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Synthesis and characterization of calcium and manganese-doped rare earth oxide La_(1-x)Ca_xFe_(0.9)Mn_(0.1)O_(3-δ) for cathode material in IT-SOFC

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Journal of Rare Earths 2011年第11期29卷 1066-1069页

作者：赵捷李晨孔令龙吴雪薇马永昌 School of Materials Science & Engineering Tianjin University of Technology Tianjin Key Lab for Photoelectric Materials and Devices Key Laboratory of Display Materials and Photoelectric Devices(Tianjin University of Technology) Ministry of Education

In order to develop novel cathode materials with high performance for intermediate temperature SOFC（IT-SOFC）,Ca and Mn doped rare earth oxides La1-xCaxFe0.9Mn0.1O3-δ（x=0.1,0.3 and 0.5,denoted as LCFM9191,LCFM7391 and LCFM5591） were synthesized by solid state reaction（SSR） *** formation process,phase structure and microstructure of the synthesized samples were characterized using thermogravimetry/differential scanning calorimetry（TG/DSC）,X-ray diffraction（XRD） and scanning electron microscopy（SEM）.The thermal expansion coefficients（TEC） of the samples were analyzed at 100-900 oC by thermal *** electrical conductivities of the samples were measured with direct current（DC） four-terminal method from 300 to 850 *** results indicated that the samples（x=0.1 and 0.3） exhibited a single phase with orthorhombic and cubic perovskite structure,respectively after being sintered at 1200 oC for 3 *** electrical conductivity of the samples increased with temperature up to a maximum value,and then *** small polaron hopping was regarded as the conducting mechanism for synthesized samples at T≤600 *** negative temperature dependence occurring at higher temperature was due to the creation of oxygen vacancies for charge ***7391 had higher mixed conductivity（100 S/cm） at intermediate temperature and could meet the demand of cathode material for *** addition,the average TECs of LCFM9191 and LCFM7391 were 11.9×10-6 and 13.1×10-6 K-1,respectively,which had good thermal match to the common electrolytes.

关键词： rare earth oxide solid state reaction perovskite structure mixed conductivity thermal expansion

Concentration effect and temperature quenching of upconversion luminescence in Ba Gd_2ZnO_5:Er^(3+)/Yb^(3+) phosphor

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Journal of Rare Earths 2015年第7期33卷 686-692页

作者：周天民张艳秋吴中立陈宝玖 Department of Physics Dalian Maritime University

Er^3＋/yb^3＋ codoped zincate BaGd2ZnO5 phosphors were synthesized via a traditional solid state reaction. The crystal structure and phase purity were checked by means of X-ray dfluence of Eiffraction （XRD）, and the results showed that pure phase BaGd2ZnO5 phosphors with various Er^3＋/yb^3＋ concentrations were obtained. The Er^3＋ and Yb^3＋ doping concentrations on the green and red upconversion emissions was studied. It was found that both green and red upconversion emissions under 980 nm excitation were two-photon processes independent from the rare earth doping concentrations. However, the upconversion luminescence intensities greatly depended on the rare earth doping concentration. Furthermore, the population processes of upconversion luminescence and the quenching mechanisms were analyzed. The temperature-dependent green upconvcrsion luminescence was studied, and the temperature quenching process of two green upconversion emissions was modeled. The thermal quenching processes of the green upconversion emissions could be well explained by the model we proposed.

关键词： BaGd2ZnO5:Er^3+/yb^3+ phosphor solid state reaction upconversion crossover rare earths

Synthesis and Characterization of Rare Earth Ion Doped Nano ZnO

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Nano-Micro Letters 2012年第2期4卷 65-72页

作者： Rita John Rajaram Rajakumari Department of Theoretical Physics University of Madras Department of Physics Queen Mary’s College

Zinc oxide(ZnO) doped with erbium at different concentrations was synthesized by solid-state reaction method and characterized by X-ray diffraction(XRD), scanning electron microscopic(SEM), UVabsorption spectroscopy, photoluminescence(PL) study and vibrating sample magnetometer. The XRD studies exhibit the presence of wurtzite crystal structure similar to the parent compound ZnO in 1% Er^(3+)doped Zn O,suggesting that doped Er^(3+)ions sit at the regular Zn^(2+)sites. However, same studies spread over the samples with Er^(3+)content>1% reveals the occurrence of secondary phase. SEM images of 1% Er^(3+)doped ZnO show the polycrystalline nature of the synthesized sample. UV-visible absorption spectrum of Er^(3+)doped ZnO nanocrystals shows a strong absorption peak at 388 nm due to ZnO band to band transition. The PL study exhibits emission in the visible region, due to excitonic as well as defect related transitions. The magnetizationfield curve of Er^(3+)doped ZnO nanocrystals showed ferromagnetic property at room-temperature.

