氧化镨熔盐电解过程预还原反应的研究

本文通过物料的差热-热重分析、高温反应实验以及产物的x射线衍射结构分析,研究了Pr6O11高温热稳定性、Pr6O11-PrF3和Pr6O11-PrF3-C的高温反应特性.在此基础上,探讨确定了Pr6O11在电解槽内熔盐中主要的预还原反应.     

Crystal structure, thermal expansion and electrical conductivity of Pr(Ga1-xCox)0.9Mg0.1O3-δ(x=0,0.1,0.2,0.3)

Pr(Ga1-xCox)0.9Mg0.1O3-δ(x=0, 0.1, 0.2, 0.3) was synthesized using solid-state reaction technique to study the effects of Co doping on their structure and properties. Room and high temperature XRD, DSC and electrical conductivity measurement with D.C. four-probe technique were adopted in the study. The results indicated its orthorhombic-distorted perovskite structure at room temperature. PrGa0.9Mg0.1O3-δ maintained its orthorhombic-distorted structure between 298 and 1173 K. For Pr(Ga0.7Co0.3)0.9Mg0.1O3-δ, such structure existed below 873 K. From 873 to 1173 K, it possessed tetragonal structure. The transformation from orthorhombic to tetragonal structure at 873 K was of second order. The intrinsic volume thermal expansion of tetragonal structured Pr(Ga0.7Co0.3) 0.9Mg0.1O3-δ was about 50% higher than those of PrGa0.9Mg0.1O3-δ. The electrical conductivity increased with Co content. The activation energies of conduction for Pr(Ga1-xCox)0.9Mg0.1O3-δ are in range from 0.197 to 0.246 eV, much lower than 1.543 eV for PrGaO3.     

Study on Rare Earth Electrolyte of Ce_(0.9)RE_(0.1)O_(2-δ) (RE=Pr, Nd, Sm, Gd, Dy)

Thesolidelectrolyteisakeycomponentofsolidoxidefuelcell (SOFC) .Dopedceriaisoneofpromis inghigh conductingsolidelectrolyteinSOFC[1,2 ] .Butitiswell knownthatitisdifficulttosinterdopedceriabysolidstatereactioninair .TheCe0 .9RE0 .1O2 -δelectrolytematerialswerepreparedbythesol gelmethod .Thesinteringtemperatureofthesamplescandecreasetoabout 4 0 0K .Theionicconductivityandlinearthermalexpansionpropertiesofsol gelpreparedCe0 .9RE0 .1O2 -δinawidetemperaturerangewerein vestigated .Thepowder…     

Fabrication and Characterization of SOFC Anode, Ni-SDC Cermet

NiO and Ce0.8Sm0.2O1.9 were synthesized by the combination of sol gel and citric acid-nitrate low temperature self-propagating combustion method. Anode precursors which include home-made NiO and Ce0.8Sm0.2O1.9 were prepared by different NiO content and fabrication condition. The anode precursors with pure hydrogen at 820 ℃ for 2.5 h were reduced, The electrical conductivity was tested, and the effect of microstructure on electrical conductivity of Ce0.8Sm0.2O1.9 composite anodes was investigated. The results show that the anode electrical conductivity depends strongly on the anode microstructure that is dramatically affected by Ni content and fabrication condition.     

UV-Vis Spectroscopy Study on Interaction between Microperoxidase-11 and Pr Ion Under Acid Rain Stress

Interaction between rare earth ion praseodymium (Pr( Ⅲ )) and MP11 with/without hydrogen ion (H^ ) in different media( aqueous, phosphate buffer, physiological condition) were studied by UV-Vis spectroscopy. All the results indicate that Pr( Ⅲ ) interacts with MPll, increasing the non-planarity of porphyrin periphery, leading MP11 to form two conformations when titrated by Pr( Ⅲ ). Excessive Pr( Ⅲ ) acts as a contaminant in living organism. H^ and Pr( Ⅲ ) have antagonistic effect on MP11, suggesting that at suitable concentration under physiological conditions, Pr( Ⅲ ) can be used as biomodulator in protecting plants from acid rain stress or in rehabilitating the harm.     

