In this study,fluorinating vaporization combined with ETV-ICP-AES technique was used to determineyttrium for which refractory carbide is easily formed.The absolute detection limit is 12 pg,and three-ordermagnitude of ...In this study,fluorinating vaporization combined with ETV-ICP-AES technique was used to determineyttrium for which refractory carbide is easily formed.The absolute detection limit is 12 pg,and three-ordermagnitude of improvement is obtained in comparison with the conventional vaporization ETV-ICP-AES.Nomemory effect is observed.The relative standard deviation is better than 5%.Some factors affecting fluorinatingvaporization,including matrix effect are discussed.This technique is applied to determine yttrium in La<sub>2</sub>O<sub>3</sub>.展开更多
Microporous titanium dioxide films were prepared by the sol-gel methods on glass substrates, using tetrabutyl titanate as source material. In order to absorb the visible light and increase the photocatalytic activitie...Microporous titanium dioxide films were prepared by the sol-gel methods on glass substrates, using tetrabutyl titanate as source material. In order to absorb the visible light and increase the photocatalytic activities, different concentrations of neodymium ions (Nd/Ti molar ratio was 0.5%, 0.7%, 0.9%, and 1.1% respectively) were added into the sol. X-ray diffraction (XRD), X-ray photoelectron spectros-copy (XPS), and atom force microscopy (AFM) were applied to characterize the modified films. A kind of typical textile industry pollutant (Rhodamine B) was used to evaluate the photocatalytic activities of the films under visible light. The results showed that the activities of the films were improved by doping Nd ions into the sol.展开更多
A study was carried out to determine the optimum parameters for synthesis of SiC-ZrO2 composite materials by carbothermal re-duction of zircon. Test samples were prepared by mixing average mesh size of less than 30 μ...A study was carried out to determine the optimum parameters for synthesis of SiC-ZrO2 composite materials by carbothermal re-duction of zircon. Test samples were prepared by mixing average mesh size of less than 30 μm of carbon black and 40 μm of zircon with C/ZrSiO4 mass ratio of 0.2 and the extra addition amount of La2O3 was 0, 1 wt.% and 2 wt.%. Prepared samples were subjected to the car-bothermal reduction process at temperatures of 1723, 1753, 1773 and 1803 K for 4 h, respectively. The carbothermal reduction process was conducted in an atmosphere controlled tube furnace at an argon flow of 1.5 L/min. All products were examined by X-ray diffraction (XRD) to determine the transformation. The results showed that the best transformation of SiC-ZrO2 composite materials occurred at 1803 K for 4 h with the amount of 2 wt.%La2O3.展开更多
Eu-activated CaMoO4 phosphors were co-precipitated in an aqueous solution, and NH3·H2O, NH4HCO3 and (NH2)2CO as pre-cipitating aid agents were compared based on the morphology and particle size distribution of th...Eu-activated CaMoO4 phosphors were co-precipitated in an aqueous solution, and NH3·H2O, NH4HCO3 and (NH2)2CO as pre-cipitating aid agents were compared based on the morphology and particle size distribution of the phosphor samples. Sm3+ as sensitizer ion was investigated on the luminescence of CaMoO4:Eu, and it could strengthen the 406 nm absorption of this phosphor. At last, the scheelite CaMoO4:Eu and wolframite ZnMoO4:Eu were selected to compare their host absorption. The result showed that the scheelite molybdate host exhibited stronger UV absorption than wolframite one.展开更多
It is indicated from a study of transport of rare earth ions through the emulsion liquid mem-brane of bis（2,4,4-trimethylpentyl）phosphinic acid-Span 80-toluene that transporting rare earth ions com-pletely and rapid...It is indicated from a study of transport of rare earth ions through the emulsion liquid mem-brane of bis（2,4,4-trimethylpentyl）phosphinic acid-Span 80-toluene that transporting rare earth ions com-pletely and rapidly was realized under the optimum experimental conditions:1.0×10<sup>-3</sup>～3.0×10<sup>-3</sup>mol/Lbis（2,4,4-trimethylpentyl）phosphinic acid and 2%～4%（W/V）Span 80 in toluene solution as membranephase,0.50～2.0 mol/L HCl as inner phase,rare earth ion solutions with pH 3.5～5.0 as outer phase.Ac-cording to the differences of transport behavior for rare earth ions,it is possible to separate rare earth ionsfrom mixed solutions of rare earth ions by this liquid membrane system.展开更多
