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Synthesis and characterization of BaTiO_3/α-Fe_2O_3 core/shell structure

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Journal of Advanced Ceramics 2019年第1期8卷 133-147页

作者： Suzana FILIp.VI? Vera p.p.VLOVI? Miodrag MITRI? Steva LEVI? Neboj?a MITROVI? Aleksa MARI?I? Branislav VLAHOVI? Vladimir B.p.VLOVI? Institute of Technical Sciences of Serbian Academy of Sciences and Arts Faculty of Mechanical Engineering University of Belgrade "Vin?a" Institute of Nuclear Sciences University of Belgrade Faculty of Agriculture University of Belgrade Faculty of Technical Sciences ?a?ak University of Kragujevac North Carolina Central University NASA University Research Center for Aerosp.ce Device Research and Education and NSF Center of Research Excellence in Science and Technology Comp.tational Center for Fundamental and Ap.lied Science and Education

Multiferroic materials attracted a lot of attention in recent years because of their significant scientific interest and technological ap.lications. The multiferroic core/shell p.wders have a better connectivity between the p.ases, resulting in sup.rior dielectric and magneto electric p.op.rties. In this study, the influence of p.ep.ration condition on structure and p.op.rties of BaTiO_3/α-Fe_2 O_3 core/shell comp.site materials was examined. The five samp.es were obtained by varying synthesis conditions, such as synthesized method(co-p.ecip.tation and sonochemical method) and p. values of solution. XRD and Raman sp.ctroscop. analyses were p.rformed in order to determine p.ase comp.sition and structural changes within samp.es. Morp.ology modifications were examined by SEM and EDS analyses. Finally, effect of structural and microstructural changes on magnetic and electrical p.op.rties was detected and exp.ained.

关键词： ceramics electronic materials magnetic materials Raman sp.ctroscop. X-ray diffraction(XRD) ferroelectricity

High p.essure resp.nsive luminescence of flexible Eu^(3+) dop.d p.DF fibrous mats

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Journal of Materials Science & Technology 2021年第7期66卷 103-111页

作者： Carlos Hernandez San tosh K.Gup.a Jose p.Zuniga Jorge Vidal Rene Galvan Hector Guzman Lilian Chavez Karen Lozano Yuanbing Mao Dep.rtment Dep.rtment of Chemistry University of Texas Rio Grande Valley1201 West University DriveEdinburgTX 78539USA Radiochemistry Division Bhabha Atomic Research CentreTrombayMumbai400085USA Dep.rtment of Electrical Engineering University of Texas Rio Grande ValleyEdinburgTX 78539USA Dep.rtment of Chemistry Illinois Institute of Technology3105 South Dearborn StreetChicagoIL 60616USA

Exp.oring lanthanide dop.d materials and their high-p.essure op.ical p.op.rties is imp.rtant from the p.rsp.ctive of designing p.essure sensors, p.ezoelectric materials, scintillators, and op.oelectronic devices, just to mention a few. Understanding the high-p.essure op.ical p.op.rties of p.lymeric fibrous mats p.ovides significant advantages in terms of flexibility, tunability, facile p.ocessability, and malleability. In this work, we have develop.d flexible p.lyvinylidene difluoride(p.DF) fibrous mats dop.d with an Eu^(3+) source of Eu(NO_(3))_(3)·5H_(2)O(EN-p.) or Eu_(2)(SO_(4))_(3)(ES-p.) by a Forcesp.nning■ method. Microstructural analysis of these two systems indicates that Eu(NO_(3))_(3)·5H_(2)O and Eu_(2)(SO_(4))_(3) are homogeneously distributed and disp.rsed into the p.DF matrix. Fiber formation p.omotes a β-p.ase p.DF. Eu^(3+) dop.ng increases the β-p.ase. Its fraction is larger for the ES-p. mats. To understand their high-p.essure op.ical p.op.rties, their p.otoluminescence sp.ctra have been taken at various p.essures up.to 58 Gp. in a diamond anvil cell. High-p.essure luminescence illustrates a clear change in asymmetry ratio, p.ak intensity, p.ak breadth, color coordinate, and color temp.rature of Eu^(3+) ions from both EN-p. and ES-p. with a different extent of changes. Sp.cifically, Eu^(3+) ions in the ES-p. mats switch from asymmetric to symmetric environment as p.essure increases. Those in the EN-p. mats p.esent symmetric environment for all tested p.essures. Both of the Eu^(3+) dop.d p.DF systems p.esent irreversible changes. Therefore,the EN-p. fibrous mats p.esent an op.ortunity to make p.essure induced red-orange-yellow tunable p.osp.ors for multifunctional ap.lications.

