Lanthanoidtellurate Ln2TeO6

Lanthanoid Tellurates Ln₂TeO₆ The crystal structure of La₂TeO₆, orthorhombic, a = 551.0, b = 944.1, c = 1038.7 pm, and crystallographic data of other isostructural lanthanoid tellurates (up to Yb₂TeO₆) formerly described as hexagonal, have been determined. For a second modification of the Yb compound, the Na₂SiF₆ structure has been confirmed.     

Chirality and Magnetic Properties of One-dimensional Ln (Ln = Gd,Dy) Polymers

The usage of the achiral ligand, in lanthanide chemistry, successfully obtained two series of chiral lanthanide complexes, formulated d - and l -{Gd[IN][HIN][CH₂OCH₂O]}_n (abbreviated as Gd ) and d - and l -{Dy[IN][HIN][CH₂OCH₂O]}_n (abbreviated as Dy , HIN = isonicotinic acid). Crystallographic researches determined that four compounds are all one-dimensional (1D) chain structures and crystallized in a chiral space group. In addition, CH₂OHCH₂OH acts as not only solvent but also the bridge ligand. Besides, single crystal circular dichroism (CD) spectra conformed compounds Gd-_L and Gd-_D , Dy-_L and Dy-_D are enantiomers respectively. Magnetically, compound Gd showed predominant magnetocaloric effect (MCE) of 26.20 J · kg^–1 · K^–1 at 2.5 K for ΔH = 7 T, while there is ferromagnetic interactions in compound Dy .     

Phase diagrams of the Ln2S3-EuS (Ln = La-Gd) systems

The phase diagrams of the Ln₂S₃-EuS (Ln = La-Gd) systems were studied. In these systems, continuous series of solid solutions form between γ-Ln₂S₃ and EuLn₂S₄ (Th₃P₄ structural type), and also eutectics between EuLa₂S₄ and a solid solution based on EuS form at the following coordinates: 71.5 mol % EuS, 2280 K; 66.5 mol % EuS, 2240 K; and 63.5 mol % EuS, 2100 K. The characteristics of the forming compounds are the following: EuLa₂S₄: a = 0.8759 nm, T _melt = 2420 K, and H = 2380 MPa; EuNd₂S₄: a = 0.8615 nm, T _melt = 2380 K, and H = 2530 MPa; and EuGd₂S₄: a = 0.8507 nm, T _melt = 2300 K, and H = 2670 MPa.     

Darstellung und Kristallstrukturen von Ln2Al3Si2 und Ln2AlSi2 (Ln: Y,Tb–Lu)

Synthesis and Crystal Structures of Ln ₂Al₃Si₂ and Ln ₂AlSi₂ ( Ln : Y, Tb–Lu) Eight new ternary aluminium silicides were prepared by heating mixtures of the elements and investigated by means of single‐crystal X‐ray methods. Tb₂Al₃Si₂ (a = 10.197(2), b = 4.045(1), c = 6.614(2) Å, β = 101.11(2)°) and Dy₂Al₃Si₂ (a = 10.144(6), b = 4.028(3), c = 6.580(6) Å, β = 101.04(6)°) crystallize in the Y₂Al₃Si₂ type structure, which contains wavy layers of Al and Si atoms linked together by additional Al atoms and linear Si–Al–Si bonds. Through this there are channels along [010], which are filled by Tb and Dy atoms respectively. The silicides Ln₂AlSi₂ with Ln = Y (a = 8.663(2), b = 5.748(1), c = 4.050(1) Å), Ho (a = 8.578(2), b = 5.732(1), c = 4.022(1) Å), Er (a = 8.529(2), b = 5.719(2), c = 4.011(1) Å), Tm (a = 8.454(5), b = 5.737(2), c = 3.984(2) Å) and Lu (a = 8.416(2), b = 5.662(2), c = 4.001(1) Å) crystallize in the W₂CoB₂ type structure (Immm; Z = 2), whereas the structure of Yb₂AlSi₂ (a = 6.765(2), c = 4.226(1) Å; P4/mbm; Z = 2) corresponds to a ternary variant of the U₃Si₂ type structure. In all compounds the Si atoms are coordinated by trigonal prisms of metal atoms, which are connected by common faces so that Si₂ pairs (d_Si–Si: 2.37–2.42 Å) are formed.     

