 and Ba(InxZr1−x)O3−x/2

This paper describes the results of electron microscopy, high-temperature powder neutron diffraction, and impedance spectroscopy studies of brownmillerite-structured Ba₂In₂O₅ and perovskite structured Ba(In_xZr_1−x)O_3−x/2. The ambient temperature structure of Ba₂In₂O₅ is found to adopt Icmm symmetry, with disorder of the tetrahedrally coordinated (In³⁺) ions of the type observed previously in Sr₂Fe₂O₅. Ba₂In₂O₅ undergoes a ∼6-fold increase in its ionic conductivity over the narrow temperature range from ∼1140 K to ∼1230 K, in broad agreement with previous studies. This transition corresponds to a change from the brownmillerite structure to a cubic perovskite arrangement with disordered anions. Electron microscopy investigations showed the presence of extended defects in all the crystals analyzed. Ba(In_xZr_1−x)O_3−x/2 samples with x=0.1 to 0.9 adopt the cubic perovskite structure, with the lattice parameter increasing with x.     

The pillared layered framework of Ba3(In1−xMx)2(HXO4)6 (0≤x≤1; M=Fe,Cr; X=P,As): synthesis,crystal structure,thermal stability and Mössbauer spectroscopy

The hydrothermal synthesis, single crystal structure analysis, spectroscopic and thermal stability studies of the compounds Ba₃(In_1−xM_x)₂(HXO₄)₆ (0≤x≤1; M=Cr, Fe; X=P, As) are reported. The 3D framework of these new phosphates can be described as a pillared layered framework. The metal cations (In³⁺, Fe³⁺, and Cr³⁺) occupy two crystallographically independent octahedral sites, M(1) and M(2). The layers are formed of M(2)O₆ octahedra and (HPO₄) tetrahedra sharing corners, with M(1)O₆ octahedra serving as pillars between adjacent layers. Single crystal study of Ba₃(In_0.5Fe_0.5)(HPO₄)₆ shows that indium and iron segregate between the two metal sites with Fe occupying primarily the site M(1) and In located primarily in M(2) site. Interactions between the building units within the layers occur through hydrogen bonding. Barium cations are located between the pillars, in 8-membered ring tunnels and are coordinated by 12 oxides. The phases loose three water molecules through condensation of six HXO₄ groups to form Ba₂M₂(X₂O₇)₃ at temperatures between 480 and 600 °C. Mössbauer spectroscopy shows the presence of high-spin Fe³⁺ in octahedral coordination.     

Thermochemical investigation of Zr doping in LiNi8/12Co2/12Mn2/12O2 based on phase equilibria simulation

The doping behavior of Zr in LiNi_8/12Co_2/12Mn_2/12O₂ (LNCM) is investigated by a simulation of the phase equilibria for the Li-(M^*,Zr)-O system (M^* = Ni, Co, Mn) based on first-principles calculations followed by a thermochemical post-analysis of the resultant phase diagrams. The results indicate that the stable state at the synthetically stoichiometric composition of LNCM with Zr is a mixture of undoped LNCM with a Li₂ZrO₃ secondary phase; doping of Zr in the LNCM crystal is not thermodynamically favored. The energies of various states comprising LNCM supercells with defects, secondary phases, and Zr doping are examined, and the equilibrium doping concentration of Zr is calculated by considering the entire LNCM:Zr crystal as a statistical combination of these states. The doping concentration of Zr in the LNCM crystal is calculated to be very low, which enables balanced control between doping and coating, as recently reported through experimentation. The dopability of Zr is expected to increase with the depletion of O₂ supply during the heating of a system with a precisely controlled Li to M^* ratio, but this behavior is affected by the formation of defects, especially by M^* substitution for Li.     