The structure of the yttrium modified Co-base alloy layers formed by laser cladding on 2Cr13 and1Cr18Ni9Ti steel surfaces and its hot corrosion performance have been investigated systematically.The re-sults show that ...The structure of the yttrium modified Co-base alloy layers formed by laser cladding on 2Cr13 and1Cr18Ni9Ti steel surfaces and its hot corrosion performance have been investigated systematically.The re-sults show that the Y-containing cobalt base clad alloy has a finer microstructure and higher corrosion re-sistance to the salt mixture of 75% Na<sub>2</sub>SO<sub>4</sub>+25%NaCl at high temperature.The unique properties are ob-tained with addition of 0.875% Y for the formation of a continuous and compact oxide scale.The compactscale may act as a barrier for the inward diffusion of oxygen and sulphur and also for the outward diffusionof alloying elements.展开更多
We succeed in inserting a number of nitrogen atoms into the R<sub>2</sub>Fe<sub>17</sub>and RTiFe<sub>11</sub>intermetalliccompounds.The nitrides retain original Th<sub>2</...We succeed in inserting a number of nitrogen atoms into the R<sub>2</sub>Fe<sub>17</sub>and RTiFe<sub>11</sub>intermetalliccompounds.The nitrides retain original Th<sub>2</sub>Zn<sub>17</sub>(or Th<sub>2</sub>Ni<sub>17<sub><</sub>/sub>and ThMn<sub>12</sub>structures,but with an increase inthe unit cell volume.The interstitial nitrogen atoms are found to have an effect of increasing the Curie tempera-ture and saturation magnetization.Moreover,a distinct effect on the magnetocrystalline anisotropy is also ob-served in these nitride compounds.Especially,NdTiFe<sub>11</sub>N<sub>0.5</sub>and SmTiFe<sub>11</sub>N<sub>2</sub> have excellent intrinsic magneticproperties favourable for permanent magnet applications.展开更多
The mechansim of the effect of rare earth(RE)on wearability of spray-welding layers has been investi-gated by adding RE in ppm into Nickel base self-fluxing alloy powder.The test results show that the microalloy-ing e...The mechansim of the effect of rare earth(RE)on wearability of spray-welding layers has been investi-gated by adding RE in ppm into Nickel base self-fluxing alloy powder.The test results show that the microalloy-ing effect of RE can refine the structure of spray-welding layers,and change the amount,size,shape and distri-bution of hard phase in spray-welding layers.The wearability of spray-welding layers is increased consequently.展开更多
Methodsfor the synthesis of acidic phenyl-and substituted phenylphosphonates bearing a branched longchain ester alkyl group are described.These synthetic routes are incomparably superior to other methods in vari-ous a...Methodsfor the synthesis of acidic phenyl-and substituted phenylphosphonates bearing a branched longchain ester alkyl group are described.These synthetic routes are incomparably superior to other methods in vari-ous aspects including better reaction yield and higher purity of the product.The behaviour of themono(2-butyloctyl)esters and mono(2-methyldodecyl)esters of both phenyl-and o-methylphenylphosphonicacids thus obtained in extraction of lanthanum,praseodymium,neodymium and lutecium as representatives oflight and heavy rare earths,is investigated and discussed on the basis of their chemical structure.The dependenceof the extraction constants and separation factors accords with the Reactivity-Selectivity Principle in solvent ex-traction proposed by us.The composition and structure of the extracted species have been characterized byinfra-red and proton nuclear magnetic resonance spectroscopy in addition to elemental analyses.展开更多
The corrosion behavior of coatings of pure zinc and Zn-Al,Zn-Al-RE alloys in NaCl solu-tions was studied by salt-spray experiments,even corrosion experiments and electrochemical measurementsof bi-directional polarizat...The corrosion behavior of coatings of pure zinc and Zn-Al,Zn-Al-RE alloys in NaCl solu-tions was studied by salt-spray experiments,even corrosion experiments and electrochemical measurementsof bi-directional polarization curves and a.c.impedance in weak polarization region consistent regularitieswere obtained by these different methods,viz.,the corrosion resistance of Zn could be enhanced by alloying itwith Al,and particularly with Al-RE.The causes of enhancement of corrosion resistance by RE were alsodiscussed.展开更多
