Mesomorphism of Lanthanide(Ⅲ) 4-Hexyloxybenzoates

The 4-alkoxybenzoic acids are well-known liquid crystals showing several mesophases(nematic,smectic C phase or both)depending on the alkoxy chain length and whereby the rigid core of the mesogen is formed by intermolecular hydrogen bonds.In this paper it is shown that the thermal behaviour of lanthanide salts of 4-hexyloxybenzoic acids depends on the lanthanide ion(Ln=La,Pr,Nd,Sm,Eu).The lanthanum(Ⅲ)and praseodymium(Ⅲ)4-hexyloxybenzoates exhibit a smectic A mesophase.No mesophase is found for the corresponding compounds of heavier lanthanides.The thermal properties of the lanthanide(Ⅲ)4-hexyloxybenzoates were investigated by differential scanning calorimetry(DSC),polarising thermo-optical microscopy and synchrotron X-ray radiation.     

Synthesis and Thermal Behaviour of Lanthanide Complexes of 4′[（Cholesteryloxy）Carbonyl]—Benzo—15—Crown—5

Lanthanide complexes of a steroid-substituted benzocrown ether were synthesised.The metal-to-ligand ratio of the metal complexes is1:1,The ligand4′[(Cholesteryloxy)Carbonyl]-Benzo-15-Crown-5 is a monotropicliquid crystal,displaying a cholesteric mesophase.The lanethanide complexes with nitate counter-ions form a highly viscous mesophase,decomposing at the clearing point ,The transition temperatures change as a function of the lanthanide ion.The corresponding lanthanide complexes with dodecylsulphate(DOS)counter-ions do not form a mesophase,In both cases ,the metal complexes have a much lower melting point than the parent ligand.     

Characteristics of Trivalent Lanthanides in Coordination Chemistry

Some basic characteristics of lanthanide-oxygen bonds in various trivalent lanthanide metal-organic complexes are quantitatively studied by the bond valence model. Some important relationships among the electronegativity, bond valence parameter, bond length and lanthanide coordination number in these complexes are generally found , which show that for each trivalent lanthanide cation all calculated parameters may well be correlated with its coordination number in their coordination complexes. Specifically ,32 new data for the bond valence parameter are first calculated in this work. An approximate linear relationship between the Ln - O bond valence parameter and the coordination number of Ln^3 is obtained. The Ln - O bond length increases with the increase in the lanthanide coordination number. The difference of electronegative values decreases with the increase in the lanthanide coordination number.     

Low Temperature Preparation of Ceria Solid Solutions Doubly Doped with Rare-Earth and Alkali-Earth and Their Properties as Solid Oxide Fuel Cells

Solidoxidefuelcells (SOFCs)haveseveraldis tinctadvantages ,e .g .,highenergyconversioneffi ciency ,wideadaptabilitytofuels ,theusageofnon preciousmaterials ,noliquids ,nocorrosions ,modularconstructionandmuchlowerproductionofNOx,SOxandnoise .Therefore ,theyreceiveincreasingatten tion[1,2 ] .AtypicalSOFCwhichutilizesyttria stabi lizedzirconia (YSZ)astheelectrolyterequireshighoperationtemperaturesuchas 10 0 0℃togainhighe noughionicconductivity .Loweringtheoperationtem peratureto 80 0℃wou…     

Thermal Stability and Luminescence Properties of Eu^3＋ and Tb^3＋ Complexes with a Silica Matrix by Sol-Gel Method

Ternary complexes of europium and terbium with benzoic acid and 1, 10-phenanthroline [RE(BA)3phen] (BA=benzoate phen=1,10-phenanthroline) were introduced into a silica matrix by sol-gel method. The thermal stability and luminescence behavior of the complexes in silica gels were studied in comparison with the corresponding solid-state complexes by thermal decomposition, excitation and emission spectra. The thermal stability of the complexes is enhanced in silica gel matrix and the luminescence remaines unchanged.     

Experiments of Applying the Rare-Earth Modifying Agents in New Dental Materials Preparation

Harmless rare-earth modifying agents were prepared by orthogonal experiments. A new resin material was synthesized with the qualities such as rigidity, rubbing abrasion, aging, luster and plasticity better than the dental resin materials in common used. It could be used as the substitutes for the applied resin teeth materials.     

