Ca4IrO6, Ca3MgIrO6 and Ca3ZnIrO6

Single crystals of tetracalcium iridium hexaoxide, Ca₄IrO₆, tricalcium magnesium iridium hexaoxide, Ca₃MgIrO₆, and tricalcium zinc iridium hexaoxide, Ca₃ZnIrO₆, were prepared via high-temperature flux growth and structurally characterized by single-crystal X-ray diffraction. The three compounds are isostructural and adopt the K₄CdCl₆ structure type, comprised of chains of alternating face-shared [CaO₆], [MgO₆] or [ZnO₆] trigonal prisms and [IrO₆] octahedra, surrounded by columns of Ca²⁺ ions.     

Sr3(BS3)2 und Sr3(B3S6)2: Zwei neue nicht‐oxidische Chalkogenoborate mit trigonal‐planar koordiniertem Bor

Sr₃(BS₃)₂ and Sr₃(B₃S₆)₂: Two Novel Non‐oxidic Chalcogenoborates with Boron in a Trigonal‐Planar Coordination The thioborates Sr₃(BS₃)₂ and Sr₃(B₃S₆)₂ were prepared from strontium sulfide, amorphous boron and sulfur in solid state reactions at a temperature of 1123 K. In a systematic study on the structural cation influence on this type of ternary compounds, the crystal structures were determined by single crystal X‐ray diffraction. Sr₃(BS₃)₂ crystallizes in the monoclinic spacegroup C2/c (No. 15) with a = 10.187(4) Å, b = 6.610(2) Å, c = 15.411(7) Å, β = 102.24(3)° and Z = 4. The crystal structure of Sr₃(B₃S₆)₂ is trigonal, spacegroup R3¯ (Nr. 148), with a = 8.605(1) Å, c = 21.542(4) Å and Z = 3. Sr₃(BS₃)₂ contains isolated [BS₃]^3— anions with boron in a trigonal‐planar coordination. The strontium cations are found between the layers of orthothioborate anions. Sr₃(B₃S₆)₂ consists of cyclic [B₃S₆]^3— anions and strontium cations, respectively.     

Sr5Ge2N6 – A Nitridogermanate with Edge‐sharing Double Tetrahedra

The new nitridogermanate Sr₅Ge₂N₆ was obtained as a coarsely crystalline product by Na‐flux technique employing a reaction of Sr, Na, NaN₃ and GeO₂ in weld shut tantalum‐tubes at temperatures up to 760 °C. The crystal structure was determined by single‐crystal X‐ray methods: (Sr₅Ge₂N₆, space group C2/c (no. 15), a = 1040.8(2), b = 652.08(13), c = 1356.5(3) pm, β = 100.29(3)°, V = 905.8(3)·10⁶ pm³, Z = 4, 1240 observed reflections, 61 parameters, R1 = 0.031). In the solid, there are edge‐sharing [Ge₂N₆]¹⁰⁻ double tetrahedra surrounded by Sr²⁺ ions. Sr₅Ge₂N₆ was found to be isotypic with Ca₅Si₂N₆.     

Synthesis,Persistent Luminescence,and Thermoluminescence Properties of Yellow Sr3SiO5:Eu2+,RE3+ (RE=Ce,Nd, Dy,Ho, Er,Tm, Yb) and Orange‐Red Sr3−xBaxSiO5:Eu2+, Dy3+ Phosphor

Sunlight‐excitable orange or red persistent oxide phosphors with excellent performance are still in great need. Herein, an intense orange‐red Sr_3?xBa_xSiO₅:Eu²⁺,Dy³⁺ persistent luminescence phosphor was successfully developed by a two‐step design strategy. The XRD patterns, photoluminescence excitation and emission spectra, and the thermoluminescence spectra were investigated in detail. By adding non‐equivalent trivalent rare earth co‐dopants to introduce foreign trapping centers, the persistent luminescence performance of Eu²⁺ in Sr₃SiO₅ was significantly modified. The yellow persistent emission intensity of Eu²⁺ was greatly enhanced by a factor of 4.5 in Sr₃SiO₅:Eu²⁺,Nd³⁺ compared with the previously reported Sr₃SiO₅:Eu²⁺, Dy³⁺. Furthermore, Sr ions were replaced with equivalent Ba to give Sr_3?xBa_xSiO₅:Eu²⁺,Dy³⁺ phosphor, which shows yellow‐to‐orange‐red tunable persistent emissions from λ=570 to 591 nm as x is increased from 0 to 0.6. Additionally, the persistent emission intensity of Eu²⁺ is significantly improved by a factor of 2.7 in Sr_3?xBa_xSiO₅:Eu²⁺,Dy³⁺ (x=0.2) compared with Sr₃SiO₅:Eu²⁺,Dy³⁺. A possible mechanism for enhanced and tunable persistent luminescence behavior of Eu²⁺ in Sr_3?xBa_xSiO₅:Eu²⁺,RE³⁺ (RE=rare earth) is also proposed and discussed.     

