ChemInform Abstract: Mixed‐Valent Neptunium(IV/V) Compound with Cation—Cation‐Bound Six‐Membered Neptunyl Rings.

Na_xNp^IV(Np^VO₂)₆ (OH)_1+xCl₉(H₂O)_8‐x (0 < x ≤ 1) is synthesized by evaporation of a neptunium(V) acidic (HCl) stock solution over several months to complete dryness.     

Strukturuntersuchungen an Usoviten: Ba2CaMIIV2F14 (MIII = Mn,Fe), Ba2CaMnFe2F14 und Ba2CaCuM2IIIF14 (MIII = Mn,Fe, Ga)

Structural Studies with Usovites: Ba₂CaM^IIV₂F₁₄ (M^III = Mn, Fe), Ba₂CaMnFe₂F₁₄ and Ba₂CaCuM₂^IIIF₁₄ (M^III = Mn, Fe, Ga). Single crystals of six compounds Ba₂CaM^IIM₂^IIIF₁₄ were prepared to refine their usovite type structure (space group C2/c, Z = 4) using X‐ray diffractometer data. The cell parameters of the phases studied with M^IIM₂^III= MnV₂, FeV₂, CuMn₂, MnFe₂, CuFe₂ und CuGa₂ are within the range 1374≤a/pm≤1384, 534≤b/pm≤542, 1474≤c/pm≤1510, 91, 3≤ß/°≤93, 2. The atoms Ca and M^II are incompletely ordered on the 8‐ and 6‐coordinated positions, 4e and 4b, respectively. In the case of Ba₂CaFeV₂F₁₄ and Ba₂CaCuGa₂F₁₄ there is reciprocal substitution (x≈0, 1): (Ca_1‐xM_x^II) (4e) and (M_1‐x^IICa_x) (4b). In the case of the other usovites Ca‐enriched phases Ba₂Ca(M_1‐y^IICa_y)M₂^IIIF₁₄ occured (up to y≈0, 35), exhibiting partial substitution at the octahedral position (4b) only, showing a corresponding increase in M^II‐F distances. The distortion of [M^IIF₆] and [M^IIIF₆] octahedra within the structure is considerably enhanced on replacement by Cu^II and Mn^III. The results of powder magnetic susceptibility measurements of Ba₂CaMnV₂F₁₄ and Ba₂CaFeV₂F₁₄ (T_N≈7K) are reported.     

Study of Sb‐doped SnO2 Gray Ceramic Pigment with Cassiterite Structure

In this study, Sb_xSn_1?xO₂ (0 ≤ x ≤ 0.5) compositions were synthesized by the ceramic method from Sb₂O₃‐SnO₂ and Sb₂O₅‐SnO₂ mixtures and characterized by Differential thermal analysis (DTA) and thermogravimetric analysis (TG), X‐ray diffraction, UV‐V‐NIR spectroscopy and CIE L*a*b* (Commission Internationale de l'Eclairage L*a*b*) parameters measurements. Solid solutions with cassiterite structure were obtained at 1300 °C. These solid solutions are stable into glazes. From Sb₂O₃, light gray coloured materials were obtained. From Sb₂O₅, bluish gray coloured materials were obtained at 1300 °C/6h when x ≥ 0.3. Sb_xSn_1?xO₂ with 0.3 ≤ x < 0.5, T = 1300 °C and Sb₂O₅ might be established as compositional range, fired temperature and antimony precursor to obtain gray ceramic pigments in this system.     

Synthesis,Crystal Structure and Reducibility of K2NiF4 Type Oxides Sm2—xSrxCuO4

K2NiF4 type compounds Sm2-xSrxCuO4(0≤x≤1.2)were prepared.Rietveld refinement of powder diffraction data shows that the crystal system of these compounds belongs to T′ type tetragonal structure of space group I4/mmm,and the addition of Sr causes a dramatic shift of the O(I) ions along the c axis from Sm(Sr) toward Cu while scarcely affecting the Cu-O(Ⅱ）bond in basal CuO4 phane.From XRD data,it can be seen that when 0.0≤x≤0.6,Sm2-xSrxCuO4 belongs to a singlephase K2NiF4 type structure,while at x≥0.7,both the free SrO phase and the CuO phase exist in these compounds.From the results of XPS and rietveld refinement,it can be seen that after replacing Sm^3 with Sr^2 of lower valence,the valence of Cu and Sm does not change apparently,and thus some defect must be formed at the oxygen ion positions and/or position A on A2BO4 to keep charge balance and to stabilize the structure.     

