Darstellung und elektronenmikroskopische Untersuchung neuer Verbindungen des Typs Ln3MO4Cl5 (Ln = La?Nd; M = Ge,V)

Preparation and Electronmicroscopic Investigation of New Compounds Ln₃MO₄Cl₅ (Ln = La? Nd; M = Ge, V) By heating mixtures of LnOCl, LnCl₃ und GeO₂ (2:1:1) in evacuated silica tubes (Pt-shells inside) the compounds Ln₃GeO₄Cl₅ (Ln = La? Nd) were prepared. The case that the temperature of preparation (La: T = 900°C, 8d; Ce: T = 800°C, 9d; Pr, Nd: T = 650°C, 13 d) had to be reduced from Ln = La to Ln = Nd indicates a decreasing thermodynamic stability in this direction. The compound La₃VO₄Cl₅ was prepared by heating (900°C, 8d) a mixture (2:1:1) of LaOCl, LaCl₃ and VO₂ and was investigated by electronmicroscopic techniques.     

Synthese und Aufbau von (4-Picolinium)[LnCl4(H2O)3] (Ln = La,Ce, Pr,Nd)

Preparation and Crystal Structure of (4-Picolinium)[LnCl₄(H₂O)₃] (Ln = La, Ce, Pr, Nd) The complex water containing chlorides (4-Picolinium)[LnCl₄(H₂O)₃] (Ln = La, Ce, Pr, Nd) were prepared for the first time, and the crystal structures of (4-Picolinium)[LnCl₄(H₂O)₃] (Ln = La, Pr) were determined on single crystals by X-ray methods. The isotypic compounds crystallize with triclinic symmetry, space group P1 , Z = 2. Surprisingly there exist the dimeric complex anions [Ln₂Cl₈(H₂O)₆]^2? (Ln = La, Pr).     

Ln3UO6Cl3 (Ln=La,Pr, Nd) -. Die ersten Oxochlorouranate der Seltenen Erden

Ln₃UO₆Cl₃ (Ln=La, Pr, Nd) — The First Oxochlorouranates of the Rare Earths . The new compounds Ln₃UO₆Cl₃ (Ln=La, Pr, Nd) were prepared by heating stoichiometric amounts of LnOCl/Ln₂O₃/U₃O₈ (7 : 1 : 1) (Ln=La, Nd) and PrOCl/Pr₆O₁₁/U₃O₈ (12 : 1 : 2) in silica ampoules (5 d, 1000°C, Ln=La; 9 d 800°C, Ln=Pr, Nd) in the presence of an excess of chlorine [p(Cl₂, 25°C)=1 atm]. Single crystals were obtained by chemical transport reactions using chlorine [p(Cl₂, 25°C)=1 atm] as transport agent [T₂=1000°C→T₁=900°C (Ln=La); T₂=840°C→T₁=780°C (Ln=Pr, Nd)]. Crystals of Ln₃UO₆Cl₃ (Ln=La, Pr, Nd) were investigated by X-ray diffraction methods and La₃UO₆Cl₃ additionally by high resolution electron microscopy. The compounds Ln₃UO₆Cl₃ crystallize in the hexagonal spacegroup P6₃/m (No. 176) with Z=2 formula units per unit cell. Isotypical structure refinements resulted in R=3.04% respectively R_w=1.91% (Ln=La), R=4.72% respectively R_w=3.80% (Ln=Pr) and R=3.99% respectively R_w=2.49% (Ln=Nd). Uranium is coordinated with six oxygen atoms forming a trigonal prism. Lanthanide ions are 10-coordinated (6 oxygen atoms, 4 chlorine atoms).     