The effect of rare earth element on the solidification behavior of Al-Mg alloy was investigated in adirectional solidification apparatus.It was found that during the solidification process.the rare earth elementsegreg...The effect of rare earth element on the solidification behavior of Al-Mg alloy was investigated in adirectional solidification apparatus.It was found that during the solidification process.the rare earth elementsegregated in the liquid at sold-liquid interface,changed the solidification morphology and reduced thesecondary arm spacing markedly.展开更多
An isothermal section of Nd-Fe-B system at 1000℃ and the phase equilibrium relationship in Fe-Ndand Nd-B binary systems were investigated with diffusion couple by means of metallographic observation,electron micropro...An isothermal section of Nd-Fe-B system at 1000℃ and the phase equilibrium relationship in Fe-Ndand Nd-B binary systems were investigated with diffusion couple by means of metallographic observation,electron microprobe analysis and X-ray diffraction.It was shown that there are three stable ternary com-pounds,Nd<sub>2</sub>Fe<sub>14</sub>B,Nd<sub>2</sub>Fe<sub>7</sub>B<sub>6</sub> and Nd<sub>9</sub>Fe<sub>3</sub>B<sub>8</sub> in Nd-Fe-B system at 1000℃.None of these phases has solu-bility,that is,they are exactly stoichiometric phases.On the other hand,there exist rather wide two-phaseregions between Nd<sub>2</sub>Fe<sub>7</sub>B<sub>6</sub> and liquid as well as between Nd<sub>9</sub>Fe<sub>3</sub>B<sub>8</sub> and liquid.It was identified that there isno NdFe<sub>2</sub> compound in the system under atmospheric pressure.展开更多
The CO<sub>2</sub> quenching method has been used for the first time to determine the active complex concen-tration in Nd（naph）<sub>3</sub>-Al（i-Bu）<sub>3</sub> catalyst system ...The CO<sub>2</sub> quenching method has been used for the first time to determine the active complex concen-tration in Nd（naph）<sub>3</sub>-Al（i-Bu）<sub>3</sub> catalyst system for polymerization of phenylacetylene intopolyphenylacetylene（PPA）films.The kinetics and mechanism of this polymerization have been investigatedby CO<sub>2</sub> quenching and IR,UV analytical methods.The kinetic equation can be expressed asRp=k[M][Cp],and the apparent activation energy is about 13.6 kJ/mol.There is self-termination ofchain propagating.Models for formation of the active complex and polymerization mechanism are proposed.展开更多
Glasses with the composition of 65GeO212Ga2O3-10BaO-8Li2O-5La2O3(molar ratio) doped with 1.526 wt.%, 3.006 wt.%, 5.836 wt.%, 11.028 wt.%, and 15.678 wt.% Tm2O3, respectively, were fabricated by conventional melting me...Glasses with the composition of 65GeO212Ga2O3-10BaO-8Li2O-5La2O3(molar ratio) doped with 1.526 wt.%, 3.006 wt.%, 5.836 wt.%, 11.028 wt.%, and 15.678 wt.% Tm2O3, respectively, were fabricated by conventional melting method. According to the absorption spectra and the Judd-Ofelt theory, the J-O strength parameters (Ω2,Ω4, Ω6) were calculated, with which the radiative transition probabilities,branching ratios and radiative lifetimes were obtained. The infrared emission spectra (with 808 nm LD excitation) at～1.47 and～1.8 μm of various concentrations of Tm3+-doped glasses were studied. The emission intensity at～1.8 μm reached to the maximum when the Tm2O3-doping concentration was near to be～3.006 wt.% (1.0 mol.%), and then decreased as doping concentration increased further. The mechanism of the fluorescence intensity change was explained with the cross-relaxation effect and the concentration quenching effect of Tm3+. Meanwhile, according to McCumber theory, the absorption and emission cross-sections corresponding to the 3F4→3H6 transitions of Tm3+ at 1.8 μm was obtained. For Tm3+-doped germanate glasses, the maximum emission cross-section reached a value higher than that re-ported for fluorozircoaluminate glasses. It is expected to be a favorable candidate host for～2.0 μm mid-inflated laser because the glass shows favorable optical spectra.展开更多
A method for determination of trace rare earth elements in biological sample by ICP-AES withtungsten-spiral electrothermal vaporization（TETV-ICP-AES）sampling has been developed in this work.Several influencing facto...A method for determination of trace rare earth elements in biological sample by ICP-AES withtungsten-spiral electrothermal vaporization（TETV-ICP-AES）sampling has been developed in this work.Several influencing factors including desolvation and vaporization parameters,carrier gas flow rate and ma-trix effect were investigated in detail.Under optimal experimental conditions,the detection limits for La,Nd,Gd,Dy,Ho,Yb,Lu and Y were obtained in the range of 10<sup>-9</sup>～10<sup>-11</sup> g,and they are comparable to and,inmost instances,better than those for the GFAAS and conventional pneumatic nebulisation-ICP-AES.Theprecision（RSD）obtained for this method is less than 6%.展开更多