Suppressing the P2–O2 Phase Transition of Na0.67Mn0.67Ni0.33O2 by Magnesium Substitution for Improved Sodium‐Ion Batteries

Room‐temperature sodium‐ion batteries (SIBs) have shown great promise in grid‐scale energy storage, portable electronics, and electric vehicles because of the abundance of low‐cost sodium. Sodium‐based layered oxides with a P2‐type layered framework have been considered as one of the most promising cathode materials for SIBs. However, they suffer from the undesired P2–O2 phase transition, which leads to rapid capacity decay and limited reversible capacities. Herein, we show that this problem can be significantly mitigated by substituting some of the nickel ions with magnesium to obtain Na_0.67Mn_0.67Ni_0.33?xMg_xO₂ (0≤x≤0.33). Both the reversible capacity and the capacity retention of the P2‐type cathode material were remarkably improved as the P2–O2 phase transition was thus suppressed during cycling. This strategy might also be applicable to the modulation of the physical and chemical properties of layered oxides and provides new insight into the rational design of high‐capacity and highly stable cathode materials for SIBs.     

ChemInform Abstract: Gold-Tin Ordering in SrAu2Sn2.

The solid solutions SrAu_xSn_4-x (1.7 ≤ x ≤ 2.2) are prepared by high-frequency melting of the elements (Nb ampules, 950—1150 K, 2—12 h).     

Synthesis and Structure Analysis of Aurivillius Phases Pb1‐xBi4‐+Ti1‐xMnxO15

Synthesis Pb_1‐xBi_4+xTi_4‐xMn_xO₁₅ compounds (0 ≤ × ≤ 1) were carried out by molten salts method using eutectic mixture of Na₂SO₄/K₂SO₄ salts (1:1 molar ratio) as the flux. The samples were characterized by X‐ray powder diffraction and refined by Le Bail method using Rietica program. The refinement results revealed that the compounds with the composition 0 ≤ x ≤ 0.6 formed Aurivillius phase with the space group A2₁am while the other composition (x ≥ 0.8) showed another phase beside A2₁am. The ratio b/a of the lattices constants for all the samples are larger than 1 indicating the direction of the orthorhombic along the b axis of their cells. The lattice parameters and volume of the unit cells decrease as the Mn content increasing from x = 0 to 0.6, for x ≥ 0.8 a second phase were observed. The morphologies of Pb_1‐xBi_4+xTi_4‐xMn_xO₁₅ samples were observed by SEM and show plate‐like aggregate crystals, typical of layered compounds belonging to the Aurivillius phase.     

Half Antiperovskites VI: On the Substitution Effects in Shandites InxSn2–xCo3S2

In the shandite type solid solution In_xSn_2–xCo₃S₂ the transition from half metal ferromagnetic Sn₂Co₃S₂ to the new thermoelectric InSnCo₃S₂ is related to A = In, Sn on different crystallographic sites. Effects and origin of crystal and electronic structure changes induced by A = In are now investigated within the solid solution 0 ≤ x ≤ 2 including In₂Co₃S₂. Effects are studied from X‐ray data, ¹¹⁹Sn Mößbauer spectroscopy, and ab initio calculations. Their origin is explored by DFT modeling on site preference of In and Sn in a supercell, electric field gradients (EFG), spin polarization, band structures, and direct space analyses (ELF, AIM). Indium is found to cause the crystal structure distortion on one A site, the electronic structure distortion to the other, as a consequence of inverted anisotropic bonding.     

Fe and Cr K‐edges EXAFS Study of Double Perovskite (Sr2‐xCax)FeMoO6 (0 ≤ x ≤ 2.0) and Sr2CrMO6 (M = Mo,W) Systems

The local structure of the double perovskite (Sr_2‐xCa_x)FeMoO₆ (0 ≤ × ≤ 2.0) and Sr₂CrMO₆ (M = Mo, W) systems have been probed by extended X‐ray absorption fine structure (EXAFS) spectroscopy at the Fe and Cr K‐edges. We found Fe‐O (ave) distance apparently decreases from 1.999 Å (x = 0) to 1.991 Å (x = 1.0) in (Sr_2‐xCa_x)FeMoO₆ (tetragonal structure). When x is increased further from 1.5 to 2.0, the Fe‐O bond distance decreased from 2.034 Å to 2.012 Å (monoclinic structure). In addition, Cr‐O, Sr‐Cr, and Cr‐Mo bond distances in Sr₂CrWO₆ are all slightly larger than the bond distances of Sr₂CrMoO₆, which is due to the ionic radius of the W⁵⁺ (0.62 Å) which is larger than the ionic radius of Mo⁵⁺ (0.61 Å). The results are consistent with our XRD refinements data.     

