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| 1 | Effect of doped strontium on catalytic properties of La_(1-x)SrxMnO_(3) for rhodamine B degradation显示文摘A series of La_(1-x)Sr_(x)MnO_(3) samples were prepared by sol-gel method and used to degrade rhodamine B(RhB) in water.All samples were characterized by X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),N_(2) adsorption-desorption,temperature-programmed reduction of H_(2)(H_(2)-TPR) and temperature-programmed desorption of O_(2)(O_(2)-TPD).The results show that the degradation of RhB is highly dependent on the initial pH value of solution.Sr doping enhances the degradation ability of LaMnO_(3) for RhB in the time range of 0-40 min under a strong acidic environment,but all samples exhibit similar degradation rate from 40 to 60 min.In La_(0.7)Sr_(0.3)MnO_(3)-RhB reaction system,there are two different degradation pathways,including N-de-ethylation,chromophore cleavage,ring-opening and mineralization.La_(1-x)Sr_(x)MnO_(3)(x ≤0.3) has the perovskite structure of La-Mn oxides,while La_(0.6)Sr_(0.4)MnO_(3) exhibits a Sr_(0.4)MnLa_(0.6)O_(2).98 perovskite phase.Sr doping leads to distortion of rhombohedral crystal structure and increases the relative content of Mn^(4+).The perovskite structure is stable in strong acidic environment during RhB degradation,but the relative content of Mn^(4+)and Mn^(3+) on the material surface changes.Sr doped LaMnO_(3) achieves specific surface area of 58.8 m^(2)/g and total pore volume of 0.152 cm^(3)/g.Furthermore,Sr^(2+)doping improves redox properties of La-Mn oxides,and the presence of defects makes oxygen diffusion easier compared with the undoped samples. | Jiaxiu Guo YueJing Ting Shen Hongdi Luo Juan Liang Shandong Yuan | 2021 | Journal of Rare Earths2021，39，11： | 2 |
| 2 | CaTiO_(3)-Sm_(0.9)Nd_(0.1)AlO_(3) ceramics with a moderate dielectric constant and a high quality factor prepared by sol-gel auto combustion method显示文摘CaTiO_(3)-LnAlO_(3)(Ln=La,Nd,Sm) is a perovskite-type microwave material system characterized by a moderate dielectric constant εr,a high quality factor Q×f,and a small temperature coefficient of resonant frequency τf,making this system promising for microwave devices.However,its high synthesis temperature and sintering temperature limit its industrial applications.In our work,single phase0.7 CaTiO_(3)-0.3 Sm_(0.9)Nd_(0.1)AlO_(3)(7 CT-3 SNA) was synthesized via the sol-gel auto combustion method using citric acid as fuel at a relatively low temperature.After being calcined at 600℃ for 2 h,wellcrystallized 7 CT-3 SNA powders with 30-50 nm average particle size were achieved,suggesting good sintering activity.The new and narrow order band at about 800 cm^(-1) in the Raman spectra indicates a high ordering degree in the B site of 7 CT-3 SNA solid solution.Compared with the solid-state reaction method and co-precipitation method,the 0.7 CT-0.3 SNA ceramics fabricated by the current method possess a much lower calcination temperature,a similar εr value,and an improved Q × f value.The optimum microwave dielectric properties of εr=43.54,Q×f=54375 GHz,and τf=-6.3 ×10^(-6)/℃ are obtained for the CTSA ceramics derived from the sol-gel auto combustion process.Therefore,the 7 CT-3 SNA ceramics prepared in this study are potential dielectric materials for microwave applications,indicating that the sol-gel auto combustion method is a good alternative strategy for the fabrication of CaTiO_(3)-LnAlO_(3) ceramics. | Jiamao Li Minghu Wei Chenghao Wu Shengdao Tang | 2021 | Journal of Rare Earths2021，39，11： | 1 |
| 3 | Kinetics process of room temperature phosphorescence and fluorescence of gadolinium porphyrin in aqueous solution显示文摘The behavior of room temperature phosphorescence quenching and fluorescence enhancing of gadolinium labeled sinoporphyrin sodium(Gd-DVDMS) in the aqueous solution were studied.Gd-DVDMS was characterized by various techniques including mass spectra,Fourier transform infrared spectra and transmission electron microscopy.The optical behavior was monitored through UV-vis absorption spectra and photoluminescence spectra.The result shows that the phosphorescence intensity gradually quenches,almost disappears after dissolved 120 min,meanwhile the fluorescence intensity enhances 5 times.The above behavior is attributed to the decreased population of Gd-DVDMS as first excited triplet state(T1),Based on the time-invariant of both absorption spectra and phosphorescence decay curves at710 nm of Gd-DVDMS in different dissolution time,the reason for the decreased population of GdDVDMS in T1 state is that the intersystem crossing from first excited state(S1) to T1 is prevented.In addition,the fluorescent decay curves of Gd-DVDMS initially dissolved in the aqueous solution and dissolved for 120 min were also measured for comparison.The big change in fluorescent lifetime further proves the conclusion that intersystem crossing is prevented,meanwhile,the increase in fluorescence intensity is demonstrated.In this work,the possibility of decomposition of Gd-DVDMS is excluded because the phosphorescence decay curve in Gd-DVDMS aqueous solution is sensible to DVDMS. | Ting Liu Xiyu Zhang Honglin Zhang Hua Zhao Zhiguo Zhang Ye Tian | 2021 | Journal of Rare Earths2021，39，10： | 0 |
| 4 | Mn掺杂LaNi_(1-x)Mn_(x)O_(3)的合成及在可见光下的光催化活性显示文摘采用溶胶-凝胶法制备LaNi_(1-x)Mn_(x)O_(3)(x=0,0.2,0.4,0.6,0.8,1.0)钙钛矿型氧化物光催化材料,借助X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、光电子能谱(XPS)等现代分析测试手段表征LaNi_(1-x)Mn_(x)O_(3)的物相、微观形貌及分子振动与键能的变化,并以可见光下对甲基橙的降解率为指标评价其光催化性能。结果表明,Mn掺杂使衍射峰向低角度偏移,引起晶格扩张,导致LaNi_(1-x)Mn_(x)O_(3)晶体粒径增大;掺杂后Mn^(4+)/Mn^(3+)与Oads/Olatt的峰面积比例增加,提高了催化剂的氧化能力、界面电子转移率和表面吸附氧的数量,进而使其光催化活性提高;当Mn掺杂量为40%时,获得的LaNi_(0.6)Mn_(0.4)O_(3)具有最优的光催化性能,可见光照射120 min对甲基橙的降解率高达99.46%,循环利用五次后降解率仍可达86.97%,这表明LaNi_(0.6)Mn_(0.4)O_(3)具有较好的稳定性和循环利用性。在光催化降解过程中自由基活性按从高到低排序为:h^(+)、e^(-)、·OH。 | 曾鹂 彭同江 孙红娟 李瑶 杨敬杰 | 2021 | 材料导报2021，35，24： | 0 |
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