共查询到19条相似文献,搜索用时 78 毫秒
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ZnO是一种宽带隙Ⅱ-Ⅵ族半导体,具有良好的光电耦合特性和稳定性,在光、电、磁功能集成等新型器件方面可获得重要应用.近来的研究表明,过渡金属掺杂的ZnO基半导体有望成为实现高居里温度稀磁半导体的候选材料,是目前研究的热点.总结了近几年人们在Fe、Co、Ni、Cu、Mn等过渡金属掺杂的ZnO基稀磁半导体的发光特性研究结果,讨论了过渡金属掺杂后ZnO中观察到的可见发光机制,分析认为过渡金属掺杂ZnO的可见光发射主要与这些发光过渡金属引入后所产生的缺陷有关,而紫外发光峰的变化则与过渡金属掺入后ZnO晶体质量与禁带宽度的改变相关. 相似文献
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以碳酸锂、草酸亚铁、磷酸二氢铵、葡萄糖为原料,添加不同的过渡金属乙酸盐(乙酸锰、乙酸钴、乙酸镍、乙酸锌),在氩气保护下采用高温固相法制备LiFePO4/C复合材料.采用X射线衍射、扫描电子显微镜、同步热分析、恒电流充放电、电化学阻抗、循环伏安等方法研究掺杂金属离子及掺杂量对LiFePO4/C晶体结构和电化学性能的影响.结果表明,LiFe0.9M0.1PO4/C(M=Mn、Co、Ni、Zn)样品的晶体结构均与橄榄石型LiFePO4相同.掺杂过渡金属阳离子可以提高LiFeP04/C的还原电位,降低氧化电位,缩小氧化还原峰间距,提高化学反应的可逆性.掺杂后的样品在5C下的放电性能较好,以LiFe0.9Ni0.1PO4/C的放电容量最高,达到89 mAh/g. 相似文献
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以碳酸锂、草酸亚铁、磷酸二氢铵、葡萄糖为原料,添加不同的过渡金属乙酸盐(乙酸锰、乙酸钴、乙酸镍、乙酸锌),在氩气保护下采用高温固相法制备LiFePO_4/C复合材料。采用X射线衍射、扫描电子显微镜、同步热分析、恒电流充放电、电化学阻抗、循环伏安等方法研究掺杂金属离子及掺杂量对LiFePO_4/C晶体结构和电化学性能的影响。结果表明,LiFe_(0.9)M_(0.1)PO_4/C(M=Mn、Co、Ni、Zn)样品的晶体结构均与橄榄石型LiFePO_4相同。掺杂过渡金属阳离子可以提高LiFePO_4/C的还原电位,降低氧化电位,缩小氧化还原峰间距,提高化学反应的可逆性。掺杂后的样品在5C下的放电性能较好,以LiFe0.9Ni0.1PO4/C的放电容量最高,达到89mAh/g。 相似文献
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采用Sol—gel法制备了Ni^2+、Fe^3+和Cu^2+离子掺杂TiO2薄膜,并对其进行了XRD、AFM表征。通过对掺杂TiO2薄膜结构分析发现,过渡金属离子掺杂TiO2后并没有导致TiO2的晶型改变,但Ni^2+、Fe^3+和Cu^2+离子掺杂后使TiO2的晶格发生畸变,产生晶格缺陷,从而使TiO2晶体中电子浓度发生变化,影响光催化性能。 相似文献
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Ⅰ-Ⅲ-Ⅵ族多元量子点具有粒径尺寸小、半峰宽较宽、Stokes位移大、抗光漂白能力强、绿色环保等优异的物理化学性质,通过改变其化学成分可以实现发射范围在可见光到近红外光区域连续调谐,同时避免了Cd、Hg、Pb等重金属元素和Se、Te、P、As等剧毒阴离子的使用。上述优点使其成为替代传统二元量子点的理想材料,因此在太阳能电池、发光二极管、光探测器、生物成像等领域具有广阔的应用前景。与二元量子点相比,多元量子点由于含有多种不同类型的金属离子,存在金属离子反应速率不同的问题,使得晶体内部缺陷较多,因此荧光性能仍有待提高。掺杂过渡金属离子(例如Zn2+、Mn2+或Cu+)可有效调控多元量子点的带隙宽度,不仅可增大量子点的Stokes位移,还能促进辐射复合,从而有效拓宽发光范围,提高量子产率。本文详细阐述了掺杂型Ⅰ-Ⅲ-Ⅵ族多元量子点的发光机理,分别介绍了有机相和水相合成法制备该类型量子点的特点,通过有机相合成的多元量子点具有结晶性好、荧光量子产率高的优点,而水相合成的多元量子点具有安全环保、生物相容性好等明显优势。同时,本文综述... 相似文献
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采用改进的微乳液法制备了Fe、Co掺杂ZnO纳米材料,并对制备材料的结构和形貌分别进行了X射线衍射(XRD)及扫描电子显微镜(SEM)表征。为了明确温度对ZnO纳米材料光学性质的影响,使用温控仪进行降温操作,对制备的ZnO及Fe、Co掺杂ZnO材料进行了光学性质的对比研究,得到变温条件下Zn0及Fe、Co掺杂ZnO纳米... 相似文献
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利用酸催化的溶胶-凝胶法合成了一系列不同掺杂量的Fe3 /TiO2、Cr3 /TiO2纳米复合微粒.用XRD和TEM研究了Fe3 、Cr3 的掺杂对TiO2纳米粒子尺寸和相结构的影响.结果表明:掺杂离子不同,对TiO2纳米粒子尺寸和相结构的影响不同.在所研究的掺杂量范围内(x:0.0000~0.1000),TiO2纳米粒子的粒径随Cr3 掺杂量的增加呈减小的趋势,但幅度不大;而Fe3 的掺杂则会引起TiO2粒子的团聚和晶粒的长大;由XRD分析可知:在掺杂量范围内,不会发生Fe2O3、Cr2O3等相的偏析,但Fe3 的掺杂引起了TiO2在低温条件下由锐钛矿向金红石的相转变.通过UV-Vis光谱的研究发现:Fe3 、Cr3 的加入,可以使TiO2对光的吸收拓展到可见区,同时随着掺杂量的增加,对可见光的吸收强度显著增强. 相似文献
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Nikolai Gaponik Stephen G. Hickey Dirk Dorfs Andrey L. Rogach Alexander Eychmüller 《Small (Weinheim an der Bergstrasse, Germany)》2010,6(13):1364-1378
Some 25 years ago it was found that semiconductor nanocrystals emitted light. Since then tremendous progress has been made with respect to increasing the emission quantum yields, extending the spectral range that may be addressed, from the UV across to the near infrared, and improving the color purity. Here some major lines in these developments are reviewed, touching on milestones as well as on the principles of the most successful preparative approaches. 相似文献