Phase equilibria in the V2O5-NaVO3-Ca(VO3)2-Mn2V2O7 system and interactions of phases with H2SO4 and NaOH solutions

Phase composition of the V₂O₅-NaVO₃-Ca(VO₃)₂-Mn₂V₂O₇ system was studied, and a subsolidus phase diagram constructed. The tetrahedration of the diagram is determined by the fact that the end-member of Ca_1–x Mn _x (VO₃)₂ solid solution is in equilibrium with all compounds of the system (V₂O₅, NaVO₃, Ca(VO₃)₂), vanadium β-bronzes Na _x V₂O₅ (0.22 ≤ x ≤ 0.40) and κ-bronzes (0.25 ≤ x ≤ 0.45, 0 ≤ y ≤ 0.16), Mn₂V₂O₇, and Na₂Mn₃(V₂O₇)₂ and with the end-members of reciprocal solid solutions based on calcium and sodium metavanadates. At 20°C, the degree of vanadium dissolution α for Na₂Ca(VO₃)₄ is 100% for 0.5 ≤ pH ≤ 10; for the other phases of the system, vanadium dissolution ranges from 100 to 10% for pH below 3.5; in the alkaline pH range, ≤ 10%. Sodium for calcium substitution in Ca(VO₃)₂ increases α in aqueous NaOH to 20%. For Na₂Mn₃(V₂O₇)₂, α decreases from 92 to 80% as pH changes from 0.5 to 2.5; at pH above 4, α = 30%.     

An Expanded Family of Dysprosium–Scandium Mixed‐Metal Nitride Clusterfullerenes: The Role of the Lanthanide Metal on the Carbon Cage Size Distribution

A large family of dysprosium–scandium (Dy‐Sc) mixed‐metal nitride clusterfullerenes (MMNCFs), Dy_xSc_3?xN@C_2n (x=1, 2, 2n=68, 70, 76–86) have been successfully synthesized and isolated. Among these, the C₇₀ and C₈₂‐based MMNCFs are two new cages that have never been isolated for MMNCFs. Synthesis of Dy_xSc_3?xN@C_2n was accomplished by the “selective organic solid” route using guanidinium thiocyanate as the nitrogen source, and their isolation was fulfilled by recycling HPLC. UV/Vis‐NIR spectroscopic study indicates that almost all Dy_xSc_3?xN@C_2n MMNCFs are kinetically stable fullerenes with optical band gaps beyond 1 eV. This feature is distinctly different to their counterparts Dy₃N@C_2n (78≤2n≤88), whose for optical band‐gaps are below 1 eV for relatively large cages such as C₈₄ and C₈₆. An FTIR spectroscopic study in combination with DFT calculations enables reasonable assignments of the cage isomeric structures of all isolated Dy_xSc_3?xN@C_2n (x=1, 2, 2n=68, 70, 76–86) MMNCFs. The carbon cage size distribution of Dy_xSc_3?xN@C_2n (2n=68, 70, 76–86) is compared to the reported Dy₃N@C_2n (78≤2n≤8) homogeneous NCF and Dy_xSc_3?xN@C_2n (78≤2n≤88) MMNCF families, revealing that the medium‐sized Dy metal plays a crucial role on the expanded cage size distribution of MMNCFs. As a result, Dy_xSc_3?xN@C_2n MMNCFs are the largest MMNCF family reported to date.     

ChemInform Abstract: (Sr1-xBax)FeO2 (0.4 ≤ x ≤ 1): A New Oxygen-Deficient Perovskite Structure.

The new oxygen-deficient perovskites of title are prepared by reaction of (Sr_1-xBa_x)FeO_3-δ (x = 0.4, 0.5, 0.6, 0.7, 0.8, 0.9; δ ≤ 0.5; obtained from stoichiometric mixtures of SrCO₃, BaCO₃, and Fe₂O₃ at 1473 K in air for 48 h) with an excess of CaH₂ at 593 K for 3—14 d (0.4 ≤ x ≤ 0.9) and NaH at 413 K for 3 d (x = 1.0).     