Cyano-bridged Ln^3＋-Cr^3＋ Binuclear Complexes [Ln（L）x（H2O）y^- Cr（CN）6]·mL·nH2O （Ln=La-Nd,x=5, y=2, m=1 or 2, n=2 or 2.5; Ln-Sm-Dy,Er, x=4, y=3, m=0, n=1.5 or 2.0; L= 2-pyrrolidinone）： Structure,Magnetism and Spin Density Map

In order to shed light upon the nature and mechanism of 4f-3d magnetic exchange interactions, a series of binuclear complexes of lanthanide（3＋） and chromium（3＋） with the general formula [Ln（L）5（H2O）2Cr（CN）6]·mL· nH2O （Ln=La （1）, Ce （2）, Pr （3）, Nd （4）; x=5, y=2, m=1 or 2, n=2 or 2.5; L=2-pyrrolidinone） and [Ln（L）4（H2O）3Cr（CN）6] ·nH2O （Ln=Sm （5）, Eu （6）, Gd （7）, Tb （8）, Dy （9）, Er （10）; x=4, y=3, m=0, n= 1.5 or 2.0; L=2-pyrrolidinone） were prepared and the X-ray crystal structures of complexes 2, 6 and 7 were determined. All the compounds consist of a Ln-CN-Cr unit, in which Ln^3＋ in a square antiprism environment is bridged to an octahedral coordinated Cr^3＋ ion through a cyano group. The magnetic properties of the complexes 3 and 6-10 show an overall antiferromagnetic behavior. The fitting to the experimental magnetic susceptibilities of 7 give g= 1.98, J=0.40 cm^-1, zJ＇= -0.21 cm^-1 on the basis of a binuclear spin system （Scd=7/2, Scr=3/2）, revealing an intra-molecular Gd^3＋-Cr^3＋ ferromagnetic interaction and an inter-molecular antiferromagnetic interaction. For 7 the calculation of quantum chemical density functional theory （DFT）, combined with the broken symmetry approach, showed that the calculated spin coupling constant was 20.3 cm^-1, supporting the observation of weak ferromagnetic intra-molecular interaction in 7. The spin density distributions of 7 in both the high spin ground state and the broken symmetry state were obtained, and the spin coupling mechanism between Gd^3＋ and Cr^3＋ was discussed.     

Heterometallic Clusters [CuSn3S9]5− and [Cu6Sn6S20]10−: Solvothermal Synthesis and Characterization of 4f–3d Thiostannates

Two types of 4f–3d thiostannates with general formula [Hen]₂[Ln(en)₄(CuSn₃S₉)] ? 0.5 en ( Ln1 ; Ln=La, 1 ; Ce, 2 ) and [Hen]₄[Ln(en)₄]₂[Cu₆Sn₆S₂₀] ? 3 en ( Ln2 ; Ln=Nd, 3 ; Gd, 4 ; Er, 5 ) were prepared by reactions of Ln₂O₃, Cu, Sn, and S in ethylenediamine (en) under solvothermal conditions between 160 and 190 °C. However, reactions performed in the range from 120 to 140 °C resulted in crystallization of [Sn₂S₆]^4? compounds and CuS powder. In 1 and 2 , three SnS₄ tetrahedra and one CuS₃ triangle are joined by sharing sulfur atoms to form a novel [CuSn₃S₉]^5? cluster that coordinates to the Ln³⁺ ion of [Ln(en)₄]³⁺ (Ln=La, Ce) as a monodentate ligand. The [CuSn₃S₉]^5? unit is the first thio‐based heterometallic adamantane‐like cluster coordinating to a lanthanide center. In 3 – 5 , six SnS₄ tetrahedra and six CuS₃ triangles are connected by sharing common sulfur atoms to form the ternary [Cu₆Sn₆S₂₀]^10? cluster, in which a Cu₆ core is enclosed by two Sn₃S₁₀ fragments. The topological structure of the novel Cu₆ core can be regarded as two Cu₄ tetrahedra joined by a common edge. The Ln³⁺ ions in Ln1 and Ln2 are in nine‐ and eightfold coordination, respectively, which leads to the formation of the [CuSn₃S₉]^5? and [Cu₆Sn₆S₂₀]^10? clusters under identical synthetic conditions. The syntheses of Ln1 and Ln2 show the influence of the lanthanide contraction on the quaternary Ln/Cu/Sn/S system in ethylenediamine. Compounds 1 – 5 exhibit bandgaps in the range of 2.09–2.48 eV depending on the two different types of clusters in the compounds. Compounds 1 , 3 , and 4 lost their organic components in the temperature range of 110–350 °C by multistep processes.     

