Crystal growth,structure and properties of bismuth triborate BiB3O6 crystal

BiB3O6(BIBO) single crystals with size of 46×23×10 mm3 and weight of 26.0 g have been successfully grown by top-seeded method. Problems encountered in the growth process of this crystal have been discussed in detail, and the methods of growing high-quality large crystals have been put forward. The relationship between their structure and properties is studied. The space group of monoclinic BiB3O6 is C2 and the cell parameters are a = 7.1203(7)(?), b = 4.9948(7)(?), c = 6.5077(7) (?), β= 105.586(8)", and V = 222.93(5)(?)3. The density of BIBO is4.8965 g/cm3. The Mohs's scale of hardness is 5.5-6. There is no cleavage face in the crystal. The transmittance of BIBO is about 80 percent in the range from visible coherent light to near-infrared light. The ultraviolet cutoff wavelength is at 276 nm. BiB3O6 is a biaxial crystal and has two sets of axes, and the relative orientation of ( X, Y, Z) with regard to (a, b, c) is: X//b, ( Y, c) =47.2°, (Z, a) = 31.6°, determined by X-ray analysis combined with pol     

SYNTHESIS AND X-RAY POWDER DIFFRACTION DATA OF A NEW COMPOUND:K_6FeNb_(15)O_(42)

A new compound K_6FeNb_(15)O_(42) was prepared for the first time by solid state reaction in K_2O Fe_2O_3-Nb_2O_5 ternary system. The X-ray powder diffraction data of the title compound was measured. K_6FeNb_(15) O_(42) crystallizes in the hexagonal system with unit cell parameters a=9.1320(4)(?),c=12.0670(9)(?), and space group P63/mcm(193), z=1. The calculated and mea sured densities are 4.489 g/cm~3 and 4.485 g.cm~3, respec tively.     

Oxygen adatoms and vacancies on the(110) surface of CeO_2

The behavior of oxygen on ceria surfaces is closely related with the applications of ceria as a catalyst and oxygen conductor in solid-oxide fuel cells. Here, the atomic configurations of oxygen adatoms and vacancies on the(110) surface of CeO_2 have been studied combining aberration-corrected transmission electron microscopy and first-principles calculations. The oxygen adatoms were estimated to be located on top of Ce atoms with 50% coverage, forming a c(2×2) reconstruction. The oxygen vacancies can form stable configuration, with the Ce atoms partly reduced.     

SYNTHESIS AND CHARACTERIZATION OF A NEW NIOBATE: Sr6Ti7Nb9O42

A new niobate Sr_6Ti_7Nb_9O_(42) was synthesized for the first time by solid state reaction in SrO-TiO_2Nb_2O_5 ternary system. The new compound was characterized by EPMA, XRD, SEM and DTA. The X-ray owder diffraction data of Sr_6Ti_7Nb_9O_(42) were firstly reported in the paper. Sr_6Ti_7Nb_9O_(42) crystallizes the hexagonal system with unit cell parameters a=8.9991(4)(?), c=11.5118(9)(?), and space group P6_3/mcm(193), z=1. The calculated and measured densities are 4.783 g/cm~3 and 4.764 g/cm~3, respectively.     

STRENGTH EFFECT OF F MINERAL ADMIXTURE ON CEMENT CONCRETE

F mineral admixture (FMA) is made of the fin-ely divided powder of natural zeolite with a bitof other agent. When FMA is used to displace about10% (by weight) of the ordinary portland cement(OPC) (strength grade 575#) in concrete and mixedwith a suitable amount of super plasticizer (w/c=0.31-0.35), then a high-strength concrete withcompressive strength about 80 MPa and slump about180 MM can be obtained. The strength of thisconcrete is about 10-15% higher than that of thecorresponding concrete mixing with pure OPC, andits bleeding decreases greatly. It makes no segre-gation and separation, and thus it satisfies therequirement of pumping concrete in construction.     

The fabrication and optimization of OTFT formaldehyde sensors based on Poly(3-hexythiophene)/ZnO composite films

Formaldehyde(HCHO),a colorless and pungent-smelling gas,is confirmed be a huge threat to human health.The detection of formaldehyde is necessary and important.The Poly(3-hexythiophene)(P3HT)/ZnO organic-inorganic composite thin film was fabricated and used as the sensitive layer of organic thin film transistors(OTFT) by spray-deposited method to detect HCHO at room temperature.The process parameters such as P3HT/ZnO weight ratios and airbrushed masses were optimized.The results showed that P3HT/ZnO OTFT exhibited good sensing response to HCHO.Airbrushed mass of 1ml was the optimal mass,and the 1:1 and 1:5 weight ratios of P3HT/ZnO exhibited better sensing properties compared with others.OTFT gas sensors based on P3HT/ZnO composite film provides a novel promising approach to the detection of HCHO.     

