Eu2+在M3La3(BO3)4(M=Ca,Sr,Ba)中的发光性质

本文研究了Eu²⁺离子在M_yAl_xBO_y+3/2(1+x)(M=Ca,Sr,Ba)基质中的发光性质及磷和卤素对发光的影响。 采用以H₂和N₂混合气体为还原气氛在高温下进行固相反应的方法合成了一系列磷光体。发现,在CaAl_xBO_2.5+3/2x基质中,当X在0.5～2的范围内时及在Sr_yAl₂BO_{4 6+}基质中,当y在2～6的范围时掺入的Eu³⁺不能被H₂还原为Eu²⁺。其他Eu²⁺激活的磷光体一般都产生f～d跃迁的宽带发射,发射峰的波长随着基质组成的不同可在400～600nm的区间的变化。     

Electroconductivity of Solid Electrolytes in the Systems K3–2x M x PO4 (M = Ca, Sr, Ba)

Solid electrolytes K_{3 – 2x} M _x PO₄ (M = Ca, Sr, Ba) are synthesized and the temperature and concentration dependences of their electroconductivity are studied. Adding calcium and strontium stabilizes the high-temperature -form of K₃PO₄ at room temperature, while barium-containing solid electrolytes undergo an eutectoid decomposition below 430°C. Maximum electroconductivity is exhibited by K_{3 – 2x} Sr _x PO₄ (7.1 × 10^–3 and 1.25 × 10^–1 S cm^–1 at 300 and 700°C).     

Oxidation resistance of LnSiON powders (Ln=Y,Gd and La)

For application of LnSiON (Ln=Y, Gd and La) oxynitride materials, e.g. as host-lattices for lamp phosphors, oxidation resistance up to about 600 °C in air is a prerequisite. In this study we prepared LnSiON (Ln=Y, Gd and La) powders by solid state reaction and observed via TGA/DTA-experiments that most compounds are oxidation resistant up to 600 °C in air. The stability in air at high temperatures increases going from Ln₅(SiO₄)₃N, Ln₄Si₂O₇N₂, LnSiO₂N, Ln₂Si₃O₃N₄ to Ln₃Si₈O₄N₁₁. This is explained by an increasing cross-linking between the siliconoxygennitrogen tetrahedra in this sequence. For the lattices with less cross-linking between the siliconoxygennitrogen tetrahedra we observed that the oxidation resistance decreases slightly going from Y and Gd to La. For these lattices, also, an additional weight gain was observed during the oxidation reaction, which was higher than expected for complete oxidation. The additional weight gain was ascribed to an intermediate phase in which nitrogen retention takes place.     

MO-RE2O3-B2O3(M=Mg,Ca,Sr,Ba;RE=La,Eu,Gd)玻璃的发光性质

在空气中采用高温固相反应方法合成的17MO－（8-x-y)-75B2O3-xGd2O3(MLBEG,M-Mg,Ca,Sr,Ba)玻璃，在紫外光（λex=350nm)激发下发射蓝光和红光，在绿色光（λex=532nm)激发下发射红光，电子自旋共振谱研究表明玻璃体系中有Eu^2 离子存在，蓝色区的宽带发射是Eu^2 离子的5d-4f跃迁发射：红色区的窄带发射是Eu^3 离子的5Do-7FJ(J=1,2,3,4)跃迁发射，发现玻璃中的碱土金属离子对Eu^3 /Eu^2 离子的比例有很大影响，选择不同的碱土金属离子可以调节玻璃蓝色光和红色光的相对发射强度，MLBEG玻璃的发光性质可用于转换太阳能，增强植物的光合作用。     

La1—xMxCoO3（M=Ca,Sr）还原性的研究

以XPS和XRD手段研究了La_(1-x)M_xCoO_3复合氧化物的还原性质,得到还原程度次序为La_(1-x)Sr_xCoO_3>La_(1-x)Ca_xCoO_3>LaCoO_3;相同离子取代系列随x增大,还原容易进行,探讨了取代钴酸镧的氢还原机理。     

The vibrational spectra of (CH3)3MCCCCM(CH3)3, with M = C,Si, Ge,or Sn

Infrared spectra from 200 to 4000 cm⁻¹ and Raman spectra from 80 to 4000 cm⁻¹ have been recorded for the molecules (CH₃)₃MCCCCM(CH₃)₃ with M = C, Si, Ge, or Sn. Solid samples and solutions in several solvents have been used. Assignments of the fundamentals were made on the assumption of D_3d symmetry, which proved quite satisfactory. In all, 140 of the 188 spectroscopically-active fundamentals for the four molecules have been assigned.The in-phase CC stretch is 115–135 cm⁻¹ higher than the out-of-phase one. This is in sharp contrast to cumulated double bonds, where the in-phase stretch is roughly half the out-of-phase one. A rationalization of this is given.     