Rare earth transition metal sulfides,LnMS3

Ternary rare earth transition metal sulfides LnMS₃ with Ln = La, Nd, and Gd, and M = V and Cr; as well as Ln = La and M = Mn, Fe, Co, and Ni have been prepared and characterized. The vanadium and chromium sulfides crystallize in a monoclinic layer structure isotypic with LaCrS₃, while the other LnMS₃ sulfides crystallize in a hexagonal structure. Chemical shifts of the metal K-absorption edge and XPS binding energies of core levels indicate that the transition metal is trivalent in the V and Cr sulfides, while it is divalent in the Mn, Fe, Co, and Ni sulfides. Electrical and magnetic properties of the sulfides are discussed in terms of their structures and the electronic configurations of the transition metal ions.     

Synthese und Struktur der Nitridoborat‐Nitride Ln4(B2N4)N (Ln = La,Ce) des Formeltyps Ln3+x(B2N4)Nx (x = 0, 1, 2)

Synthesis and Structure of Nitridoborate Nitrides Ln₄(B₂N₄)N (Ln = La, Ce) of the Formula Type Ln_3+x(B₂N₄)N_x (x = 0, 1, 2) The missing member of the formula type Ln_3+x(B₂N₄)N_x with x = 1 was synthesized and characterized for Ln = La and Ce. According to the single‐crystal X‐ray structure solution Ce₄(B₂N₄)N crystallizes in the space group C2/m (Z = 2) with the lattice parameters a = 1238.2(1) pm, b = 357.32(3) pm, c = 905.21(7) pm and β = 129.700(1)°. The anisotropic structure refinement converged at R1 = 0.039 and wR2 = 0.099 for all independent reflections. A powder pattern of La₄(B₂N₄)N was indexed isotypically with a = 1260.4(1) pm, b = 366.15(3) pm, c = 919.8(1) pm and β = 129.727(6)°. A structure rational for nitridoborates and nitridoborate nitrides containing B₂N₄ ions with the general formula Ln_3+x(B₂N₄)N_x with x = 0, 1, 2 is presented.     

Systematic Investigation of Reaction‐Time Dependence of Three Series of Copper–Lanthanide/Lanthanide Coordination Polymers: Syntheses,Structures, Photoluminescence,and Magnetism

Three series of copper–lanthanide/lanthanide coordination polymers (CPs) Ln^IIICu^IICu^I(bct)₃(H₂O)₂ [Ln=La ( 1 ), Ce ( 2 ), Pr ( 3 ), Nd ( 4 ), Sm ( 5 ), Eu ( 6 ), Gd ( 7 ), Tb ( 8 ), Dy ( 9 ), Er ( 10 ), Yb ( 11 ), and Lu ( 12 ), H₂bct=2,5‐bis(carboxymethylmercapto)‐1,3,4‐thiadiazole acid], Ln^IIICu^I(bct)₂ [Ln=Ce ( 2 a ), Pr ( 3 a ), Nd ( 4 a ), Sm ( 5 a ), Eu ( 6 a ), Gd ( 7 a ), Tb ( 8 a ), Dy ( 9 a ), Er ( 10 a ), Yb ( 11 a ), and Lu ( 12 a )], and Ln^III₂(bct)₃(H₂O)₅ [Ln=La ( 1 b ), Ce ( 2 b ), Pr ( 3 b ), Nd ( 4 b ), Sm ( 5 b ), Eu ( 6 b ), Gd ( 7 b ), Tb ( 8 b ), and Dy ( 9 b )] have been successfully constructed under hydrothermal conditions by modulating the reaction time. Structural characterization has revealed that CPs 1 – 12 possess a unique one‐dimensional (1D) strip‐shaped structure containing two types of double‐helical chains and a double‐helical channel. CPs 2 a – 12 a show a three‐dimensional (3D) framework formed by Cu^I linking two types of homochiral layers with double‐helical channels. CPs 1 b – 9 b exhibit a 3D framework with single‐helical channels. CPs 6 b and 8 b display visible red and green luminescence of the Eu^III and Tb^III ions, respectively, sensitized by the bct ligand, and microsecond‐level lifetimes. CP 8 b shows a rare magnetic transition between short‐range ferromagnetic ordering at 110 K and long‐range ferromagnetic ordering below 10 K. CPs 9 a and 9 b display field‐induced single‐chain magnet (SCM) and/or single‐molecule magnet (SMM) behaviors, with U_eff values of 51.7 and 36.5 K, respectively.     