Superior Na‐Storage Performance of Low‐Temperature‐Synthesized Na3(VO1−xPO4)2F1+2x (0≤x≤1) Nanoparticles for Na‐Ion Batteries

Na‐ion batteries are becoming comparable to Li‐ion batteries because of their similar chemical characteristics and abundant sources of sodium. However, the materials production should be cost‐effective in order to meet the demand for large‐scale application. Here, a series of nanosized high‐performance cathode materials, Na₃(VO_1?xPO₄)₂F_1+2x (0≤x≤1), has been synthesized by a solvothermal low‐temperature (60–120 °C) strategy without the use of organic ligands or surfactants. The as‐synthesized Na₃(VOPO₄)₂F nanoparticles show the best Na‐storage performance reported so far in terms of both high rate capability (up to 10 C rate) and long cycle stability over 1200 cycles. To the best of our knowledge, the current developed synthetic strategy for Na₃(VO_1?xPO₄)₂F_1+2x is by far one of the least expensive and energy‐consuming methods, much superior to the conventional high‐temperature solid‐state method.     

Structural and Electrochemical Study of Vanadium‐Doped TiO2 Ramsdellite with Superior Lithium Storage Properties for Lithium‐Ion Batteries

Titanium‐oxide‐based materials are considered attractive and safe alternatives to carbonaceous anodes in Li‐ion batteries. In particular, the ramsdellite form TiO₂(R) is known for its superior lithium‐storage ability as the bulk material when compared with other titanates. In this work, we prepared V‐doped lithium titanate ramsdellites with the formula Li_0.5Ti_1?xV_xO₂ (0≤x≤0.5) by a conventional solid‐state reaction. The lithium‐free Ti_1?xV_xO₂ compounds, in which the ramsdellite framework remains virtually unaltered, are easily obtained by a simple aqueous oxidation/ion‐extraction process. Neutron powder diffraction is used to locate the Li channel site in Li_0.5Ti_1?xV_xO₂ compounds and to follow the lithium extraction by difference‐Fourier maps. Previously delithiated Ti_1?xV_xO₂ ramsdellites are able to insert up to 0.8 Li⁺ per transition‐metal atom. The initial gravimetric capacities of 270 mAh g^?1 with good cycle stability under constant current discharge conditions are among the highest reported for bulk TiO₂‐related intercalation compounds for the threshold of one e^? per formula unit.     

Systems Li<Subscript>2</Subscript>O(Na<Subscript>2</Subscript>O)-CdO-V<Subscript>2</Subscript>O<Subscript>5</Subscript>: Phase composition and phase diagrams

The subsolidus phase composition of the M₂O-CdO-V₂O₅ systems with M = Li or Na is studied. Double orthovanadates MCdVO₄ and MCd₄(VO₄)₃ form solid solutions of composition Li_{1 ? 2x/3}Cd _x/3CdVO₄ (0 ≤ x ≤ 1, orthorhombic space group Cmcm, modulation at x = 0.6) and Na_{3 ? 2x} Cd_{3 + x} (VO₄)₃ (0 ≤ x ≤ 0.10 and 0.30 ≤ x ≤ 1, orthorhombic space group Cmcm and Pn2₁ a or Pnma, respectively). In the range 0.10 < x < 0.30, the end-members of the solid solutions coexist. Isothermal sections of the systems are mapped.     

Application of Nanosized Cu0.5Co0.5Fe2O4 Spinel Ferrite as a Nanocatalyst in the Synthesis of 14‐Aryl‐14H‐dibenzo[a,j]xanthene Derivatives under Solvent‐free Conditions

Copper and cobalt substituted spinel ferrites Cu_1‐xCo_xFe₂O₄ (0≤X≤1) have been synthesized by using hydrothermal method. The resultant spinel ferrites were systematically characterized by different techniques such as X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X‐ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FT‐IR). It was indicated that all the resultant spinel ferrites obtained by the hydrothermal method had the single‐phase crystalline. The resultant spinel ferrites were employed in the synthesis of 14‐aryl‐14‐H‐dibenzo[a,j]xanthene derivatives. It was found that the nanocatalyst Cu_0.5Co_0.5Fe₂O₄ displays the best performance in the synthesis of 14‐aryl‐14H‐dibenzo[a,j]xanthenes. The catalyst was reused several times without significant loss of its activity for the preparation of desired product. In addition high yields of the products, solvent‐free conditions and reusability of the catalyst are other worthwhile advantages of the present study.     

