In this paper we report structural and optical properties of Magnesium substituted Zinc Oxide (Zn1-xMgxO) nanocrystals (~10-12nm) synthesized by low temperature route. In the low temperature synthesis route it was possible to reach x = 0.17 without segregation of Mg rich phase. The exact chemical composition has been established by quantitative analysis. Rietveld analysis of the XRD data confirms the Wurzite structure and a continuous compaction of the lattice (in particular the c-axis parameter) as x increases. There is an enhancement of the strain in the lattice as the Mg is substituted. The bandgap also gets enhanced as x is increased and reaches a value of 4eV for x = 0.17. From the TEM and the XRD data it has been concluded that when there is a phase segregation for x > 0.17, there is a shell of Mg(OH)2 on the ZnO. The absorption also shows persistence of the excitoinc absorption on Mg substitution. The nanocrystals show near band edge photo luminescence (PL) at room temperature which shows blue shift on Mg incorporation. In addition to the near band edge emission the ZnO and Zn1-xMg xO alloy nanocrystals show considerable emission in the blue-green region at wavelength of ~550 nm. We find that the relative intensity of the green emission increases with the Mg concentration for very low x (upto x = 0.05) and on further increase of the Mg concentration there is a sharp decrease of relative intensity of the green emission eventually leading to a complete quenching of blue emission. It is concluded that due to phase segregation (for x \geq 0.20), the formation of the shell of Mg(OH)2 on the ZnO leads to quenching of the green emission .However, this shell formation does not have much effect on the near band edge PL.
Structural fingerprinting in the transmission electron microscope: Overview and opportunities to implement enhanced strategies for nanocrystal identification
Structural, magnetic, and optical properties of zinc- and copper- substituted nickel ferrite nanocrystals
铁氧体纳米晶由于其丰富的物理性质而成为人们感兴趣的材料。在这里,我们将掺杂剂Zn和Cu添加到镍铁氧体纳米晶体Ni 1-xMxFe 2 O 4(0<=x<=1,M{ \in }{Cu,Zn})中,并表征样品的相关性质如何相应地改变。基本上,这些掺杂导致Fe+3离子重排到两个预先存在的八面体和四面体位置。事实上,这,我们表明,诱导相关的磁性掺杂样品。在Cu掺杂的情况下,Jahn-Teller效应也出现了,我们通过样品的FTIR光谱来识别。此外,我们发现掺杂样品的晶格参数增加,以及掺杂样品的超顺磁性行为,而Jahn-Teller效应排除了CuFe 2 O 4纳米晶体中类似的行为。采用室温光致发光法研究了Zn和Cu掺杂对镍铁氧体纳米晶光学性质的影响。
Impact of the Ligand Shell on Structural Changes and Decomposition of All-Inorganic Mixed-Halide Perovskite (CsPbX3) Nanocrystals under X-Ray Illumination
Nucleation of Al Nanocrystals in Solute-Substituted Al Metallic Glasses I: Structural characterization
高Al含量金属玻璃中的一次晶化是由内部结构类似于面心立方Al的纳米尺度区域驱动的。通过比较涨落电子显微镜(FEM)数据和FEM模拟的面心立方Al团簇在致密随机堆积基质中的分布,提取Al 88 Y 7 Fe 5基础玻璃和Al含量为1 at.%的玻璃中有序区域的直径和体积分数Cu替代Y或Al。纳米晶体的尺寸和密度作为等温退火时间的函数,对于相同的合金进行测量。在等温退火条件下,晶相的体积分数增加,相变不是单纯的晶粒粗化,而是晶相的体积分数低于淬火态样品中有序区的体积分数,因此并非所有有序区都起到晶核的作用。合金化有序区域的直径和体积分数的变化与结晶温度、成核速率和结晶密度的变化相关。没有观察到相分离的证据,相似组成的分子动力学淬火结构模型的FEM模拟没有显示实验中观察到的特征。
Structural, Dielectric, and Electrical Transport Properties of Al3+ Substituted Nanocrystalline Ni-Cu Spinel Ferrites Prepared Through the Sol-Gel Route
Synthesis and Structural Analysis of an Emissive Colloidal Argyrodite Nanocrystal: Canfieldite Ag8SnS6
Istituto Italiano di Tecnologia(意大利理工大学);University of Toronto(多伦多大学);Concordia University(康考迪亚大学);Momentum Transfer GmbH(Momentum Transfer有限公司);University of Toronto, Department of Materials Science and Engineering(多伦多大学材料科学与工程系)