Synthesis,Magnetism, and Thermostability of a Series of Two‐Dimensional Lanthanide–Nickel Heterometallic Coordination Polymers

A series of Ln–Ni heterometallic coordination polymers, {[Ln₂Ni(MIDA)₄(H₂O)₆](H₂O)₄} (Ln = La ( 1 ), Ce ( 2 ), Pr ( 3 ), and Nd ( 4 ); H₂MIDA = N‐methyl‐iminodiacetic acid), were obtained under hydrothermal conditions. Single crystal X‐ray diffraction revealed that they feature two‐dimensional isomorphic frameworks, which could be viewed as the construction by one‐dimensional {Ln}_n chain connecting by bridges of [Ni(MIDA)₂]². The magnetic measurements reveal that compounds 2 – 4 exhibit antiferromagnetic properties. TGA results indicate compounds 1 and 4 have good thermostability with the critical temperature of 375 °C.     

Phase Equilibria Laws in the SrS-Ln2S3 (Ln = Yb-Lu,Y, or Sc) Systems

Complex sulfides with the SrS: Ln₂S₃ ratio equal to 3: 1, 1: 3, or 1: 4 for Ln = Y or Lu have been predicted on the basis of thermodynamic analysis of previously designed SrS-Ln₂S₃ (Ln = Tb, Dy, or Er) phase diagrams. Phase diagrams for the SrS-Ln₂S₃ (Ln = Tm, Lu, or Sc) systems have been designed for the first time. These systems form congruently melting compounds SrLn₂S₄ (CaFe₂O₄ type structure, orthorhombic crystal system). Unit cell parameters, heats of melting, and microhardnesses have been determined. For SrTm₂S₄, the respective values are as follows: a = 1.181 nm, b = 1.421 nm, c = 0.396 nm, 2040 K, ΔH _m = 188 kJ/mol, 3500 MPa; for SrLu₂S₄: a = 1.187 nm, b = 1.416 nm, c = 0.392 nm, 2070 K, ΔH _m = 190 kJ/mol, 3540 MPa; and for SrSc₂S₄: a = 1.180 nm, b = 1.410 nm, c = 0.390 nm, 2100 K, ΔH _m = 206 kJ/mol, 3650 MPa. The increase in the melting temperatures and the heats of melting calculated for the SrLn₂S₄ compounds correlate with their classification as thio salts.     

Neue thermische Abbauprodukte von Ln2CeMO6Cl3 (M = Nb,Ta; Ln = La–Sm) – Darstellung von strukturverwandtem (La, Tb)3,5TaO6Cl4–x

