Growth of Mixed Rare Earth Tartrate Crystals (Y(1-x)Sm_x)_2(C_4H_4O_6)_3·zH_2O from Silica Gels

Experiments performed on the grwth of mixed crystals of rare earth tartrates (Y1-xSmx)2 (C4H4O6)3.zH2O (0≤x≤1) from silica gels at 35~40℃ and 25~30℃ employing single-diffusion technique. are discussed. The crystals maintain spherulitic morphology, irrespective of the value of x, concentration of upper and lower reactants, gel pH, gel age and gel temperature. Formation Of Liesegang rings in this system is a temperature dependent phenomenon. It is shown that with the increase of the value of x the system passes from Liesegangring phenomenon to singlezone phenomenon. Operative mechanism of crystallization in the higher (35~40℃) and lower temperature ranges (25~30℃) is explained. Seeded growth experiments indicate the possibility of increasing the size of the spherulites in the gel medium     

Fabrication and optimization of La_(0.4)Sr_(0.6)Co_(0.2)Fe_(0.7)Nb_(0.1)O_(3-δ) electrode for symmetric solid oxide fuel cell with zirconia based electrolyte

La_(0.4)Sr_(0.6)Co_(0.2)Fe_(0.7)Nb_(0.1)O_(3-δ)(LSCFN)was applied as both anode and cathode for symmetrical solid oxide fuel cells(SSOFCs)with zirconia based electrolyte.The cell with LSCFN electrode was fabricated by tape-casting and screen printing.Fabrication process was optimized firstly by comparing co-sintering and separate-sintering of electrode and electrolyte.To further improve the LSCFN electrode properties,oxygen ionic conductor of Gd_(0.1)Ce_(0.9)O_(2-δ)(GDC)was added into the LSCFN electrode.The preferred composition of LSCFN-GDC composite electrode was found to be 1:1 in weight ratio with polarization resistance of 0.16Ωcm~2at 800~℃.The maximum power densities of LSCFN-GDC||GDC/YSZ/GDC||LSCFN-GDC tested in H_2and CH_4with 3%H_2O were 395 m W cm~(-2)and 124 m W cm~(-2)at 850~?C,respectively,which were much higher than that of LSCFN||GDC/YSZ/GDC||LSCFN cells at same condition,possibly due to the extension of the triple phase boundary induced by the addition of GDC.The cell showed reasonable stability using H_2and CH_4with 3%H_2O as fuels and no significant power output degradation was observed after total 200 h operation.     

Effect of Doping and High-Temperature Annealing on the Structural and Electrical Properties of Zn_(1-X)Ni_XO(0≤X≤0.15) Powders

This paper reported the synthesis,crystal structure and electrical conductivity properties of Ni-doped ZnO powders(i.e.Zn 1 X Ni X O binary system,X=0,0.0025,0.005,0.0075 and in the range 0.01≤X≤0.15).Iphase samples,which were indexed as single phase with a hexagonal(wurtzite) structure in the Zn 1 X Ni X O binary system,were determined by X-ray diffraction(XRD).The widest range of the I-phase was determined as 0≤X≤0.03 at 1200 C;above this range the mixed phase was observed.The impurity phase was determined as NiO when compared with standard XRD data,using the PDF program.We focused on single I-phase ZnO samples which were synthesized at 1200 C because of the widest range of solubility limit at this temperature.It was observed that the lattice parameters a and c of the I-phase decreased with Ni doping concentration.The morphology of the I-phase samples was analyzed with a scanning electron microscope.The electrical conductivity of the pure ZnO and single I-phase samples were studied by using the four-probe dc method at temperatures between 100 and 950 C in air atmosphere.The electrical conductivity values of pure ZnO and 3 mol% Ni-doped ZnO samples at 100 C were 2×10 6 and 4.8×10 6 1 ·cm 1,and at 950 C they were 1.8 and 3.6 1 ·cm 1,respectively.In other words,electrical conductivity increased with Ni doping concentration.     

