Synergistic effect of La and Co co-doping on room-temperature ferromagnetism enhancement of TiO2 nanoparticles

The synergistic influence of lanthanum and cobalt co-doping on room temperature ferromagnetism (RTFM) of TiO₂ system is investigated. A series of Ti_0.97?xCo_0.03La_xO₂ nanoparticles were prepared and their structures and properties were systematically studied with X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) spectroscopy, UV–vis spectrophotometer, Raman spectra and magnetic measurement techniques, respectively. Detailed experimental characterizations indicate that the as-prepared La and Co co-doped samples exhibit single anatase phase, and all the samples exhibit strong visible photoluminescence associated with oxygen vacancies and a clear ferromagnetic hysteresis loop, both of which were dramatically enhanced with La and Co co-doping, and the maximum saturation magnetization (M_s) reaches 1.38 emu/g at the La content of 6 mol%. It is speculated that oxygen vacancies modulated by ionic La play an important role in the enhanced RTFM, which can be attributed to the bound magnetic polarons (BMPs) formed via ferromagnetic coupling between two neighboring Co²⁺ ions mediated by oxygen vacancy (F⁺ center). Our results present an alternative method to obtain high performance RTFM.     

Solid superbase derived from lanthanum–magnesium composite oxide and its catalytic performance in the knoevenagel condensation under solvent-free condition

We report for the first time the synthesis of a novel solid superbase that was derived from lanthanum–magnesium composite oxide and KOH through thermal treatment. The as-prepared material shows base strength (H_–) above 26.5 and is a high-efficiency catalyst for solvent-free Knoevenagel condensation at room temperature. The results of the present study open up a new dimension for the use of composite oxides as new support materials in the synthesis of superbases.     

Performance improvement by metal deposition at the cathode active site in solid oxide fuel cells

In this study, the performance improvement of the SOFC single cell and its underlying mechanism was investigated. Furthermore, an application of the identified electrochemical mechanism is proposed and tested experimentally. The deposition of Platinum (Pt) at electrochemically active sites for the oxygen reduction reaction is determined to be responsible for the improved performance. Pt migration from a current collector to the cathode active sites originates from the oxygen partial pressure difference between current collector and triple phase boundary, and the electrochemical reduction reaction. It is supported by the confirmation of Pt particles at the cathode active sites by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and calculations of the thermodynamic equilibrium partial pressure values. In addition, correlation of the initial performance change and the quantities of Pt deposition are investigated. This selective Pt deposition mechanism at the active sites is applied to the LSCF cathode, as well.     

聚锑酸离子交换剂的制备及分离锶和钇

以三氧化二锑为原料,双氧水为氧化剂,经氧化回流法制备聚锑酸无机离子交换剂.该聚锑酸离子交换剂对锶-钇混合溶液中的锶具有较好的选择性吸附能力.通过正交实验设计法对反应影响因素进行了优化,结果表明,在60 ℃时加入40 mL水和12 mL H_2O_2氧化10 g Sb_2O_3固体,反应120 min可制得对Sr~(2+)和Y~(3+)具有较高分离系数的聚锑酸离子交换剂.理化性能研究表明,产物是一种阳离子交换剂,对溶液中的Sr~(2+)和Y~(3+)的动态吸附分离具有较高的选择性.     

Improvement of Fracture Toughness Lanthanum Zirconate

Thermalbarriercoatings(TBCs)havefoundan increasingnumberofapplicationsinprotectinghigh temperaturemetalliccomponents,forexample,TBCsaredepositedontransitionpieces,combustion lines,first stagebladesandvanes,andotherhot pathcomponentsofgasturbineseithertoincreasethe inlettemperaturewithaconsequentimprovementof theefficiencyortoreducetherequirementsfora coolingsystem[1].Thereareseveralceramicsthat havebeenevaluatedasTBCmaterials[2].Lanthanum zirconatewasrecentlyproposedasapromisingTBC materia…     

Thermal Instability and Microstructure of Strontium M-type Hexaferrite Nanoparticles Synthesized by Citrate Approach