Contributions on the Investigation of Inorganic Nonstoichiometric Compounds. XLV. New Thermal Decomposition Products of Ln₂CeMO₆Cl₃ – Preparation of Structure‐related (La, Tb)_3.5TaO₆Cl_4–x The thermal decomposition (T £ 900–1050°C) of Ln₂CeMO₆Cl₃ (M = Nb, Ta; Ln = La, Ce, Pr, Nd, Sm) leads to the formation of two mixed‐valenced phases (Ln, Ce)_3.25MO₆Cl_3.5–x (phase ‘‘AB”︁”︁) and (Ln, Ce)_3.5MO₆Cl_4–x (phase ‘‘BB”︁”︁) and to the formation of chlorine according to redox‐reactions between Ce⁴⁺ and Cl^–. Single crystals of both phases (Ln, Ce)_3.25MO₆Cl_3.5–x (‘‘AB”︁”︁) and (Ln, Ce)_3.5MO₆Cl_4–x (‘‘BB”︁”︁) were obtained by chemical transport reactions using both powder of Ln₂CeMO₆Cl₃ (phase ‘‘A”︁”︁) and powder of (Ln, Ce)_3.25MO₆Cl_3.5–x (phase ‘‘AB”︁”︁) as starting materials and chlorine (p{Cl₂; 298 K} = 1 atm) or HCl (p{HCl; 298 K} = 1 atm) as transport agent. A crystal of (La, Ce)_3.25NbO₆Cl_3.5–x (”︁AB”︁”︁) (space group: C2/m, a = 35.288(1) Å, b = 5.418(5) Å, c = 9.522(1) Å, β = 98.95(7)°, Z = 4) was investigated by x‐ray diffraction methods, a crystal of (Pr, Ce)_3.5NbO₆Cl_4–x (”︁BB”︁”︁) was investigated by synchrotron radiation (λ = 0.56 Å) diffraction methods. The lattice constants are a = 18.863(6) Å, b = 5.454(5) Å, c = 9.527(6) Å, β = 102.44(3)° and Z = 4. Structure determination in the space group C2/m (No. 12) let to R1 = 0.0313. Main building units are NbO₆‐polyhedra with slightly distorted trigonally prismatic environment for Nb and chains of face‐sharing Cl₆‐octahedra along [010]. The rare earth ions are coordinated by chlorine and oxygen atoms. These main structure features confirmed the expected relation to the starting material Ln₂CeMO₆Cl₃ (phase ”︁A”︁”︁) and to (Ln, Ce)_3.25MO₆Cl_3.5–x (phase ”︁AB”︁”︁).     

Studies on the Thermal Decomposition of Rare Earth Caproates

The thermal decomposition of rare earth caproates with general formula Ln(C₅H₁₁COO)₃ nH₂O, (where Ln=Y, La-Pr, n=l; Ln=Nd-Er, n=2; Ln=Tm-Lu, n=3) were studied in an air atmosphere. On heating, the hydrated caproates are dehydrated in one step and then the anhydrous complexes decompose to the oxides (Ln₂O₃, Pr₆O₁₁) with formation of the intermediate Ln₂O₂CO₃ (La, Pr-Gd) or directly to the oxides Ln₂O₃, CeO₂, Tb₄O₇(Y, Ce, Tb-Lu). Caproates of rare earth elements are liquefied during dehydration.     

Phase Equilibria in the Sc2S3-Ln2S3 (Ln = Dy,Er, or Tm) Systems

Phase diagrams for the Sc₂S₃-Ln₂S₃ (Ln = Dy, Er, or Tm) systems were designed in the range from 1000 K to melting temperatures. The Ln₃ScS₆ compounds that are formed in these systems crystallize in monoclinic space group P2₁/m, and melt congruently: for Dy₃ScS₆, a = 1.118 nm, b = 1.262 nm, c = 0.354 nm, β = 94.7°, 1800 K, H = 2600 MPa; for Er₃ScS₆, a = 1.113 nm, b = 1.258 nm, c = 0.353 nm, β = 94.5°, 1830 K, H = 2800 MPa; for Tm₃ScS₆, a = 1.112 nm, b = 1.229 nm, c = 0.352 nm, β = 94.3°, 1835 K, H = 2940 MPa. The LnScS₃ (Ln = Dy or Er) complex sulfides, with orthorhombic structures, space group Pnma, melt incongruently: for DyScS₃, a = 0.700 nm, b = 0.637 nm, c = 0.943 nm, 1810 K, H = 3800 MPa; and for ErScS₃, a = 0.697 nm, b = 0.633 nm, c = 0.942 nm, 1800 K, H = 3800 MPa. As the ionic radii rLn3+ and rSc3+ approach Ln Sc to each other in the row Dy-Er-Tm, the solubility in Sc₂S₃ increases, at 1670 K being equal to 13 mol % Dy₂S₃, 30 mol % Er₂S₃, and 40 mol % Tm₂S₃. LnScS₃ (Ln = Dy or Er) forms a two-sided homogeneity region, at 1670 K lying in ranges of 43–56 mol % Ln₂S₃. The eutectic temperatures and compositions are as follows: 1700 K and 66 mol % Dy₂S₃, 1730 K and 81 mol % Dy₂S₃, 1740 K and 65 mol % Er₂S₃, 1700 K and 83 mol % Er₂S₃, 1730 K and 70 mol % Tm₂S₃, and 1755 K and 84 mol % Tm₂S₃.     