Preparation and Characterization of Fe_3O_4 Magnetic Nano-particles by ~(60)Co Υ-ray Irradiation

By using a new method, 60CoΥ-ray irradiation, Fe3O4 magnetic nano-particles were successfully synthesized at room temperature under ambient pressure. The structure, morphology and magnetic properties of these nano-particles were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM), respectively. The radiation formation mechanism was also discussed. The results show that the absorbed dose can greatly influence the structure, morphology and magnetic properties of the products. XRD and TEM studies show that the product prepared byΥ-ray irradiation (10 kGy) is pure Fe3O4 phase and the mean diameter of these nano-particles is about 21 nm. The Fe3O4 nano-particles synthesized byΥ-ray irradiation (10 kGy) are mainly in small cubic shape and the size uniformity of these particles is good.     

Growth and Solvent Effects of a Promising Nonlinear Optical Sodium Paranitrophenolate Dihydrate (NO_2-C_H_4-ONa·2H_2O) Single Crystal

Sodium paranitrophenolate dihydrate (NPNa·2H2O) is an excellent semiorganic nonlinear optical (NLO) material, crystallizes both in water and methanol with high degree of transparency. Good optical quality single crystals of dimension upto 18 mm×6 mm×3 mm are obtained by isothermal solvent evaporation technique. The solubility of the crystal in different solvents was measured gravimetrically. The single crystals of NPNa·2H2O show variation in physical properties and growth rate in different solvents. Methanol or ethanol solution yields crystals of bipyramidal shape with clear morphology. However, methanol grown crystal is exhibiting improved hardness parameters and possesses excellent thermal stability as compared to water grown crystals. The effects of solvent on hardness parameter along with thermal and optical properties of NPNa·2H2O was revealed in this paper.     

Cobalt-free Composite Ba_(0.5)Sr_(0.5)Fe_(0.9)Ni_(0.1)O_(3-δ)-Ce_(0.8)Sm_(0.2)O_(2-δ) as Cathode for Intermediate-Temperature Solid Oxide Fuel Cell

New cobalt-free composites consisting of Ba0.5Sr0.5Fe0.9Ni0.1O3-δ(BSFN) and Ce0.8Sm0.2O2-δ(SDC) were investigated as possible cathode materials for intermediate-temperature solid oxide fuel cell (IT-SOFC). BSFN, which was synthesized by auto ignition process, was chemically compatible with SDC up to 1100℃ as indicated by X-ray diffraction analysis. The electrical conductivity of BSFN reached the maximum value of 57 S·cm-1 at 450℃. The thermal expansion coefficient (TEC) value of BSFN was 30.9×10-6K-1 , much higher than that of typical electrolytes. The electrochemical behavior of the composites was analyzed via electrochemical impedance spectroscopy with symmetrical cells BSFN-SDC/SDC/BSFN-SDC. The area specific interfacial polarization resistance (ASR) decreased with increasing SDC content of the composite. The area specific interfacial polarization resistance (ASR) at 700℃ is only 0.49, 0.34 and 0.31 Ω·cm2 when 30, 40, and 50 wt% SDC was cooperated to BSFN, respectively. These results suggest that BSFN-SDC is a possible candidate for IT-SOFC cathode.     

FAB MASS SPECTROMETRY OF THE PHENOLATEBRIDGED N_8O_3 SCHIFFBASE CRYPTANDS

<正> The fast atom bobardment mass spectra of phenolate-bridged N_8O_3 Schiff-2base cryptands derived from tris (2-aminoethyl) amine (tren) with 2, 6-dlformyl-4-R-phenol (Cryptand H_3L~1, R=OMe) H_3L~3, Br, and H_3L~4, Ph) in the presence of NaOH or KON in methanol at ambient temperature was investigaed and compared with IR, UV-Vis, ~1H and ~(13)H NMR. The characteristic spectra of the cryptates posseessing different proton form cryptands were discussed.     