Defect-dicubane Ni2Ln2 (Ln = Dy, Tb) single molecule magnets

Two pairs of Ni(2)Dy(2) and Ni(2)Tb(2) complexes, [Ni(2)Ln(2)(L)(4)(NO(3))(2)(DMF)(2)] {Ln = Dy (1), Tb (2)} and [Ni(2)Ln(2)(L)(4)(NO(3))(2)(MeOH)(2)]·3MeOH {Ln = Dy (3), Tb (4)} (H(2)L is the Schiff base resulting from the condensation of o-vanillin and 2-aminophenol) possessing a defect-dicubane core topology were synthesized and characterized. All four complexes are ferromagnetically coupled, and the two Dy-analogues are found to be Single Molecule Magnets (SMMs) with energy barriers in the range 18-28 K. Compound 1 displays step-like hysteresis loops, confirming the SMM behavior. Although 1 and 3 show very similar structural topologies, the dynamic properties of 1 and 3 are different with blocking temperatures (3.2 and 4.2 K at a frequency of 1500 Hz) differing by 1 K. This appears to result from a change in orientation of the nitrate ligands on the Dy(III) ions, induced by changes in ligands on Ni(II).     

SCMEH-MO calculations on lanthanide systems. III. Ln(CO)6, Ln(OC)6 (Ln = Nd,Sm)

The SCMEH-MO method with average relativistic and spin-orbit effects has recently been applied to study the electronic structure and bonding in samarium pentamethylcyclopentadienyls. In this report the same approach has been utilized in studying the electronic structures of Nd and Sm hexacarbonyls. In contrast to the stable transition metal d-block carbonyls, these lanthanide carbonyls are found to be quite unstable. These findings are based on calculated electronic structures and bond energies. © 1996 John Wiley & Sons, Inc.     

The thermodynamic properties of Ln2BaO4 (Ln = Sm, Dy, Ho)

The thermodynamic properties of the Ln₂BaO₄ phases (Ln = Dy, Ho, Sm) were studied by the electromotive force method with a fluoride electrolyte (890–1180 K), solution calorimetry in 1.07 N hydrochloric acid at 298.15 K, and differential scanning calorimetry (298–860 K). The experimental data were jointly processed, and the thermodynamic functions of the compounds over the temperature range 298–1200 K were calculated.     

Syntheses and Single-crystal Structures of Ln_3Sn_(0.25)GeS_7 (Ln=La,Sm)

Two new quaternary sulfides,La3Sn0.25GeS71 and Sm3 Sn0.25GeS72,have been synthesized by a facile solid-state reaction,and their crystal structures were determined by singlecrystal X-ray diffraction analysis.The two compounds crystallize in the P6 3 space group,and the crystal data are as follows-La3Sn0.25GeS7:a=10.3335(7),c=5.8455(7),Z=2;Sm3Sn0.25GeS7:a=9.999(3),c=5.787(2),Z=2.Single-crystal analysis indicated that the two compounds consist of three types of building blocks:LnS 8 anti-tetragonal prism,SnS 6 octahedron,and GeS 4 tetrahedron.     

Defect chemistry and physical properties of Ln0.5Sr0.5FeO3 (Ln: La,Pr)

A defect chemical model for the behavior of acceptor and donor-doped LaFeO₃ as a function of oxygen pressure is proposed. The nonstoichiometric deviation is calculated as a function of oxygen partial pressure, pO₂, at different temperatures. The defect structure of complex oxides is described within the point defects approach.The results show that the conductivity is dependent on pO₂ and temperature. Thermoelectric power values indicate clearly the nature of the dominant specie in charge transport. Stability regimes and compensation mechanisms at various oxygen partial pressures and temperatures are proposed. This model also examines the charge compensation mechanisms that dominate under the different regimes.From equilibrium constants, partial molar enthalpy and partial molar entropy of oxygen in Ln_0.5Sr_0.5Fe O_3?δ (Ln: La, Pr) are estimated.     