Effects of Rare Earth Pr/Ce on Tribological Behavior of ADC12 Alloy

The microstructure and microhardness of ADC12 alloy that was mixed with 0,0.3,0.6,and 0.9 wt.% rare earth praseodymium/cerium (Pr/Ce) were studied.The addition of Pr/Ce improved the microhardness of the alloys.The ADC12+0.6 wt% Pr/Ce alloy displayed the smallest grain size and maximal microhardness.The tribological behavior of the alloys was tested by the pin-on-disc dry sliding friction pair with a sliding velocity of 0.21 m/s under various loads (20,40,60,80 N).The wear morphology was observed by a scanning electron microscope (SEM) and the wear mechanism was discussed.The result indicated that the wear resistance of ADC12+0.6 wt% Pr/Ce alloy was the most optimal.The wear rate relative to the matrix is reduced by 67.5% under a load of 20 N.The wear mechanism is adhesive wear.     

Preparation of natural brucite nanofibers by the dispersion method

The preparation of natural brucite nanofibers through dispersion by the wet process is described. The test results indicate that brucite fibers can be well dispersed by using sodium dioctyl sulfosuccinate (OT) as the dispersant at a dispersant/fiber mass ratio of 0.15:1, dispersing for 30 min at a water/solid mass ratio of 20:1. The prepared nanofibers were characterized with X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM). It is shown that the prepared single brucite nanofiber is around 30 nm in diameter and the talus of the nonsingle brucite nanofibers is about 50-150 nm in diameter. Natural brucite mineral fibers were treated by the dispersion method to obtain nanomaterials. These fibers have significant advantages over artificial nanofibers both in yield and in cost.     

Synthesis and Properties of a One-Dimensional Mixed-Ligand Cd(Ⅱ) Complex with Helical Structure

The title complex,[[Cd(Him)(OH-BDC)(H2O)2]·3H2O]n(1) (Him is imidazole,OH-H2BDC is 5-hydroxyisophthalic acid),was synthesized by liquid/liquid diffusion method at room temperature.The complex crystallizes in orthorhombie,space group P212121,with a = 0.671 6(7),b = 1.380 6(2),c =1.7421(2) nm,V = 1.615 2 (3) nm3,C11 H18 CdN2O10,Mr = 450.67,Dc = 1.853 g/cm3,μ =1.407 mm-1,F(000) = 904,Z = 4,the final R1 = 0.020 9 and wR 2 = 0.045 3 for 3 211 observed reflections (Ⅰ＞ 2σ (Ⅰ)).In the structure of 1,the OH-BDC ligands exhibiting bis-bidentate coordimtion mode bridge the adjacent Cd centers to form a one-dimensional helical chain and the second ligand Him acting as terminal ligands are attached to the helical chain.It is notable that a series of complicated hydrogen bonds (e.g.,N-H ...O,O-H...O) exist in the structure,which link neighboring helices into a three-dimensional supramolecular architecture.An observed intense blue luminescence with an emission band peaking at 390 nm for 1 may be resulted from ligand-to-metal charge transfer (LMCT).     

Influence of Cement Types and Mineral Admixtures on Resistance of Mortar to Sulfate Attack under Lower Temperature

Mortar prisms made with different cements or mineral admixtures plus 30% mass of limes tone filler were stored in 2% magnesium sulfate solution at 5±1 ℃ for 1 year and their visual appearance,strength development were measured at intervals.The formation of thaumasite was checked and confirmed by XRD and FTIR.The results show that the relative resistance to thaumasite form of sulfate attack of the cements is outlined below,from best to worst:sulphoaluminate cement,sulfate resisting Portland cement,OPC.The resistance to thaumasite form of sulfate attack of mortar is remarkably improved by the addition of silica fume or ground granulated blastfurnace slag (SL),and the better the resistance to thaumasite form of sulfate attack,the more the addition of SL is.The thaumasite form of sulfate attack is decreased to a certain degree by a lower replacement of cement with fly ash,but it is accelerated by the addition of a higher amount of fly ash due to its lower reactivity.     