Synthesis of La_(0.9)Sr_(0.1)Ga_(0.8)Mg_(0.2)O_(3-δ) Powder for Solid Oxide Fuel Cell by a Nitrate-Citrate Combustion Route

A nitrate-citrate combustion route to synthesize La0.9Sr0.1Ga0.8Mg0.2O3-σ powder for solid oxide fuel cell application was presented. This route is based on the gelling of nitrate solutions by the addition of citric acid and ammonium hydroxide, followed by an intense combustion process due to an exothermic redox reaction between nitrate and citrate ions. The optimum technical parameters are that the pH value is 5, and the molar ratio of citric acid to the total metallic ion is 1.5:1. X-ray diffraction characterization of calcined gel shows that pure phase was synthesized after calcination at 1400℃for 10 h, and the TEM result shovvs the calcined powder with average particle size is about 150 nm. The grain resistance contributes to the total resistance of sintered peliet below 500℃. The conductivity of the sintered peliet at 800℃ was 0.07 S-1·cm-1 higher than the conductivity of YSZ (0.05 S-1·cm-1 at 800℃)     

In-situ One-pot Preparation of LiFePO4/Carbon-Nanofibers Composites and Their Electrochemical Performance

A novel in-situ route was employed to synthesize LiFePO4/carbon-nanofibers (CNFs) composites. The route combined high-temperature solid phase reaction with chemical vapor deposition (CVD) using Fe2O3 and LiH2PO4 as the precursors for LiFePO4 growth and acetylene (C2H2) as the carbon source for CNFs growth. The composites were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) specific surface area, field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The electrochemical performance of the composites was studied by galvanostatic cycling and cyclic voltammetry (CV). The results showed that the in-situ CNFs growth could be realized by the catalytic effect of the Fe2O3 precursor. The sample after 80 min CVD reaction showed the best electrochemical performance, indicating a promising application in high-power Li-ion batteries.     

Thermal Stability of Amorphous Hydride Mg_(50)Ni_(50)H_(54) and Mg_(30)Ni_(70)H_(45)

The thermal stability of amorphous ternary hydrides Mg_(50)Ni_(50)H_(54) and Mg_(30)Ni_(70)H_(45) and their corre-sponding amorphous binary alloys Mg_(50)Ni_(50) and Mg_(30)Ni_(70) were studied with X-ray diffraction(XRD) and differential scanning calorimetry(DSC). Samples of the amorphous alloys were preparedby mechanical alloying and the amorphous hydrides were obtained by charging the alloys with gas-eous hydrogen at 3.0 MPa and 423 K. It was found that the amorphous hydrides released most oftheir hydrogen before the crystallization of the essentially hydrogen depleted amorphous alloy. Thecrystallization temperature of amorphous Mg_(50)Ni_(50)H_(54) elevated and that of amorphousMg_(30)Ni_(70)H_(45) did not change in relation to the original binary amorphous alloy. This is very excep-tional for amorphous hydrides. The reason for the effects of hydrogen absorption/desorption on thecrystallization of amorphous alloys was discussed.     

Sintering Behavior and Microwave Dielectric Properties of MgTiO3 Ceramics Doped with B2O3 by Sol-Gel Method

The B2O3-doped MgTiO3 powders and ceramics have been prepared by sol-gel method using Mg(NO3)2·6H2O, Ti(C4H9O)4 and H3BO3 as the starting materials. The sintering behavior and microwave dielectric properties of ceramics prepared from powders with different particle sizes were investigated. The gels were calcined at 650, 700, 750, 800, 850 and 900 C and the derived particle sizes of powders were 20-30 nm, 30-40 nm, 40-60 nm, 60-90 nm, 90-120 nm and 120-150 nm, respectively. The nanoparticles with the size of 30-60 nm benefited the sintering process with high surface energy whereas nanoparticles with the size of 20-30 nm damaged the microwave dielectric properties due to the pores in the ceramics. The addition of B2O3 used as a liquid sintering aid reduced the sintering temperature of MgTiO3 ceramic, which was supposed to enter the MgTiO3 lattice and resulted in the formation of (MgTi)2(BO3)O phase. The B2O3-doped MgTiO3 ceramic sintered at 1100 C and prepared from the nanoparticles of 40-60 nm had compact structure and exhibited good microwave dielectric properties: εr=17.63, Q × f=33,768 GHz and τ f= 48×10 6 C 1.     

