Y2O3与MgO复合掺杂ZrO2材料的电性能研究

利用交流复阻抗分析技术对Y2O3与 MgO复合掺杂ZrO2材料的电性能进行了研究.发现随着Y2O3掺入量的增加,参与跃迁的氧空位增多,并促进烧结体的密度提高,气孔率降低,使得晶粒边界的电阻减少,导致(ZrO2)1-x-y(YO1.5)x(MgO)y陶瓷电导率增大.烧结温度的提高也是增加 (ZrO2 )1-x-y(YO1.5)x(MgO)y陶瓷电导率的重要因素之一.     

Influence of cobalt on performance of Cu-CeO_2 catalysts for preferential oxidation of CO

Copper and cobalt oxides supported on CeO_2 were investigated for preferential oxidation of carbon monoxide(CO-PROX) in the presence of excess hydrogen and CO_2.(Cuo)_(1-x)(Co_3 O_4)_(x/3)-(CeO_2)_(2.5)(x=0,0.25,0.50,0.75,0.85 and 1) catalysts were prepared by coprecipitation method.These mixed oxide catalysts were characterized by several physicochemical techniques,such as BET surface area(S_(BET)),X-ray diffraction(XRD),high resolution transmission electron microscopy(HRTEM),temperature programmed reduction(TPR) and X-ray photoelectron spectroscopy(XPS).XRD studies show the peaks related to CuO and Co_3 O_4 phases in copper and cobalt containing CeO_2 catalysts.The average particle size of the CeO_2 crystallites is in the range of 8-10 nm as evaluated from HRTEM studies.XPS studies demonstrate that Cu,Co and Ce in(cuO)_(1-x)(Co_3O_4)_(x/3)-(CeO_2)_(2.5) catalysts are presented in+2 and +1,+3 and +2 and +4 and +3 oxidation states,respectively.The catalyst with x=0.75 shows better activity and selectivity towards CO-PROX.Though the catalyst with only copper(CuO-CeO_2,x=0) shows good activity but reverse water gas shift(RWGS) reaction is noticed at high temperature.On the other hand,RWGS reaction is suppressed on the cobalt containing CuO-ceO_2 catalyst.Cobalt on CeO_2 with x=1 shows hardly any activity for PRoX reaction at low temperatures.No methanation activity is observed on CuO-CeO_2 or Co_3O_4-CeO_2 catalysts.In contrast,combination of copper and cobalt on CeO_2 shows methanation of CO where enhanced activity is observed with increasing in cobalt content.     

镍钴酸锂的制备与电性能研究

以共沉淀法制得前驱体Ni0.8Co0.2(OH)2,再与LiOH.H2O混合通氧气于600℃恒温15h得到LiNi0.8Co0.2O2。X射线衍射分析表明合成的材料LiNi0.8Co0.2O2具有规整的-αNaFeO2层状结构。SEM表明材料颗粒呈类球体,大小均一。以0.1C电流充放电,首次放电比容量为176mA.h/g,循环20次后容量大幅度衰减。交流阻抗图谱表明材料充电态的电化学阻抗明显低于放电态的电化学阻抗。     

Effect of Nb~(5+) and Cu~(2+) codoping on thermal properties of Gd_2Zr_2O_7 ceramic

In this work,Nb⁵⁺and Cu²⁺were selected to partially substitute Zr4+in Gd₂Zr₂O₇for studying the phase structure,microscopic morphology and thermal properties.Gd₂(Zr_(1-3 x/2)Nb_xCU_x/2)₂O₇(x=0,0.05,0.1,0.15,0.2,0.25)ceramic materials were synthesized by high-temperature solid-state reaction method.The results show that the Gd₂(Zr_(1-3 x/2)Nb_xCu_x/2)₂O₇ceramics present cubic pyrochlore structure with clear grain boundaries and dense cell structure.And the thermal expansion coefficient of Gd₂(Zr_(1-3 x/2)Nb_xCu_x/2)₂O₇ceramics gradually decreases because of the incorporation of Nb⁵⁺and Cu²⁺into Zr-site in Gd₂Zr₂O₇.Meanwhile,its thermal conductivity decreases firstly and then increases with the doping of Nb⁵⁺and Cu²⁺,which reaches the lowest value for the composition of Gd₂(Zr_0.85Nb_0.1Cu_0.05)₂O₇.     