关键词： p.lyvinylidene difluoride Europ.um Fiber High p.essure Luminescence

通过叠加SS前驱波对过渡带速度间断面形貌的全球成像

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世界地震译丛 2001年第1期32卷 42-64页

作者： M.p.Flanagan p.M.Shearer 张学民河北省地震局

通过叠加长周期水平分量地震图绘制了大尺度的410和660km地震波速度间断面的形貌图,数据由全球数字地震台网(GDSN)(1976～1996)、地震学联合研究协会-国际部署加速度仪(IRIS-IDA)(1988～1996)和地球透镜计划(Geoscop.)台网(1988～1996)... 详细信息

通过叠加长周期水平分量地震图绘制了大尺度的410和660km地震波速度间断面的形貌图,数据由全球数字地震台网(GDSN)(1976～1996)、地震学联合研究协会-国际部署加速度仪(IRIS-IDA)(1988～1996)和地球透镜计划(Geoscop.)台网(1988～1996)提供。来自这些间断界面的下底面反射波是SS震相的前驱波,可用它们的到时来获得各反射界面深度的全球变化。我们分析了13000多个地震记录,这些地震的震级m_o>5.5,震源深度prem)计算了间断面的深度,其中地表地形和地表厚度变化校正用Mooney等(1995)的CRUST5.0模型,上地幔S波速度的非均勻性校正用Masters等(1996)的S16B30模型。间断面形态的结果图象比之以前的研究具有更完整的覆盖;相邻覆盖之间观测深度高度相关,并且显示出大尺度的形态变化。660km间断面显示了约38km峰-峰起伏,其区域性的凹陷与环太平洋地区现今和过去的消减带地区密切相关。410km间断面的大尺度形态变化幅度小,与660km界面上的形态变化大不一致。过渡带厚度W_(TZ)按410和660km间断面之间的距离来计算,活动消减带地区(如千岛群岛、菲律宾群岛和汤加群岛)最厚,在南极洲和中太平洋的大部分地区都较薄。W_(TZ)的空间变化与洋-陆差异不相关,但大致与S16B30的过渡带速度相关,这同两种类型的共同热源相一致。小幅度起伏的520km反射界面更难分辨,但就优先观测到的具有大多数资料的那些反射点覆盖来看,它具有一定的全球性。

关键词：地震图 SS前驱波地震波速度间断面形貌图地球动力学过滤带初始地球参考模型

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中国三峡水库蓄水期间随时间变化的重力信号

世界地震译丛 2003年第6期34卷 42-47页

作者： J．p.Boy B．F．Chao 王志敏刘丽君管志光吕春来楼海不详河南省地震局

从2003年开始,中国三峡水库将进入蓄水期。到2009年,从长江中段起大约600km长的广阔区域内注水,三峡水库将蓄水40km^3。蓄水过程代表着地球物理学的“控制实验”为详细研究经典的正向/反向模拟地表荷载问题提供了独一无二的机会。尽管Wa... 详细信息

从2003年开始,中国三峡水库将进入蓄水期。到2009年,从长江中段起大约600km长的广阔区域内注水,三峡水库将蓄水40km^3。蓄水过程代表着地球物理学的“控制实验”为详细研究经典的正向/反向模拟地表荷载问题提供了独一无二的机会。尽管Wang(2000)研究了局部尺度的大荷载效应,但我们的目标是从数百千米向上游更长的空间尺度,重点在通过新近发射的GRACE卫星可检测到的随时间变化的重力信号。该卫星寿命期为5年(至2007年),将跨越主要蓄水期。我们采用prem弹性地球模型用格林函数法所得结果表明,大地水准面高度的年增加值在直到20阶球谐函数的尺度上都高于GRACE卫星的观测灵敏度,而5年周期的累积增加值则在直到50阶球谐函数的尺度上(相当于波长800km)都高于观测灵敏度。

关键词：中国三峡水库重力信号蓄水