硼钨铜气相渗稀土的导电及热敏性能

采用气相渗的方法对K7CuBW1 1 O39导电材料进行了稀土Eu的化学热扩渗 ,研究了扩渗前后材料的导电性能。根据材料的TG DTA测试结果确定了稀土扩渗的温度 ,经ICP分析测试表明 ,微量的Eu可渗入到试样中 ;利用四电极法和交流阻抗法对扩渗前后的材料分别进行了导电性能的测试 ,结果表明扩渗后试样的电导率比扩渗前的电导率提高了 4.0 7× 10 4 倍。分析电导率与温度的变化关系曲线 ,发现此材料在45 0K附近具有热敏特性 (PTC) ,为杂多化合物的应用增加了一个新方向。     

Nanocrystalline La2Mo2O9 and Its Characterization

In this work, both the thermal expansion and electrical conductivity of nanocrystalline La2Mo2O9 were studied.The nanocrystalline powder of La2Mo2O9 was obtained by sol-gel method, and with the help of SHP (superhigh pressure)up to 4.5 × 104 atm at 700 ℃ for a short time, and the nanocrystalline powder was densified without obvious particle size growth. The electrical conductivity of nanocrystalline La2Mo2O9 was one orderof magnitude lower than that of the microcrystalline sample at the same temperature. Owing to the phase transition, the microcrystalline La2Mo2O9 has an abrupt increase of thermal expansion with a peak value of 48 × 10-6 K-1 at 556 ℃. For the nanocrystalline material, the peak value increases to 112 × 10-6 K-1 at 520 ℃. On the other hand, above 600 ℃ the significant growth of particle size of the nanocrystalline La2Mo2O9 was observed, accompanying by a tremendous increase of thermal expansion with a peak value of third higher than that of La2Mo2O9.     

Crystal structure,thermal expansion and electrical conductivity of Pr（Ga1-xCox）0.9Mg0.1O3-δ （x=0, 0.1, 0.2, 0.3）

Pr（Ga1-xCox）0.9Mg0.1O3-δ （x=0, 0.1, 0.2, 0.3） was synthesized using solid-state reaction technique to study the effects of Co doping on their structure and properties. Room and high temperature XRD, DSC and electrical conductivity measurement with D.C. four-probe technique were adopted in the study. The results indicated its orthorhombic-distorted perovskite structure at room temperature. PrGa0.9Mg0.1O3-δ maintained its orthorhombic-distorted structure between 298 and 1173 K. For Pr（Ga0.7Co0.3）0.9Mg0.1O3-δ, such structure existed below 873 K. From 873 to 1173 K, it possessed tetragonal structure. The transformation from orthorhombic to tetragonal structure at 873 K was of second order. The intrinsic volume thermal expansion of tetragonal structured Pr（Ga0.7Co0.3）0.9Mg0.1O3-δ Was about 50% higher than those of PrGa0.9Mg0.1O3-δ. The electrical conductivity increased with Co content. The activation energies of conduction for Pr（Ga1-xCox）0.9Mg0.1O3-δ are in range from 0.197 to 0.246 eV, much lower than 1.543 eV for PrGaO3.     