Growth, Optical, Mechanical, Dielectric and Theoretical Studies on Potassium Pentaborate Tetrahydrate (KB_5O_8·4H_2O) Single Crystal by Modified Sankaranarayanan-Ramasamy Method

A nonlinear optical single crystal of potassium pentaborate tetrahydrate (KB5O8·4H2O) has been grown from aqueous solution by using unidirectional crystal growth method of Sankaranarayanan-Ramasamy (SR) with a due modification in the growth assembly. Potassium pentaborate crystal of 60 mm length and 10 mm diameter has been grown along (100) plane with a growth rate of 3 mm per day within a period of 20 days. The grown crystal was subjected to single crystal X-ray diffraction analysis to confirm that the cry...     

Effect of (Ba0.6Sr0.4)TiO3（BST） Doping on Dielectric Properties of CaCu3Ti4O12（CCTO）

The effect of (Ba(0.6)Sr(0.4))TiO3(BST) addition on dielectric properties of CaCu3Ti4O(12) (CCTO) ceramic was investigated. Ceramic samples with the chemical formula (1-x)CaCu3Ti4O(12) + x(Ba(0.6),Sr(0.4))TiO3 (x=0, 0.05, 0.1, and 0.2) were synthesized from high purity oxide powders by the conventional solid-state synthesis method. X-ray diffraction (XRD) analysis showed the existence of BST as a secondary phase alongside CCTO. Scanning electron microscopy (SEM) investigation showed a slight decrease in grain size of doped CCTO samples. Density measurements showed that porosity content increased with increasing BST addition indicating low densification due to high melting point secondary phase addition. Dielectric constant of undoped CCTO (x=0) showed lack of stability with frequency which dropped drastically between 104 and 105Hz and accompanied by high dielectric loss. Addition of BST into CCTO caused the dielectric constant to slightly decrease but improved stability with frequency compared to the undoped sample. The decrease in dielectric constant of doped CCTO samples was suggested to be partly due to the decrease in average grain size and increase in porosity with BST addition. Nevertheless, a high value of dielectric constant was still maintained around ～104 range for all doped samples. The dielectric loss (tanδ) of all BST-doped samples was lower than that of pure CCTO sample at the frequency range of 103 to 105 Hz probably due to the increase of grains boundary resistivity. The activation energy of grains boundary (E(gb)) showed higher values as compared to the activation energy of grains (Eg ) for all samples and conforms to the internal barrier layer capacitor (IBLC) model.     

GAS-PHASE ION-MOLECULAR REACTION OF HEXANUCLEAR RUTHENIUM CARBONYL COMPOUND WITH TRIPHENYL-PHOSPHINE

<正> Hexanuclear ruthenium cluster compound Ru_6C (CO)_(17) has interesting activity in the gase-phase. The ion-molecular reaction of Ru_6C (CO)_(17) with triphcnylphosphine was investigated by EI-MS. The experimental results showed that Ru_6C (CO)_(17) could undergo the ligand substitution by PPh_2 or PPh_3 to initially yield monosubstituted product [Ru_6C(CO)_(16)PPh_2]~+ or [Ru_6C (CO)_(16)PPh_3]~+.     

Synthesis of Macroscopic Zr（C6H5PO3）2 Tubes

A new method of infiltration-diffusion is used to synthesize macroscopic α-Zr（C6H5PO3）2 （α-ZrBP） tube. Compared to the routine method, no HF was used and a fiberlike product with several millimeters in length was obtained. SEM （scanning electronic microscopy） result indicates that these fibers are tubes. The wall of the tubes is composed of the flake of α-ZrBP overlapped with each other. As we know, it is the first report on the synthesis of millimeter-scale supramolecular assembly of α-ZrBP.     