Electroconductivity of Solid Solutions Cs3–2x M x PO4 (M = Ba, Sr, Ca, Mg)

Solid solutions Cs_{3 – 2x} M _x PO₄ (M = Ba, Sr, Ca, Mg) are synthesized and their thermal behavior and electroconductivity are examined. Adding elements of Subgroup IIA of the periodic table into cesium orthophosphate shifts the phase transition, which occurs in pure Cs₃PO₄ at 450–620°, towards lower temperatures and raises the cesium cation conductivity at low temperatures. The electroconductivity of a high-temperature modification of Cs₃PO₄ is weakly dependent on the presence and concentration of such additives, which points to structural disordering of the cesium sublattice.     

La1—xMxCoO3（M=Ca,Sr）表面状态的XPS研究

合成了一系列钙钛矿复合氧化物La_(1-x)M_(?)CoO_3(M=Ca,Sr),并用XPS研究了LaCoO_3中的La~(3+)部分被Ca~(2+)或Sr~(2+)取代后表面状态的变化。由XPS的O_(10)谱图拟合得到的吸附氧O(2)百分数与取代量x呈现规律性变化。对Ca_(2p)与Sr_(3d)谱图也进行峰拟合处理,其中结合能较高的Sr(2)、Ca(2)可指认为周围有氧离子缺位物种。Ca(2)或Sr(2)百分数与吸附氧百分数的关系可用取代后表面状态的变化来解释。     

Protonic and Oxygen Conduction of Perovskites ATi0.95M0.05O3 - α (A = Ca,Sr, Ba; M = Mg,Sc) in Humid Air

Measurements of the total conduction (450-1030°C) and transport numbers for ions and protons (450-850°C) of titanates ATi_0.95M_0.05O_{3 -} (A = Ca, Sr, Ba; M = Mg, Sc) in humid air are performed. Partial conductions (ionic, protonic, oxygen, hole) and their effective energies of activation are determined. The results are discussed within a model of separate transport of proton and oxygen ion.     

Tb~(3 )在MO(M=Ca,Sr)中的长余辉发光

长余辉发光材料的研究与应用,已有近100年的历史,目前仍在许多领域中有着重要应用[1].此类材料与其他光致发光材料具有相同的发光性能,只是更注重其发光的衰减过程和热释光性能.如,ZnS:Cu作为黄绿色的长余辉发光材料,在1992年以前是余辉性能最好的长余辉发光材料,一直处于发光研究工作的中心.     

Co-cation Conduction in Solid Solutions (K1 – xRbx)4P2O7–M2P2O7(M = Ca,Sr, Cd,Ba): Dependence on the Nature and Concentration of Cations M2+

Solid solutions of the structure -K₄P₂O₇, which have the composition (K_{1 – x} Rb _x )_3.8M_0.1P₂O₇(M = Ca, Sr, Cd, Ba) and (K_{1 – x} Rb _x )_{4 – 2y} Ca _y P₂O₇(y= 0.025–0.20), are synthesized. The solutions' electroconductivity is studied in the temperature range 400–600°C. The concentration dependences of the conductivity and the activation energy for conduction have extremums at x 0.6, which points to the polyalkaline effect. The effect increases with decreasing radius of cation M²⁺and with increasing concentration of calcium cations, which is explained by an increased energy nonequivalence of positions in the cation sublattice accessible to alkali ions.     

Magnetic behaviour of the MTbF6 fluoroterbates (M=Cd,Ca, Sr, (α/β)-Ba)

Neutron powder diffraction has been performed on the MTbF₆ fluorides (M=Cd, Ca, Sr, (α/β)-Ba). Four of these fluorides (Cd, Ca, Sr, β-Ba) are built of a (pseudo-) tetragonal packing of [TbF₆]^2? chains and only differs by the chains relative orientations. Thus this series represents a valuable opportunity to evaluate the Tb⁴⁺-Tb⁴⁺ magnetic interactions. All the compounds displayed antiferromagnetic order (T_N=2.70 K (Cd), 2.15 K (Ca), 2.60 K (Sr), 2.10 K (β-Ba)), except for the α form of BaTbF₆. The crystal structure of this latter fluoroterbate has also been investigated by means of high-resolution neutron powder diffraction. From Neutron Powder Diffraction data, CdTbF₆ and β-BaTbF₆ magnetic structures were determined, together with the metamagnetic behaviour of β-BaTbF₆ as a function of an external magnetic field. A tentative phase diagram is then given for β-BaTbF₆. Advantage was taken of the polymorphism of the BaTbF₆ fluoroterbate to analyse, on the basis of topological parameters such as bond distances and angles, the magnetic behaviour of its α and β forms. It was shown that superexchange interactions are present in β-BaTbF₆, and that these interactions may also rule the magnetic behaviour of the other MTbF₆ (M=Ca, Sr, Cd) tetravalent terbium fluorides.     

