Subsolidus phase relations and crystal structures of R-Ca-Cu-O (R=Nd, Sm, Gd, Tm) systems

The subsolidus phase relations of R₂O₃-CaO-CuO ternary systems (R=Nd, Sm, Gd, Tm) have been investigated by X-ray powder diffraction. All samples were synthesized at about 950° in air. There exists a ternary compound Ca_14−xR_xCu₂₄O₄₁ (x = 4 for R=Nd, Gd and x = 5 for R = Sm) and a ternary solid solution Ca_2+xR_2−xCu₅O₁₀ (R=Nd, Sm, Gd, Tm) with a wide composition range Δx of about 0.6. The compound Ca_14−xR_xCu₂₄O₄₁ possesses a layered orthorhombic structure and is isostructural to Sr_14−xCa_xCu₂₄O₄₁. The lattice parameters a and c of the compound are basically independent of the ionic radius of R, while the lattice parameter b and unit-cell volume V decrease substantially with the decrease of the ionic radii of R. The Ca_2+xR_2−xCu₅O₁₀ solid solution is isostructural to Ca_2+xY_2−xCu₅O₁₀, the structure of which is based on an orthorhombic “NaCuO₂-type” subcell containing infinite one-dimensional chains of edge-shared square planar cuprate groups crosslinked by the layered cations Ca and R that locate in the inter-chain tunnels.     

碘酸钾存在下极谱催化波法测定陈皮甙

基于陈皮甙在ＫＩＯ３存在下产生的极谱催化波，拟定了测定陈皮甙的新方法。在 ０．５５ ｍｏｌ／Ｌ ＨＡｃ－０．０１ｍｏｌ／Ｌ　ＮａＡｃ（ｐＨ ４．００±０．０５）－１．０×１０～（－３）ｍｏｌ／Ｌ ＫＩＯ３缓冲溶液中，陈皮甙催化波的峰电位为－１．３５ Ｖ（ｖｓ，ＳＣＥ），它的一阶导数峰峰电流与陈皮甙浓度在２．６ × １０～（－７）～２．６ × １０～（－６）ｍｏｌ／Ｌ范围内呈线性关系（ｒ＝０．９９７０，ｎ＝６）。本方法比现有的电化学方法灵敏度高一个数量级。可用于直接测定中草药贯众水提液中陈皮甙含量。     

新型中温固体氧化物燃料电池阴极材料Fe掺杂Sm0.5Sr0.5CoO3性能研究

本文系统研究了新型中温固体氧化物燃料电池(IT-SOFC)阴极材料Sm_0.5Sr_0.5Co_1-xFe_xO_3－δ(SSCF)的晶体结构、热膨胀系数、导电率及电化学性能。固相合成的Sm_0.5Sr_0.5Co_1-xFe_xO_3－δ化合物均为单相材料，随着掺Fe量的不同，SSCF的晶体结构发生变化，在0≤x≤0.4时，SSCF为正交晶系钙钛矿结构，在0.5≤x≤0.9时，SSCF为立方晶系钙钛矿结构。Fe掺杂可以显著的改善Sm_0.5Sr_0.5CoO₃的热膨胀系数，随着Fe含量的增加，热膨胀系数减小。在800℃下，SSCF导电率均大于100 S·cm^-1。随着Fe含量的增加，极化电阻增大；含量x=0.4时，极化电阻达到最大值；之后，随Fe含量的增加，极化电阻减小，在700～800 ℃时，Sm_0.5Sr_0.5Co_0.2Fe_0.8O_3－δ表现出了良好的氧催化活性。     