镧系离子(Ln3+)配合物近红外发光

本文阐述了镧系离子(Ln3+)配合物近红外发光机理及特点，同时就其研究进展及应用情况作了简要介绍。     

Interaction in Systems Ln2O3-CsPO3 and Ln2O3- UO3-CPO3

Abstract

The systems Ln₂O₃-CsPO₃ and Ln₂O₃-UO₃-CsPO₃ were investigated and three sets of compounds A, B, C were isolated.     

Magnetic properties of Ln2−xLn′xCo17 compounds (Ln = Gd,Dy, Ho,or Er,Ln′ = Th or Ce)

Magnetic and structural characteristics of the ternary systems Ln_2?xTh_xCo₁₇ (Ln = Gd, Dy, Ho, and Er) and Ln_2?xCe_xCo₁₇ (Ln = Gd, Dy, and Ho) are presented. Incorporation of Th in the lattice stabilizes the Th₂Zn₁₇ structure, whereas incorporation of Ce does not; if the binary system has the Th₂Ni₁₇ structure the incorporation of Ce leaves the structure unchanged. The antiferromagnetic LnCo coupling observed in the Ln₂Co₁₇ systems persists in the ternary alloys. The moment of the cobalt sublattice is decreased when more than half of the Ln is replaced by Th, suggesting that the extra electron contributed by Th enters the Co d-band or d-shell. The direction of easy magnetization is in the basal plane for all composition in the Gd, Dy, and Ho systems. In Er_2?xTh_xCo₁₇ the easy direction is along the c-axis for x = 0 and 0.2, but is in the basal plane for higher thorium contents.     

Trapping of anionic organic radicals by (TpMe2)2Ln (Ln = Sm, Eu)

Stoichiometric reaction of [ Sm(Tp(Me2))2 ], 1, with a variety of reducible ketone- and quinone-type substrates gave thermally stable, isolable radical anions/ketyls in moderate to good yields. Thus reaction with benzophenone gave [Sm(Tp(Me2))2(OCPh2)], 2, with fluorenone [Sm(Tp(Me2))2(eta1-OC13H8)], 3, and di-tert-butylparaquinone [Sm(Tp(Me2))2(eta1-OC6H2(tBu)2O)], 4, each of which was structurally characterized. In the case of the less-hindered benzoquinone, an unimetallic semiquinone [Sm(Tp(Me2))2(OC6H4O)], 5, could be isolated, although it was unstable with respect to formation of the dimetallic complex [Sm(Tp(Me2))2]2(mu-OC6H4O), 6. Compound 6 was structurally characterized, as was its anthraquinone analogue [Sm(Tp(Me2))2]2(mu-OC14H8O), 7. When the analogous reaction was carried out between the less-reducing [Eu(Tp(Me2))2] and benzoquinone, only the europium analogue of the semiquinone 5, [Eu(Tp(Me2))2(OC6H4O)], 8, could be isolated. The use of the sterically hindered 3,5-di-tert-butyl-o-benzoquinone allowed isolation of [Sm(Tp(Me2))2(DTBSQ)], 9.     

高温高压法提取金属富勒烯Lnm@C2nLn=Y, Gd, Tb)

笼内金属富勒烯以其独特的结构性质和潜在的应用价值而引起了人们极大的注意 [1～ 3] ,但因制备技术复杂、产率低以及将其从伴生的空心富勒烯中分离出来比较困难而使其研究受到很大的限制 .笼内金属富勒烯的分离提取始终是金属富勒烯研究的一个重要分支 .通常的方法是将放电得到的烟炱采用甲苯索氏提取的方法粗提 ,然后用高压液相色谱法分离得到纯品 ,笼内金属富勒烯的产率仅为烟炱的 0 .1 % [4～ 6] .我们改进了常规的提取方法 ,建立了一种新的提取方法—高温高压提取法 .具体的做法是采用甲苯索氏提取法从烟炱中提取出空心富勒烯和少量金…     

