Structural,magnetic and electronic properties of oxides containing divalent europium,LiEu2LnO4 (Ln ≡ Y,Gd, Dy)

The structural, electronic and magnetic properties of a new series of oxides containing divalent europium (LiEu^II₂Ln^IIIO₄) have been investigated by X-ray diffraction, Mössbauer spectroscopy (¹⁵¹Eu, ¹⁵⁵Gd, ¹⁶¹Dy) and bulk magnetic measurements. These isostructural compounds crystallize with the orthorhombic LiEu₃O₄ structure. They order ferro(ferri)magnetically at about the same temperature of 14 K. The ¹⁵⁵Eu Mössbauer spectra were analysed consistently with two non-equivalent Eu(II) sites in agreement with the structural data. The ¹⁶¹Dy hyperfine-field value indicated a nearly fully saturated J_z, while quadrupolar data suggested slight crystal-field admixture.     

Enthalpies of Dilution of Aqueous Solutions of HCl, MgCl2}, CaCl2, and BaCl2 at 300, 325, and 350°C

Dilution enthalpies, measured using isothermal flow calorimetry, are reported for aqueous solutions of BaCl₂ at 300°C and 11.0 MPa, MgCl₂, CaCl₂, and BaCl₂ at 325°C and 14.8 MPa, and at 350°C and 17.6 MPa. Previously collected dilution enthalpies for aqueous solutions of MgCl₂ and CaCl₂ at 300°C and 10.3 MPa and for aqueous solutions of HCl at 250, 275, and 300°C at 10.3 MPa and 320°C at 12.8 MPa were included with the new data at 300°C and 11.0 MPa and at 350°C and 17.6 MPa when fitting the Pitzer parameters. The concentration range of the chloride solutions was 0.5 to 0.02 molal. Parameters for the Pitzer excess Gibbs ion–interaction equation were determined from the fits of the experimental heat data. Equilibrium constants, enthalpy changes, entropy changes, and heat-capacity changes for the association of alkaline earth metal ions and H⁺ with chloride ion were estimated from the heat data. For all systems, the enthalpy and entropy changes are positive and show accelerating increases with temperature. The resulting equilibrium constants show significant, but smaller, increases with temperature.     

Synthesis and Characterization of Ethylthioethylcyclopenta-dienyl Organolanthanide Complexes:Cp_2~(Th)LnCl(Ln=Gd,Dy),Cp_2LnCp~(Th)(Ln=Yb,Sm,Dy,Y) and Cp~(Th)ErCl_2·2THF

Introduction Functional substituted cyclopentadienyl organolan-thanide complexes continue to attract considerable at-tention because these donor-functionalized side chains can increase the stability of highly reactive organolan-thanide complexes by forming the additional in-tramolecular chelating coordination with the central metal, and for early lanthanide complexes, the enhanced stability offers the opportunity to explore the reactivity of the remaining ligands.1-4 In addition, the in-tramol…     

Thermal decomposition of RE(C2H5CO2)3·H2O (RE = Dy,Tb, Gd,Eu and Sm)

The thermal decomposition of Dy(III), Tb(III), Gd(III), Eu(III), and Sm(III) propionate monohydrates was studied in argon by means of simultaneous differential thermal analysis and thermogravimetry, infrared-spectroscopy, X-ray diffraction, and optical microscopy. After dehydration, which takes place below 120 °C, all salts decompose into dioxycarbonates with simultaneous release of CO₂ and C₂H₅COC₂H₅ (3-pentanone) between 250 and 460 °C. However, whereas the anhydrous Dy-, Tb-, and Gd-propionates appear to transform into RE₂O₂CO₃ (rare earth [RE] = Dy, Tb, Gd) in a single step, an intermediate stage involving a RE₂O(C₂H₅CO₂)₄ composition was evidenced in the case of the Eu- and Sm-propionates. For all compounds, further decomposition of RE₂O₂CO₃ into the corresponding sesquioxides (RE₂O₃) is accompanied by the release of CO₂. The thermal decomposition of Dy- and Tb-propionates occurs entirely in the solid state. In contrast the dehydrated Gd-, Eu-, and Sm-propionates melt at increasingly higher temperatures. Evidence for recrystallization was found in conjunction with the onset of decomposition of these three propionates.     