CaS：Ce，Sm的制备及性能表征

采用碳还原法制备了CaS：Ce，Sm样品，并研究了反应机理、还原原理以及灼烧温度对CaS晶格形成和光激励发光的影响。样品的XRD测试表明，采用碳还原法制备的CaS：Ce，Sm样品，具有纯CaS的面心立方结构，晶格常数a=0.569 4 nm，样品的激发光谱是峰值分别位于295 nm和461 nm的宽带谱，样品的荧光光谱是峰值位于503 nm、560 nm、600 nm和655 nm带谱，光激励发光光谱是峰值分别位于500 nm，565 nm和605 nm的宽带谱，光激励激发光谱是峰值位于1 150 nm的宽带谱。     

The Intrusion of the Meissen Pluton (Elbe Valley-Zone): Evidence from Geochemical and Isotopic Data

Abstract

Geochemical and mineralogical investigations of plutonic rocks from the Meiβen massif indicate different magmatic evolution trends of the Freital sequence as well as for the central part of the complex Constant ε-Nd_T-345 values of ?1.5 of the Freital sequence and major/trace element data point to a fractional crystallization process. Based on ε-Nd values, ¹⁴⁷Sm/¹⁴⁴Nd ratios as well as on geochemical data affinities to alkali basalts cannot be excluded.

Analogous conclusions have been drawn regarding mineral chemical data [10] and cathodoluminescence spectra of apatite [13]. Assimilation of old continental crust, reflected by relics of apatite and zircon, may be the reason that the ε-Nd values plot at the lower end of the “mantle array”. The pyroxene-monzodiorite from Gröba belongs to the same source environment as the Freital sequence (Nd-characteristics).

The geological evolution of the central part of the studied plutonic complex is completely different to the Freital sequence: most of the intrusions show signatures of open system fractionation processes. The ε-Nd_T-345 value of ?1.46 of the Leuben monzonite indicates a narrow relation to the Freital sequence, whereas the ε-Nd_T-345 value of +2.27 of the Spitzgrund monzonite either reflects the derivation of another basic material then the Freital-type or the participation of other mixing component(s) from geologically young crust.

Fabric and mineral chemical investigations of the porphyry-like granite GII point to a mixing process of basic xenocrysts, resembling the corresponding minerals of the Freital sequence, and granite melts [10]. Large amounts of old zircon cores [11] indicate the inheritance of continental crust components by the Hauptgranit. Isotopic investigations on various granitic samples (GII, Hauptgranit and Riesensteingranit) reflect an increasing trend towards the crustal source(s) of their parental melts. The ε-Nd_T-345 values are ?3.75, ?4.16 and ?6.13, respectively.

Chemical parameters and the ε-Nd_T value of the Riesensteingranit agree with data of granites from the Saxonian Granulite Massif (see e.g. Wand et al. [8]; von Quadt, 1992). Thus, it may be possible that both granite types derived from similar sources.     

混合熔盐法低温合成Sm2Ti2S2O5及其光催化分解水产氢

以TiO2、TiS2及Sm2O3为前驱体,分别加入LiCl-KCl与LiCl-CsCl的最低共熔混合物作为熔盐,在较低温度下成功合成了Sm2Ti2S2O5(STSO)颗粒。通过对比不同温度下所制备产物的X射线衍射图,首次表明STSO的热力学结晶温度在520℃左右,远低于之前报道的650℃的最低合成温度。扫描电子显微镜照片显示,采用2种混合熔盐制备的STSO都呈片状形貌;同一合成温度下,采用LiCl-CsCl熔盐制备的STSO的厚度小于LiCl-KCl所得产物。采用出射光波长大于420 nm的氙灯作为光源,在含有Na2S-Na2SO3空穴牺牲剂的溶液中,所制备的STSO颗粒表现出最高35μmol·h-1的光催化分解水产氢活性以及20 h以上的产氢稳定性。     

盐酸后处理制备高效制氢光催化剂Zn2In2S5

采用水热法制备了ZnIn₂S₄固溶体, 并通过用盐酸对其进行后处理获得了系列Zn_mIn₂S_m+3(m≥2, 整数)固溶体. 通过X射线衍射(XRD)、 扫描电子显微镜(SEM)、 透射电子显微镜(TEM)、 X射线光电子能谱(XPS)、 紫外-可见漫反射光谱(UV-Vis DRS)、 荧光光谱(PL)和电化学测试对催化剂的组成、 结构和性能进行了表征. 研究了系列固溶体可见光光催化制氢活性. 结果表明, ZnIn₂S₄固溶体经0.5 mol/L HCl处理后能转化为Zn₂In₂S₅固溶体, 其制氢活性为ZnIn₂S₄固溶体的2.2倍, 并且具有良好的稳定性.     