Li4Ca3Si2N6 and Li4Sr3Si2N6 – Quaternary Lithium Nitridosilicates with Isolated [Si2N6]10– Ions

The isotypic nitridosilicates Li₄Ca₃Si₂N₆ and Li₄Sr₃Si₂N₆ were synthesized by reaction of strontium or calcium with Si(NH)₂ and additional excess of Li₃N in weld shut tantalum ampoules. The crystal structure, which has been solved by single‐crystal X‐ray diffraction (Li₄Sr₃Si₂N₆: C2/m, Z = 2, a = 6.1268(12), b = 9.6866(19), c = 6.2200(12) Å, β = 90.24(3)°, wR₂ = 0.0903) is made up from isolated [Si₂N₆]^10– ions and is isotypic to Li₄Sr₃Ge₂N₆. The bonding angels and distances within the edge‐sharing [Si₂N₆]^10– double‐tetrahedra are strongly dependent on the lewis acidity of the counterions. This finding is discussed in relation to the compounds Ca₅Si₂N₆ and Ba₅Si₂N₆, which also exhibit isolated [Si₂N₆]^10– ions.     

Effect of Sr2+ doping on the luminescence properties of YVO4:Eu3+,Sr2+ particles prepared by a solvothermal method

Well-dispersed Eu³⁺ and Sr²⁺ co-doped YVO₄ luminescent particles (YVO₄:Eu³⁺,Sr²⁺) on the submicron scale were prepared by a facile solvothermal method at low temperature. The effect of Sr²⁺ doping on the luminescence of YVO₄:Eu³⁺,Sr²⁺ particles was investigated by fixing the Eu³⁺ doping concentration at 7 mol%. It was found that the luminescence intensity of the as-prepared YVO₄:Eu³⁺,Sr²⁺ particles increased with the Sr²⁺ doping concentration x to reach a two-fold enhancement when x = 5 %, and then decreased for higher x. We also investigated the effect of thermal annealing on the luminescence properties of the YVO₄:Eu³⁺ and YVO₄:Eu³⁺,Sr²⁺ particles. A remarkable enhancement in their luminescence properties was observed after annealing at 900 °C in air for 30 min. It was showed that the annealed YVO₄:Eu³⁺,Sr²⁺ particles exhibited a two-fold stronger emission than the annealed YVO₄:Eu³⁺. This work indicates that Sr²⁺ doping is beneficial to the luminescence enhancement for both the as-prepared and annealed YVO₄:Eu³⁺,Sr²⁺ particles.     

Alkaline Earth Metal Zirconate Perovskites MZrO3 (M=Ba2+, Sr2+, Ca2+) Derived from Molecular Precursors and Doped with Eu3+ Ions

The effect of alkaline earth metal alkoxides on the protonation of zirconocene dichloride was investigated. This approach enabled the design of compounds with preset molecular structures for generating high‐purity binary metal oxide perovskites MZrO₃ (M=Ba²⁺, Sr²⁺, Ca²⁺). Single‐source molecular precursors [Ba₄Zr₂(μ₆‐O)(μ₃,η²‐OR)₈(OR)₂(η²‐HOR)₂(HOR)₂Cl₄], [Sr₄Zr₂(μ₆‐O)(μ₃,η²‐OR)₈(OR)₂(HOR)₄Cl₄], [Ca₄Zr₂(μ₆‐O)(μ₃,η²‐OR)₈(OR)₂Cl₄], and [Ca₆Zr₂(μ₂,η²‐OR)₁₂(μ‐Cl)₂(η²‐HOR)₄Cl₆] ? 8 CH₂Cl₂ were prepared via elimination of the cyclopentadienyl ring from Cp₂ZrCl₂ as CpH in the presence of M(OR)₂ and alcohol ROH (ROH=CH₃OCH₂CH₂OH) as a source of protons. The resulting complexes were characterized by elemental analysis, IR and NMR spectroscopy, and single‐crystal X‐ray diffraction. The compounds were then thermally decomposed to MCl₂/MZrO₃ mixtures. Leaching of MCl₂ from the raw powder with deionized water produced highly pure perovskite‐like oxide particles of 40–80 nm in size. Luminescence studies on Eu³⁺‐doped MZrO₃ revealed that the perovskites are attractive host lattices for potential applications in display technology.     