Phase equilibria in the solid state and colour properties of the CuO–In2O3 system

Phase equilibria up to solidus line in CuO?CIn₂O₃ system have been investigated using XRD and DTA/TG methods. According to the results, only one compound of the formula Cu₂In₂O₅ formed in the system studied. Its thermal stability was determined in the air and argon proving that the compound did not melt but underwent decomposition. The decomposition of Cu₂In₂O₅ in the air atmosphere began at 1080?°C, while in argon at 835?°C. Additional studies were undertaken to determine the hitherto unknown colour properties of samples representing the CuO?CIn₂O₃ system in the equilibrium state.     

Exploration of the superconducting properties of Y3Ba5Cu8O18 with and without Ca doping by magnetic measurements

The superconducting Y₃Ba₅Cu₈O₁₈ (Y-358) and Y₃Ba₅Ca₂Cu₈O₁₈ (YCa-358) compounds have been synthesized by using the sol–gel method. Hence, the influence of doping of Ca into the compound Y-358 has been studied by comparing the resistivities, DC magnetizations both M(H) and M(T),flux pinning properties, AC susceptibilities and critical current densities of the undoped and doped compounds, at low temperatures. The AC susceptibility and resistivity measurements showed that the superconducting transition temperature, T_c, is suppressed (about 6 K) with the addition of Ca into the main compound. The hysteresis loops of YCa-358 show peak like projecting parts at temperatures below 45 K and around zero applied field that may be due to the local modulation of the composition in YCa-358. Such a behavior has been observed for the first time. The critical current densities, J_c, determined from the hysteresis measurements decrease with the addition of Ca into Y-358. At 15 K, the maximum values of J_c, for the compounds Y-358 and YCa-358 are found to be 8 × 10⁴ A/cm² and 4.5 × 10⁴ A/cm², respectively. The flux pinning force, F_p, calculated from the field dependence of the J_c values shows that the irreversibility line shifts to lower magnetic fields with the doping of Ca into Y-358. Furthermore, the measurements of the inphase and out off components of the ACsusceptibilities clearly demonstrate that the superconducting volume fraction of Y-358 decreases with the addition of Ca.     

Hydration and forms of oxygen-hydrogen groups in Oxyfluorides Ba2 ? 0.5x In2O5 ? x F x

A number of fluorine-substituted compounds were synthesized from brownmillerite Ba₂In₂O₅. The homogeneity range of the Ba_{2 ? 0.5x} In₂O_{5 ? x} F _x solid solution (x ?? 0.3) was determined by X-ray diffractometry. The studied phases were found to be able to incorporate water from the gas phase, due to which their orthorhombic structure transforms into tetragonal one. The degree of hydration decreased as the fluorine content in the solid solution increased. As in the case of Ba₂In₂O₅, the energetically nonequivalent hydroxo groups were found to be the main form of oxygen-hydrogen groups.     

Preparation of novel visible-light-driven In<Subscript>2</Subscript>O<Subscript>3</Subscript>–CaIn<Subscript>2</Subscript>O<Subscript>4</Subscript> composite photocatalyst by sol–gel method

Novel visible-light-activated In₂O₃–CaIn₂O₄ photocatalysts were developed in this paper through a sol–gel method. The photocatalytic activities of In₂O₃–CaIn₂O₄ composite photocatalysts were investigated based on the decomposition of methyl orange under visible light irradiation (λ > 400 nm). The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrum (EDS), X-ray photoelectron spectroscopy (XPS) and UV–vis diffused reflectance spectroscopy (DRS). The results revealed that the In₂O₃–CaIn₂O₄ composite samples with different In₂O₃ and CaIn₂O₄ content can be obtained by controlling the synthesis temperature, and the composite photocatalysts extended the light absorption spectrum toward the visible region. The photocatalytic tests indicated that the composite samples demonstrated high visible-light activity for decomposition of methyl orange. The significant enhancement in the In₂O₃–CaIn₂O₄ photo-activity under visible light irradiation can be ascribed to the efficient separation of photo-generated carriers in the In₂O₃ and CaIn₂O₄ coupling semiconductors.     