关键词： Erbium doped zinc oxide solid state reaction X-ray diffraction Photoluminescence VSM Room-temperature ferromagnetism

Reducing Packing Factor of Znln2S4 to Promote Photocatalytic Activity

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Chemical Research in Chinese Universities 2020年第6期36卷 1102-1107页

作者： HU Keyan XU Zian LIU Yiting HUANG Fuqiang state Key Laboratory of High-performance Ceramics and Super Fine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050P.R.China School of Mechanical and Electrical Engineering Jingdezhen Ceramic InstituteJingdezhen 333403P.R.China Department of Materials Science and Engineering City University of Hong KongTat Chee AvenueKowloonHong Kong 999077P.R.China state Key Laboratory of Precision Spectroscopy East China Normal UniversityShanghai 200062P.R.China Beijing National Laboratory for Molecular Sciences and state Key Laboratory of Rare Earth Materials Chemistry and Applications College of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871P.R.China

Due to the quite sluggish charge-carrier separation in semiconductor photocatalysts,the photocatalytic ac-tivity of these materials is still far inferior than ***,a novel approach to reducing the packing factor(PF)of Znln2S4 semiconductors to improve the charge-carrier separation is *** well-crystallized Zn1-xIn2S4-x(x=0,0.05,0.1)powders were productively prepared through solid-state *** structures were verified by the high-resolution transmission electron microscopy,powder X-ray diffraction,and X-ray photoelectron *** PE values of Zn1-xIn2S4-x(x=0,0.05,0.1)samples were calculated to be *** *** *** the PF for Zn1-xIn2S4-x with increasing x can promote the separation of photoexcited carriers,and this process was endorsed by their photoelectric response and photoluminescence emission *** Zn0.9In2S3.9 sample with a lower PF value presents roughly 21 times higher photocurrent density and four times higher photodegrading rate of methyl orange than those of pristine ZnIn2S4.

关键词： Charge-carrier separation Packing factor Zm-xIn2S4-r solid state reaction Photocatalytic activity

Preparation of Cu/ZrO2 catalysts for methanol synthesis from CO2/H2

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Frontiers of Chemical Science and Engineering 2012年第1期6卷 47-52页

作者： Xinmei LIU Shaofen BAI Huidong ZHUAN Zifeng YAN state Key Laboratory for Heavy Oil Processing Key Laboratory of Catalysis(China National Petroleum Corporation)Chiina University of PetroleumQingdao 266555China

Cu/ZrO2 catalysts for methanol synthesis from CO2/H2 were respectively prepared by deposition coprecipitation （DP） and solid state reaction （SR） methods. There is an intimate interaction between copper and zirconia, which strongly affects the reduction property and catalytic performance of the catalysts. The stronger the interaction, the lower the reduction temperature and the better the performance of the catalysts. Surface area, pore structure and crystal structure of the catalysts are mainly controlled by preparation methods and alkalinity of synthesis system. The conversion of CO2 and selectivity of methanol are higher for DP catalysts than for SP catalysts.

关键词： Cu/ZrO2 methanol synthesis depositioncoprecipitation solid state reaction C02/H2

Electrical conductivity of Gd doped BiFeO3-PbZrO3 composite

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Frontiers of Materials Science 2013年第3期7卷 295-301页

作者： Santosh Kumar SATPATHY Nilaya Kumar MOHANTY Ajay Kumar BEHERA Banarji BEHERA Pratibindhya NAYAK Materials Research Laboratory School of Physics Sambalpur University Jyoti Vihar Burla-768019 Odisha India