Effects of Synthetic Parameters in Pechini Method on the Formation and Properties of （ZrO2） 0. 92 （ Sc2O3 ） 0.08 Solid Solution

Homogeneous (ZrO2)0.92 (Sc2O3)0.08 solid solution in fluorite cubic structure was prepared from the gels with altered molar ratios of citric acid (CA) to metal ions (M) and ethylene glycol (EG) via a polymerization route (Pechini method). Due to the enhanced chemical homogeneity (high level of mixing of metal ions and ligands) in the polymeric gels, Sc-doped zirconia can be crystallized at temperatures as low as 400 ~C. During the evolution from amorphous gel to the crystallized (ZRO2)0.92 (Sc203)0.08 fine powder, the bonding nature between carboxylate groups and Zr/Sc cations changed: unidentate→bridging→ionic upon calcination. The molar ratios of CA/M (1～4) and CA/EG (0.2～4) were demonstrated to affect the thermal behavior of the gels and thus the particle properties of the derived nanoparticulate oxide powders (including particle size and surface area). The as-sintered sample compacted from the nanosized powders prepared by calcining the gel with the highest content of organics (CA/M =4and CA/EG=0.2) exhibited the best sinterability and the highest oxide ion conductivity.     

Analysis of Valence Electron Structure of RE in Solid Solution in Medium and Low Carbon Steel

According to EET theory, the valence electron structures of RE in the solid solution of austenite, pearlite and martensite were calculated. The influence of RE in solid solution on phase transformation of pearlite and recrystallization of martensite was explained by the valence electron structure data of phases. Calculating results indicate that C element is favorite to enhance the number of RE in the solid solution. RE in the solute solution shortens the incubation period of proeutectoid ferrite, increases its quantity and carbon content, decreases the quantity of pearlite and thickness of its lamellas and lamellar spacing, then the strength and hardness of pearlite are improved and granular pearlite can be obtained. RE dissolved in martensite intensifies martensite, enhances tempering stability of martensite, increases its recrystallization temperature and prolongs the holding time needed during tempering.     

Fractionation of Rare Earth Elements in Plants Ⅰ. Fractionation Patterns and Their Forming Mechanisms in Different Organs of Triticum Aestivum

Fractionations of rare earth elements (REEs) and the forming mechanisms in plants were studied using Triticum aestivum as plant material with application of exogenous REEs and hydroponic culture. REEs were significantly fractionated in different parts of Triticum aestivum. M-type tetrad effect could be observed in both root and shoot of Triticum aestivum, which might result from the different abilities of REEs to form phosphate precipitation. Middle REEs (MREEs), light REEs (LREEs) and heavy REEs (HREEs) were enriched in root, stem and leaf of Triticum aestivum, respectively. REE speciation calculations using VMINTEQ program show REEs in simulated xylem solution mainly exist as REE-EDTA- and RE3 , but only HREEs are enriched in REE-EDTA-, while LREEs are enriched in the other REE species. It is suggested that the fractionation between LREEs and HREEs might be caused by the uptake of REE-EDTA- in Triticum aestivum leaves, but might result from the uptake of the other REE species in their stems.     

Preparation and Characterization of Cex Th1-xO2 Solid Solutions Prepared by Sol-Gel Method

Ceriumoxidehasbeenwidelystudiedinrecent yearsbecauseofitsusefulnessindifferentareasof chemistry.Incatalyticfield,forexample,CeO2has beenusedasanimportantcomponentofautomotive three waycatalystsforreducingtheexhaust.The mainroleofceriainthree waycatalystsi…     

Synthesis, Structure and Ionic Conductivity of La2／3-x Li3x MoO4

AlargenumberofM0 .5A0 .5M′O4 (M :rareearthion ,Bi3+,Fe3+,Cr3+,etc .A :alkaliion ,Cu+,Ag+,etc .M′ :Mo ,W )withtetragonalscheelite typestructurehavegoodcatalyticproperties .Aslumines centsubstrates ,theyhaveexcellentsensitizationtolu minescenceofrareearthion .Manyresearchesontheirstructure ,catalytic ,magneticandluminescentproper tieshavebeenmadesince 196 0s[1～ 10 ] .Thegeneralformulaforcompoundswiththetetragonalscheelite typestructureisAM′O4 wherethecationM′istetrahe drallycoordinat…     

