Eu3+掺杂Sr3Y2TeO9的红色荧光粉

采用高温固相法制备了一系列Sr₃Y_2-xTeO₉∶xEu³⁺新型红色荧光粉,研究了Sr₃Y_2-xTeO₉∶xEu³⁺的物相结构、发光性能、衰减寿命以及热稳定性。研究结果表明新型红色荧光粉Sr₃Y_2-xTeO₉∶xEu³⁺能在近紫外光或蓝光激发下发出强烈的红光,并确定了Sr₃Y_2-xTeO₉∶xEu³⁺的浓度猝灭机制是电偶极-电偶极之间相互作用。其色坐标结果表明,随着掺杂浓度的增加该荧光粉的色坐标均在红色区域。温度相关荧光发射光谱揭示了该荧光粉具有良好的热稳定性。荧光衰减曲线显示在Sr₃Y_2-xTeO₉∶xEu³⁺荧光粉中当x=0.34时为最佳掺杂浓度,其平均荧光寿命为0.619 ms。综合以上研究结果表明新型红色荧光粉Sr₃Y_2-xTeO₉∶xEu³⁺在荧光转换近紫外激发白光二极管中具有良好的应用前景。     

Disilberoxotellurat(VI), Ag2TeO4

Disilver Oxotellurate(VI), Ag₂TeO₄ Ag₂TeO₄ was synthesised by reaction of Ag₂O and TeO₂ applying an elevated oxygen pressure. According to a single crystal structure determination (C2/c, a = 9.0588(9), b = 9.2456(8), c = 13.623(1) Å, β = 91.758(8)°, Z = 12, 1289 independent reflections, R1 = 2.32 %, wR2 = 5.51 %), Ag₂TeO₄ contains a novel chain‐like polyanion with tellurium in an octahedral coordination. The TeO₆ octahedra are connected via common edges and vertices in a way that the resulting polyanion represents a section of the rutile structure type. Ag₂TeO₄ shows diamagnetic and insulating behaviour, it decomposes at 560 °C into Ag₂TeO₃ and oxygen.     

Reactions of tellurates(IV) of some 2nd group metals with basic oxides

Calcium, strontium and barium tellurates(IV) were heated, in N₂ atmosphere, with stoichiometric amounts of CaO, SrO and BaO, respectively. The products of reactions, proceeding at 380–620°C, contained orthotellurate and telluride anions formed in disproportionation.     

Why should transition metal chalcogenides be investigated as water splitting precatalysts even though they transform into (oxyhydr)oxides?

The extensive investigation of 3d transition metal chalcogenide (sulphides, selenides, tellurides) precatalysts has shown that they transform into (oxyhydr)oxides during the oxygen evolution reaction (OER) and likely during industrial hydrogen evolution reaction (HER) conditions, as predicted by their Pourbaix diagrams. The phases formed from chalcogenide precatalysts are often more active, due to anion leaching induced effects. But are chalcogenides suitable to be used sacrificially, are they abundant, cheap, and non-toxic enough? Is their unique chemical nature really required? This review answers these questions by discussing the role of chalcogenides in the reconstruction/transformation process. Furthermore, it examines the role of remaining traces of chalcogenates (sulphate, selenate) that were recently shown to improve the OER activity and can break the 1OH/1OOH scaling relations.     

A linear bridging angle in the pyrovanadate group within the crystal structure of Hg2V2Te2O11

The title compound, dimercury(II) divanadium(V) ditellurium(IV) undecaoxide, Hg₂V₂Te₂O₁₁, is a new representative within the family of divalent oxovanadato(V)tellurates(IV). The anionic framework is made up of disphenoidal [TeO₄] polyhedra that are linked by corner‐sharing to two neighbouring pyrovanadate units, resulting in chains of six‐membered rings propagating parallel to [10]. The bridging O atom of the pyrovanadate unit is located on an inversion centre, leading to a staggered conformation and a linear V—O—V angle between the two [VO₄] tetrahedra. The anionic chains are connected by interjacent six‐coordinate Hg²⁺ cations into a three‐dimensional framework. The 5s² lone electron pair of the Te^IV atom is stereochemically active and protrudes into the free space of the chain links.     

Speciation of Tellurium(VI) in Aqueous Solutions: Identification of Trinuclear Tellurates by 17O, 123Te,and 125Te NMR Spectroscopy

Tellurates have attracted the attention of researchers over the past decade due to their properties and as less toxic forms of tellurium derivatives. However, the speciation of Te(VI) in aqueous solutions has not been comprehensively studied. We present a study of the equilibrium speciation of tellurates in aqueous solutions at a wide pH range, 2.5–15 by ¹⁷O, ¹²³Te, and ¹²⁵Te NMR spectroscopy. The coexistence of monomeric, dimeric, and trimeric oxidotellurate species in chemical equilibrium at a wide pH range has been shown. NMR spectroscopy, DFT computations, and single-crystal X-ray diffraction studies confirmed the formation and coexistence of trimeric tellurate anions with linear and triangular structures. Two cesium tellurates, Cs₂[Te₄O₈(OH)₁₀] and Cs₂[Te₂O₄(OH)₆], were isolated from the solution at pH 5.5 and 9.2, respectively, and studied by single-crystal X-ray diffractometry, revealing dimeric and tetrameric tellurate anions in corresponding crystal structures.     

Electrophoretic and Chromatographic Separation of Iodide,Iodate, Tellurite and Tellurate

Two procedures for separation of iodine and tellurium anions are described. Electrophoresis and paper chromatography were used to study the radioactive and radiochemical purity of carrier free Na¹³¹J solution.