Synthesis and phosphorescence properties of Dy3+ and (Pr3+–Dy3+) in MgTiO3

Using tetra-n-butyl titanate and magnesium nitrate as raw materials, Dy³⁺ and Pr³⁺ ions in the matrix of magnesium titanate (MgTiO₃) was successfully synthesized by a modified solid-state reaction. The mixtures to achieve a solid-state reaction were heated in porcelain crucibles at 600?°C for 2?h, 900?°C for 6?h, and 1000.0?°C for 2?h. The reaction products obtained in an air atmosphere were characterized by X-ray powder diffractions. The optimization of reaction conditions were carried out by thermal gravimetry and differential thermal analysis methods. Surface and elemental analyses were performed by using on SEM instrument. The excitation and emission spectra were recorded by photoluminescence spectrophotometer.     

Synthesis,Crystal Structure,and Properties of [Dy(p-ABA)3Phen · H2O] · 1.5H2O1

(1.10-Phenanthroline)-tris(4-amidobenzoate)dysprosium, [Dy(p-ABA)₃Phen · H₂O] · 1.5H₂O (where p-ABA = p-amidobenzoate and Phen = 1.10-phenanthroline) has been synthesized. The complex was characterized by elemental analysis, UV, IR spectroscopy, and molar conductance. The crystal structure was determined by X-ray crystallography. The coordination number of the mononuclear complex is nine. The crystals are triclinic, space group P1 with a = 10.4484(13) Å, b = 12.2015(15) Å, c = 14.0170(17) Å; α = 92.800(2)°, β = 102.7220(10)°, γ = 108.880(2)°. Z = 2, d _c = 1.617 mg m^?3, F(000) = 786. R1 = 0.0327, and wR2 = 0.0911.     

Comparative Analysis of the Properties of Tween‐20, Tween‐60, Tween‐80, Arlacel‐60, and Arlacel‐80

Foamability and foam stability, emulsifying power, surface tension, and interfacial tension were investigated for Tween‐20 (polyoxyethylene sorbitan monolaurate), Tween‐60 (polyoxyethylene sorbitan monostearate), Tween‐80 (polyoxyethylene sorbitan monooleate), Arlacel‐60 (Sorbitan stearate), and Arlacel‐80 (Sorbitan oleate). Among all the surfactants tested for their foaming power and foamabilty, Arlacel‐60 and Arlacel‐80 showed the best results; the foaming power and foamability was found to be 100%. The surfactants having foam stability more than 50% can be considered as metastable and those less than 50% are considered as low‐stability foams. In case of surface tension and interfacial tension property measurements, Arlacel‐80 showed the best results. At 1% surfactant concentration, the surface tension and interfacial tension of Arlacel‐80 was found to be 29.9 dynes/cm and 1.1 dynes/cm at 30°C ambient temperature. Also, Arlacel‐60 was found to exhibit the best emulsifying power among all the surfactants tested. At 30°C, the emulsifying property of Arlacel‐60 was 6 hours.     

First-principles study of structural,elastic, electronic and optical properties of rutile GeO2 and α-quartz GeO2

Structural parameters, elastic, electronic, bonding and optical properties of rutile GeO₂ and α-quartz GeO₂ have been investigated using the plane-wave ultrasoft pseudopotential technique based on the first-principles density functional theory (DFT). The ground-state properties obtained by minimizing the total energy are in favorable agreement with the previous work. Two phases of GeO₂ are found to be elastically stable and we have derived the bulk, shear and Young’s modulus, Poisson coefficient for rutile GeO₂ and α-quartz GeO₂. We estimated the Debye temperature of rutile GeO₂ and α-quartz GeO₂ from the acoustic velocity. Electronic and chemical bonding properties have been studied from the calculation of band structure, density of states and charge densities. Furthermore, in order to clarify the mechanism of optical transitions for rutile GeO₂ and α-quartz GeO₂, the complex dielectric function, refractive index, extinction coefficient, optical reflectivity, absorption coefficient, energy-loss spectrum and the complex conductivity function are calculated, which show the significant optical anisotropy in the components of polarization directions (100) and (001) for rutile GeO₂ and α-quartz GeO₂.     

Preparation,Characterization and Thermal Decomposition Kinetics of the Complexes [Dy(p-NBA)_3Phen]_2·3H_2O and [Dy(m-NBA)_3Phen]_2·4H_2O

The title complexes [Dy(p-NBA)3Phen]2·3H2O(I) and [Dy(m-NBA)3Phen]2·4H2O(Ⅱ) were synthesized, in the two molecular formulas of which NBA is nitrobenzoate and Phen is 1,10-phenanthroline. The characterizations of the complexes were carried out by means of elemental analysis, UV, IR, XRD and molar conductivity. The thermal decomposition of the two complexes were studied under the non-isothermal condition by DSC, TG-DTG and IR methods in detail. The kinetic parameters of the dehydration process were also obtai...     