ZrO_2-Al_2O_3(Y_2O_3)材料的相结构研究

本文通过X衍射技术和多晶法计算研究了ZrO_2-Al_2O_3和ZrO_2-Al_O_3-Y_2O_3陶瓷材料的相结构变化。结果表明,在ZrO_2-Al_2O_3体系中,在低Al_2O_3含量时,主要相是单斜相。随着Al_2O_3含量增大,单斜相比率系数X_m下降,四方相含量明显增大。在ZrO_2-Al_2O_3体系中添加Y_2O_3后,Y_2O_3可以促进形成四方相和稳定相系的作用,使三元系转变为四方结构。烧结温度对ZrO_2-Al_2O_3系相结构变化影响不明显,但对ZrO_2-Al_2O_3-Y_2O_3系影响较大,低Y_2O_3含量时,温度升高可促进相系的转移;而高Y2O_3含量时,已完全转变为四方结构。所以,烧结温度对相结构变化无影响。     

系列层状K2La2Ti3O10的制备及光催化性能

通过固相反应法合成了一系列不同尺寸的K2La2Ti3O10,考察了原料TiO2粒径对固相反应速率及产物尺寸、形貌的影响,得到了不同粒径下原料的最佳配比;以降解甲基橙为探针考察其光催化性能.结果表明减小原料粒径,反应温度降低、速率加快;有利于合成小尺寸、大比表面积(可达11.83 m2·g-1)的层状K2La2Ti3O10,而且光催化性能提高.     

离子交换树脂法制备纳米La_2O_3及表征

以La(NO3)3.6H2O为原料,用强碱性阴离子交换树脂为沉淀剂,制备了纳米La2O3。前驱物及产物进行了TG-DTA、XRD、TEM、HRTEM、SAED、BET等表征。实验结果表明,前驱物是La(OH)3,产物为宽约20nm~25nm、长约为80nm~200nm的板状或棒状La2O3纳米多晶体。     

The oxygen potential of the systems Fe+FeCr2O4+Cr2O3 and Fe+FeV2O4+V2O3 in the temperature range 750–1600°C

From electromotive force (emf) measurements using solid oxide galvanic cells incorporating ZrO₂-CaO and ThO₂?YO_1.5 electrolytes, the chemical potentials of oxygen over the systems Fe+FeCr₂O₄+Cr₂O₃ and Fe+FeV₂O₄+V₂O₃ were calculated. The values may be represented by the equations: $$\begin{gathered} 2Fe\left( {s,1} \right) + O_2 \left( g \right) + 2Cr_2 O_3 \left( s \right) \to 2FeCr_2 O_4 \left( s \right) \hfill \\ \Delta \mu _{O_2 } = - 151,400 + 34.7T\left( { \pm 300} \right) cal \hfill \\ = - 633,400 + 145.5T\left( { \pm 1250} \right) J \left( {750 to 1536^\circ C} \right) \hfill \\ \Delta \mu _{O_2 } = - 158,000 + 38.4T\left( { \pm 300} \right) cal \hfill \\ = - 661,000 + 160.5T\left( { \pm 1250} \right) J \left( {1536 to 1700^\circ C} \right) \hfill \\ 2Fe\left( {s,1} \right) + O_2 \left( g \right) + 2V_2 O_3 \left( s \right) \to 2FeV_2 O_4 \left( s \right) \hfill \\ \Delta \mu _{O_2 } = - 138,000 + 29.8T\left( { \pm 300} \right) cal \hfill \\ = - 577,500 + 124.7T\left( { \pm 1250} \right) J \left( {750 to 1536^\circ C} \right) \hfill \\ \Delta \mu _{O_2 } = - 144,600 + 33.45T\left( { \pm 300} \right) cal \hfill \\ = - 605,100 + 140.0T\left( { \pm 1250} \right) J \left( {1536 to 1700^\circ C} \right) \hfill \\ \end{gathered} $$ . At the oxygen potentials corresponding to Fe+FeCr₂O₄+Cr₂O₃ equilibria, the electronic contribution to the conductivity of ZrO₂?CaO electrolyte was found to affect the measured emf. Application of a small 60 cycle A.C. voltage with an amplitude of 50 mv across the cell terminals reduced the time required to attain equilibrium at temperatures between 750 to 950°C by approximately a factor of two. The second law entropy of iron chromite obtained in this study is in good agreement with that calculated from thermal data. The entropies of formation of these spinel phases from the component oxides can be correlated to cation distribution and crystal field theory.     