Effects of the penetration temperature on structure and electrical conductivity of samarium modified BaTiO3 powders

Gaseous penetration technique was adopted to improve the electrical conductivity of BaTiO3 powders and the effects of penetration temperature on the structure and electrical conductivity of Sm-modified BaTiO3 powders were studied.It was observed that the penetration of Sm made the resistivity of BaTiO3 powders decrease with the increase in the penetration temperature and decreased to the lowest point of 4.20×102 ?·m when the penetration temperature was 950 oC.The relationship curve of the temperature and resistivity of the samples was also established preliminarily to get the mathematical expression by the fitting method.Through X-ray diffraction (XRD) analysis,the new phases of Sm2O3 and Ba4Ti2O27 were detected.It was indicated that intricate reactions related to Sm took place during the penetration process and led to the Ti-rich state of the system.The Fourier transform infrared (FTIR) spectrum illustrated that the bonds of Ti–O octahedron was strengthened by substitution of Sm3+ at Ti4+ sites,which led to the growth of Ti:Ba ratio.The analysis results of scanning electron microscopy (SEM) indicated that the particle size of Sm-modified BaTiO3 powders progressed with the penetration temperature increasing.     

Electrical Properties and Microwave Synthesis of Mixed Rare Earth Oxide Ln0.7Sr0.3-xCaxCo0.9Fe0.1O3-δ

In order to lower the raw materials cost and develop a novel cathode materials for intermediate temperature solid oxide fuel cell(ITSOFC), using mixed rare earth replacing the expensive pure La2O3 as the raw materials, the powders of Ln0.7Sr0.3-xCaxCo0.9Fe0.1O3-δ (Ln=the mixed rare earth, x=0.05, 0.10, 0.15) for the applications as the cathode materials were prepared by microwave sintering process. The crystal structure and the particles morphology of the obtained powders were characterized by XRD and SEM, the electrical conductivity of all samples sintered at 1200 ℃ for 3 h was also measured as the function of the temperature from 100 to 800 ℃ by DC four-probe method in air. The experimental results show that due to the influence of mixed rare earth the powders of Ln0.7Sr0.3-xCaxCo0.9Fe0.1O3-δ synthesized at 1200 ℃ for 0.5 h with the mean particle size of 1～20 μm was of perovskite and cubic fluorite phase as well a little SrO phase, the electrical conductivity of the samples decreases with the adding Ca2+ content, and are all higher than 100 S·cm-1 from 500 to 700 ℃ when x≤0.10. Ln0.7Sr0.3-xCaxCo0.9Fe0.1O3-δ. Can meet the demand of the electrical properties for the cathode materials in ITSOFC.     

Effect of rare earth addition on microstructural, mechanical and electrical characteristics of Cu-6%Fe microcomposites

Cu-6%Fe (mass fraction) microcomposites containing (0-0.30)% rare earth elements were prepared by cold drawing and intermediate heat treatments. Microstructure was observed, and mechanical properties and electrical conductivity were measured for alloys at various drawing strain levels. Adding rare earth elements could reduce the size of primary Fe and Cu dendrites of Cu-6%Fe. Ultimate tensile strength increased but electrical conductivity decreased with the increase of drawing strain. Rare earth additions in Cu-6%Fe slightly increased the strength at low strain and effectively improved the conductivity at high strain. Both strain hardening rate and conductivity loss of Cu-6%Fe containing rare earths were reduced at lower strain than Cu-6%Fe.     

Rare Earth Co-Permeation of K6HCoGeW11O40 and Its Conductivity

ＡｓａｋｉｎｄｏｆＨＰＣ (ｈｉｇｈｐｒｏｔｏｎｃｏｎｄｕｃ ｔｏｒ)ｍａｔｅｒｉａｌｓ ,ＰＯＭｓ (ｐｏｌｙｏｘｏｍｅｔａｌａｔｅｓ)ｈａｖｅｒｅｃｅｉｖｅｄｍｕｃｈａｔｔｅｎｔｉｏｎｒｅｃｅｎｔｌｙｆｏｒｉｔｓｈｉｇｈｅｒｐｒｏｔｏｎｃｏｎｄｕｃｔｉｖｉｔｉｅｓａｔｒｏｏｍｔｅｍｐｅｒａｔｕｒｅａｎｄｌｏｗｅｒａｃｔｉｖａｔｉｏｎｅｎｅｒｇｙ[1 ,2 ] .Ｈｏｗｅｖｅｒ ,ｔｈｅｐｒｏｐｅｒｔｙｏｆｌｏｓｉｎｇｗａｔｅｒｓａｔｍｏｄｅｒａｔｅｃｏｎｄｉｔｉｏｎ(ａｂｏｕｔ 6 0℃ )ｌｉｍｉｔｓｉｔｓａｐｐｌ…     