Thermal behaviour of hydrated lanthanide complexes with heptanedioic acid

The multi-step dehydration and decomposition of trivalent lanthanum and lanthanide heptanediate polyhydrates were investigated by means of thermal analysis completed with infrared study. Further more, X-ray diffraction data for investigated heptanediate complexes of general stoichiometry Ln₂(C₇H₁₀O₄)₃.nH₂O (wheren=16 in the case of La, Ce, Pr, Nd and Sm pimelates,n=8 for Eu, Gd, Tb, Dy, Er and Tm pimelates,n=12 for Ho, Yb and Lu pimelates) were also reported.

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Zusammenfassung Mittels TG, DTG, DTA wurde in Verbindung mit IR-Methoden der mehrstufige Dehydratations- und der Zersetzungsvorgang der Polyhydrate der PimelinsÄuresalze von dreiwertigem Lanthan und dreiwertigen Lanthanoiden untersucht. Röntgendiffraktionsdaten der untersuchten Heptandiat-Komplexe mit der allgemeinen Formel Ln₂(C₇H₁₀O₄)₃ nH₂O (mitn=16 für Ln=La, Ce, Pr, Nd und Sm,n=8 für Ln=Eu, Gd, Tb, Dy, Er und Tm sowien=12 für Ln=Ho, Yb und Lu) werden ebenfalls gegeben.

     

Double molybdates of rare earth elements and zirconium

The results of the study of Ln₂(MoO₄)3—Zr(MoO₄)₂ molybdate systems, which made it possible to obtain new double molybdates, are summarized. The specific features of phase formation in double salt systems were determined and the formation of phases with the compositions given by three formulas Ln₂Zr₃(MoO₄)₉ (Ln = La—Tb), Ln₂Zr₂(MoO₄)₇ (Ln = Sm—Y), and Ln₂Zr(MoO₄)₅ (Ln = Tb—Lu) was established. Phase diagrams of the systems were constructed and the interrelation between the composition and the structure of the obtained phases was determined; in addition, crystallographic, thermal, and dielectric characteristics of the obtained compounds were studied.     

Synthese und Kristallstrukturen von Bromid—Thiosilicaten Ln3Br[SiS4]2 der Lanthanide (Ln = La,Ce, Pr,Nd, Sm,Gd)