Chemischer Transport fester Lösungen. 11 [1] Mischphasen und Chemischer Transport in den Systemen CrIII/InIII/GeIV/O,GaIII/InIII/GeIV/O,MnIII/InIII/GeIV/O und FeIII/InIII/GeIV/O

Chemical Vapor Transport of Solid Solutions. 11 Mixed Phases and Chemical Vapor Transport in the Systems Cr^III/In^III/Ge^IV/O, Ga^III/In^III/Ge^IV/O, Mn^III/In^III/Ge^IV/O und Fe^III/In^III/Ge^IV/O By means of chemical vapor transport methods the following mixed phases have been prepared: Cr_{0, 18}In_{1, 82}Ge₂O₇ (Cl₂, 950 → 850 °C), (Ga_{0, 6}In_{1, 4})₂Ge₂O₇ (Thortveitit‐type, Cl₂, 1050 → 950 °C), (Ga_{1, 9}In_{0, 1})₂Ge₂O₇ (Ga₂Ge₂O₇‐type, 1050 → 950 °C), (In_{1, 9}Mn_{0, 1})₂Ge₂O₇ (Thortveiti‐type, Cl₂, 1000 → 800 °C), mixed phase crystallizing in the Mn₂Ge₂O₇‐structure showing a composition near MnInGe₂O₇ (Cl₂, 1000 → 800 °C), Mn_{6, 5}In_{0, 5}GeO₁₂ (Braunit‐type, Cl₂, 1000 → 800 °C), (Fe_xIn_1‐x)Ge₂O₇ (Thortveitit‐type with x = 0…0, 94; Cl₂, 840 → 780 °C). Changing the compositions of the starting materials showed no effect on the composition of the deposit except for the system Fe₂O₃‐In₂O₃‐GeO₂.     

Superconductivity in (Cu0.5Tl0.25Li0.25)Ba2Ca2Cu3−ySiyO10−δ samples

The (Cu_0.5Tl_0.25Li_0.25)Ba₂Ca₂Cu_3?ySi_yO_10?δ (y = 0, 0.25 0.5, 0.75, 1.0, 1.25) superconductor samples have been prepared by solid-state reaction method. The critical temperature and as well as the magnitude of diamagnetism is increased up to Si concentration y = 1.0, however, from the doping level y = 1.25 a decrease in the critical temperature along with the vanishing of the diamagnetism was observed. The carrier’s in the conducting CuO₂/SiO₂ planes were optimized by carrying out post-annealing in oxygen and an increase in the critical temperature was observed in all Si doped samples. The doping efficiency of Cu_0.5Tl_0.5Ba₂O_4?δ charge reservoir layer in (Cu_0.5Tl_0.25Li_0.25)Ba₂Ca₂Cu_3?ySi_yO_10?δ (y = 0, 0.25 0.5, 0.75, 1.0, 1.25) samples is enhanced by doping Li⁺¹ ion; as alkali metals are known to easily loose their outer most electron which could be supplied to CuO₂/SiO₂ conducting planes and would suppress the anti-ferromagnetism in the inner conducting planes. The FTIR absorption measurements have provided an indirect evidence of Si substitution at in CuO₂ planes.     

Solid‐state NMR study of dopant effects on the chemical properties of Mg‐, In‐, and Al‐doped SnP2O7

The effects of doped low‐valence cations on the properties of the SnP₂O₇ proton conductor at ambient temperature are investigated from changes in solid‐state NMR spectra and nuclear magnetic relaxation times. Although the T₁H values increased with decreasing acidity as a result of cation exchange, the ¹H chemical shifts moved to lower field in Al‐ and In‐doped materials compared with undoped ones. Furthermore, the shifts changed to higher field in Mg‐doped materials, suggesting the existence of different protonic species in those materials. The bulk phosphate chemical shifts in the ³¹P dipolar‐decoupling MAS NMR spectra were very similar, regardless of the nature and amount of the doping species. On the other hand, by ¹H/³¹P cross‐polarization MAS NMR, P₂O₇ signals interacting with an interstitial proton [Q¹(proton)] were observed in all the undoped and doped SnP₂O₇, while acidic P–OH‐type phosphate signals [Q¹(acid)] were additionally observed in the Mg‐doped conductor. The different affinity of the proton with the dopants and phosphates caused lower conductivity and larger activation energy in the Mg‐doped materials, compared with those in the In‐ and Al‐doped materials. Copyright © 2014 John Wiley & Sons, Ltd.     

