Crystallization of nanostructured cobalt hydroxide carbonate at ambient conditions: a key precursor of Co3O4

2016 ◽  
Vol 80 (6) ◽  
pp. 995-1011 ◽  
Author(s):  
J. González-López ◽  
Á. Fernández-González ◽  
A. Jiménez
Keyword(s):  
Transformation Process ◽  
Cobalt Hydroxide ◽  
Small Range ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
Lamellar Crystal ◽  
X Ray ◽  
Platelet Morphology ◽  
Transmission Electron ◽  
Material Sciences

AbstractCrystals of Co2CO3(OH)2have been synthesized under ambient conditions, in contrast to hydrothermal methods reported previously. We have developed a simple but efficient methodology to obtain an initial amorphous phase that evolves to a crystalline cobalt hydroxide carbonate after one week of maturation. X-ray diffraction analysis indicates that this phase crystallizes in the space groupP21/a(a= 12.886(6),b= 9.346(3),c= 3.156(1) Å, β = 110.358(6)°). The platelet morphology of Co2CO3(OH)2agrees with its lamellar crystal structure. High-resolution transmission electron microscopy (HRTEM) reveals that each individual platelet is comprised of nanodomains disoriented with respect to their neighbours. The kinetics and the activation energy (Ea= 6.26 kJ mol–1) of the transformation process have been estimated using the rate constant method. The precipitation of solids leads to a decrease in the cobalt concentration in the solution (∼88%) reaching values of ∼150 ppm, which can be considered a successful reduction from the perspective of water quality. The calcination in air of the synthetized platelets produced exclusively Co3O4. The thermo-X-ray difraction results confirm that Co2CO3(OH)2is transformed over a small range of temperatures (225–235°C) into pure Co3O4. HRTEM images show that the lamellar nanomorphology is preserved in the Co3O4phase. Therefore, understanding the crystallization behaviour of Co2CO3(OH)2can help to minimize environmental problems caused by cobalt pollution and may facilitate the management of methods to obtain phases with specific nanomorphologies used widely in material sciences.

Growth and assembly of monodisperse Ag nanoparticles by exchanging the organic capping ligands

2009 ◽  
Vol 24 (2) ◽  
pp. 352-356 ◽  
Author(s):  
Chenhui Hao ◽  
Dingsheng Wang ◽  
Wen Zheng ◽  
Qing Peng
Keyword(s):  
Ag Nanoparticles ◽  
Transformation Process ◽  
Probable Mechanism ◽  
Oriented Attachment ◽  
X Ray Diffraction ◽  
X Ray ◽  
Monodisperse Nanoparticles ◽  
Transmission Electron ◽  
Organic Capping ◽  
Capping Ligands

Nearly monodisperse Ag nanoparticles capped with octadecylamine were prepared by direct thermal decomposition of silver nitrate in octadecylamine. Then the “oriented attachment” assembly process of these monodisperse nanoparticles was exhibited by exchanging the organic capping ligands, and Ag short nanorods capped with dodecanethiol could be obtained as a result. The composition of Ag was analyzed by x-ray diffraction, and the morphological change from nanoparticle to short-nanorod was examined by transmission electron microscopy. Moreover, we also propose a probable mechanism for this transformation process.

The effect of TiO2 addition on the thermal behavior of sol-gel derived β-spodumene powders

1999 ◽  
Vol 14 (1) ◽  
pp. 97-102 ◽  
Author(s):  
Moo-Chin Wang
Keyword(s):  
Phase Transformation ◽  
Sol Gel ◽  
Transformation Process ◽  
X Ray Diffraction ◽  
Crystallization Sequence ◽  
X Ray ◽  
Transmission Electron ◽  
Tio2 Addition ◽  
A Minor ◽  
Increasing Temperature

The effect of TiO2 addition on the crystallization and phase transformation process in Li2O · Al2O3 · 4SiO2 gels with various TiO2 contents was investigated using differential thermal analysis, x-ray diffraction, and transmission electron microscopy. The activation energy increased from 98.2 to 184.6 kcal/mol as the TiO2 content rose from 2.0 to 8.0 wt. %. The crystallization sequence and phase transformation were similar in LAS gels with various wt.% of TiO2 additions, except in the case of a 2.0 wt.% TiO2 content. During calcination from 800 to 1200 °C, crystallization of the β-spodumene phase progressed with increasing temperature, and a minor crystalline phase, rutile, also appeared.