Synthesis and Crystal Structures of Lanthanide Bromide Thiosilicates Ln₃Br[SiS₄]₂ (Ln = La, Ce, Pr, Nd, Sm, Gd) Single crystals of the bromide—thiosilicates Ln₃Br[SiS₄]₂ were prepared by reaction of lanthanide metal (Ln = La, Ce, Pr, Nd, Sm, Gd), sulfur, silicon and bromine in quartz glass tubes. The thiosilicates crystallize in the monoclinic spacegroup C2/c (Z = 4) isotypically to the iodide analogues Ln₃I(SiS₄)₂ and the A—type chloride—oxosilicates Ln₃Cl[SiO₄]₂ with the following lattice constants: La₃Br[SiS₄]₂: a = 1583.3(4) pm, b = 783.0(1) pm, c = 1098.2(3) pm, β = 97.33(3)° Ce₃Br[SiS₄]₂: a = 1570.4(3) pm, b = 776.5(2) pm, c = 1092.2(2) pm, β = 97.28(2)° Pr₃Br[SiS₄]₂: a = 1562.6(3) pm, b = 770.1(2) pm, c = 1088.9(2) pm, β = 97.50(2)° Nd₃Br[SiS₄]₂: a = 1561.4(4) pm, b = 766.0(1) pm, c = 1085.3(2) pm, β = 97.66(3)° Sm₃Br[SiS₄]₂: a = 1555.4(3) pm, b = 758.5(2) pm, c = 1079.9(2) pm, β = 98.28(2)° Gd₃Br[SiS₄]₂: a = 1556.5(3) pm, b = 750.8(1) pm, c = 1074.5(2) pm, β = 99.26(2)° In the crystal structures the bromide ions form chains along [001] with trigonal planar coordination by lanthanide cations, while the [SiS₄]^4‐—building units display isolated distorted tetrahedra.     

Spin dimer analysis of the three-dimensional antiferromagnetic ordering in the quaternary manganese sulfides BaLn2MnS5 (Ln=La, Ce, Pr)

The quaternary manganese sulfides BaLn₂MnS₅ (Ln=La, Ce, Pr) consist of (MnS₄)⁶⁻ anions separated with short S?S distances slightly longer than the van der Waals distance. Nevertheless, these sulfides are known to undergo a three-dimensional (3D) antiferromagnetic ordering at a reasonably high temperature (i.e., T_N=58.5, 62.0 and 64.5 K for Ln=La, Ce and Pr, respectively). The origin of this observation was probed by studying the Mn-S?S-Mn super-superexchange interactions of BaLn₂MnS₅ on the basis of spin dimer analysis. The non-bonding S?S contacts in the vicinity of the van der Waals distance are found essential in determining the strengths of the Mn-S?S-Mn super-superexchange interactions. The antiferromagnetic spin exchange between adjacent (MnS₄)⁶⁻ anions along the c-direction (J₂) is calculated to be stronger than that in the ab-plane (J₁) by a factor of ∼10, so that the strongly interacting spin units of BaLn₂MnS₅ (Ln=La, Ce, Pr) are 1D chains made up of the exchange paths J₂. The relative strengths of the spin exchange interactions for the J₁ and J₂ paths are consistent with the finding that the Néel temperatures of BaLn₂MnS₅ are reasonably high, and they increase in the order BaLa₂MnS₅<BaCe₂MnS₅< BaPr₂MnS₅.     

Electrospinning synthesis and luminescence properties of one-dimensional La(9.33)(SiO4)6O2: Ln3+ (Ln = Ce, Eu, Tb) microfibers

One-dimensional La(9.33)(SiO(4))(6)O(2): Ln(3+) (Ln = Ce, Eu, Tb) microfibers were fabricated by a simple and cost-effective electrospinning method. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL) and low voltage cathodoluminescence (CL) as well as kinetic decay were used to characterize the resulting samples. SEM and TEM results indicated that the diameter of the microfibers annealed at 1000 °C for 3 h was 200-245 nm. The microfibers were further composed of fine and closely linked nanoparticles. La(9.33)(SiO(4))(6)O(2): Ln(3+) (Ln = Ce, Eu, Tb) phosphors showed the characteristic emission of Ce(3+) (5d → 4f), Eu(3+) ((5)D(0)→(7)F(J)) and Tb(3+) ((5)D(3,4)→(7)F(J)) under ultraviolet excitation and low-voltage electron beams (3-5 kV) excitation. An energy transfer from Ce(3+) to Tb(3+) was observed in the La(9.33)(SiO(4))(6)O(2): Ce(3+), Tb(3+) phosphor under ultraviolet excitation and low-voltage electron beam excitation. Luminescence mechanisms were proposed to explain the observed phenomena. Blue, red and green emission can be realized in La(9.33)(SiO(4))(6)O(2): Ln(3+) (Ln = Ce, Eu, Tb) microfibers by changing the doping ions. So the La(9.33)(SiO(4))(6)O(2): Ln(3+) (Ln = Ce, Eu, Tb) phosphors have potential applications in full-color field emission displays.     