Endohedral Plumbaspherenes of the Group 9 Metals: Synthesis,Structure and Properties of the [M@Pb12]3− (M=Co,Rh, Ir) Ions

The icosahedral [M@Pb₁₂]³⁻ (M=Co( 1 ), Rh( 2 ), Ir( 3 )) cluster ions were prepared from K₄Pb₉ and Co(dppe)Cl₂ (dppe=1,2-bis(diphenylphosphino)ethane)/[Rh(PPh₃)₃Cl]/[Ir(cod)Cl]₂ (cod=1,5-cyclooctadiene), respectively, in the presence of 18-crown-6/ 2,2,2-cryptand in ethylenediamine/toluene solvent mixtures. The [K(2,2,2-cryptand)]⁺ salt of 1 and the [K(18-crown-6)]⁺ salt of 3 were characterized via X-ray crystallography; the ions 1 and 3 are isostructural and isoelectronic to the [Rh@Pb₁₂]³⁻ ( 2 ) ion as well as to the group 10 clusters [M′@Pb₁₂]²⁻ (M′=Ni, Pd, Pt). The ions are all 26-electron clusters with near perfect icosahedral I_h point symmetry. Clusters 1 – 3 show record downfield ²⁰⁷Pb NMR chemical shifts due to σ-aromaticity of the cluster framework. Calculated and observed ²⁰⁷Pb NMR chemical shifts and ²⁰⁷Pb–^xM J-couplings (^xM=⁵⁹Co, ¹⁰³Rh, ¹⁹³Ir) are in excellent agreement and DFT analysis shows that the variations of ²⁰⁷Pb NMR chemical shifts for the [M@Pb₁₂]^{2, 3−} ions (M=Co, Rh, Ir, Ni, Pd, Pt) are mainly governed by the perpendicularly oriented σ₁₁ component of the chemical shift anisotropy tensor. The laser desorption ionization time-of-flight (LDI-TOF) mass spectra contain the molecular ions as well as several new gas phase clusters derived from the parents. The DFT-minimized structures of these ions are described.     

Regularities of change in the structural parameters of EuLnCuS<Subscript>3</Subscript> (Ln = La–Nd,Sm, Gd,Ho)

Regularities of change in the structural parameters of EuLnCuS₃ (Ln = La–Nd, Sm, Gd, Ho) at an annealing temperature of 970 and 1170 K have been established. A decrease in the Ln³⁺ ionic radius results in the consecutive change of structural types (STs) for the compounds: α-EuLnCuS₃ (Ln = La, Ce, Pr, Nd; BaLaCuS₃ ST) → β-EuLnCuS₃ (Ln = Ce, Pr, Nd; Ba2MnS₃ ST) → γ-EuLnCuS₃ (Ln = Sm, Gd, Ho; Eu₂CuS₃ST). The change of structural types for EuLnCuS₃ leads to a jump-like change in their unit cell parameters and the transformation of coordination polyhedra shaped as a one-capped trigonal prism LnS₇ (α and β phases) into an octahedron LnS₆ (γ phases). The appearance of morphotropic changes correlates with the tetrad effect.     

Structure and bonding energy analysis of cationic metal-ylyne complexes of molybdenum and tungsten, [(MeCN)(PMe3)4M≡EMes]+ (M = Mo, W; E = Si, Ge, Sn, Pb): a theoretical study

The molecular and electronic structures and bonding analysis of terminal cationic metal-ylyne complexes (MeCN)(PMe(3))(4)M≡EMes](+) (M = Mo, W; E = Si, Ge, Sn, Pb) were investigated using DFT/BP86/TZ2P/ZORA level of theory. The calculated geometrical parameters for the model complexes are in good agreement with the reported experimental values. The M-E σ-bonding orbitals are slightly polarized toward E except in the complex [(MeCN)(PMe(3))(4)W(SnMes)](+), where the M-E σ-bonding orbital is slightly polarized toward the W atom. The M-E π-bonding orbitals are highly polarized toward the metal atom. In all complexes, the π-bonding contribution to the total M≡EMes bond is greater than that of the σ-bonding contribution and increases upon going from M = Mo to W. The values of orbital interaction ΔE(orb) are significantly larger in all studied complexes I-VIII than the electrostatic interaction ΔE(elstat). The absolute values of the interaction energy, as well as the bond dissociation energy, decrease in the order Si > Ge > Sn > Pb, and the tungsten complexes have stronger bonding than the molybdenum complexes.     

