Phase- and Size-Controlled Synthesis of Hexagonal and Cubic CoO Nanocrystals

Seo, Won Seok; Shim, Jae Ha; Oh, Seung Jin; Lee, Eun Kwang; Hur, Nam Hwi; Park, Joon T.

doi:10.1021/ja050359t

Cited by 228 publications

(209 citation statements)

References 15 publications

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“…We found new Bragg spots indicated by yellow arrowheads in Fig. 4B and C, which were indexed by the (111) spacing of 2.63 Å and (220) spacing of 1.51 Å of CoO, respectively (Seo et al, 2005). From the measurements of the lattice spacing in diffraction patterns, we can determine the actual temperature of the specimens in the TEM, rather than relying on the set (input) temperature in the heating controller.…”

Section: Methodsmentioning

confidence: 97%

Structural and Morphological Changes of Co Nanoparticles and Au-10at.%Pd Thin Film Studied by in Situ Heating in a Transmission Electron Microscope

Ji¹,

Park

2017

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The microstructural changes in Co nanoparticles and an Au-10at.%Pd thin film have been investigated using an in situ heating holder with a micro-electro-mechanical system (MEMS). In Co nanoparticles, two phases (face-centered cubic and hexagonal closepacked crystal structures) were found to coexist at room temperature and microstructures at temperatures, higher than 1,000°C, were observed with a quick response time and significant stability. The actual temperature of each specimen was directly estimated from the changes in the lattice spacing (Bragg-peak separation). For the Au-10at.%Pd thin film, at a set temperature of 680°C, the actual temperature of the sample was estimated to be 1,020°C±123°C. Note that the specimen temperature should be carefully evaluated because of the undesired effects, i.e., the temperature non-uniformity due to the sample design of the MEMS chip, and distortion due to thermal expansion.

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Section: Methodsmentioning

confidence: 97%

Structural and Morphological Changes of Co Nanoparticles and Au-10at.%Pd Thin Film Studied by in Situ Heating in a Transmission Electron Microscope

Ji¹,

Park

2017

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“…CoO nanocrystals with various sizes and morphologies have been synthesized via several chemical synthetic procedures [23][24][25][26][27], including the thermal decomposition of organometallic compounds such as Co 2 (CO) 8 [28], Co(II) cupferronate [29], and Co(acac) 3 (acac = acetylacetonate) [30] or metal-oleate complexes [31]. There have been fewer reports of LiCoO 2 nanocrystals with well-defined crystal morphologies due to the synthetic difficulties involved in preparing such materials [32].…”

Section: Introductionmentioning

confidence: 99%

Shape control of CoO and LiCoO2 nanocrystals

Wang

et al. 2010

Nano Res.

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Shape control of nanocrystals has become a significant subject in materials science. In this work, we describe a convenient way to achieve morphology-controllable synthesis of CoO nanocrystals including octahedrons and spheres as well as LiCoO 2 polyhedrons and spheres. In particular, we explain the formation of CoO octahedrons exposing only high-energy (111) facets using theoretical calculations; these should also be a useful tool for directing future face-controlled preparation of other nanocrystals. More importantly, the as-obtained LiCoO 2 nanocrystals showed different electrochemical performance depending on their morphology, indicating that Li-insertion/deintercalation dynamics might be crystal face-sensitive.

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“…Because different shapes and crystallographic forms are generally believed to be responsible for their widely varying electrical and optical properties, fabricating transition metal oxide architectures with controlled structures and morphologies is highly desirable. [1][2][3][4][5][6][7][8] However, methods to manipulate these nanostructures often include the use of templates, which have to be removed after the reaction. [7,8] Thus, to create spontaneous generation of novel patterns with tailored structures and shapes by a template-free and simple method remains a challenge.…”

Section: Introductionmentioning

confidence: 99%

Hydrothermal Synthesis of Structure‐ and Shape‐Controlled Manganese Oxide Octahedral Molecular Sieve Nanomaterials

Yuan

Shen

et al. 2006

Adv Funct Materials

218

127

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Highly uniform single‐crystal Na‐OMS‐2 (OMS: octahedral molecular sieve), pyrolusite, and γ‐MnO2 nanostructures with an interesting 3D urchinlike morphology have been successfully prepared using a hydrothermal method based on a mild and direct reaction between sodium dichromate and manganese sulfate. The crystal phases, shapes, and tunnel sizes of the manganese dioxide nanostructures can be tailored. Reaction temperature, concentrations of the reactants, and acidity of the solution play important roles in controlling the synthesis of these manganese dioxides. Field‐emission scanning electron microscopy and transmission electron microscopy (TEM) studies show that the nanomaterials obtained are constructed of self‐assembled nanorods. X‐ray diffraction and TEM results indicate that the constituent manganese dioxide particles are single‐crystalline materials. Energy dispersive X‐ray analysis and magnetic studies imply that chromium cations may be incorporated into the framework and/or tunnels of the manganese dioxides. A mechanism for the growth of manganese dioxides with urchinlike architectures is proposed.

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Phase- and Size-Controlled Synthesis of Hexagonal and Cubic CoO Nanocrystals

Cited by 228 publications

References 15 publications

Structural and Morphological Changes of Co Nanoparticles and Au-10at.%Pd Thin Film Studied by in Situ Heating in a Transmission Electron Microscope

Structural and Morphological Changes of Co Nanoparticles and Au-10at.%Pd Thin Film Studied by in Situ Heating in a Transmission Electron Microscope

Shape control of CoO and LiCoO2 nanocrystals

Hydrothermal Synthesis of Structure‐ and Shape‐Controlled Manganese Oxide Octahedral Molecular Sieve Nanomaterials

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