Synthesis of 4-acylpyrazolone Schiff base ligand grafted silica and selectivity in adsorption of lanthanides from aqueous solutions

The Schiff base form of the 4-acylpyrazoione ligand was immobilized on the silica surface by reaction of 3-aminopropyl silica with 4-acetyl-5-methyl-2-phenyl-2,4-dihydro-pyrazol-3-one in 97% yield, producing grafted silica with 0.77 mmol/g ligand loading. This surface modified silica was shown to be selective in the adsorption of Yb3+ ions from dilute aqueous solutions, for which 98% adsorption was observed from a 1.0×10-5 mol/L aq. solution at pH 6.7, after 24 h at room temperature. Six other lanthanides studied Eu3+, Gd3+, Nd3+, Tb3+,Sm3+ and La3+ showed moderate to weaker adsorptions of 39%, 28%, 16%, 12%, 11% and 5% respectively under similar conditions.     

Hydrothermal Synthesis and Crystal Structure of a New Dimeric Lanthanum(Ⅲ) Complex

A new dimeric lanthanum(Ⅲ) complex [La2(phen)2(C7H3N2O6)6](phen=1,10-phenanthroline) was synthesized by the hydrothermal method and determined by single crystal X-ray diffraction analysis. The La(Ⅲ) ion is coordinated to seven oxygen atoms from five carboxylate groups and two nitrogen atoms from a phen ligand,forming a monocapped square antiprismatic geometry. Six carboxylate groups coordinate to two La(Ⅲ) ions in three modes which are chelating bidentate,bridging bidentate and bridging tridentate. The crystal is triclinic with space group P-1,a=1.2030(4) nm,b=1.2962(5) nm,c=1.3330(5) nm,α=104.410(5)°,β=114.048(4)°,γ＝100.054(4)°,V=1.7467(10) nm3,Mr=952.46,Z=2,Dc=1.811 g·cm-3,F(000)=944,S=1.017,μ=1.320 mm-1,with R1=0.0298 and wR2=0.0625.     

Status of Research on Application of High Purity Rare Earth Oxides in Solid Oxide Fuel Cells

The solid oxide fuel cell (SOFC) is a high-efficient and environmentally friendly power generation system.The rare earth oxide materials are used extensively in the manufacturing of SOFC components.In particular, the CeO2doped with Gd2O3 or Sm2O3, lanthanide perovskite oxides are indispensable and key materials for developing the intermediate temperature SOFC.The research and development status of application of high purity rare earth oxides in SOFC was overviewed.The rare earth oxide-based and -doped materials were discussed for the SOFC components.Concerning the rare earth oxides applicable to SOFC, several topics were also pointed out for further researching and developing.     

Synthesis, Characterization and Crystal Structure of Quaternary Complex of Gadolinium （Ⅲ）

Ａｎｕｍｂｅｒｏｆｌａｎｔｈａｎｉｄｅｔｅｒｎａｒｙｃｏｍｐｌｅｘｅｓｃｏｎ ｔａｉｎｉｎｇｈｅｔｅｒｏｃｙｃｌｉｃａｍｉｎｅｓｈａｖｅｂｅｅｎｒｅｐｏｒｔｅｄｓｉｎｃｅ1960 [1] .Ｉｎｒｅｃｅｎｔｙｅａｒｓｍｕｃｈａｔｔｅｎｔｉｏｎｈａｓｂｅｅｎｐａｉｄｔｏｑｕａｔｅｒｎａｒｙｃｏｍｐｌｅｘｅｓｏｆｌａｎｔｈａｎｉｄｅｓｂｅｃａｕｓｅｏｆｉｎ ｔｅｒｅｓｔｉｎｇｓｔｒｕｃｔｕｒｅ ,ｃｏｏｒｄｉｎａｔｉｏｎｍｏｄｅ ,ｃｏｍｐｅｔｉｔｉｏｎｒｅ ａｃｔｉｏｎａｎｄｐｒｏｐｅｒｔｙ[2～ 9] .ＥＳＲｃａｎｅ…     