Synthesis,Crystal Structure and Anti-lung Cancer Activity of a New Dy(Ⅱ) Complex

A new Dy-based coordination polymer, namely {[Dy(cptpy)_2(H_2O)_2](TPT)(Cl)}_n(1, Hcptpy = 4-(4-carboxyphenyl)-4,2?:6?,4??-terpyridine, TPT = 2,4,6-tri(4-pyridyl)-1,3,5-triazine, DMA = N,N-dimethylacetamide) has been solvothermally synthesized by the reactions of DyCl_3, Hcptpy and TPT in a mixture solvent of DMA and H_2O. Single-crystal X-ray structural analysis reveals that 1 is a 1D linear chain coordination polymer with quadrangle channels which are occupied by the TPT ligands. The compound has been characterized by singe-crystal analyses, thermogravimetry analyses and powder X-ray diffraction measurements. The antitumor activity of compound 1 and its corresponding organic ligands Hcptpy and TPT were then investigated against four human lung cancer cell lines(NCI-H460, Calu-3, A549 and NCI-H292) by MTT assay. It was found that compared with Hcptpy and TPT, compound 1 exerted rather potent activity against all of these cell lines.     

A systematic study on the crystal structure and properties of RuSr2RCu2O8−δ (R=Gd,Tb, Dy,Y, Ho,Er)

The coexistence of superconductivity and magnetic order seems to take place in the so-called ruthenate-cuprates (Ru-1212). A systematic study is carried out on crystal structure of the RuSr₂RCu₂O_8−δ phases (R=Gd, Tb, Dy, Y, Ho, Er) synthesized under high pressure by X-ray powder diffraction. RuSr₂RCu₂O_8−δ (R=Gd, Tb, Dy, Y, Ho, Er) has the Ru-1212-type structure of a tetragonal symmetry and the RuO₆ octahedra rotate around the c-axis with an additional small rotation around an axis perpendicular to c. The DC-magnetization data establish that compounds with R=Gd, Y, Ho, Er exhibit ferromagnetic order below about 140 K, and the Meissner effect was observed at low temperature for R=Y compound.     

Syntheses,structures, magnetic properties,and photoluminescence of compounds Ln(2,2′-Bipy)(C4H8NCS2)3 · 0.5CH2Cl2 (Ln = Sm,Eu, Tb,Dy, and Tm)

Five compounds of the composition Ln(2,2′-Bipy)(C₄H₈NCS₂)₃ · 0.5CH₂Cl₂ (Ln = Sm (I), Eu (II), Tb (III), Dy (IV), and Tm (V); 2,2′-Bipy = 2,2′-bipyridine) are synthesized. According to the X-ray diffraction data (CIF file CCDC 986259), the crystal structure of compound I consists of molecules of the mononuclear complex [Sm(2,2′-Bipy)(C₄H₈NCS₂)₃] and solvate molecules CH₂Cl₂ (2 : 1). The coordination polyhedron N₂S₆ of the Sm atom is a distorted tetragonal antiprism. The X-ray diffraction analysis shows that compounds I–V are isostructural. The magnetic properties of compounds I–V are analyzed in the temperature range from 2 to 300 K. At 300 K compounds I and III are photoluminescent in the visible spectral range. The photoluminescence intensity of compound I considerably exceeds that of complex III.     

Aurivillius family of layered perovskites,BiREWO6 (RE = La,Pr, Gd,and Dy): Synthesis,characterization, and photocatalytic studies

The present work deals with the synthesis, characterization, and photocatalytic studies of layered perovskites belonging to Aurivillius family. Layered perovskites of various chemical compositions, BiREWO₆ (RE = La, Pr, Gd, and Dy), were synthesized by an ethylene glycol–assisted sol–gel method. These materials were characterized by X-ray diffraction, scanning electron microscopy–energy dispersive spectroscopy (EDS), Fourier transform infrared, Raman, and ultraviolet–visible diffuse reflectance techniques. The composition of all these materials was obtained from EDS. The unit cell lattice parameters were attained from Rietveld refinement program, Fullprof.2k, by refining the d-lines of BiREWO₆. The band gap energy of these samples was obtained from the Kubelka–Munk plot. The photocatalytic activity of all the samples was evaluated by photodegradation of methylene blue. The mechanistic degradation pathway of methylene blue was studied using radical quenchers.     