Synthesis and Raman Spectra of Cupric Oxide Quantum Dots

1999 ◽  
Vol 571 ◽  
Author(s):  
J.F. Xu ◽  
W. Ji ◽  
Z.X. Shen ◽  
S.H. Tang ◽  
X.R. Ye ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Raman Spectra ◽  
Single Phase ◽  
Cupric Oxide ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
One Step ◽  
Diffraction Peaks

ABSTRACTWe have synthesised CuO quantum dots by using a method of one-step solid state reaction under ambient conditions, and investigated them by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Raman scattering technique. The XRD shows that the sample is composed of single phase CuO with a monoclinic structure. The particle size estimated from the x-ray diffraction peaks is about 12 nm, consistent with the TEM result. The Raman spectra show that there are three Raman peaks at 282, 332 and 618 cm−1, which are much broader and shifted several cm−l to lower frequencies in comparison with those of bulk CuO crystal. The temperature dependence of the Raman spectra in the range 77–873 K is also presented.

scholarly journals Hexagonal β-Co(OH)2 Nanoparticle as a Precursor in a Solution-Processed LiCoO2 and Its Electrochemical Properties

2018 ◽  
Author(s):  
Rashmirekha Samal ◽  
Prem Prakash Dahiya ◽  
Subhasish Basu Majumder ◽  
Barsha Dash ◽  
Kali Sanjay ◽  
...  
Keyword(s):  
Electrochemical Performance ◽  
Retention Rate ◽  
Nitrate Solution ◽  
Solution Process ◽  
Phase Evolution ◽  
Cobalt Nitrate ◽  
Cobalt Hydroxide ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

Crystalline β-cobalt hydroxide (β-Co(OH)2) of different morphologies have been successfully synthesized with the addition of sodium hydroxide to cobalt nitrate solution and aging in the mother liquor. The rate of NaOH addition, ranging from 0.1 mL/min to 10 mL/min, influences the surface morphology with the obtained storage capability of the respective electrode. Characterization of the β-Co(OH)2 was fully developed, including X-ray diffraction, scanning and transmission electron microscopy, and BET analyses. At a lower rate of NaOH addition, particles are like platelets, while for a higher rate (≥2 mL/min) grains are fused together forming a larger crystallite size. This result is supported by the X-ray diffraction structural analysis, where the phase evolution of (002) plane becomes distinct for the higher rate of NaOH addition. Lithium cobalt oxide (LiCoO2) was synthesized through oxidation from the as-prepared β-Co(OH)2 and LiOH. The electrochemical performance of as obtained LiCoO2 is investigated using charge-discharge and cyclic voltammetric studies. The precursor β-Co(OH)2 prepared at a lower rate of 0.1 mL/min in LiCoO2 demonstrated the best electrochemical performance of 155 mAh/g. After 50 cycles, the capacity retention rate was 67% compared with the first cycle. Finally, we have attempted to correlate the amount of the available OH- ions with the formation of platelets and the discharge capacity. This work has developed a methodology for the synthesis of LiCoO2 using β-Co(OH)2 in a facile chemical solution process.

Time Evolution of the Microstructure of VO2(B) Films Deposited on Glass by MOCVD

2002 ◽  
Vol 749 ◽  
Author(s):  
M. B. Sahana ◽  
G. N. Subbanna ◽  
S. A. Shivashankar
Keyword(s):  
Electron Microscopy ◽  
Vanadium Dioxide ◽  
Deposition Time ◽  
Chemical Vapor ◽  
Rutile Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Platelet Morphology ◽  
Transmission Electron ◽  
M Phase

ABSTRACTThin films of VO2(B), a metastable polymorph of vanadium dioxide, have been grown on glass by low-pressure metalorganic chemical vapor deposition (MOCVD). The films grown for 90 minutes have atypical microstructure, comprising micrometer-sized, island-like entities made up of numerous small, single-crystalline platelets (≅1 μm) emerging orthogonally from larger ones at the center. Microstructure evolution as a function of deposition time has been examined by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The metastable VO2(B) transforms to the stable rutile (R) phase at 550°C in inert ambient, which on cooling convert reversibly to M phase. Electron microscopy shows that annealing leads to the disintegration of the VO2(B) platelets into small crystallites of the rutile phase VO2(R), although the platelet morphology is retained. The magnitude of the jump in resistance at the semiconductor-to-metal, VO2(M)→VO2(R) phase transition depends on the arrangement of polycrystalline platelets in the films.