A new family of octanuclear Cu4Ln4 (Ln = Gd, Tb and Dy) spin clusters

The reaction of Cu(OAc)2 and Ln(OAc)3 (Ln = Gd, Tb and Dy) with 2-amino-2-methyl-1,3-propanediol (ampdH2) under solvothermal conditions has afforded a new family of isostructural octanuclear Cu4Ln4 complexes with the formula [Cu4Ln4(OAc)12(ampdH)8(OH2)2] (Ln = Gd (1), Tb (2) and Dy(3)) in good yield. Variable temperature magnetic susceptibility measurements reveal weak intramolecular exchange interactions for 1 and 2. Ferromagnetic coupling is observed for 1 and attributed to Cu...Gd interactions. In contrast, the magnetic susceptibility behaviour of 2 arises from a combination of intramolecular exchange interactions and the crystal field splitting of the (7)F6 ground state of the Tb(III) ions.     

甘氨酸辅助水热合成不同形貌的CaF2:Ln3+(Ln=Eu,Tb)微米晶

以KBF4和K2SiF6作为氟源,采用简单的甘氨酸辅助水热法制得了一系列具有不同形貌的CaF2:Ln3+(Ln =Eu,Tb)微米晶,如立方体、空心多面体和空心球.由XRD、FTIR、SEM及PL对产物的纯度、晶相、形貌和荧光性质进行了表征.XRD结果显示所有产物均为结晶良好的立方相CaF2.SEM结果表明,在添加甘氨酸的情况下,由KBF4得到的产物为空心多面体结构,而由K2SiF6制得的产物是由许多纳米块自组装成的空心球.研究发现甘氨酸、氟源种类、时间等反应参数在不同形貌CaF2:Ln3+(Ln=Eu,Tb)的形成过程中发挥关键作用,并提出了可能的反应机理.     

Crystal structures of Ln4Ni3O8 (Ln = La, Nd) triple layer T'-type nickelates

Single-phase Ln4Ni3O8 (Ln = La, Nd) nickelates were synthesized and their crystal structures were determined by Rietveld refinement of powder neutron diffraction data. The crystal structures of these mixed-valent Ni1+/Ni2+ phases belong to the T'-type and are built by intergrowth of LnO2 fluorite layers with triple NiO2 infinite-layer structural blocks. The major driving force of transformation of the LnO rock-salt block of the parent Ln4Ni3O10-delta Ruddlesden-Popper phases to the fluorite arrangement in the reduced Ln4Ni3O8 phases is attributed to internal structural stress. This transformation allows longer Ni-O bonds in Ln4Ni3O8 without overstretching of the Ln-O bonds, especially in the equatorial plane. The observed displacement of Ni atoms from the outer NiO2 planes toward the Ni atom of the central NiO2 plane in Ln4Ni3O8 is ascribed to large electrostatic repulsion from the fluorite part of the structure. X-ray absorption spectra near the K-edge of Ni suggest that the charge density on the nickel ion is similar for all members of the T'-type Lnn+1NinO2n+2 homologous series, which correlates with nearly constant Ni-O bond lengths observed in all the reduced nickelates. This suggests that the formal changes in the valence state of Ni affect the covalency of the Ni-O bond.     

Phase diagrams of the systems Ln2S3-Ln2O3 (Ln = Gd, Dy)

For the first time, the phase diagrams of the systems Gd₂S₃-Gd₂O₃ and Dy₂S₃-Dy₂O₃ were constructed within the temperature range from 870 K to the melting point. In the systems, compounds Gd₂O₂S and Dy₂O₂S form in hexagonal symmetry with the unit cell parameters a = 0.3858 nm, c = 0.6667 nm and a = 0.3802 nm, c = 0.6591 nm, respectively. The compounds melt congruently at 2430 and 2370 K, respectively. Their microhardnesses are 4900 and 5150 MPa, respectively. The coordinates of eutectics are the following: 21 mol % Gd₂O₃, T _eu = 1875 K; 83 mol % Gd₂O₃, T _eu = 2270 K; 20 mol % Dy₂O₃, T _eu = 1780 K; and 81 mol % Dy₂O₃, T _eu = 2220 K.