scholarly journals Defects in paramagnetic Co-doped ZnO films studied by transmission electron microscopy

2013 ◽  
Vol 114 (24) ◽  
pp. 243503 ◽  
Author(s):  
A. Kovács ◽  
A. Ney ◽  
M. Duchamp ◽  
V. Ney ◽  
C. B. Boothroyd ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Zno Films ◽  
Transmission Electron ◽  
Doped Zno ◽  
Co Doped

Room-temperature Ferromagnetism in Nanostructured Co-doped ZnO

2005 ◽  
Vol 877 ◽  
Author(s):  
M. Wei ◽  
N. Khare ◽  
K. A. Yates ◽  
D. Zhi ◽  
J. L. MacManus-Driscoll
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Chemical Vapour ◽  
Zno Films ◽  
Transmission Electron Microscopy Analysis ◽  
Transmission Electron ◽  
Doped Zno ◽  
Co Doped

AbstractNanosized Co-doped ZnO samples were synthesized using an ultrasonic spray assisted chemical vapour deposition method. Microstructural and magnetic properties of these samples were studied. The room-temperature ferromagnetism was observed in the Co-doped ZnO. Also, x-ray analysis revealed a wurtzite ZnO structure with a small change of the lattice constants due to the doping of Co in ZnO. Raman spectroscopy of the Co-doped ZnO films indicated direct substitution of Co. Scanning electron microscopy showed nanostructured Co-doped ZnO with a ring or cup shape. Transmission electron microscopy analysis revealed nano grains within the rings of an average diameter of around 10 nm. Both energy dispersive spectroscopy and energy-filtered transmission electron microscopy indicated a uniform distribution of Co.

Eu3+/Tb3+ Co-Doped Cerium Oxide Transparent Nanocomposite for Color-Tunable Emission

NANO ◽  
2018 ◽  
Vol 13 (10) ◽  
pp. 1850119
Author(s):  
Xiaoyan Li ◽  
Yunlong Yu ◽  
Xiangfeng Guan ◽  
Peihui Luo ◽  
Linqin Jiang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Transmission Electron Microscopy ◽  
Sol Gel ◽  
Homogeneous Precipitation ◽  
Transmission Electron ◽  
Color Tunable ◽  
Co Doped ◽  
Tunable Emission

Eu[Formula: see text]/Tb[Formula: see text] co-doped nanocomposite containing CeO2 nanocrystals was successfully prepared by an in situ sol–gel polymerization approach. High-resolution transmission electron microscopy demonstrated the homogeneous precipitation of CeO2 nanocrystals among the polymethylmethacrylate (PMMA) matrix. The thermal stability and UV-shielding capability of the obtained nanocomposite were improved with increase of CeO2 content. The tuning of the emissive color from green and yellow to red can be easily achieved by varying the dopant species and concentration. These results suggested that the obtained nanocomposite could be potentially applicable in transparent solid-state luminescent devices.

scholarly journals Reversible Redox Property of Co(III) in Amorphous Co-doped SiO2/γ-Al2O3 Layered Composites

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5345
Author(s):  
Shotaro Tada ◽  
Shota Saito ◽  
Akito Mori ◽  
Hideki Mizuno ◽  
Shiori Ando ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Redox Reactions ◽  
Composite Powder ◽  
Amorphous Sio2 ◽  
X Ray ◽  
Transmission Electron ◽  
Reversible Redox ◽  
Co Doped

This paper reports on a unique reversible reducing and oxidizing (redox) property of Co(III) in Co-doped amorphous SiO2/γ-Al2O3 composites. The Fenton reaction during the H2O2-catalyzed sol–gel synthesis utilized in this study lead to the partial formation of Co(III) in addition to Co(II) within the composites. High-resolution transmission electron microscopy (HRTEM) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) analyses for the composite powder sample with a composition of Al:Si:Co = 85:10:5 showed the amorphous state of the Co-doped SiO2 that modified γ-Al2O3 nanocrystalline surfaces. In situ X-ray absorption fine structure (XAFS) spectroscopic analysis suggested reversible redox reactions of Co species in the composite powder sample during heat-treatment under H2 at 500 °C followed by subsequent cooling to RT under Ar. Further analyses by in situ IR spectroscopy combined with cyclic temperature programmed reduction/desorption (TPR/TPD) measurements and X-ray photoelectron spectroscopic (XPS) analysis revealed that the alternating Co(III)/(II) redox reactions were associated with OH formation (hydrogenation)-deformation (dehydrogenation) of the amorphous aluminosilicate matrix formed in situ at the SiO2/γ-Al2O3 hetero interface, and the redox reactions were governed by the H2 partial pressure at 250–500 °C. As a result, a supported mesoporous γ-Al2O3/Co-doped amorphous SiO2/mesoporous γ-Al2O3 three-layered composite membrane exhibited an H2-triggered chemical valve property: mesopores under H2 flow (open) and micropores under He flow (closure) at 300–500 °C.

Study on superstructure in ion co-doped BiFeO 3 by using transmission electron microscopy

2015 ◽  
Vol 24 (4) ◽  
pp. 046101
Author(s):  
Shi-Zhou Pu ◽  
Chao Guo ◽  
Mei-Ya Li ◽  
Zhen-Lian Chen ◽  
Hua-Min Zou
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Transmission Electron ◽  
Co Doped

The Study of Co-Doped NbC / Cr3C2 on the Application of Ultrafine WC-10%Co Cemented Carbides

2013 ◽  
Vol 320 ◽  
pp. 320-324
Author(s):  
Hao Yu ◽  
Xian Quan Jiang ◽  
Ai Min Jiang ◽  
Rong Yu ◽  
Jin Wei Wang
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Grain Size ◽  
Cemented Carbides ◽  
Vacuum Sintering ◽  
Inhibition Of Growth ◽  
Transmission Electron ◽  
Effective Reduction ◽  
Co Doped

In this paper, ultrafine WC-10%Co cemented carbides were prepared by vacuum sintering. For inhibition of growth of WC grains during sintering, NbC and Cr3C2 were used as inhibitors. With the transformation of co-doped inhibitors content, the grain growth is inhibited and the grain size achieves 490 nm at 0.4% Cr3C2 / 0.3% NbC. The mechanism that co-doped NbC / Cr3C2 on the effective reduction of ultrafine WC-10%Co cemented carbides was analyzed. The 0.4% Cr3C2 / 0.3% NbC addition equipped with the best integrated mechanical properties was obtained in this study. And sintered samples were investigated with scanning and transmission electron microscopy (SEM).

Influence of Co-Doping on the Sintering Map of an Ultra Fine and Ultra Pure Alpha Alumina Powder

2006 ◽  
Vol 45 ◽  
pp. 55-60 ◽  
Author(s):  
Guillaume Bernard-Granger ◽  
Christian Guizard
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Liquid Phase ◽  
Transient Liquid Phase ◽  
Alumina Powder ◽  
Co Doping ◽  
Transmission Electron ◽  
The One ◽  
Alpha Alumina ◽  
Co Doped

The sintering map of an ultra fine and ultra pure α-alumina powder, doped with MO and DO2 (M for mono-valence cations, D for bi-valence cations), has been built from isothermal sintering experiments. It has been compared with the one obtained in a previous study with the same un-doped α-alumina raw powder. It seems that a transient liquid phase appears above a critical temperature in the co-doped material during sintering. It is proposed that this transient liquid phase is promoting densification and minimizing grain growth, as confirmed by transmission electron microscopy (TEM).

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