The microstructure and tensile properties of the extruded Mg-Zn-Zr-RE alloy bars are studied.Theextruded bar without previous homogenization has the highest tensile strength,whereas the tensile strength of theextruded...The microstructure and tensile properties of the extruded Mg-Zn-Zr-RE alloy bars are studied.Theextruded bar without previous homogenization has the highest tensile strength,whereas the tensile strength of theextruded bar previously homogenized at 400℃ or 380℃ is lower.During long time homogenization,the trans-formation of rare earth compounds Mg<sub>3</sub>REZn<sub>6</sub>（Z phase）and Mg<sub>3</sub>RE<sub>2</sub>Zn<sub>3</sub>（W phase）into Mg<sub>41</sub>RE<sub>5</sub> andMg Zn phases occurr and the MgZn phase grow up.In addition,the dynamic recrystallization takes place in sub-sequent extrusion that caused decrease of the tensile strength.展开更多
The deoxidation,desulfuration,deoxysulfuration constants and the standard Gibbs energies(inJ mol<sup>-1</sup>)of formation of the following rare earth compounds as the equilibrium phases in Ni-base solutio...The deoxidation,desulfuration,deoxysulfuration constants and the standard Gibbs energies(inJ mol<sup>-1</sup>)of formation of the following rare earth compounds as the equilibrium phases in Ni-base solutionsare given:Ce<sub>2</sub>O<sub>3</sub>:lgK=-（6.0729×10<sup>4</sup>/T）+16.50 △G<sup>0</sup>=-1.162460×10<sup>6</sup>+315.84TCe<sub>2</sub>O<sub>2</sub>S:lgK=-（5.1450×10<sup>4</sup>/T）+12.46 △G<sup>0</sup>=-9.84850×10<sup>5</sup>+238.50TCe<sub>2</sub>S<sub>3</sub>:lgK=-（7.2232×10<sup>4</sup>/T）+27.98 △G<sup>0</sup>=-1.382600×10<sup>6</sup>+535.55TY<sub>2</sub>O<sub>3</sub>:lgK=-（4.2572×10<sup>4</sup>/T）+7.74 △G<sup>0</sup>=-8.14920×10<sup>5</sup>+148.16TY<sub>2</sub>O<sub>2</sub>S:lgK=-（3.3146×10<sup>4</sup>/T）+3.85 △G<sup>0</sup>=-6.34460×10<sup>5</sup>+73.72TY<sub>2</sub>S<sub>3</sub>:lgK=-（1.22487×10<sup>5</sup>/T）+55.78 △G<sup>0</sup>=-2.344630×10<sup>0</sup>+1067.76TInteraction coefficients between Ce.Y and O are also given:e<sub>o</sub><sup>?</sup>=-（3.33451×10<sup>5</sup>/T）+149.7 e<sub>O</sub><sup>?</sup>=-（1.63437×10<sup>5</sup>/T）+71.8The phase equilibria for Ni-Ce-S-O and Ni-Y-S-O solutions at 1600℃ provide the basis for pre-dicting the sequence and type of Ce and Y equilibrium phases formed in Ni-base solutions.The formulascontrolling the morphology of inclusion formed in liquid Ni by Ce or Y addition are also given.展开更多
The polymerization of 1-octene with Nd(P<sub>204</sub>)<sub>3</sub>-AlEt<sub>3</sub> catalyst has been successfully carried out for thefirst time.Some features of polymerization of ...The polymerization of 1-octene with Nd(P<sub>204</sub>)<sub>3</sub>-AlEt<sub>3</sub> catalyst has been successfully carried out for thefirst time.Some features of polymerization of 1-octene are described.The 1-octene oligomer prepared has anaverage molecular weight of about 10<sup>3</sup> with molecular weight distribution of about 2.It has a terminal doublebond,which can be transferred into terminal carboxy group by direct oxidation with KMnO<sub>4</sub> in acidic solution,and then can be esterified with polyglycol.展开更多
The magnetism and surface behaviour of Pt-Dy/γ-Al<sub>2</sub>O<sub>3</sub> catalysts were studied respectively bymeans of a Faraday magnetic balance and the method of carbon disulfide.The ferr...The magnetism and surface behaviour of Pt-Dy/γ-Al<sub>2</sub>O<sub>3</sub> catalysts were studied respectively bymeans of a Faraday magnetic balance and the method of carbon disulfide.The ferromagnetic impurity in thesupport,γ-Al<sub>2</sub>O<sub>3</sub>,at low temperature was corrected for the first time.The magnetic susceptibilities of the cat-alysts follow the sequence in different stage of preparation:χ<sub>uncalcined</sub>【χ<sub>calcined</sub>【χ<sub>reduced</sub>.The magnetic susceptibilities of the catalysts decrease as they adsorb hydrogen,cyclohexane or benzene.There is a correlation between the aromatization yield of cyclohexane or heptane on these catalysts and themagnetic susceptibility of the catalysts.Since addition of Dy increases the number of adsorption sites and therelevant proportions of weak adsorption sites,the abilities of sulfur-resistance and cyclohexanedehydrogenation are improved.In Pt-Dy/γ-A:<sub>2</sub>O<sub>3</sub> catalysts,Dy improves the aromatization activity andstability of the catalyst and plays the role of the electron promoter.展开更多
