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Crystal structure,morphology and luminescent properties of rare earth ion-doped SrHPO4 nanomaterials
Undoped and rare earth ions(Eu3+, Ce3+, Tb3+) doped β-Sr HPO4 nanomaterials were successfully prepared by a facile hydrothermal method. The crystal structure, morphology and luminescent properties were characterized by X-ray powder diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), photoluminescence(PL) spectra and luminescence decay curves. The results indicated that the undoped and rare earth ions doped Sr HPO4 nanomaterials(the doping concentration was not above 7%) were well crystallized, with the same crystal structure(β-Sr HPO4). Nevertheless, the doping of rare earth ions could lead to the changing of morphology from nanoflakes to nanocrystals. Under the excitation of UV light, rare earth ions(Eu3+, Ce3+, Tb3+) doped β-Sr HPO4 nanocrystals exhibited the characteristic emission of Eu3+, Ce3+ and Tb3+ ions, respectively. The luminescence decay curves of β-Sr HPO4:Eu3+ and β-Sr HPO4:Ce3+,Tb3+ nanocrystals conformed to the double exponential fluorescence decay, and the average lifetimes were 1.14 and 4.12 ms, respectively. The luminescence decay curve of β-Sr HPO4:Ce3+ was fitted into a single exponential function, and the lifetime was about 0.78 ns. 相似文献
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某钢筋混凝土拱桥的健康检测及安全评估 总被引:1,自引:0,他引:1
某钢筋混凝土拱桥使用近30年,已不确定结构是否处于安全使用状态。通过无损检测和现场静力荷载试验,对整桥进行全面健康检测,安全评估分析认为该桥安全储备不足,需要进行维修加固。 相似文献
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浅谈禹州市学校防雷工作现状与防御对策 总被引:1,自引:0,他引:1
本文结合禹州市目前的学校防雷工作现状,总结分析了近年来禹州市在学校防雷工作的主要做法、经验以及当前工作中存在的问题,提出了今后建立健全防雷减灾工作责任制。二是制定落实应急措施加强学校防雷工作的思路及措施:进一步消除了学校防雷设施存在隐患,确保了学校师生及教学设施的安全。 相似文献
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Monodispersed and water-soluble TbF3 nanoparticles were synthesized at a relatively low temperature in aqueous solution using citric acid as an additive,and characterized by X-ray diffraction(XRD),field emission scanning electron microscopy(FE-SEM),Fourier transform infrared spectra(FTIR),photoluminescence(PL) spectra and lifetime.The as-prepared TbF3 nanoparticles had orthorhombic structure and were composed of monodispersed spherical particles with an average particle size of 50 nm.The excitation spectrum... 相似文献
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介绍了嘉陵江上某特大桥原状及病害情况,分析了裂缝类型及产生原因,针对裂缝成因提出不同的处理方法,对病害中预制构件与现浇砼之间存在的脱粘现象,讨论了解决的办法,最后介绍了拱桥的加固措施,为同类桥梁的病害治理提供了成功的经验。 相似文献
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为了探究颗粒堆积结构变化对近壁面颗粒传热过程的影响,构建了近壁面两颗粒的非稳态传热模型,研究了不同初始温度条件下颗粒组合角度变化对近壁面颗粒传热特性的影响规律。结果表明:初始温度越高,所需换热时间越长,颗粒组合角度增加,使得换热时间明显减少。初始温度为1073K时,换热面平均热流密度值呈先迅速下降后缓慢下降的趋势。同一时刻,组合角度越大,颗粒平均温度越低。不同组合角度颗粒的固相传热率均达到0.8以上。颗粒组合角度越大,固相传热占比越小,辐射传热占比越大。在换热前期,辐射传热率最高可达0.57,对传热过程的影响不可忽略。 相似文献