纳米La_2O_3粉晶的制备及其表征

以La(NO_3)_3·6H_2O、NH_4HCO_3和聚乙二醇为原料,利用沉淀法制备了纳米La_2O_3粉体,利用XRD,TG-DTA和TEM等测试方法对干凝胶热分解过程及最终形成的纳米La_2O_3粉体进行了分析和表征,XRD法考察了前驱体在不同热处理条件下产物物相和晶粒度的变化情况,实验结果表明,在适当工艺参数下,前驱体经720℃,1h焙烧所得产物为平均粒径小于50nm的La_2O_3粉体.     

Rare earths (Ce,Y, Pr) modified Pd/La_2O_3-ZrO_2-Al_2O_3 catalysts used in lean-burn natural gas fueled vehicles

14%REO_x-2.5%La_2 O_3-33.5%ZrO_2-50%Al_2 O_3(RE = Ce, Y, Pr) composites were prepared by a coprecipitation method. The Pd catalysts were obtained by an aqueous solution of Pd(NO_3)_2 loaded on the rare earths modified composites with an initial wet impregnated method. The experiment results show that catalytic activity of the rare earths modified Pd/La_2 O_3-ZrO_2-Al_2 O_3 catalysts is better than bare sample for methane oxidation. The structural characterization results reveal that the rare earths modified Pd catalysts increase amounts of surface active oxygen species by X-ray photoelectron spectroscopy(XPS) analysis and improve the dispersion of active component from H2-temperature programmed reduction(H2-TPR) measurement compared with bare sample. Especially,Pd/14%Y_2 O_3-2.5%La_2 O_3-33.5%ZrO_2-50%Al_2 O_3 sample exhibits highly active stability, it is related to the Pd particles highly dispersion,which was observed by transmission electron microscope(TEM) images.     

Phase equilibria in the system NiO-CaO-SiO2 and gibbs energy of formation of CaNiSi2O6

Phase relations in the pseudoternary system NiO-CaO-SiO₂ at 1373 K are established. The coexisting phases are identified by X-ray diffraction and energy-dispersive X-ray analysis of equilibrated samples. There is only one quaternary oxide CaNiSi2O6 with clinopyroxene structure. The Gibbs energy of formation of CaNiSi₂O₆ is measured using a solid state galvanic cell incorporating stabilized zirconia as the solid electrolyte in the temperature range of 1000 to 1400 K: From the electromotive force (emf) of the cell, the Gibbs energy of formation of CaNiSi₂O₆ from NiO, SiO₂, and CaSiO₃ is obtained. To derive the Gibbs energy of formation of the quaternary oxide from component binary oxides, the free energy of formation of CaSiO₃ is determined separately using a solid state cell based on single crystal CaF₂ as the electrolyte: The results can be expressed by the following equations:      