Temperature-Dependent Emission of Pr^3＋ -Doped LaB3O6 under Vacuum Ultraviolet Excitation

The vacuum ultraviolet （VUV） luminescent properties of Pr^3＋ -activated LaB3O6 were investigated with highenergetic synchrotron radiation from 20 to 300 K. In the emission spectra, the parity-forbidden 4f^2→4f^2 and parity-allowed 4f5d→4f^2 transitions were observed simultaneously. In addition, it was also observed that the intensity of 4f5d→4f^2 emission bands increased relative to the intensity of 4f^2→4f^2 emissions with increasing temperature. The thermal equilibrium model of energy levels was employed with respect to the lowest 4f5d state and ^1S0 state of LaB3O6：Pr^3＋ , as a result of which the fitted curve had a good agreement with the experiment values, which clarified the physical nature of temperature-dependent emission characteristics of Pr^3＋ in LaB3O6.     

HPHT synthesis and electrical transport properties of SmxCo4Sb12

Samarium-filled skutterudites SmxCo4Sb12(x=0.5,1.0) skutterudite thermoelectric(TE) materials with enhanced power factor were prepared by high-pressure and high-temperature(HPHT) technique.The microstructure properties were characterized with X-ray diffraction and scanning electron microscopy.The electrical resistivities and Seebeck coefficients of those samples were measured in the temperature range of 300-723 K,and the samples of SmxCo4Sb12 showed n-type conduction.The Seebeck coefficient in absolute valu...     

Conduction properties of condensed lanthanum phosphates:La(PO3)3 and LaP5O14

Single crystals of LaP3O9·3H2O were prepared using a classical method of aqueous chemistry whereas those of the ultraphosphate LaP5O14 were obtained by flux method.Thermal treatment of LaP3O9·3H2O up to 700 °C allowed us to obtain the lanthanum polyphosphate La(PO3)3.The conductivity as well as the vibrational study of the lanthanum ultraphosphate and polyphosphate were analysed in order to explain the mechanism of conduction.Activation energies of 0.45 and 0.84 eV,deduced from the Arrhenius relation,were respectively found for the polyphosphate and the ultraphosphate.Taking into account the structural features of these materials we linked the origin of their electrical properties to the incorporation of atmospheric humidity.Thus,it was a proton conduction phenomenon which took place as a result of the establishment of hydrogen bonds as well as the reorganisation of water molecules already incorporated into these structures.Referring to the Grotthuss mechanism,a proton transfer model inside the polyphosphate's structure was suggested.     

Al_2O_3弥散增强Cu基高导电率复合材料的制备及性能研究

采用高能球磨结合放电等离子烧结的方法制备0.5%、1.0%和2.0%的Al_2O_3弥散增强Cu基复合材料。研究Al_2O_3在Cu基体中的分布状态,以及对复合材料强度、硬度、导电性能和摩擦系数的影响。结果表明:弥散分布于晶界处的Al_2O_3颗粒导致复合材料的硬度和抗拉强度都提高,而伸长率、电导率降低和摩擦系数降低。1.0%Al_2O_3/Cu复合材料的相对密度达到98.22%、电导率为48.38 MS/m,硬度102.7 HV,抗拉强度264.97 MPa,摩擦系数0.28。     