Einkristall-Röntgenstrukturanalyse von Sr3TiGa10O20

Single Crystal X-Ray Analysis of Sr₃TiGa₁₀O₂₀ Single crystals of Sr₃TiGa₁₀O₂₀ were prepared by recrystallisation of a molten oxide mixture and investigated by X-Ray technique. It crystallizes with monoclinic symmetry, space group C–C2/m, a = 15.451, b = 11.579, c = 5.051 Å, β = 108.57°, Z = 2. Sr₃TiGa₁₀O₂₀ belongs to the Pb₃GeAl₁₀O₂₀ type, showing Ga³⁺ in tetrahedral and octahedral coordination. The octahedral coordinated point positions are occupied by Ga³⁺ and Ti⁴⁺ statistically.     

Über die Verbindung Sr7Mn4O15 und Beziehungen zur Struktur von Sr2MnO4 und α-SrMnO3

On the Compound Sr₇Mn₄O₁₅ and Structure Relations to Sr₂MnO₄ and α-SrMnO₃ The “compound” hitherto described as a α modification of Sr₂MnO₄ is shown to consist of a mixture of SrO and the new monoclinic compound Sr₇Mn₄O₁₅ crystallizing in the space group P 2₁/c, a = 681.78(6), b = 962.24(8), c = 1038.0(1) pm, β = 91.886(7)°, Z = 2. Up to 0.3 mm long black crystals were grown from prereacted Sr₇Mn₄O₁₅, SrO, and SrCl₂ at 1350°C in a sealed platinum tube under argon. Its structure is related to α-SrMnO₃. It contains layers of cornershared double octahedra [O_2/2OMnO₃MnO₂O_1/2]^7? parallel to (100). Above 100 K the magnetism of Sr₇Mn₄O₁₅ follows the Curie Weiss law with Θ ～ -426 K and a moment μ_eff = 3.62 μ_B corresponding Mn⁴⁺.     

A novel Sr3Y(PO4)3-based white light-emitting phosphor

The Sr₃Y(PO₄)₃:0.05Sm³⁺, Sr₃Y(PO₄)₃:0.005Tb³⁺, and Sr₃Y(PO₄)₃:0.005Tb³⁺, 0.05Sm³⁺ phosphors were synthesized using a conventional solid-state reaction technique at high temperature and their photoluminescence properties under ultraviolet (UV) excitation were studied. We observed the UV sensitization of Sm³⁺ emission (565, 600, and 648 nm) by Tb³⁺ in Sr₃Y(PO₄)₃:0.005Tb³⁺, 0.05Sm³⁺, that leads to a white light emission with the CIE coordinate (0.367, 0.312) of Sr₃Y(PO₄)₃:0.005Tb³⁺, 0.05Sm³⁺ phosphor under UV excitation. The emission is a result of partial energy transfer from Tb³⁺ to Sm³⁺, which is discussed in detail in terms of the corresponding excitation and emission spectra.     

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.     

Sr2(OLi2Sr4)[CrN4]2, ein Nitridochromat(VI)‐Oxid mit Sauerstoff in tetragonal‐bipyramidaler Koordination durch Lithium und Strontium

Sr₂(OLi₂Sr₄)[CrN₄]₂, a Nitridochromate(VI)‐Oxide with Oxygen in Tetragonal‐Bipyramidal Coordination by Lithium and Strontium Green gleaming crystals of Sr₂(OLi₂Sr₄)[CrN₄]₂ were prepared by reaction of Li, Sr and CrN/Cr₂N (approximate 1 : 1 mixture) with flowing nitrogen at 900 °C (molar overall composition Li : Sr : Cr = 6 : 1 : ∼3). The oxygen content results from a leak in the gas supply. The crystal structure was determined by single crystal methods (triclinic; P1; a = 615.87(9) pm, b = 682.50(10) pm, c = 754.30(8) pm, α = 82.302(14)°, β = 75.197(10)°, γ = 70.133(13)°; Z = 1) and contains distorted tetragonal bipyramids (OLi₂Sr₄)⁸⁺ and [Cr^VIN₄]^6–‐tetrahedra besides Sr²⁺.     