The dried gel of SrFe12O19, prepared by citrate approach, was investigated by means of infrared spectroscopy （ IR ）, thermogravimetric analysis （ TG ）, differential scanning calorimetry （ DSC ）, X- ray diffraction（ XRD ） techniques, energy dispersive spectroscopy（ EDS ）, and transmission electron microscopy（ TEM ）. The thermal instability and the thermal decomposition of low-temperature strontium M-type hexaferrite crystallized at about 600℃ were confirmed for the first time by XRD method. The decomposition of the low-temperature strontium M-type hexaferrite took place at about 688.6℃ determined by DSC investigation. The low-temperature strontium M-type hexaferrite nanopartieles were decomposed into SrFeO2.5 with an orthorthombic cell and Fe2O3 with a tetragonal cell as well as possibl α-Fe2O3 . The agglomerated particles with sizes less than 200 nm obtained at 800℃ were plesiomorphous to strontium M-type hexaferrite. The thermally stable strontium M-type hexaferrite nanopartieles with sizes less than 100um cotdd take place at 900 ℃ . Up to 1000 ℃ , the phose transformotion to form strontium M-type hexaferrite was ended, the calcinations with the sizes more than 1μm were composed of α-Fe2O3 and strontium M-type hexaferrite. The method of distinguishing γ-Fe2O3 with a spinel structure from Fe2O3 with tetragonal cells by using powder XRD method was proposed. Fe2O3 with tetragonal cells to be crystallized before the crystallization of thermally stable strontium M-type hexaferrite was confirmed for the first time. The reason why α- Fe2O3 as an additional phase appears in the calcinations is the cationic vacancy of stroutium M-type hexaferrite , SrFe12-x□O19 （0≤x ≤0.5）.     

Novel Phase Transition in BaPr2Mn2O7

The rare earth manganite BaLn2Mn2O7 (Ln=rare earth element) has a Sr3Ti2O7-type layered perovskite structure with double-block oxygen octahedra belonging to the Ruddlesden-Popper-type homologous series AO(ABO3)2. In Pr-manganite, a novel phase transition was first observed in situ at 1040 K by a thermal transmission electron microscope. At 1040 K, reflections began to split along the c-direction in the selected area diffraction pattern. This indicates that a new phase appears in the original phase matrix; the c length of the new phase is 1.5% longer than that of the original phase. After about 5 min, the original phase disappears. No change in the crystal symmetry (space group I4/mmm) is observed above 1040 K.     

双层锰氧化物薄膜中的应力效应

双层钙钛矿结构的La2-2xSr1 2xMn2O7(X=0.32)单相薄膜生长在具有不同晶格参数的两种衬底上，测量发现，两种衬底上生长的La2-2xSr1 2xMn2O7(X=0.32)薄膜具有迥然不同的金属－绝缘体转变温度TM－1及其他物性，界面应力的研究表明这是衬底晶格数不同引起膜内应变的结果，在衬底的压应力下，薄膜的电阻－温度曲线的峰值（TM－1）向高温移动且电阻率（ρ）下降；相反，对于衬底张力应力下的薄膜，TM－1下降ρ上升，这些结果可以用双交换模型做很好的解释。     

Relaxor Behavior of (Sr0.8Ba0.2)TiO3 Ceramic Solid Solution Doped with Bismuth

The dielectric properties of (Sr_0.8Ba_0.2)_1-1.5xBi_xTiO₃ ceramics in the range 0 x 0.18 are investigated. A ferroelectric relaxor behavior is observed. The degree of the diffuseness and the relaxation of the phase transition increases as the Bi content increases. A random electric field is suggested to be responsible for the relaxor behavior observations. The dependence of the diffuseness on the grain size is presented.     

氯化锶水溶液的净化和SrCl2的制取

生产锶盐的过程中都存在ＳｒＣｌ２溶液的净化，本文讨论了锶的氯盐溶液净化的方法和影响因素，得到了ＳｒＣｌ溶液沉淀法降钙钡及其它杂质净化方法。