Preparation of the Phosphors BaAl_2O_4:Eu, RE (RE=Dy, Ho) by Microwave Heating Technique and Observation of Long Phosphorescence

TheMAI=O'fEu= (M=Ca,Sr,Ba)havebeenknowntobeexcelIentphosphorsunderultravioletandcath0de-rayexcitation'-'.Studies0ntheph0sphorswerem0stlypertbrmedinl960sandearlyl970smainlyf0rlampandcathode-raytubeapplicati0n.Inl990sthephosphorSrAl=O#fEu= hasbeenfoundtobeablet0maintainitsaftergl0wf0rafairlylongdurati0n'-'.lnthesereports.MAl=O'fEu' werepreparedmainl}byahightemperaturesolidstatemethod,whichexpendedquitel0ngreacti0ntime0f2-4hatahightemperature0fl20O~l500"Cinareducingatm0sphereandconsumedag…     

Aggregation Stability of SiO2, FeOOH, ZrO2, CeO2, and Natural Diamond Sols and Their Binary Mixtures: 2. The Photometric Study of Heterocoagulation of SiO2–FeOOH, SiO2–ZrO2, SiO2–CeO2, and CeO2–Natural Diamond Binary Systems in KCl Solutions

The aggregation stability of 1 : 1 and 3 : 1 (by volume) binary mixtures of two hydrophobic (SiO₂–FeOOH), one hydrophobic and one hydrophilic (SiO₂–ZrO₂, SiO₂–CeO₂), and two hydrophilic (CeO₂–natural diamond) sols was studied by photometry over a wide range of KCl concentrations at pH 6 and 3. The stability of the mixed binary sols was determined by the stability of the sol with a predominant particle number concentration. In the SiO₂–FeOOH system, the phenomenon of heteroadagulation stabilization was caused by the electrostatic factor of the stability of adsorbed SiO₂ particles and, in the SiO₂–ZrO₂ system, by the structural factor of the stability of adsorbed hydrophilic ZrO₂ particles. The stability of binary mixtures containing one or two hydrophobic components is qualitatively explained in terms of the Derjaguin theory of heterocoagulation of hydrophobic colloids. The stability of the binary system of two hydrophilic components (CeO₂–natural diamond) is determined by the structural component of the interaction energy of particles.     

Syntheses, structure, and luminescent properties of novel hydrated rare earth borates Ln2B6O10OH4•H2O (Ln = Pr, Nd, Sm, Eu, Gd, Dy, Ho, and Y)

Ln(2)B(6)O(10)(OH)(4)?H(2)O (Ln = Pr, Nd, Sm-Gd, Dy, Ho, and Y), a new series of hydrated rare earth borates, have been synthesized under hydrothermal conditions. A single crystal of Nd analogue was used for the structure determination by X-ray diffraction. It crystallizes in the monoclinic space group C2/c with lattice constants a = 21.756(4), b = 4.3671(9), c = 12.192(2) ?, and β = 108.29(3)°. The other compounds are isostructural to Nd(2)B(6)O(10)(OH)(4)?H(2)O. The fundamental building block (FBB) of the polyborate anion in this structure is a three-membered ring [B(3)O(6)(OH)(2)](5-). The FBBs are connected by sharing oxygen atoms forming an infinite [B(3)O(5)(OH)(2)](3-) chain, and the chains are linked by hydrogen bonds, establishing a two-dimensional (2-D) [B(6)O(10)(OH)(4)?H(2)O](6-) layer. The 2-D borate layers are thus interconnected by Ln(3+) ions to form the complex three-dimensional structure. Ln(2)B(6)O(10)(OH)(4)?H(2)O dehydrates stepwise, giving rise to two new intermediate compounds Ln(2)B(6)O(10)(OH)(4) and Ln(2)B(6)O(11)(OH)(2). The investigation on the luminescent properties of Gd(2-2x)Eu(2x)B(6)O(10)(OH)(4)?H(2)O (x = 0.01-1.00) shows a high efficiency of Eu(3+) f-f transitions and the existence of the energy transfer process from Gd(3+) to Eu(3+). Eu(2)B(6)O(10)(OH)(4)?H(2)O and its two dehydrated products, Eu(2)B(6)O(10)(OH)(4) and Eu(2)B(6)O(11)(OH)(2), present the strongest emission peak at 620 nm ((5)D(0) → (7)F(2) transition), which may be potential red phosphors.     