Room temperature gas sensor based on tube-like hydroxyapatite modified with gold nanoparticles

The main goal of this work is to explore the possibility of using Au-modified hydroxyapatite(HA) as a potential sensor material. Tube-like HA structure was fabricated with the aid of a Nafion N-117 cation exchange membrane and gold(Au) nanoparticles were added by a hydrothermal method. The morphology, structure and composition were characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD), and X-ray photoelectron spectroscopy(XPS). The gas sensing properties were also investigated. Results show that Au nanoparticles are dispersed into the HA powder, which is tube-like, with rough inner and outer surfaces. Compared with pure HA, Au-modified HA exhibits improved sensing properties for NH_3. 5%(mass fraction) Au-modified HA shows the highest response with relatively short response/recovery time. The response is up to 79.2% when the corresponding sensor is exposed to 200×10~(-6) NH_3 at room temperature, and the response time and recovery time are 20 s and 25 s, respectively. For lower concentration, like 50×10~(-6), the response is still up to 70.8%. Good selectivity and repeatability are also observed. The sensing mechanism of high response and selectivity for NH_3 gas was also discussed. These results suggest that Au-HA composite is a promising material for NH_3 sensors operating at room temperature.     

Preparation and Property of Bisphenol A Bis （diphenyl phosphate） Oligomer

Bisphenol A bis(diphenyl phosphate)oligomer(BDP)is prepared successfully from the reactants consisting of phosphorus oxychloride(POCl3),bisphenol A and phenol with a Friedel-Crafts catalyst.The resultant products were examined with thermo-gravimetric analysis(TGA)and high performance liquid chromatography(HPLC).Thermogravimetry data shows that BDP decomposes at 375 ℃ when 5% weight lost.Experiments results show that catalyst is preferably AlCl3 and the amount of it is preferably 1% relative to bisphenol A by mole.POCl3/bisphenol A mole ratio is preferably about 5∶1 to 6∶1.Experiments unclosed that a seal apparatus is very important to the properties of product.     

Synthesis and Dielectric Properties of New Niobate BiTi3Nb7O30

A new niobate Ba5 BiTi3Nb7O30 was synthesized by the solid-state reaction. It was characterized by X-ray diffraction and dielectric constant measurements. The results show that Ba5BiTi3Nb7O30 is paraelectric at room temperature and belongs to tetragonal 4/ mmm symmetry with unit cell parameters a = 1.25020 nm, c =0.39704 nm. Ba5BiTi3Nb7O30 has only one phase transition, paraelectric to ferroelectric, below 0℃.     

INITIAL BINDING CAPACTIES OF CHLORIDE ION OF COMPONENTS IN HIGH-PERFORMANCE CONCRETE

An investigation is reported on the influence of different components of high performance concrete (HPC) on the initial binding capacities (IBC) of chloride ion. The testing results demonstrate that cement has the largest IBC, and the relative binding ratio is as high as 30% of total ion amount. Among the mineral admixtures, fly ash has the largest IBC of chloride ion. The IBC of silica fume is about 14.4% ,which is smaller than that of fly ash. The IBC of refined ground blast-furnace slag (microslag) is abnormal due to the influence of sulfate ion contained. The addition of superplasticizer and corrosion inhibitor containing calcium nitrite weakens the IBC of mixtures. The fluidity and pore-filling effect of mineral admixtures are studied with paste samples with W/C ratio of 0.3. The influence mechanism of various components in high-performance concrete in IBC is studied further through SEM and Mercury Instrusion Porosimetry tests with paste samples at the age of 3 days.     

Electrogenerative leaching of nickel sulfide concentrate with ferric chloride

In order to utilize the chemical energy in hydrometallurgical process of sulfide minerals reasonably and to simplify the purifying process, the electrogenerative process was applied and a dual cell system was introduced to investigate FeCl3 leaching of nickel sulfide concentrate. Some factors influencing the electrogenerative leaching, such as electrode structure, temperature and solution concentration were studied. The results show that a certain quantity of electrical energy accompanied with the leached products can be acquired in the electrogenerative leaching process.The output current and power increase with the addition of acetylene black to the electrode. Varying the components of electrode just affects the polarization degree of anode. Increasing FeCl3 concentration results in a sharp increase in the output of the leaching cell when c(FeCl3) is less than 0.1mol/L. The optimum value of NaCl concentration for electrogenerative leaching nickel sulfide concentrate with FeCl3 is 3.0 mol/L. Temperature influences electrogeneratire leaching by affecting anodic and cathodic polarization simultaneously. The apparent activation energy is determined to be 34.63 kJ/mol in the range of 298 K to 322 K. The leaching rate of Ni^2 is 29.3% after FeCl3 electrogenerative leaching of nickel sulfide concentrate for 620 min with a filter bag electrode.     