The present paper proposes a new method of spectrophotometry based on linear combination ofmultiwavelength data by means of selecting a set of properly weighted coefficients and combination methods.It is clear that th...The present paper proposes a new method of spectrophotometry based on linear combination ofmultiwavelength data by means of selecting a set of properly weighted coefficients and combination methods.It is clear that the weighted combination absorbance attained is only in direct proportion to the concentrationof the analysed component and independent of coexisting interferents.The accuracy of the analytical resultsis improved greatly for the analysis of light rare earths with the coexistence of heavy rare earths.The analyti-cal error from the reagent blank and co-coloration of light and heavy rare earths have also been overcome.The greatly improved linearity and additivity of absorbance are obtained.展开更多
文摘In this study,fluorinating vaporization combined with ETV-ICP-AES technique was used to determineyttrium for which refractory carbide is easily formed.The absolute detection limit is 12 pg,and three-ordermagnitude of improvement is obtained in comparison with the conventional vaporization ETV-ICP-AES.Nomemory effect is observed.The relative standard deviation is better than 5%.Some factors affecting fluorinatingvaporization,including matrix effect are discussed.This technique is applied to determine yttrium in La<sub>2</sub>O<sub>3</sub>.
基金Project supported by the State Key Laboratory of Urban Water Resource and Environment (HIT 08UWQA05) and National Key Laboratory of Vacuum and Cryogenics Technology and Physics (9140C550201060C55)
文摘Microporous titanium dioxide films were prepared by the sol-gel methods on glass substrates, using tetrabutyl titanate as source material. In order to absorb the visible light and increase the photocatalytic activities, different concentrations of neodymium ions (Nd/Ti molar ratio was 0.5%, 0.7%, 0.9%, and 1.1% respectively) were added into the sol. X-ray diffraction (XRD), X-ray photoelectron spectros-copy (XPS), and atom force microscopy (AFM) were applied to characterize the modified films. A kind of typical textile industry pollutant (Rhodamine B) was used to evaluate the photocatalytic activities of the films under visible light. The results showed that the activities of the films were improved by doping Nd ions into the sol.
基金Project supported by the National Natural Science Foundation of China (50274021) and Baoshan Iron and Steel Co., Ltd.
文摘A study was carried out to determine the optimum parameters for synthesis of SiC-ZrO2 composite materials by carbothermal re-duction of zircon. Test samples were prepared by mixing average mesh size of less than 30 μm of carbon black and 40 μm of zircon with C/ZrSiO4 mass ratio of 0.2 and the extra addition amount of La2O3 was 0, 1 wt.% and 2 wt.%. Prepared samples were subjected to the car-bothermal reduction process at temperatures of 1723, 1753, 1773 and 1803 K for 4 h, respectively. The carbothermal reduction process was conducted in an atmosphere controlled tube furnace at an argon flow of 1.5 L/min. All products were examined by X-ray diffraction (XRD) to determine the transformation. The results showed that the best transformation of SiC-ZrO2 composite materials occurred at 1803 K for 4 h with the amount of 2 wt.%La2O3.
基金Project supported by the National Natural Science Foundation of China (50372086) and the Minstry of Science and Technology of China (2006AA03A133)
文摘Eu-activated CaMoO4 phosphors were co-precipitated in an aqueous solution, and NH3·H2O, NH4HCO3 and (NH2)2CO as pre-cipitating aid agents were compared based on the morphology and particle size distribution of the phosphor samples. Sm3+ as sensitizer ion was investigated on the luminescence of CaMoO4:Eu, and it could strengthen the 406 nm absorption of this phosphor. At last, the scheelite CaMoO4:Eu and wolframite ZnMoO4:Eu were selected to compare their host absorption. The result showed that the scheelite molybdate host exhibited stronger UV absorption than wolframite one.
