Effects of La(NO_3)_3 Treatment on Photocattalytic Activity of TiO_2 Films Prepared by Micro-Arc Oxidation

Effects of La(NO_3)_3 Treatment on Photocattalytic Activity of TiO_2 Films Prepared by Micro-Arc Oxidation     

Synthesis and Characterization of Mesoporous Europium (Ⅲ) Silicate Molecular Sieves

The luminescent nanosized Eu-MCM (1:10) was synthesized by means of sol-gel-assisted self-assembly under basic conditions at room temperature. The results of 29Si-MAS NMR show that the peaks are Q4, Q3, Q2 [(SiO)4-mSi-(OH)m (m=0, 1, 2), at -δ111, -δ103, -δ90], and q3, q2, q1, q0 [(SiO)4-nSi-(O-Eu)n (n=1, 2, 3, 4 ), at -δ83, -δ72, -δ55, -δ47]. The result proves Eu3 doped Si-O framework. The HRTEM image shows that the regular uniform nanoparticles with a diameter of 15 nm possess large pore with Φ8 nm, which is consistent with the result of N2 adsorption. The patterns of selected-area electron diffraction, XRD, and pore-size distribution plot of Eu-MCM (1:10) show that the sample of Eu-MCM (1:10) possesses the both of crystal and amorphous phases. The FT IR results indicate that the peaks near 970 cm-1 are assigned to the deformation vibration of silanol group. The as-product was calcined at 800 ℃ and the mesoporous material possesses enormous specific areas and large pores, which shows that the mesoporous material is ultrastable.     

Characterization of (Y,Gd) BxV1-xO4-x:Eu Phosphor Prepared by Coprecipitation Reaction

White body-color (Y, Gd)BxV1- xO4-x :Eu3 phosphors were prepared by coprecipitation reaction. Under VUV excitation at 147 nm, the red emission colorimetric purity of (Y, Gd)BxV1- xO4-x :Eu3 phosphor is much better than that of commercial PDP (plasma display panels) phosphor (Y, Gd)BO3:Eu3 . But its relative emission intensity is only about 90% of the commercial phosphor.     

Y2O3和La2O3对金属陶瓷内衬显微硬度和耐蚀性的影响

研究了钇、镧等添加物对金属陶瓷内衬显微硬度和耐蚀性的影响。结果表明:加入Y2O3、L a2O3和S iO2可使陶瓷层的孔隙度降低,一定程度上使耐蚀性增加。L a2O3对提高陶瓷层性能的效果比Y2O3要好。     

Effect of Ce^＋ Ion Implantation upon Oxidation Resistance of Superalloy K38G

The addition of small quantities of reactive ele ments (RE) or other elements with high oxygen affini ty, usually in the order of 0 1%~0 2% mass frac tion, will result in a beneficial effect on the oxidationresistance to superalloys[1~4].A number of mechanisms have been proposed toexplain the beneficial effect of RE additions on theCr2O3 forming alloys, including physical blocking byRE ions or second phase particles at grain boundaries,pegging effect between the oxide and the …     

Effects of Rare Earth Oxide on Viscosity of Mold Fluxes for Continuous Casting

The effects of RE (rare earth) oxide on viscosity of mold fluxes were investigated with a rotary viscometer. The results show that : (1) The viscositv of mold fluxes is remarkably inereased by RE oxide addition, especially when the mass fraction of RE oxide is more than 10%. (2) By addition of RE oxide, precipitation of the insohlble particles with high melting point from the molten slag with the decreasing of the temperature leads to the inerease of viscosity. Viscosity curve shows that RE oxide is soluble in some extent in mold fluxes. When RE oxide is in a state of supersaturation, the existence of insoluble particles also makes the viscosity of mold fluxes increase. (3) Not only the viscositv of nlold fluxes can be reduced, but also the capacity to dissolve and absorb RE oxide can be increased by Li2O, B2O3 and BaO. However, the contents of Li2O, B2O3, and BaO should be controlled to suitable levels. (4) The solidification temperature of mold fluxes can be increased by the addition of RE oxide, which is unfavorable to heat transfer and luhrication of mold fluxes between steel shell and mold.     

Low Temperature Phase Transition Behavior of Ca-Doped Lanthanum Chromites

Phase transition of LaCrO3 and doped-LaCrO3 was studied by DSC, TG and XRD, and thermal expansion during the transition was analyzed. It is found that phase transition of LaCrO3 begins at about 240℃ and ends at about 265 ℃. Temperatures of phase transition rise obviously with increasing Ca^2＋ content. The transition of LaCrO3 and Ca-doped LaCrO3 from orthorhombic to rhombohedral is accompanied with endothermic reaction. No obvious change occurs in mass, but remarkable shrinkage occurs during phase transition.     

Research on Poly （Styrene-Crylicacid）-Suported Neodymium Complex Catalytic Copolymerization of Styrene and 4-Vinylpyridine

Research on Poly(Styrene-Crylicacid)-Suported Neodymium Complex Catalytic Copolymerization of Styrene and 4-Vinylpyridine     

Existing State and Partitioning of Rare Earth on Weathered Ores

The existing state and partitioning of rare earth （RE） on weathered ores in Longnan County（LN）, Xingfeng County（XF） and Ninghua County（NH） were characterized systematically by standard geological analytical methods. It is found that RE in the weathered rare earth ores exist as four phases： （a） water soluble, （b） ion-exchangeable, （c） colloidal sediment （oxides）, （d） minerals, in which mainly as ion exchangeable phase, accounting for nearly 80% of total RE, with about 20% in the form of colloid sediment phase and mineral phase, but very little as aqueous soluble phase. These rare earth partitioning were mainly chosen mid-heavy RE elements, occupying above 60%, but not equal in the four phases. The mid-heavy RE elements were primarily enriched in the ion exchangeable phase up to 40%, while the containment of cerium dioxide is below 2 %. The cerium deficiency occurs in the ion exchangeable phase in weathered ore. It results from that the Ce^3＋ is oxidized into Ce^4＋ and changes into CeO2. For LN ore, the containment of Y is high in weathered ore because Y-minerals are abundant in original rock.     

Trace and Rare Earth Element Geochemistry of Micrite Mound Carbonates and Other Related REE Mineralized Carbonates from Bayan Obo Area in Inner Mongolia

Whatismicritemound?Itisthegeological body,whichismadefrommicro carbonate,micro andothersubstancesformedataspecificenviron ment,whoseshapeislikesmallhill[1,2].However, itcannotbefoundinthepre Cambriansedimentary rocksduetotheverystrongalterationduringthe…