Extraction of85Sr by the nitrobenzene solution of bis-1,2-dicarbollylcobaltate in the presence of dibenzo-18-crown-6

Extraction of strontium by the nitrobenzene solution of bis-1,2-dicarbollylcobaltate in the presence of dibenzo-18-crown-6 (DB18C6, L) has been investigated. the equilibrium data and the typical maxima concerning the dependencies of the Sr distribution ratios on the total analytical concentration of DB18C6 in the system under study can be explained assuming that the particles Sr²⁺, SrL²⁺, SrL₂ ²⁺, SrHL³⁺ and SrHL₂ ³⁺ are extracted into the nitrobenzene phase. The values of the corresponding extraction and stability constants of the extracted species in nitrobenzene saturated with water have been determined.     

Synthese und Kristallstruktur des ersten Oxonitridoborates — Sr3[B3O3N3]

Synthesis and Crystal Structure of the First Oxonitridoborate — Sr₃[B₃O₃N₃] The cyclotri(oxonitridoborate) Sr₃[B₃O₃N₃] was synthesized at 1450 °C as coarsely crystalline colourless crystals by the reaction of SrCO₃ with poly(boron amide imide) using a radiofrequency furnace. The structure was solved by single‐crystal X‐ray diffractometry (Sr₃[B₃O₃N₃], Z = 4, P2₁/n, a = 663.16(2), b = 786.06(2), c = 1175.90(3) pm, η = 92.393(1)°, R1= 0.0441, wR2 = 0.1075, 1081 independent reflections, 110 refined parameters). Besides Sr²⁺ there are hitherto unknown cyclic [B₃O₃N₃]^6— ions (B—N 143.7(10) — 149.1(9) pm, B—O 140.5(8) — 141.4(8) pm).     

Zur Verbindungsbildung von MeO:M2O3. VI. Darstellung und Strukturaufklärung von Sr1,33 Pb0,67 Al6O11

Compound Formation MeO: M₂O₃. VI. Synthesis and Structure Determination of Sr_1,33 Pb_0,67 Al₆O₁₁ Single crystal of Sr_1,33Pb_0.67Al₆O₁₁ could be prepared with a PbO flux. (Space group D–Pnnm, a = 22.13, b = 4.88, c = 8.42 Å, Z = 4) Sr²⁺ and Pb²⁺ are statistically intercalated into a framework of AlO₆ octahedra and AlO₄ tetrahedra. The typical coordination of Sr²⁺ and Pb²⁺ is realized by occupying different positions in the same cavern.     

Sr2MgOsO6: A Frustrated Os6+ (5d2) Double Perovskite with Strong Antiferromagnetic Interactions

The Os⁶⁺ (t_2g²) double perovskite Sr₂MgOsO₆ was prepared as polycrystalline material from the respective binary metal oxides. Sr₂MgOsO₆ crystallizes with the tetragonal space group I4/m. Magnetization and specific heat measurements show a broad anomaly near 100 K, but no well‐defined cusp. The magnetism is governed by strong antiferromagnetic interactions. Sr₂MgOsO₆ constitutes a new example for the peculiar, poorly understood magnetism of 5d² ions on a frustrated fcc lattice, where spin‐orbit coupling and orbital physics are expected to play an important role.     

Twinning and structure of Eu0.6Sr0.4MnO3

The crystal structure of europium strontium manganese trioxide, Eu_0.6Sr_0.4MnO₃, has been refined using a multiply twinned single crystal containing six twin components. The MnO₆ octa­hedra show Jahn–Teller distortions with nearly fourfold symmetry, but the octa­hedral tilting scheme reduces the crystal symmetry to ortho­rhom­bic (space group Pbnm). The refinement of site occupancies and the analysis of difference Fourier maps show that the Eu³⁺ and Sr²⁺ cations occupy different crystallographic positions with eightfold and twelvefold coordination, respectively.     