基金Supported by the National Natural Science Foundation of China
文摘It is indicated from a study of transport of rare earth ions through the emulsion liquid mem-brane of bis（2,4,4-trimethylpentyl）phosphinic acid-Span 80-toluene that transporting rare earth ions com-pletely and rapidly was realized under the optimum experimental conditions:1.0×10<sup>-3</sup>～3.0×10<sup>-3</sup>mol/Lbis（2,4,4-trimethylpentyl）phosphinic acid and 2%～4%（W/V）Span 80 in toluene solution as membranephase,0.50～2.0 mol/L HCl as inner phase,rare earth ion solutions with pH 3.5～5.0 as outer phase.Ac-cording to the differences of transport behavior for rare earth ions,it is possible to separate rare earth ionsfrom mixed solutions of rare earth ions by this liquid membrane system.
基金Research Project supported by the Corrosion Science Laboratory,Academia Sinica
文摘The structure of the yttrium modified Co-base alloy layers formed by laser cladding on 2Cr13 and1Cr18Ni9Ti steel surfaces and its hot corrosion performance have been investigated systematically.The re-sults show that the Y-containing cobalt base clad alloy has a finer microstructure and higher corrosion re-sistance to the salt mixture of 75% Na<sub>2</sub>SO<sub>4</sub>+25%NaCl at high temperature.The unique properties are ob-tained with addition of 0.875% Y for the formation of a continuous and compact oxide scale.The compactscale may act as a barrier for the inward diffusion of oxygen and sulphur and also for the outward diffusionof alloying elements.
文摘We succeed in inserting a number of nitrogen atoms into the R<sub>2</sub>Fe<sub>17</sub>and RTiFe<sub>11</sub>intermetalliccompounds.The nitrides retain original Th<sub>2</sub>Zn<sub>17</sub>(or Th<sub>2</sub>Ni<sub>17<sub><</sub>/sub>and ThMn<sub>12</sub>structures,but with an increase inthe unit cell volume.The interstitial nitrogen atoms are found to have an effect of increasing the Curie tempera-ture and saturation magnetization.Moreover,a distinct effect on the magnetocrystalline anisotropy is also ob-served in these nitride compounds.Especially,NdTiFe<sub>11</sub>N<sub>0.5</sub>and SmTiFe<sub>11</sub>N<sub>2</sub> have excellent intrinsic magneticproperties favourable for permanent magnet applications.
文摘The mechansim of the effect of rare earth(RE)on wearability of spray-welding layers has been investi-gated by adding RE in ppm into Nickel base self-fluxing alloy powder.The test results show that the microalloy-ing effect of RE can refine the structure of spray-welding layers,and change the amount,size,shape and distri-bution of hard phase in spray-welding layers.The wearability of spray-welding layers is increased consequently.
基金supported by the National Natural Science Foundation of China
文摘Methodsfor the synthesis of acidic phenyl-and substituted phenylphosphonates bearing a branched longchain ester alkyl group are described.These synthetic routes are incomparably superior to other methods in vari-ous aspects including better reaction yield and higher purity of the product.The behaviour of themono(2-butyloctyl)esters and mono(2-methyldodecyl)esters of both phenyl-and o-methylphenylphosphonicacids thus obtained in extraction of lanthanum,praseodymium,neodymium and lutecium as representatives oflight and heavy rare earths,is investigated and discussed on the basis of their chemical structure.The dependenceof the extraction constants and separation factors accords with the Reactivity-Selectivity Principle in solvent ex-traction proposed by us.The composition and structure of the extracted species have been characterized byinfra-red and proton nuclear magnetic resonance spectroscopy in addition to elemental analyses.
文摘The corrosion behavior of coatings of pure zinc and Zn-Al,Zn-Al-RE alloys in NaCl solu-tions was studied by salt-spray experiments,even corrosion experiments and electrochemical measurementsof bi-directional polarization curves and a.c.impedance in weak polarization region consistent regularitieswere obtained by these different methods,viz.,the corrosion resistance of Zn could be enhanced by alloying itwith Al,and particularly with Al-RE.The causes of enhancement of corrosion resistance by RE were alsodiscussed.
文摘The effect of rare earth element on the solidification behavior of Al-Mg alloy was investigated in adirectional solidification apparatus.It was found that during the solidification process.the rare earth elementsegregated in the liquid at sold-liquid interface,changed the solidification morphology and reduced thesecondary arm spacing markedly.