Synthesis and crystal structure of [NEt4]2[HFe3Rh(CO)12], the first tetranuclear FeRh hydridocarbonyl cluster

The anion [HFe₃Rh(CO)₁₂]²⁻ was obtained by reaction of [HFe(CO)₄]⁻ with Rh₂(CO)₄Cl₂ in refluxing THF. Its solid state structure consists of a tetrahedron of metal atoms with three edge-bridging and nine terminal carbonyl groups. The hydridic ligand bridges a face containing the rhodium atom. [NEt₄]₂[HFe₃Rh(CO)₁₂] crystallizes in the orthorhombic space group Pnnma, with a 19.983(5) Å, b 15.168(4) Å. c 11.915(2) Å, V 3611(2) ų, Z = 4, R = 0.043, R_w = 0.054 for 1680 unique reflections with I > 3σ(I).     

Mobility of the dppm ligand in dinuclear RuRh complexes: formation of trinuclear RuRh2 and RuRhCu derivatives,and X-ray structure of a new heterobimetallic hydrido-bridged complex

Protonation of RuRhH₂Cl(COD)(dppm)₂ (1) (COD = 1,5 cyclooctadiene, dppm = bisdiphenylphosphinomethane) with HBF₄ · Et₂O gives [RuRhHCl(COD)-(dppm)₂]BF₄ (2), which has been shown to contain two chelating dppm ligands on ruthenium and a bridging hydride (RuH 2.08(7) Å; RhH 1.64(8) Å). Complex 2 reacts with CO to give [RuRhHCl(CO)₃(dppm)₂]BF₄ (3) containing two bridging dppm groups. Reaction of 1 with 0.5 molar equivalents of [RhCl(COD)]₂ at 80°C affords the trinuclear RuRh₂H₂Cl(PhPCH₂PPh₂)(COD)₂(dppm) (4) in low yield (25%), and that with CuCl at room temperature gives RuRhCuH₂Cl₂ (COD)(dppm)₂ (5) in high yield. Complex 5 is not very stable in solution and is converted into RuCuH₂Cl(dppm)₂ (6), a typical adduct between a Lewis acid and a hydride complex, which can be more easily obtained from RuH₂(dppm)₂ and CuCl in toluene at 80°C.     

Crystal Structures of Ln（NO3）3（Ln=La,Yb）Complexes with 12—crown—4

ＣｒｙｓｔａｌＳｔｒｕｃｔｕｒｅｓｏｆＬｎ（ＮＯ_３）_３（Ｌｎ＝Ｌａ，Ｙｂ）Ｃｏｍｐｌｅｘｅｓｗｉｔｈ１２－ｃｒｏｗｎ－４ＭａｏＪｉａｎｇ－Ｇａｏ；ＪｉｎＺｈｏｎｇ－Ｓｈｅｎｇ；ＹｕＦｅｎｇ－Ｌａｎ（ＬａｂｏｒａｔｏｒｙｏｆＲａｒｅＥａｒｔｈＣｈｅｍ...     

MMgF4(M=Ca,Sr, Ba)体系中Eu和Tb的电荷迁移

于不同气流中, 合成了MMgF4:xEu,yTb复合氟化物磷光体。该体系中Eu^3^+和Eu^2^+共存。Tb的存在影响Eu的价态存在形式。ESR测试表明, 随Tb的掺入浓度增加, Eu^2^+的浓度呈规律性变化。随Eu的掺入, 样品的XPS谱中出现了四价铽的Tb3d5/2特征伴峰。认为Eu^3^+和Tb^3^+之间存在电荷迁移平衡。即Eu^3^++Tb^3^+=Eu^2^++Tb^4^+。通过半定量手段研究了SrMgF4中这一衡的平衡常数。     

Solvent dependence of peak frequencies and bandwidths of the ν4 vibration of the series CH3MCl3, M  C,Si, Ge,Sn

The Raman spectra of the carbon—chlorine symmetric stretching mode, ν₄, of the Group IVA methylmetal trichlorides (CH₃MCl₃, M  C, Si, Ge, Sn) were acquired in a number of solvents of varying molecular properties. Non-linear curve fitting procedures were used to separate the four band components resulting from chlorine isotope splitting.The band maxima of the two lighter members of the series were observed to shift to lower frequency with increasing solvent polarizability, indicating the predominance of solute—solvent dispersion forces. In the germanium and tin compounds, on the other hand, the peak frequencies were correlated, instead, with solvent dipole moment. This result is in contrast to earlier studies on the ν₁ (CH₃ symmetric stretching) vibration, for which dispersion interactions are the dominant frequency displacement mechanism in all four compounds.The bandwidths of the ν₄ vibration were found to depend on dipolar interactions in the germanium and tin compounds. However, this correlation was not observed for the two lighter series members, nor for the carbon—chlorine antisymmetric stretching vibration in CH₃SnCl₃.