Electronic structures and physical properties of pure aluminum metal

By one-atom theory, the electronic structure of pure Al metal with f.c.c, structure has been determined to be [Ne](3s_c)~(1.8790)(3p_c)~(0.4982)(3s_f 3p_f)~(0.6228). According to this electronic structure, the potential curve, lattice constant, cohesive energy, elastisity, and the temperature dependence of the linear thermal expansion coefficients have been calculated. The electronic structures and characteristic properties of Al metals with b. c. c., h.c.p. structures and liquid have been studied. It is argued that the pure Al metal with f. c.c. structure can exist naturally, but with b. c. c.and h. c.p. structures cannot.##属性不符     

Microstructural evolution in a powder metallurgical Ti-7Mo alloy with continuous oxygen gradient

A titanium alloy containing continuous oxygen gradient was prepared by powder metallurgy(P/M) and the composition–property relationship was studied on a single sample. The alloy was sintered with layered powder of different oxygen contents via vacuum sintering and spark plasma sintering(SPS), respectively. After subsequent heat treatments, high-throughput characterizations of the microstructures and mechanical properties by localized measurements were conducted. The Ti-7% Mo(molar fraction) alloy with an oxygen content ranging from 1.3×10~(-3) to 6.2×10~(-5)(mass fraction) was obtained, and the effects of oxygen on the microstructural evolution and mechanical properties were studied. The results show that SPS is an effective way for fabricating fully dense Ti alloy with a compositional gradient. The average width of α′ phase coarsens with the increase of the content of oxygen. The content of α″ martensitic phase also increases with the content of oxygen. At oxygen contents of 3×10~(-3) and 4×10~(-3)(mass fraction), the Ti alloys present the lowest microhardness and the lowest elastic modulus, respectively. The results also indicate that the martensitic phases actually decrease the hardness of Ti-7Mo alloy, and oxygen effectively hardens the alloy by solid solution strengthening. Therefore, the high-throughput characterization on a microstructure with a gradient content of oxygen is an effective method for rapidly evaluating the composition–property relationship of titanium alloys.     

Structure and Chemical Bond of Thermoelectric Ce-Co-Sb Skutterudites

The correlations among composition, structure, chemical bond and thermoelectric property of skutterudites CoSb3 and CeCo5Fe3Sb12 have been studied by using density function and discrete variation (DFT-DVM) method. Three models for this study were proposed and calculated by which the "rattling" pattern was described. Model 1 is with Ce in the center, model 2 is with Ce away the center and near to Sb, and model 3 is also with Ce away the center but near to Fe. The calculated results show that in model 3, the ionic bond is the strongest, but the covalent bond is the weakest. Due to the different changes between ionic and covalent bond, there is less difference in the stability among the models 1, 2 and 3. Therefore, these different models can exist at the same time, or can translate from one to another more easily. In other words, the "rattling" pattern has taken place. Unfilled model of CoSb3, without Ce and Fe, is called model 4. The covalent bond of Co-Sb or Fe-Sb in models 1, 2 and 3 is weaker than that of     

Fabrication of Porous Polycaprolactone/Carboxymethylcellulose Scaffolds by using Salt Leaching Technique

The purpose of this work was to fabricate three-dimensional porous scaffolds by using the salt leaching technique. This technique is simple and it does not need the pressure or dislike expensive equipment.The study selected polycaprolactone blended with carboxymethylcellulose that is the additive. The ratios of them were derived from mixture design in Minitab program that was 98/2(P1), 93.5/6.5(P2), 89/11(P3),84.5/15.5(P4), and 80/20(P5), respectively. The scanning electron microscopy(SEM) was a...     

Preparation, Characterization and Dielectric Property of Sr5 LaTi3 Nb7O30 Ceramic

Sr5LaTi3Nb7O30 ceramic was prepared by the conventional high temperature solid-state reaction route. The sintered samples were characterized by X-ray diffraction, scanning electron microscopy ( SEM ), differential thermal calorimetry ( DSC ) and dielectric measurements. The results show Sr5LaTi3Nb7O30 belongs to paraclectric phase of filled tetrngonal TB structure at room temperature, and undergoes a diffuse phase transition in the temperature range of -54-34℃ . And Sr5LaTi3Nb7O30 ceramic shows a high dielectric constant of 479 with a low dielectric loss of 0.005 at 1MHz . In comparison with Ba-based ceramics with TB structure, the temperature coefficients of the dielectric constant ( τt ) is significantly reduced.