文摘An isothermal section of Nd-Fe-B system at 1000℃ and the phase equilibrium relationship in Fe-Ndand Nd-B binary systems were investigated with diffusion couple by means of metallographic observation,electron microprobe analysis and X-ray diffraction.It was shown that there are three stable ternary com-pounds,Nd<sub>2</sub>Fe<sub>14</sub>B,Nd<sub>2</sub>Fe<sub>7</sub>B<sub>6</sub> and Nd<sub>9</sub>Fe<sub>3</sub>B<sub>8</sub> in Nd-Fe-B system at 1000℃.None of these phases has solu-bility,that is,they are exactly stoichiometric phases.On the other hand,there exist rather wide two-phaseregions between Nd<sub>2</sub>Fe<sub>7</sub>B<sub>6</sub> and liquid as well as between Nd<sub>9</sub>Fe<sub>3</sub>B<sub>8</sub> and liquid.It was identified that there isno NdFe<sub>2</sub> compound in the system under atmospheric pressure.
文摘The CO<sub>2</sub> quenching method has been used for the first time to determine the active complex concen-tration in Nd（naph）<sub>3</sub>-Al（i-Bu）<sub>3</sub> catalyst system for polymerization of phenylacetylene intopolyphenylacetylene（PPA）films.The kinetics and mechanism of this polymerization have been investigatedby CO<sub>2</sub> quenching and IR,UV analytical methods.The kinetic equation can be expressed asRp=k[M][Cp],and the apparent activation energy is about 13.6 kJ/mol.There is self-termination ofchain propagating.Models for formation of the active complex and polymerization mechanism are proposed.
基金Project supported by the National Natural Science Foundation of China (60777030), the Open Foundation of Key Laboratory of Ningbo City ((2007A22010), and K.C. Wong Magna Fund in Ningbo University
文摘Glasses with the composition of 65GeO212Ga2O3-10BaO-8Li2O-5La2O3(molar ratio) doped with 1.526 wt.%, 3.006 wt.%, 5.836 wt.%, 11.028 wt.%, and 15.678 wt.% Tm2O3, respectively, were fabricated by conventional melting method. According to the absorption spectra and the Judd-Ofelt theory, the J-O strength parameters (Ω2,Ω4, Ω6) were calculated, with which the radiative transition probabilities,branching ratios and radiative lifetimes were obtained. The infrared emission spectra (with 808 nm LD excitation) at～1.47 and～1.8 μm of various concentrations of Tm3+-doped glasses were studied. The emission intensity at～1.8 μm reached to the maximum when the Tm2O3-doping concentration was near to be～3.006 wt.% (1.0 mol.%), and then decreased as doping concentration increased further. The mechanism of the fluorescence intensity change was explained with the cross-relaxation effect and the concentration quenching effect of Tm3+. Meanwhile, according to McCumber theory, the absorption and emission cross-sections corresponding to the 3F4→3H6 transitions of Tm3+ at 1.8 μm was obtained. For Tm3+-doped germanate glasses, the maximum emission cross-section reached a value higher than that re-ported for fluorozircoaluminate glasses. It is expected to be a favorable candidate host for～2.0 μm mid-inflated laser because the glass shows favorable optical spectra.
文摘A method for determination of trace rare earth elements in biological sample by ICP-AES withtungsten-spiral electrothermal vaporization（TETV-ICP-AES）sampling has been developed in this work.Several influencing factors including desolvation and vaporization parameters,carrier gas flow rate and ma-trix effect were investigated in detail.Under optimal experimental conditions,the detection limits for La,Nd,Gd,Dy,Ho,Yb,Lu and Y were obtained in the range of 10<sup>-9</sup>～10<sup>-11</sup> g,and they are comparable to and,inmost instances,better than those for the GFAAS and conventional pneumatic nebulisation-ICP-AES.Theprecision（RSD）obtained for this method is less than 6%.
文摘The microstructure and tensile properties of the extruded Mg-Zn-Zr-RE alloy bars are studied.Theextruded bar without previous homogenization has the highest tensile strength,whereas the tensile strength of theextruded bar previously homogenized at 400℃ or 380℃ is lower.During long time homogenization,the trans-formation of rare earth compounds Mg<sub>3</sub>REZn<sub>6</sub>（Z phase）and Mg<sub>3</sub>RE<sub>2</sub>Zn<sub>3</sub>（W phase）into Mg<sub>41</sub>RE<sub>5</sub> andMg Zn phases occurr and the MgZn phase grow up.In addition,the dynamic recrystallization takes place in sub-sequent extrusion that caused decrease of the tensile strength.