Magnetic, Optoelectronic, and Rietveld refined structural properties of Al3+ substituted nanocrystalline Ni-Cu spinel ferrites: An experimental and DFT based study
PEG- and PVP-assisted wet-chemical synthesis of ZnS nanocrystals via hydrothermal and co-precipitation methods for route-dependent structural and bandgap tuning
Ghulam Ishaq Khan Institute of Engineering Sciences and Technology(古拉姆·伊沙克汗工程科学与技术学院);University of Illinois Urbana-Champaign(伊利诺伊大学厄巴纳-香槟分校)
Operando pair distribution function analysis of nanocrystalline functional materials: the case of $\mathrm{TiO_{2}}$-bronze nanocrystals in Li-ion battery electrodes
本文提出并应用一个 PDF 分析工具箱,对锂离子电池中 3 nm TiO₂-青铜纳米晶体的非原位与 operando 数据建模,识别原始及嵌锂相并刻画循环中的相演化。
Sinusoidal Displacement Describes Disorder in CsPbBr3 Nanocrystal Superlattices
Istituto Italiano di Tecnologia(意大利理工大学);Università Cattolica del Sacro Cuore(天主教大学);Lund University(隆德大学);Massachusetts Institute of Technology(麻省理工学院);Istituto di Cristallografia (CNR-IC)(晶体学研究所(国家研究委员会));MAX IV Laboratory(MAX IV 实验室)
Synthesis of La0.5Ca0.5-x xMnO3 nanocrystalline manganites by sucrose assisted auto combustion route and study of their structural, magnetic and magnetocaloric properties
采用蔗糖改性自燃烧法制备了高锰酸盐La0.5Ca0.5-xxMnO 3(LCMO)纳米材料。晶体结构的X射线衍射图的Rietveld细化证实了具有Pbnm空间群的单相斜方晶系(No.62)。在LCMO结构中自愿产生Ca空位,以研究它们对系统中磁行为的影响。磁化率被发现是高度增强的样品与Ca-空位。在254 K附近,两种样品都发生了顺磁-铁磁相变。这种转变的特点是,在样品中的钙空位的磁化率的急剧跳跃。在6 T的磁场下,两种化合物的最大熵变分别为2.30 J kg ~(-1)K ~(-1)和2.70 J kg ~(-1)K ~(-1)。间接法计算的磁热绝热温度变化值为5.6 K和5.2 K的非空位和Ca空位化合物,分别为。在这项工作中报道的Ca-空隙La0.5Ca0.5-xxMnO 3(x=0.05)的磁热效应比LCMO的整体增强。制备LCMO材料的技术有利于提高磁热效应和磁行为。因此,我们得出结论,这种成本较低的环境友好系统可以被认为是磁制冷应用的更有利的候选人,然后通常的Gd基化合物。
Exciton Transport in Disordered Perovskite Nanocrystal Solids
Condensed Matter Physics Center, IFIMAC, Universidad Autónoma de Madrid(马德里自治大学凝聚态物理中心IFIMAC);Departamento de Física de la Materia Condensada, Facultad de Ciencias, Universidad Autónoma de Madrid(马德里自治大学理学院凝聚态物理系);Instituto de Ciencia de Materiales de Madrid, ICMM, Consejo Superior de Investigaciones Científicas, CSIC(西班牙国家研究委员会马德里材料科学研究所ICMM);Departamento de Química Inorgánica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid(马德里康普顿斯大学化学学院无机化学系)
Transformation-mediated twinning governs plasticity in body-centered cubic nanocrystals under extreme loading
University of West Bohemia in Pilsen(西波希米亚大学);University of Helsinki(赫尔辛基大学);National Centre for Nuclear Research(国家核研究中心);Universitat Politècnica de Catalunya(加泰罗尼亚理工大学)
Dye-Sensitized Ternary Copper Chalcogenide Nanocrystals: Optoelectronic Properties, Air Stability and Photosensitivity
我们报告的铜硫硒化物以及硒化铜纳米晶体与有机π系统钴β-四氨基酞菁的配体交换的效果,并分析这些混合材料的薄膜的结构,光学和电学性质的变化。紫外-可见吸收光谱和拉曼光谱表明配体与纳米晶表面有很强的相互作用。掠入射小角度X射线散射研究表明,在配体交换后,粒子间距离显着收缩。对于缺铜的硒化铜,这种收缩对电传输的影响可以忽略不计,而对于缺铜的硫化硒化铜,电导率增加了8个数量级,并导致类似金属的温度依赖性传输。我们讨论了这些差异,在光的电子与离子传输在两种材料中的不同贡献,并强调其在环境条件下的传输性能的稳定性的影响。与光电流测量,我们证明了高的光响应度为200-400 A W-1的酞菁封端的硫化硒化铜,并强调在这方面的有机π-系统,作为一个电子连接器和光敏剂在同一时间的有益作用。
Healing of topological defects while crystallizing nanocrystals
Facultad de Ciencias Físico, Matemáticas y Naturales, Universidad Nacional de San Luis(圣路易斯国立大学物理、数学和自然科学学院);Instituto de Física Aplicada, CONICET(阿根廷国家科学研究委员会应用物理研究所);Condensed Matter Theory group, Centro Atómico Bariloche, CNEA(阿根廷核能委员会巴里洛切原子中心凝聚态理论组);Instituto Balseiro, CNEA and Universidad Nacional de Cuyo(阿根廷核能委员会巴尔塞罗研究所和门多萨国立大学);Low Temperatures Lab, Centro Atómico Bariloche, CNEA(阿根廷核能委员会巴里洛切原子中心低温实验室);Instituto de Nanociencia y Nanotecnología, CONICET-CNEA, Nodo Bariloche(阿根廷国家科学研究委员会-核能委员会纳米科学与技术研究所巴里洛切节点)