恒电流库仑分析法测定铬矿中三氧化二铬

在0.1mol/LH2SO4-H3PO4介质中电解0.02mol/LFe2(SO4)3溶液,使Pt阴极上产生Fe2+;采用H2SO4-H3PO4-(NH4)2S2O8分解铬矿,用KMnO4将其中Cr3+氧化为Cr2O27-;以Fe2+对Cr2O27-进行库仑滴定,采用永停终点法确定库仑滴定终点,根据电解定律计算三氧化二铬含量。用本法和硫酸亚铁铵滴定法分别测定铬矿标样中三氧化二铬,本法相对误差为0.22%,RSD(n=11)为0.034%,测定结果的准确度和精密度明显高于硫酸亚铁铵滴定法。     

稀土杂多酸盐催化环己酮氧化合成己二酸

合成一系列稀土杂多酸盐,考察了其在环己酮氧化合成己二酸反应中的活性.结果表明,K_8H_3[La(PW_(11)O_(39_)_2]·25H_2O在环己酮氧化合成己二酸的过程中显示了较高的催化活性,反应8h,己二酸的收率可达71.9%.考察了温度,时间,反应物加入量,过氧化氢加入量,催化剂加入量等一系列条件对反应的影响,确定了最佳反应条件.     

Colloidal(Gd_(0.98)Nd_(0.02))_2O_3 nanothermometers operating in a cell culture medium within the first and second biological windows

Non-contact,self-referenced and near-infrared luminescent nanothermometers have been recognized as emerging tools in the fields of nanomedicine and nanotechnology due to their great capability of precise temperature readout at the nanoscale and real-time deep-tissue imaging.However,the development of multifunctional and biocompatible luminescent nanothermometers operating within the optically transparent biological windows with high thermal sensitivity(2.0%/K) remains challenging.Here,we present(Gd_(0.98)Nd_(0.02))_2 O_3 nanothermometers operated effectively within the first and second biological windows upon continuous-wave laser diode excitation at 808 nm.Ratiometric thermometric parameters are defined by the relative changes in the emission intensities originating from the two Stark components of the ~4 F_(3/2) level(R2 and R_1) to the ~4 I_(9/2)(900-1000 nm),~4 I_(11/2)(1035-1155 nm) and ~4 I_(13/2)(1300-1450 nm) multiplets.The thermo metric parameters are evaluated for colloidal samples in a cell culture medium and powder samples,and the highest thermal sensitivity(2.18%/K at 298 K) is attained for the former in the first biological window(both the excitation and emission in the 800-965 nm range).The repeatability and temperature uncertainty are 99% and 1.2 K,respectively.The nanothermometers are biocompatible with human MNT-1 melanoma and HaCaT cells for 24 h of exposure and nanoparticle concentration up to 0.400 mg/mL,showing their potential for applications in nanomedicine,e.g.,intracellular imaging and temperature mapping.     

硫酸铝铵原位分解制备Al2O3颗粒增强铝基复合材料

向铸铝ADC12熔体中添加脱水后的硫酸铝铵，反应分解的Al2O3原位生成颗粒增强铝基复合材料，该方法既可节约成本，同时由NH4Al（SO4）2分解的SO3对熔体具有精炼作用．SEM观察表明，Al2O3颗粒在铝基体中细小弥散分布，形成球形、不团聚的增强体颗粒．与基材相比，该复合材料的耐磨性明显提高；拉伸试验显示，复合材料的抗拉强度和延伸率有所降低．     

Samarium doping improves luminescence efficiency of Cs_3Bi_2Br_9 perovskite quantum dots enabling efficient white light-emitting diodes