基金This subject is supported by the National Natural Science Foundation of China
文摘The deoxidation,desulfuration,deoxysulfuration constants and the standard Gibbs energies(inJ mol<sup>-1</sup>)of formation of the following rare earth compounds as the equilibrium phases in Ni-base solutionsare given:Ce<sub>2</sub>O<sub>3</sub>:lgK=-（6.0729×10<sup>4</sup>/T）+16.50 △G<sup>0</sup>=-1.162460×10<sup>6</sup>+315.84TCe<sub>2</sub>O<sub>2</sub>S:lgK=-（5.1450×10<sup>4</sup>/T）+12.46 △G<sup>0</sup>=-9.84850×10<sup>5</sup>+238.50TCe<sub>2</sub>S<sub>3</sub>:lgK=-（7.2232×10<sup>4</sup>/T）+27.98 △G<sup>0</sup>=-1.382600×10<sup>6</sup>+535.55TY<sub>2</sub>O<sub>3</sub>:lgK=-（4.2572×10<sup>4</sup>/T）+7.74 △G<sup>0</sup>=-8.14920×10<sup>5</sup>+148.16TY<sub>2</sub>O<sub>2</sub>S:lgK=-（3.3146×10<sup>4</sup>/T）+3.85 △G<sup>0</sup>=-6.34460×10<sup>5</sup>+73.72TY<sub>2</sub>S<sub>3</sub>:lgK=-（1.22487×10<sup>5</sup>/T）+55.78 △G<sup>0</sup>=-2.344630×10<sup>0</sup>+1067.76TInteraction coefficients between Ce.Y and O are also given:e<sub>o</sub><sup>?</sup>=-（3.33451×10<sup>5</sup>/T）+149.7 e<sub>O</sub><sup>?</sup>=-（1.63437×10<sup>5</sup>/T）+71.8The phase equilibria for Ni-Ce-S-O and Ni-Y-S-O solutions at 1600℃ provide the basis for pre-dicting the sequence and type of Ce and Y equilibrium phases formed in Ni-base solutions.The formulascontrolling the morphology of inclusion formed in liquid Ni by Ce or Y addition are also given.
文摘The polymerization of 1-octene with Nd(P<sub>204</sub>)<sub>3</sub>-AlEt<sub>3</sub> catalyst has been successfully carried out for thefirst time.Some features of polymerization of 1-octene are described.The 1-octene oligomer prepared has anaverage molecular weight of about 10<sup>3</sup> with molecular weight distribution of about 2.It has a terminal doublebond,which can be transferred into terminal carboxy group by direct oxidation with KMnO<sub>4</sub> in acidic solution,and then can be esterified with polyglycol.
文摘The magnetism and surface behaviour of Pt-Dy/γ-Al<sub>2</sub>O<sub>3</sub> catalysts were studied respectively bymeans of a Faraday magnetic balance and the method of carbon disulfide.The ferromagnetic impurity in thesupport,γ-Al<sub>2</sub>O<sub>3</sub>,at low temperature was corrected for the first time.The magnetic susceptibilities of the cat-alysts follow the sequence in different stage of preparation:χ<sub>uncalcined</sub>【χ<sub>calcined</sub>【χ<sub>reduced</sub>.The magnetic susceptibilities of the catalysts decrease as they adsorb hydrogen,cyclohexane or benzene.There is a correlation between the aromatization yield of cyclohexane or heptane on these catalysts and themagnetic susceptibility of the catalysts.Since addition of Dy increases the number of adsorption sites and therelevant proportions of weak adsorption sites,the abilities of sulfur-resistance and cyclohexanedehydrogenation are improved.In Pt-Dy/γ-A:<sub>2</sub>O<sub>3</sub> catalysts,Dy improves the aromatization activity andstability of the catalyst and plays the role of the electron promoter.
文摘The present paper proposes a new method of spectrophotometry based on linear combination ofmultiwavelength data by means of selecting a set of properly weighted coefficients and combination methods.It is clear that the weighted combination absorbance attained is only in direct proportion to the concentrationof the analysed component and independent of coexisting interferents.The accuracy of the analytical resultsis improved greatly for the analysis of light rare earths with the coexistence of heavy rare earths.The analyti-cal error from the reagent blank and co-coloration of light and heavy rare earths have also been overcome.The greatly improved linearity and additivity of absorbance are obtained.