Synthesis and luminescent properties of Pr-doped Lu3Al5O12 translucent ceramic

Lutetium aluminum garnet (LuAG) precursors doped with different Pr3+ concentration (0.25at.%, 0.5at.%, 1.0at.%, 3.0at.%, 5.0at.%) were synthesized via a co-precipitation method using ammonium hydrogen carbonate as precipitant. The phase evolution and mor-phology of the precursor were characterized with X-ray diffractometer (XRD) and transmission electron microscopy (TEM). The resultant LuAG:Pr3+ powder was sintered into translucent ceramic without any additives in vacuum at 1150℃ and then in nitrogen atmosphere at 1700℃. Photohiminescence spectra of LuAG:Pr3+ powder and ceramic were measured at room temperature in vacuum ultraviolet (VUV) and ultraviolet (VU) region. For the 5d-4f transition of Pr3+ ions, dominant emission of ceramic samples peaking round 311 nm had higher lumines-cence intensity. And the host absorption in ceramic samples was not as intensive as that in powder samples. The luminescent intensity of LuAG:Pr3+ varied with the Pr3+ contents and the quenching concentration was about 1.0at.% for ceramic and 3.0at.% for powder, which was much higher than 0.24at.% for LuAG:Pr3+ single crystals. This phenomenon showed that the ceramic had some superiority over single crystals.     

储氧材料CeO_2-ZrO_2-La_2O_3-Pr_6O_(11)的制备与表征

采用共沉淀法制备了稀土复合氧化物CeO2-ZrO2-La2O3-Pr6O11储氧材料,通过调节分散剂和表面活性剂浓度、改变工艺参数,得到了比表面积大和高温抗老化能力强的储氧材料,并对该材料进行表征。结果表明,该材料铈、锆、镧、镨的摩尔比约为40∶50∶5∶5;粒径分布D10=1.508μm,D50=3.348μm、D90=6.824μm,材料的新鲜比表面积和1 000℃老化4h后的比表面积分别达到了101.5m2/g和40.21m2/g,具有优异的抗高温老化能力。     

Influence of Pr on Magnetic Properties and Microstructure of Melt-Spun （ Nd1-x Prx ） 10.5 （FeCoZr） 83.5 B6 Alloy

Inrareearthsores ,praseodymiumoftencoexistswithneodymiumandtheabundanceofPrisaboutonethirdofNd .Becauseofextremeexcellentpermanentmagneticpropertiesoftherareearth transitionmetalin termetalliccompoundNd2 Fe14 B ,Ndhasbeenwidelyutilizedsincethe 1980s .Withtheexploitationofrareearthsores ,Prisexcessiveinmarketandcheapinpricebecauseofitsnarrowapplication .ItisfoundthatPr2 Fe14 BhasasimilarmagneticpropertieswithNd2 Fe14 B[1] andcancertainlybeusedaspermanentmagneticmateri al[2～ 4 ] .Therefor…     

Chemical synthesis and properties of La1.9Ba0.1MO1.9Mn0.1O9 as electrolyte for IT-SOFCs

The highly phase-pure electrolyte materials with compositionLa1.9Ba0.1MO1.9Mn0.1O9（LBMMO） was prepared by the sol-gel auto-combustion method for intermediate-temperature solid oxide fuel cells （IT-SOFCs）. The details ofgel＇s auto-combustion, phase evolution, sintering, thermal expansion and electrochemical performance of LBMMO were investigated by means of thermo-gravimetry （TG）, X-ray diffxaction （XRD）, scanning electron microscopy （SEM）, transmission electron spectroscopy （TEM）, thermal expansion curve （TEC） and complex impedance spectra. The results showed that the highly phase-pure electrolyte LBMMO could be obtained after calcining at 600 ℃. The sample sintered at 900 ℃ for 4 h in air exhibited a better sinterability, and the relative density of LBMMO was higher than 96%. The electrical conductivities of the sample were 6.7x 10-3 and 25.9× 10-3 S/cm at 700 and 800 ℃ in air, respectively. Results also showed that LBMMO had moderate thermal expansion （a=16.3×10-6 K-l, between room temperature and 800 ℃） and an electrical activation energy equal to 1.32 eV）.