Promoter of (Ce-Zr)O_2 Solid Solution Modified by Praseodymia in Three-Way Catalysts

CeO2 ispresentinthemajorityoftheformulationsofthethree waycatalystsduetoitswell knownmulti pleeffectssuchas :(1)stabilizationofthepreciousmetalsdispersionandthealuminasupport[1] ,(2 )pro motionofwatergasshiftreactionandsteamreformingreaction[2 ] andsoon .TheprimaryfunctionofCeO2 intheTWCsistoprovideoxygenstoragecapacity(OSC) ,actingasanefficient“oxygenbuffer”toun dergoeffectivereduction/oxidationcyclesbyshiftingbetweenCeO2 underoxidizingconditions (oxygenstor age)andCe2 O3underreducingco…     

Structure and Electrical Conductivity of Compositely Doped Oxide Solid Electrolyte La0.8Sr0.2Ga0.8Mg0.12Co0.08O2.8

(La, Sr) (Ga, Mg) O3-δ, (LSGM) perovskite compositions doped with transition metal Co on the B-site were prepared by solid state reaction. The effect of partial substitution of Ga for Co, La0.8Sr0.2Ga0.8Mg0.12Co0.08O2.8 (LSGMC2008) on the electrical conductivity was discussed. The results showed the compacted samples sintered at 1350℃ possesses increased electrical conductivity at low temperatures. The XRD patterns of the title materials indicated that LSGMC2008 possessed orthorhombic perovskite-type structure. The grains distributed relatively uniform from SEM photo. The Arrhenius plots of ionic conductivity in air of the LSGMC2008 exhibited differing slopes in the low-and high-temperature regions, and the corresponding Ea values were much lower than that of LSGM2020. All of these suggested that even at low sintering temperature, proper amount Co doped was beneficial to improve ionic conductivity of LSGM.     

Synthesis and Photoluminescence of Three Europium (Ⅲ) Ternary Complexes with New Secondary Ligands of Different Structure

Three new 1,10-phenanthroline derivatives, dipyrido (3,2-f: 2,3-h) quinoxaline (DPQN), imidazo (5,6-f)-(1,10)-phenanthroline (IP) and 3-phenyl-imidazo (5,6-f)-(1,10)-phenanthroline (PIP) were designed and synthesized as a secondary ligand to coordinate with europium (Ⅲ) ion while dibenzoylmethane (DBM) was used as the first ligand. The compositions of the ligands and the europium (Ⅲ) ternary complexes were confirmed by elementary analysis, IR and 1H-NMR spectroscopy. The UV-visible absorption spectra, thermal stability, photoluminescence spectra, quantum yield and fluorescence life time of the Eu(Ⅲ) complexes were investigated. The effect of the structure of the secondary ligand on the photoluminescence of the complexes was discussed. The results show that the synthesized Eu(Ⅲ) complexes are good red-emitiing materials for potential application in fabrication of organic electroluminescence devices.     

Distribution of Cerium Ion in Cordierite Ceramics and Its Effect on Structure of Cordierite Crystal

Cerium addition plays an important role in sintering, transformation and phasicochemical properties of cordierite ceramics. The present work aims at studying the distribution of Ce4+ in cordierite ceramics and its effect on the structure of cordierite crystal by means of differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electronic microscope (SEM) so as to clarify the behavior of Ce4+. Results show that Ce4+ can exist in two forms of CeO2 particles and solid solution in Ce4+ -modified cordierite ceramics by the sol-gel method. The CeO2 particles separately distribute in the cordierite matrix. Ce4+ dissolves little into cordierite crystal, resulting in a decrease of lattice constants ofthe crystal. This kind of distribution behavior of Ce4+ makes us to easily tailor the properties of the cordieritc ceramics.     

Structure and heat capacity of the NaCeF4 compound

This work continued our general research program on obtaining metallic cerium by electrodeposition from NaCeF4 dis-solved in different molten fluorides. The structure of NaCeF4 (cubic or hexagonal depe...