SrS∶Eu,Sm光存储机理的研究

采用高温固相反应法在还原气氛下制备了SrS:Eu,Sm样品,利用荧光光谱仪测量了这种光存储材料的激发光谱和发射光谱.将样品用紫外灯(265 nm)照射激发饱和后,再用980 nm的红外激光器激励,利用荧光光谱仪测试得到了峰值位于599 nm的光激励发光光谱.此外还利用热释光谱仪测试了样品的热释光谱.探讨了SrS:Eu,Sm的光存储机理,认为引入的稀土离子在SrS的带隙中形成分裂能级.当用紫外光照射材料时,Eu的电子从基态被激发到激发态或基质材料的导带,其中一部分电子被辅助激活剂Sm的陷阱俘获,实现信息写入.当材料被与陷阱深度相当的红外光激励时,电子陷阱Sm2 俘获的电子才可能跃出俘获能级,与空穴在Eu的激发态和基态能级上复合,多余的能量以可见光的形式释放出来,实现信息读出.     

Microstructure–conductivity relationship in Gd- and Sm-doped ceria-based electrolytes prepared by the acrylamide sol–gel-related method

We have prepared pure electrolytes of Ce_0.8Gd_0.2O_1.9 (CGO) and Ce_0.8Sm_0.2O_1.9 (CSO), useful for SOFCs, by a sol–gel-related technique like the acrylamide method. This method consists of preparing a solution from the single oxides followed by gelation. Then, the combustion or decomposition of the organic molecules is initiated, producing nanometric calcined powders of the above-mentioned compounds. Thermal treatments were optimized in order to obtain good electrochemical properties of the electrolytes. We have observed that the synthesis temperature to obtain the pure phase is lower for the sol–gel samples than for the pellets prepared by solid-state reaction, and the final density is higher. The microstructure and composition of the powders were characterized by TEM, SEM, and EDX analysis. The electrical properties of the electrolytes were measured by impedance spectroscopy at different temperatures and oxygen partial pressures.Presented at the OSSEP Workshop Ionic and Mixed Conductors: Methods and Processes, Aveiro, Portugal, 10–12 April 2003     

Magnetic anisotropy manipulation and interfacial coupling in Sm3Fe5O12 films and CoFe/Sm3Fe5O12 heterostructures

The magnetic anisotropy manipulation in the Sm₃Fe₅O₁₂ (SmIG) films and its effect on the interfacial spin coupling in the CoFe/SmIG heterostructures were studied carefully. By switching the orientation of the Gd₃Ga₅O₁₂ substrates from (111) to (001), the magnetic anisotropy of obtained SmIG films shifts from in-plane to out-of-plane. Similar results can also be obtained in the films on Gd₃Sc₂Ga₃O₁₂ substrates, which identifies the universality of such orientation-induced magnetic anisotropy switching. Additionally, the interfacial spin coupling and magnetic anisotropy switching effect on the spin wave in CoFe/SmIG magnetic heterojunctions have also been explored by utilizing the time-resolved magneto-optical Kerr effect technique. It is intriguing to find that both the frequency and effective damping factor of spin precession in CoFe/SmIG heterojunctions can be manipulated by the magnetic anisotropy switching of SmIG films. These findings not only provide a route for the perpendicular magnetic anisotropy acquisition but also give a further path for spin manipulation in magnetic films and heterojunctions.