Achieving high-performance Li2ZnTi3O8 anode for advanced Li-ion batteries by molybdenum doping

The Li₂ZnTi_3-xMo_xO₈ (x = 0, 0.05, 0.1 and 0.15) anode materials are successfully synthesized through a simple solid-state method, and few Li₂MoO₄ phase can be found in Li₂ZnTi_3-xMo_xO₈ (x = 0.1 and 0.15). All samples are composed of nanocrystalline particles and irregular micron-sized particles with a relatively uniform particle size of 100–200 nm Li₂ZnTi_2.9Mo_0.1O₈ shows the best electrochemical properties among all samples. The Li₂ZnTi_2.9Mo_0.1O₈ delivers a charge/discharge capacity of 188.1/188.2 mA h/g at 1 A/g after 400 cycles, but the corresponding capacity of pristine Li₂ZnTi₃O₈ is only 104.5 (102.2) mA h/g. The Mo⁶⁺ doping enhances the reversible capacity, rate performance, and cycling stability of Li₂ZnTi₃O₈, especially at large current densities. The improved electrochemical performance of Li₂ZnTi_3-xMo_xO₈ can be ascribed to the enhanced electrical conductivity, improved intercalation/de-intercalation reversibility of Li ions, increased lithium-ion diffusion coefficients, and reduced charge-transfer resistance. This work provides an effective strategy to construct high-performance anode materials for advanced lithium-ion battery; this effective design strategy may be used to enhance the reversible specific capacity, and rate the performance and cycle stability of other insertion-host anode materials.     

Preparation and Dielectric Properties of Mn-Doped Ba0.6Sr0.4TiO3-MgTiO3 Composite Ceramics

Barium strontium titanate (Ba_0.6Sr_0.4TiO₃, BST) nano-powders were prepared using Ba(NO₃)₂, Sr(NO₃)₂, oxalic acid dehydrate, and tetrabutyl titanate (Ti(OC4H9)4) as precursors by the chemical co-precipitation method. The product was characterized by thermogravimetry-differential scanning calorimetry (TG-DSC) thermal analyses, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The experimental results indicated that the resulting Ba_0.6Sr_0.4TiO₃ nano-powders were homogeneous with agglomerated nature. The Ba_0.6Sr_0.4TiO₃-MgTiO₃ (BST-MT) bulk composite ceramics doped by Mn were obtained by the traditional solid phase method. The XRD patterns demonstrated that Mn-doped BST was unable to change the perovskite crystalline structure of BST materials. SEM photographs revealed that the crystalline grains became larger with increasing the content of doping Mn (<1.5% (x, molar fraction)) and then the size of grains decreased after the Mn content exceeded 1.5% in the BST ceramics, suggesting the effect of Mn doping on the morphologies of BST-MT composites. The dielectric properties of BST-MT composite ceramics doped with 0.1%-2.0% (x) Mn were investigated systematically. Two effects of Mn doping on the dielectric properties of the BST-MT composite ceramics were observed. At low Mn doping concentrations (<1.5%), Mn mainly acted as an acceptor dopant to replace Ti at the B site of ABO3 perovskite structure, leading to a diffused phase transition. It was also observed that the grain size increased drastically as the Mn content increased and thus caused the decrease of dielectric loss. At higher Mn doping concentrations (>1.5%), the grain size decreased and the suppression of permittivity and the drastic increase of the dielectric losses were observed, which indicated a “composite” mixing effect.