Interactions in the SrS-Cu2S-Ln2S3 (Ln = Gd or Er) Systems and Phase-Formation Laws in the SrS-Cu2S-Ln2S3 (Ln = La-Lu) Systems

Structure solution has been carried out for newly synthesized compounds SrLnCuS₃ (Ln = Pr, Sm, Dy, or Er). These sulfides have orthorhombic structures of the following types: SrPrCuS₃ crystallizes in a BaLaCuS₃-type structure, space group Pnma; SrLnCuS₃ (Ln = Sm or Dy) crystallize in an Eu₂CuS₃-type structure, space group Pnma; and SrErCuS₃, in a KZrCuS₃-type structure, space group Cmcm. In studies of the SrS-Cu₂S-Ln₂S₃ (Ln = Gd or Er) systems, the following tie-lines at 1050 K were located: SrLnCuS₃-SrLn₂S₄, SrLnCuS₃-SrS, SrLnCuS₃-CuLnS₂, Cu₂S-SrLnCuS₃, SrLnCuS₃-solid solution C₀ of the Cu₂S-Gd₂S₃ (β-Cu₃ErS₃) system, and Ln₂S₃-SrLnCuS₃. In the series of the SrS-Cu₂S-Ln₂S₃ (Ln = La-Lu) systems, two tendencies are observed: monotony (decrease in the unit cell parameters and volumes and increase in the melting temperatures of SrLnCuS₃ compounds in the ranges La-Nd and Sm-Lu) and periodicity (two types of triangulation of the SrS-Cu₂S-Ln₂S₃ system, three structure types, and different space groups of SrLnCuS₃ compounds; jump in the melting temperatures of the SrLnCuS₃ compounds in the range Nd-Sm).     

Lanthanoid‐Based Ionic Liquids Incorporating the Dicyanonitrosomethanide Anion

A series of low‐melting‐point salts with hexakisdicyanonitrosomethanidolanthanoidate anions has been synthesised and characterised: (C₂mim)₃[Ln(dcnm)₆] ( 1 Ln ; 1 Ln = 1 La , 1 Ce , 1 Pr , 1 Nd ), (C₂C₁mim)₃[Pr(dcnm)₆] ( 2 Pr ), (C₄C₁pyr)₃[Ce(dcnm)₆] ( 3 Ce ), (N₁₁₁₄)₃[Ln(dcnm)₆] ( 4 Ln ; 4 Ln = 4 La , 4 Ce , 4 Pr , 4 Nd , 4 Sm , 4 Gd ), and (N_1112OH)₃[Ce(dcnm)₆] ( 5 Ce ) (C₂mim=1‐ethyl‐3‐methylimidazolium, C₂C₁mim=1‐ethyl‐2,3‐dimethylimidazolium, C₄C₁py=N‐butyl‐4‐methylpyridinium, N₁₁₁₄=butyltrimethylammonium, N_1112OH=2‐(hydroxyethyl)trimethylammonium=choline). X‐ray crystallography was used to determine the structures of complexes 1 La , 2 Pr , and 5 Ce , all of which contain [Ln(dcnm)₆]^3? ions. Complexes 1 Ln and 2 Pr were all ionic liquids (ILs), with complex 3 Ce melting at 38.1 °C, the lowest melting point of any known complex containing the [Ln(dcnm)₆]^3? trianion. The ammonium‐based cations proved to be less suitable for forming ILs, with complexes 4 Sm and 4 Gd being the only salts with the N₁₁₁₄ cation to have melting points below 100 °C. The choline‐containing complex 5 Ce did not melt up to 160 °C, with the increase in melting point possibly being due to extensive hydrogen bonding, which could be inferred from the crystal structure of the complex.