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利用溶液腐蚀法制备了Mn2+、Ni2+、Fe3+、Cu2+离子掺杂的ZnO基稀磁半导体。XRD表明掺杂后的ZnO仍然保持单一的纤锌矿结构,没有任何杂质相产生。由紫外-可见光反射谱可知掺杂后吸收边发生了红移。掺杂前ZnO的带隙为3.20eV,对样品分别掺入Mn、Ni、Fe和Cu后的带隙分别为3.19eV、3.15eV、3.08eV和3.17eV。掺杂后样品的室温PL谱除了紫外发射峰外,对于Mn掺杂的样品还在蓝光区域出现了2个分别位于424nm和443nm的发射峰,Fe掺杂的样品出现了一个位于468nm的微弱发射峰,Cu掺杂的样品出现了位于469nm及535nm的很宽的发射峰。室温磁滞回线显示掺杂后样品有明显的铁磁性,掺入Mn、Ni、Fe和Cu样品的剩余磁化强度(Ms)分别为0.3902×10-3emu/cm3、0.454emu/cm3、0.372emu/cm3和0.962×10-3emu/cm3,矫顽力分别为47Oe、115.92Oe、99.33Oe和23Oe。经分析室温铁磁性来源于缺陷调制的Mn2+-Mn2+长程铁磁交换相互作用。 相似文献
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Near‐Unity Emitting Copper‐Doped Colloidal Semiconductor Quantum Wells for Luminescent Solar Concentrators 下载免费PDF全文
Manoj Sharma Kivanc Gungor Aydan Yeltik Murat Olutas Burak Guzelturk Yusuf Kelestemur Talha Erdem Savas Delikanli James R. McBride Hilmi Volkan Demir 《Advanced materials (Deerfield Beach, Fla.)》2017,29(30)
Doping of bulk semiconductors has revealed widespread success in optoelectronic applications. In the past few decades, substantial effort has been engaged for doping at the nanoscale. Recently, doped colloidal quantum dots (CQDs) have been demonstrated to be promising materials for luminescent solar concentrators (LSCs) as they can be engineered for providing highly tunable and Stokes‐shifted emission in the solar spectrum. However, existing doped CQDs that are aimed for full solar spectrum LSCs suffer from moderately low quantum efficiency, intrinsically small absorption cross‐section, and gradually increasing absorption profiles coinciding with the emission spectrum, which together fundamentally limit their effective usage. Here, the authors show the first account of copper doping into atomically flat colloidal quantum wells (CQWs). In addition to Stokes‐shifted and tunable dopant‐induced photoluminescence emission, the copper doping into CQWs enables near‐unity quantum efficiencies (up to ≈97%), accompanied by substantially high absorption cross‐section and inherently step‐like absorption profile, compared to those of the doped CQDs. Based on these exceptional properties, the authors have demonstrated by both experimental analysis and numerical modeling that these newly synthesized doped CQWs are excellent candidates for LSCs. These findings may open new directions for deployment of doped CQWs in LSCs for advanced solar light harvesting technologies. 相似文献
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《Journal of Experimental Nanoscience》2013,8(14):1082-1092
White light generation is achieved by single-step co-doping of copper and manganese into the robust ZnSe quantum dots (QDs) which were synthesised using a wet chemical route. Photoluminescence (PL) emission spectra revealed three peaks related to blue (ZnSe), green (copper related) and orange (manganese related). The PL spectra indicated no surface and/or trap state related emission. Photoluminescence excitation (PLE) measurements confirmed co-doping of copper and manganese in the same QD. PLE spectra recorded with emission wavelength fixed at copper and manganese showed a band edge at the same position, indicating the incorporation of both copper and manganese in the same QD. Time-resolved PL measurements suggest an atomic like nature of Mn and Cu in ZnSe QDs. 相似文献
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