Biomimetic Synthesis of Metal Ion‐Doped Hierarchical Crystals Using a Gel Matrix: Formation of Cobalt‐Doped LiMn2O4 with Improved Electrochemical Properties through a Cobalt‐Doped MnCO3 Precursor

We have synthesized spinel type cobalt‐doped LiMn₂O₄ (LiMn_2?yCo_yO₄, 0≤y≤0.367), a cathode material for a lithium‐ion battery, with hierarchical sponge structures via the cobalt‐doped MnCO₃ (Mn_1‐xCo_xCO₃, 0≤x≤0.204) formed in an agar gel matrix. Biomimetic crystal growth in the gel matrix facilitates the generation of both an homogeneous solid solution and the hierarchical structures under ambient condition. The controlled composition and the hierarchical structure of the cobalt‐doped MnCO₃ precursor played an important role in the formation of the cobalt‐doped LiMn₂O₄. The charge–discharge reversible stability of the resultant LiMn_1.947Co_0.053O₄ was improved to ca. 12 % loss of the discharge capacity after 100 cycles, while pure LiMn₂O₄ showed 24 % loss of the discharge capacity after 100 cycles. The parallel control of the hierarchical structure and the composition in the precursor material through a biomimetic approach, promises the development of functional materials under mild conditions.     

Novel Derivatives of the CaIn2 Type of Structure: Yb1+xMg1—xGa4 (0 ≤ x ≤ 0.058) and YLiGa4

The compounds Yb_1+xMg_1—xGa₄ (0 ≤ x ≤ 0.058) and YLiGa₄ were synthesized by direct reaction of the elements in sealed niobium crucibles. The atomic arrangement of Yb_1+xMg_1—xGa₄ (x = 0.058) represents a new structure type (space group P6¯m2, a = 4.3979(3)Å and c = 6.9671(7)Å) as evidenced by single crystal structure analysis and can be described as an ordered variant of CaIn₂. YLiGa₄ is isotypic to the ytterbium compound according to X‐ray Guinier powder data (a = 4.3168(1)Å and c = 6.8716(2)Å). Measurements of the magnetic susceptibility of both compounds reveal intrinsic diamagnetic behaviour, i.e., ytterbium in the 4f¹⁴ configuration for Yb_1+xMg_1—xGa₄ (x = 0). From electrical resistivity data both compounds can be classified as metals. The compressibility of Yb_1+xMg_1—xGa₄ (x = 0.058) as measured in diamond anvil cells by angle‐dispersive X‐ray diffraction is compatible with a valence change of the ytterbium atoms at high‐pressures and indicates a slight anisotropy which is in accordance with the structural organisation of the gallium network. X‐ray absorption spectra of the Yb L_III edge of Yb_1+xMg_1—xGa₄ (x = 0.058) at pressures up to 25.0 GPa show a two‐peak structure which reveals the presence of Yb in the 4f¹⁴ and 4f¹³ states. The amount of ytterbium in the 4f¹³ state increases in two steps with progressing compression. The bonding analysis by means of the electron localization function reveals the Zintl‐like character of both compounds and confirms the 4f¹⁴ state for the majority of ytterbium atoms.     

Computer-assisted structure simulation, synthesis, and phase formation of molybdophosphates A1−x Zr2(PO4 3−x (MoO4)x (A is an alkali metal)

Structure simulation is performed for molybdophates of variable composition A_1?x Zr₂(PO₄)_3?x (MoO₄)_x, where A is Na (0≤x≤0.6), K (0≤x≤0.6), K (0≤x≤0.3), Rb (0≤x≤0.2), or Cs (0≤x≤0.1), using the minimization of the interatomic interaction energy; these molybdophosphates crystallize in the NaZr₂(PO₄)₃ (NZP) structure type. The results of the computer-assisted structure simulation are verified by the synthesis of the molybdophosphates and their characterization by X-ray powder diffraction and IR spectroscopy. The crystallization field of the NZP molybdophosphate shrinks as the alkali cation size increases. The key factors that govern the stability of the NZP structure in alkali zirconium molybdophosphates are determined.     

ChemInform Abstract: Influence of Hydrogen Absorption on Structural and Magnetic Properties of Ce2Ni2In.

Ce₂Ni₂InH_x hydrides with x < 2 retain the Mo₂FeB₂‐type structure of Ce₂Ni₂In and crystallize in the tetragonal space group P4/mbm (powder XRD).