Metastabile Oxometallate der Lanthanoidmetalle:.Zur Kenntnis von Sr3Pr4O9 und Sr3La2Sm2O9 mit einem Beitrag über SrPr2O4

Metastable Compounds of Rare Earth Oxides. About Sr₃Pr₄O₉ and Sr₃La₂Sm₂O₉ with a Remark about SrPr₂O₄ Sr₃Pr₄O₉ (A) and Sr₃La₂Sm₂O₉ (B) are for the first time prepared and investigated by X-ray single crystal work. Both compounds crystallize with monoclinic symmetry (space group C_s⁴? Cc, Z = 4) with (A) a = 11.468; b = 7.262; c = 13.218 Å; β = 115.61°, (B) a = 11.518; b = 7.263; c = 13.290 Å; β = 115.61°. (A) and (B) are metastable with high disorder in the metal positions. All of the metal positions are occupied with a statistical distribution of Sr²⁺ and Ln³⁺. (A) decomposes in the hitherto unknown compound SrPr₂O₄. It belongs to the calciumferrite type compounds.     

Investigation on the upconversion luminescence of Sr3AlO4F:Yb3+, Er3+, Ho3+ phosphors

To develop new emission-tunable upconversion (UC) phosphors, the Sr₃AlO₄F:5%Yb³⁺, xEr³⁺, yHo³⁺ (0 ≤ x ≤ 1%, 0 ≤ y ≤ 1%) samples were prepared by conversional solid-state reaction method, and their luminescence properties upon 980 nm excitation were studied. Upon 980 nm excitation, Yb³⁺-Er³⁺ codoped Sr₃AlO₄F shows a predominant emission peak between 645 and 700 nm which is attributed to the ⁴F_9/2-⁴I_15/2 transition of Er³⁺, and the Er³⁺ green emissions have been almost quenched. In this case, the yellowish green emitting light is obtained. The possible reason was interpreted by the energy level diagram and the proposed UC mechanism. For Yb³⁺-Ho³⁺ codoped Sr₃AlO₄F, three emissions are observed obviously which are all derived from the Ho³⁺ ion. The corresponding chromaticity coordinates indicate a red emission has been gained. To realize the tunable emission, the typical Sr₃AlO₄F:5%Yb³⁺, 0.2%Er³⁺, 1%Ho³⁺ phosphor was developed, and its emission spectrum includes the emission peaks of both Er³⁺ and Ho³⁺. Correspondingly, the sample gives a yellow emission.     

Luminescence Tuning of Sr8MgCe(PO4)7:Eu2+,Mn2+ Phosphors: Structure Refinement,Site Occupancy,and Energy Transfer

Sr₈MgCe(PO₄)₇:Eu²⁺,Mn²⁺ phosphor with whitlockite‐type structure was prepared by a combustion‐assisted solid‐state reaction. The crystal structure and luminescence properties were investigated. Under UV radiation, Sr₈MgCe(PO₄)₇ host exhibits a violet‐blue emission band from Ce³⁺ ions. When Eu²⁺/Mn²⁺ are doped into the host, the samples excited with 270 nm UV radiation present multicolor emissions due to the energy transfer (ET) from Ce³⁺ to Eu²⁺/Mn²⁺. The emitting color of Sr₈MgCe(PO₄)₇:Eu²⁺ can be tuned from violet‐blue to yellow‐green, whereas Sr₈MgCe(PO₄)₇:Mn²⁺ can emit red light. Under excitation with long wavelength at 360 nm, Sr₈MgCe(PO₄)₇:Eu²⁺ phosphor shows a broadband emission from 390 to 700 nm, which is attributed to the 4f⁶5d¹→4f⁷ transition of Eu²⁺ without the contribution from Ce³⁺ emission. Tunable full‐color emitting light can be achieved in the Eu²⁺ and Mn²⁺‐codoped Sr₈MgCe(PO₄)₇ phosphor by ET_Eu–Mn through control of the levels of doped Eu²⁺ and Mn²⁺ ions. These results suggest that Sr₈MgCe(PO₄)₇:Eu²⁺,Mn²⁺ phosphor has potential applications in NUV chip pumped white LEDs.