Considering the toxicity problem of lead-based perovskite quantum dots(PQDs),the lead-free Cs₃Bi₂Br_gPQDs has been recognized as one of the promising candidates.However,the low photoluminescence quantum yields(PLQYs)hinder its practical application in optoelectronic devices.Here,w e successfully prepared Sm³⁺ions doped Cs₃Bi₂Br_gPQDs with effective white light-emission by modified ligandassisted recrystallization method.The realization of white light-emission is attributed to the broadband blue emission of excitons and the red emission(⁴G_5/2-⁶HJ(J=5/2,7/2,9/2))of Sm³⁺ions for Sm³⁺ions doped Cs₃Bi₂Br_gPQDs.More importantly,compared with the undoped Cs₃Bi₂Br_gPQDs,the PLQYs of Sm³⁺ions doped Cs₃Bi₂Br_gPQDs are improved from 10.9%to 20.8%,and the anti-water stability is also obviously improved.Finally,the Sm³⁺ions doped PQDs based white light-emitting diodes(LEDs)with luminous efficiency of 12.6 lm/W were explored,which indicates that there is a potential prospect of lead-free PQDs in white light lighting application.     

纳米氧化镧的固相合成

以LaCl_3·6H_2O和H_2C_2O_4·2H_2O为原料,用室温固相化学反应首先合成出前驱物草酸镧,经750℃分解3h,得到产物纳米氧化镧。用X-射线粉末衍射和透射电镜对产物的组成、大小、形貌进行表征。结果表明：纳米氧化镧为粒度分布均匀的长方体形结构,平均粒径12nm。并考察了表面活性剂对粒径大小和分散性的影响。     

稀土钼杂多配合物催化合成尿囊素的研究

合成制备了稀土钼杂多配合物K11[Y(PMo11O39)2],并以之作为催化剂,双氧水为氧化剂,乙二醛和尿素为原料合成尿囊素。探讨研究了催化剂量、反应温度、反应时间及n(C2H2O2)∶n(H2O2)对尿囊素收率的影响。得到了适宜的合成条件为:n(C2H2O2)∶n(H2O2)=1.0∶1.1,氧化反应温度约为5℃~8℃,尿囊素生成温度约为75℃~80℃,反应时间7小时,在该条件下尿囊素的收率可达28.75%。     

Bi_2WO_6 doped with rare earth ions:Preparation,characterization and photocatalytic activity under simulated solar irradiation

Rare-earth modification Bi_2 WO_6 composites(RE/Bi_2 WO_6) were studied by experimental performance and theory computation based on the different 4 f orbits of selected rare earth elements(La,Ce,Gd,and Yb).The prepared RE/Bi_2 WO_6 was characterized by XRD,SEM/TEM,XPS,UV-vis DRS,and N_2 adsorption to learn their physical-chemical properties.Azo dye Rhodamine B(RhB) was photodegraded as a target pollutant to investigate the photocatalytic activity of prepared RE/Bi_2 WO_6 composites.The results of experiment and computation show that four rare earth elements with different electron configurations retain the phase and morphology of Bi_2 WO_6 and enhance the removal efficiency of RhB under simulated solar irradiation.The optimum doping contents are 0.01%,0.05%,0.05% and 0.01% for La-,Ce-,Gd-,and Yb-doped Bi_2 WO_6,respectively.However,light rare earth La and Ce doped composites indicate some difference in visible light adso rption capacity and mineralization on RhB co mpared with heavy rare earth Gd and Yb doped composites.Both La/Bi_2 WO_6 and Ce/Bi_2 WO_6 possess larger pore size and higher mineralization ability than Gd/Bi_2 WO_6 and Yb/Bi_2 WO_6 under the same experimental conditions while Gd/Bi_2 WO_6 and Yb/Bi_2 WO_6 show stronger red shift to the visible light due to the more 4 f electrons.The hole oxidation plays a major role in the photodegradation of RhB by all RE/Bi_2 WO_6.     

Investigation of electroless Ni-Co-Fe-P coating on stainless steel

Cr_2O_3-forming ferritic stainless steels have been widely explored as intermediate temperature solid oxide fuel cells(SOFCs) interconnects.However,the evaporation of chromia scale might migrate to and poison the cathode,leading to degradation of the cell performance.In this study,Ni-Co-Fe-P coatings were deposited on the ferritic stainless steel by means of a cost-effective technique of electroless method.They are expected to be converted into(Ni,Co,Fe)_3O_4 spinel with a high electrical conductivity an...