Facile Synthesis of Monodisperse KY3F10 Nanospheres

2011 ◽  
Vol 233-235 ◽  
pp. 2736-2738 ◽  
Author(s):  
Ling Zhu ◽  
Xue Qiang Cao ◽  
Dao Wu Yang
Keyword(s):  
Electron Microscopy ◽  
Solution Method ◽  
Average Diameter ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
Facile Synthesis ◽  
Sem Images ◽  
X Ray ◽  
Transmission Electron ◽  
Highly Uniform

Highly uniform and monodisperse KY3F10 nanospheres, with an average diameter of 300 nm, have successfully prepared through a simple solution method employing the reaction of Ln(NO3)3 and KBF4 under ambient conditions, without any template or surfactant. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectra were used to characterize the samples. The SEM images illustrate that these spheres were actually composed of randomly aggregated nanoparticles.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

A High Resolution Study of G.P. Zones in Aluminum - 4.2 at % Silver

1982 ◽  
Vol 40 ◽  
pp. 722-723 ◽  
Author(s):  
R. Gronsky
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Computer Simulations ◽  
Structural Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Resolution Study

The phenomenon of clustering in Al-Ag alloys has been extensively studied since the early work of Guinierl, wherein the pre-precipitation state was characterized as an assembly of spherical, ordered, silver-rich G.P. zones. Subsequent x-ray and TEM investigations yielded results in general agreement with this model. However, serious discrepancies were later revealed by the detailed x-ray diffraction - based computer simulations of Gragg and Cohen, i.e., the silver-rich clusters were instead octahedral in shape and fully disordered, atleast below 170°C. The object of the present investigation is to examine directly the structural characteristics of G.P. zones in Al-Ag by high resolution transmission electron microscopy.

Identification of calcium oxalate crystals in dried or fixed tobacco leaf

1984 ◽  
Vol 42 ◽  
pp. 288-289
Author(s):  
Vicki L. Baliga ◽  
Mary Ellen Counts
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Calcium Oxalate ◽  
Growth And Development ◽  
Polarized Light ◽  
Calcium Oxalate Crystals ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

Calcium is an important element in the growth and development of plants and one form of calcium is calcium oxalate. Calcium oxalate has been found in leaf seed, stem material plant tissue culture, fungi and lichen using one or more of the following methods—polarized light microscopy (PLM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction.Two methods are presented here for qualitatively estimating calcium oxalate in dried or fixed tobacco (Nicotiana) leaf from different stalk positions using PLM. SEM, coupled with energy dispersive x-ray spectrometry (EDS), and powder x-ray diffraction were used to verify that the crystals observed in the dried leaf with PLM were calcium oxalate.

Transmission electron microscope studies in special ceramics

1978 ◽  
Vol 36 (1) ◽  
pp. 268-269
Author(s):  
A. Zangvil ◽  
L.J. Gauckler ◽  
G. Schneider ◽  
M. Rühle
Keyword(s):  
Phase Diagrams ◽  
Crystal Structures ◽  
Thin Foil ◽  
Limited Extent ◽  
Complex Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Lattice Resolution

The use of high temperature special ceramics which are usually complex materials based on oxides, nitrides, carbides and borides of silicon and aluminum, is critically dependent on their thermomechanical and other physical properties. The investigations of the phase diagrams, crystal structures and microstructural features are essential for better understanding of the macro-properties. Phase diagrams and crystal structures have been studied mainly by X-ray diffraction (XRD). Transmission electron microscopy (TEM) has contributed to this field to a very limited extent; it has been used more extensively in the study of microstructure, phase transformations and lattice defects. Often only TEM can give solutions to numerous problems in the above fields, since the various phases exist in extremely fine grains and subgrain structures; single crystals of appreciable size are often not available. Examples with some of our experimental results from two multicomponent systems are presented here. The standard ion thinning technique was used for the preparation of thin foil samples, which were then investigated with JEOL 200A and Siemens ELMISKOP 102 (for the lattice resolution work) electron microscopes.

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