Cu_3V_2O_7(OH)_2·2H_2O纳米线的制备及其电化学性能

以CuSO4.5H2O和NH4VO3为原料,采用水热法制备了Cu3V2O7(OH)2.2H2O纳米线。利用XRD、FE-SEM、TEM和HRTEM对样品的结构和表面形貌进行了表征,并对其作为锂电池正极材料的电化学行为进行了研究。电化学性能测试表明,Cu3V2O7(OH)2.2H2O纳米线电极具有较高的开路电压和较大的放电容量。     

Synthesis,Crystal Structural and Electrical Conductivity Properties of Fe-Doped Zinc Oxide Powders at High Temperatures

The synthesis,crystal structure and electrical conductivity properties of Fe-doped ZnO powders(in the range of 0.25-15 mol%) were reported in this paper.I-phase samples,which were indexed as single phase with a hexagonal(wurtzite) structure in the Fe-doped ZnO binary system,were determined by X-ray diffraction(XRD).The solubility limit of Fe in the ZnO lattice is 3 mol% at 950℃.The above mixed phase was observed.And the impurity phase was determined as the cubic-ZnFe 2 O 4 phase when compared with standard XRD data using the PDF program.This study focused on single I-phase ZnO samples which were synthesized at 950℃ because the limit of the solubility range is the widest at this temperature.The lattice parameters a and c of the I-phase decreased with Fe-doping concentration.The morphology of the I-phase samples was analyzed with a scanning electron microscope.The grain size of the I-phase samples increased with heat treatment and doping concentration.The electrical conductivity of the pure ZnO and single I-phase samples was investigated using the four-probe dc method at 100-950℃ in air atmosphere.The electrical conductivity values of pure ZnO,0.25 and 3 mol% Fe-doped ZnO samples at 100℃ were 2×10-6,1.7×10-3 and 6.3×10-4 S.cm-1,and at 950℃ they were 3.4,8.5 and 4 S.cm-1,respectively.     

Cu_3V_2O_7(OH)_2·2H_2O纳米片的制备及其在锂电池中的应用

以CuSO4.5H2O和NH4VO3为原料,采用沉淀法制备了Cu3V2O7(OH)2.2H2O纳米片。利用XRD、FE-SEM、TG对样品的结构和形貌进行了表征,并对其作为锂电池正极材料的电化学行为进行了研究。电化学性能测试表明:Cu3V2O7(OH)2.2H2O纳米片具有较高的放电容量和良好的高温放电性能,是一类性能优良的锂电池正极材料。     

Influence of Nb5+ Doping on Structure and Electrochemical Properties of Spinel Li1.02Mn2O4

The Li1.02NbxMn2-xO4 (x=0,0.005,0.01,0.02,0.04 and 0.1) materials were prepared by solid-state reaction method in which Li2CO3 , electrolytic MnO2 and Nb2O5 were used as reactants. The influences of the Nb5+ doping on structure, morphology and electrochemical performance were systemically investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV) and AC impedance. XRD test showed that the prepared samples had single spinel structure although there was impurity phase of LiNbO3 existing in Li1.02NbxMn2-xO4 phase after Nb5+ doping. The doped materials with Nb5+ had smaller lattice parameters and crystal volume compared with pristine Li1.02Mn2O4. The endurance of overcharge was largely improved. In addition, the small amount of Nb5+ doping could increase the material conductivity.     

Effect of Si3N4 Addition on the Mechanical Properties, Microstructures, and Wear Resistance of Ti-6Al-4V Alloy

In order to improve the wear resistance of Ti-6Al-4V, different amounts of Si3N4 powder were added into the alloy powder and sintered at 1250℃. Porous titanium alloy with higher wear resistance was successfully fabricated. At sintering temperature, reaction took place and a new hard phase of Ti5Si3 formed. The mechanical properties of the fabricated alloys with different amounts of Si3N4 addition were investigated. The hardness of Ti-6Al-4V, which is the index of wear resistance, was increased by the addition of Si3N4. Amounts of Si3N4 addition have very significant influences on hardness and compressive strength. In present study,titanium alloy with 5 wt pct Si3N4 addition has 62% microhardness and 45% overall bulk hardness increase,respectively. In contrast, it has a 16.4% strength reduction. Wear resistance was evaluated by the weight loss during wear test. A new phase of Ti5Si3 was detected by electron probe microanalyzer （EPMA） and X-ray diffraction （XRD） method. The original Si3N4 decomposed during sintering and transformed into titanium silicide. Porous structure was achieved due to the sintering reaction.