Theoretical study of N20, C20, and B20 clusters “squeezed” inside icosahedral C80 and He80 cages

The equilibrium geometries and spectroscopic and energetic characteristics of model endohedral M₂₀@C ₈₀ ^n? clusters, in which the guest clusters M₂₀ = N₂₀, C₂₀, and B₂₀ are squeezed inside the fullerene C ₈₀ ^n? cages (n = 0, 2, 4, and 6), have been calculated at the density functional theory B3LYP/6-31G and B3LYP/6-31G* levels. Analogous calculations with partial geometry optimization have been performed for their congeners M₂₀@He ₈₀ ^n? with a fixed icosahedral helium cage He₈₀. According to the calculations, all the structures of the N₂₀@C₈₀, C₂₀@C₈₀, and B₂₀@C₈₀ series correspond to local minima of the potential energy surface (all vibrational frequencies are real). In the first cluster, the N₂₀ guest has a structure of a dodecahedron with a diameter of ～4.0 Å. The alternative 10N₂@C₈₀ structure containing ten separated endohedral N₂ molecules is considerably less favorable and transforms without a barrier to the dodecahedral N₂₀@C₈₀ isomer upon geometry optimization. It has been suggested that, under extreme supercompresison conditions, molecular nitrogen can be associated without barriers into highly endothermal chemically bound clusters of the N₂₀ type. In the helium analogues, the relative position of the N₂₀@He₈₀ and 10N₂₀@He₈₀ structures on the energy scale is determined by the degree of compression and can change its sign with a change in the diameter of the external cage D(He₈₀). The mechanism of gradual assembly of the N₂₀ dodecahedron from the 10N₂ set has been traced with a decrease in the diameter D(He₈₀) in the range 7.5–8.6 Å. In the C₂₀@C₈₀ cluster, the C₂₀ guest has a structure of a distorted dodecahedron bound to the C₈₀ cage through four “inner” (endohedral) bonds. In the B₂₀@C₈₀ cluster, the B₂₀ guest is severely squeezed along the C₅ axis. Its equatorial atoms form ten endohedral B-C bonds to C₈₀ cage atoms. In similar systems, the division of the endoclusters into the internal guest and external cage becomes uncertain. Calculations predict that the isolated “salt” molecules of the L _n C₂₀ and L _n B₂₀ type in which the C₂₀ and B₂₀ clusters function as anions surrounded by the L atoms of alkali metals (n = 1–6) should be stable to stepwise dissociation accompanied by elimination of separate L atoms and L₂ molecules.     

Molecular and Crystal Structure of 2, 3, 5, 6-dipropylene-r-pyrone

11NTRODUCT1ONWeattemptedtosynthesizeanextractant(1)bythereactionofadipylchloridewithcyclopentanonepiperidineenamineaccordingtoHunig'sprocedure"',however,wemainlyobtainedthetitlecompound,whichmaybepossiblyapotentialmedicinet2'3i.Itsmolecularstructurewasfinallyconfirmedbythesingle-crystalstructuredeterminationafterconventionalUV,IR,lHNMR,MSandelementana-lyticalworks.2EXPER1MENTALSECT1ON2.1SynthesisToastirredsolutioncontaining8Omlofchloroform,2.8mloftri-ethylamineand1.51g(O-Olmol)…     

Synthesis, Single-crystal Structure, and Optical and Magnetic Properties of CaEr2S4

Brown needle-like crystals of CaEr2S4 were isolated as the major product from a reaction of elements and binary sulfides by a two-step flux technique. CaEr2S4 crystallizes in the orthorhombic space group Pnma with a = 12.845(4), b = 3.862(4), c = 13.001(2) , V = 645.0(7) 3, Z = 4, F(000) = 880, μ(MoKα) = 27.794 mm-1, the final R = 0.0528 and wR = 0.0562 for 1070 observed reflections with I > 3σ(I). The CaEr2S4 structure forms a three-dimensional framework that consists of interconnected tetra-octahedral Er4S18 fragments. Ca2+ cations, in a monocapped trigonal prism geometry, are stuffed in two parallel rows into the one-dimensional channels along the b direction. CaEr2S4 is an infrared-transparent semiconductor with a band gap of 1.81 eV. Magnetic susceptibility measurements over 6～300 K indicate a Curie-Weiss paramagnetic behavior for the phase, with an effective magnetic moment of 9.64(1) μB per Er3+ ion.