The composite, 0.5（BiGd0.15Fe0.85O3）-0.5（PbZrO3）, was synthesized using the solid-state reaction technique. The formation of the compound was confirmed by XRD with an orthorhombic structure at room temperature. The impedance parameters were studied using an impedance analyzer in a wide range of frequency （10z-106Hz） at different temperatures. The Nyquist plot suggests the contribution of bulk effect and a slight indication of grain boundary effect and the bulk resistance decreases with a rise in temperature. The presence of temperature-dependent relaxation process occurs in the material. Electrical modulus reveals the presence of the hopping mechanism in the materials. The value of exponent n, pre-factor A and adc were obtained by fitting ac conductivity data with Jonscher＇s universal power law. The activation energies calculated from the ac conductivity were found to be 0.50, 0.46, 0.44, 0.43, 0.42 and 0.38 eV at 1, 10, 50, 100, 500 kHz and I MHz respectively in the temperature region of 110℃-350℃. The dc conductivity was found to increase with the rise in temperature. The activation energy calculated from complex impedance plot and from the fitted Jonscher＇s power law are very close, which results similar type of charge carrier exist in conduction mechanism of the material.

关键词： solid state reaction XRD impedance electrical conductivity

Preparation and Microwave Absorption Property of Sr_2FeMoO_6 Powder

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Transactions of Nanjing University of Aeronautics and Astronautics 2017年第2期34卷 205-210页

作者： Feng Xiaomei Chen Jiankun Shen Yifu College of Materials Science and Technology Nanjing University of Aeronautics and Astronauticsnanjing 211106china

Double perovskite oxide Sr_2FeMoO_6 powder is prepared by a solid state reaction *** microwave absorption properties of Sr_2FeMoO_6 and paraffin wax composites are studied in the frequency range of 2—18GHz at room *** optimum absorption-36.7dB is achieved at 17.7GHz with a matching thickness of 5.0mm,which indicates that Sr_2FeMoO_6/paraffin composites can be potential microwave absorbers in a relatively high frequency *** excellent microwave absorption properties are attributed to the good electromagnetic match between dielectric loss and magnetic *** dielectric loss is considered to be caused by orientation polarization and interfacial polarization,while the magnetic loss is caused by natural resonance in the low frequency range,eddy current loss as well as exchange resonance in the high frequency range.

关键词： double perovskite solid state reaction microwave absorption property

Tuning surface active oxygen of lanthanum oxide via partial dissolution and regrowth of crystallites

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Journal of Natural Gas Chemistry 2011年第5期20卷 483-486页

作者： Zhiming Gao, Huili Li Key Laboratory of Cluster Science, Ministry of Education of China Department of Chemistry, School of Science, Beijing Institute of Technology, Beijing 100081, China Key Laboratory of Cluster Science Ministry of Education of China Department of Chemistry School of Science Beijing Institute of Technology Beijing 100081 China

A commercial lanthanum oxide was modified into X%-La2O3 samples via partial dissolution and regrowth of crystallites, wherein the X value denotes the weight percent of the initial metal oxide powder dissolved by nitric acid. BET measurements and TEM observations indicate that the 20%-La2O3 sample has an increased specific surface area, relatively thin and small crystallites in size. TPD/TPR profiles also show that the 20%-La2O3 sample has more surface active oxygen than the 0%-La2O3 sample. Among the four X%-La2O3 samples, the highest activity for methane oxidation was obtained over the 20%-La2O3 sample. Therefore, the present work proves that the method of partial dissolution and regrowth of crystallites are effective to modify surface property of lanthanum oxide.

关键词： solid state reaction surface oxygen crystallite regrowth TPR metal oxide

Luminescence properties of YAl_3(BO_3)_4 phosphors doped with Eu^(3+) ions

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Journal of Rare Earths 2008年第6期26卷 792-794页

作者：李桂芳曹全喜李智敏黄云霞 School of Technical Physics Xidian University

YAl3 （BO3）4： Eu^3＋ phosphors were prepared by the conventional solid state reaction. The phase structure and morphology were investigated by X-ray diffraction （XRD） and scanning electron microscope （SEM）. Doping YAl3（BO3）4： Eu^3＋ phosphors with concentration of Eu^3＋ ions of 0, 2, 5, 8 and 10 mol% were studied and their luminescent properties at room temperature were discussed. The excitation spectrum of Y0.95Eu0.05Al3（BO3）4 was composed of a broad band centered at about 252 nm and a group of lines in the longer wavelength region. In the emission spectra, the peak wavelength was about 614 nm under a 252 nm UV excitation. The optimal doping concentration of Eu^3＋ ions in YAl3（BO3）4： Eu^3＋ phosphors was 8 mol%.

关键词： YAl3(BO3)4:Eu^3+ solid state reaction luminescence phosphors rare earths