scholarly journals Effect of cerium on structural and optical properties of ZnO aerogel synthesized in supercritical methanol

2016 ◽  
Vol 34 (3) ◽  
pp. 659-664 ◽  
Author(s):  
M. Meddouri ◽  
L. Hammiche ◽  
O. Slimi ◽  
D. Djouadi ◽  
A. Chelouche
Keyword(s):  
Zinc Acetate ◽  
Structural Parameters ◽  
Fluorite Structure ◽  
Cubic Phase ◽  
Second Phase ◽  
Acetate Solution ◽  
Supercritical Methanol ◽  
Doped Zno ◽  
Zno Aerogels ◽  
Zno Aerogel

AbstractPure ZnO and Ce-doped (5 at.%) ZnO aerogels were prepared by dissociation of dihydrate zinc acetate and cerium nitrate in methanol, followed by drying in supercritical conditions of the solvent. The concentration of zinc acetate solution and the atomic ratio Ce/Zn were fixed at 0.2 mol/L and 0.05 mol/L, respectively. XRD results showed a hexagonal wurtzite structure of ZnO aerogel crystallites and a formation of a separate second phase of ceria cubic phase with fluorite structure and 7.4 nm in size. The introduction of cerium in the solution had a negative effect on the aerogel crystalline quality. The crystallites size was found to be 16 nm in pure ZnO and 27 nm in Ce-doped ZnO aerogels. The grains of Ce-doped ZnO aerogel had torus shaped morphology with hollow centers, but those of pure ZnO were flattened semispheres. The calculated values of different structural parameters showed that cerium ions introduced into the ZnO lattice occupied interstitial sites and Zn ions substituted Ce ones in ceria lattice during the formation process. FT-IR and UV-Vis absorption spectra have not revealed any particularities due to the presence of cerium atoms in ZnO, indicating that Ce (5 at.%) doping of ZnO crystallites synthesized in supercritical methanol did not strongly affect the optical gap of the semiconductor. Micro-Raman studies confirmed the formation of cubic fluorite structure ceria in ZnO aerogel and showed that Raman active modes of ZnO are amplified with the presence of ceria.

A study of structural parameters and photoluminescence of Tb doped ZnO nanoparticles

2020 ◽  
Vol 26 ◽  
pp. 58-63 ◽  
Author(s):  
A. Sharma ◽  
V.N. Rai ◽  
S. Mani ◽  
S. Chawade
Keyword(s):  
Zno Nanoparticles ◽  
Structural Parameters ◽  
Doped Zno

Zirconolite transformation under reducing conditions

1998 ◽  
Vol 13 (11) ◽  
pp. 3181-3190 ◽  
Author(s):  
B. D. Begg ◽  
E. R. Vance ◽  
B. A. Hunter ◽  
J. V. Hanna
Keyword(s):  
Perovskite Phase ◽  
Charge Compensation ◽  
Fluorite Structure ◽  
Second Phase ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Reducing Conditions ◽  
Quadrupole Resonance

The structural behavior of zirconolite (CaZrTi2O7) under reducing conditions at high temperature has been studied, mainly by scanning electron microscopy (SEM) and x-ray diffraction (XRD), but also with x-ray absorption spectroscopy, thermogravimetry, and electron paramagnetic resonance. The partial reduction of Ti4+ to Ti3+, associated with a reducing atmosphere heat treatment, led to the initial formation of perovskite (CaTiO3) as a second phase. As the concentration of Ti3+ in the zirconolite increased, so did the amount of perovskite until the zirconolite was totally transformed into a fluorite structured phase. Analysis of the reduced zirconolites showed them to be consistently deficient in Ca and enriched in Zr, in proportion to the concentration of Ti3+. To determine how electroneutrality was preserved in these reduced zirconolites, a series of zirconolites were prepared in air using In3+ and Ga3+ as models for Ti3+. These samples were then investigated by neutron and x-ray diffraction, SEM, solid state nuclear magnetic resonance (NMR), and nuclear quadrupole resonance (NQR). 71Ga MAS NMR studies of the Ga substituted zirconolite exhibited a narrow resonance at ˜13 ppm which was attributed to six-coordinate Ga incorporated in a trace perovskite phase. Broadline 71Ga NMR and 69/71Ga NQR were required to characterize the Ga incorporated in the zirconolite. The resultant quadrupolar parameters of CQ = 30.0 ± 0.05 MHz and η = 1.0 ± 0.03 indicate that the Ga site is in a highly distorted environment which would suggest that it is located on the five-coordinate Ti site within the zirconolite lattice. These results were complemented by Rietveld refinement of the neutron diffraction data from the In-doped zirconolite sample, which was optimal when all the In was located on the five-coordinate Ti site with the excess Zr located on the Ca site. It would therefore appear that charge compensation for the presence of Ti3+ in zirconolite is effected via the substitution of an appropriate amount of Zr on the Ca site. The Ti3+-stabilized fluorite structure was readily oxidized back to a single phase zirconolite upon heating in air.

Structural Characterization, and Magnetic Morphological Study of Ni+2 Doped ZnO Synthesized by Combustion Reaction Application for DMS

2012 ◽  
Vol 727-728 ◽  
pp. 511-515 ◽  
Author(s):  
R. Torquato ◽  
E. Shirsath Sagar ◽  
Ruth Herta Goldsmith Aliaga Kiminami ◽  
Ana Cristina Figueiredo de Melo Costa
Keyword(s):  
Magnetic Properties ◽  
Magnetic Measurements ◽  
Diluted Magnetic Semiconductor ◽  
Magnetic Semiconductor ◽  
Transition Metal Ions ◽  
Combustion Reaction ◽  
Second Phase ◽  
Doped Zno ◽  
Diluted Magnetic ◽  
Maximum Temperatures

ZnO is a semiconductor that can be doped with transition metal ions, and thus becomes feasible to use in the diluted magnetic semiconductor (DMS), or semiconductor with magnetic properties. In this work we have studied the influence of doping of Ni+2on the structural, morphological and magnetic properties of Zn1-xNixO system, to x = 0.07, 0.1 and 0.2 mol of Ni+2synthesized by combustion reaction. The systems were characterized by XRD, SEM and VSM. The maximum temperatures ranged from 639 K and 683 K. All systems showed a majority phase formation of ZnO, with the presence of the second phase NiO. The crystallite size for the majority phase varied between 49 and 56nm. All systems have resulted in samples with a morphology consisting of dense clusters, formed by particles pre-sintered and shaped roughly hexagonal plates. The magnetic measurements showed that the values of saturation magnetization lies between 4.6 to 28.5emu/g, remanent magnetization of 0.01 to 0.3 emu/g, coercive force values varies between 12.7 and 62.4 Oe and Curie temperature ranging from 308 to 311K.

scholarly journals Zinc Acetate/Carrageenan Gels Exhibit Potent ActivityIn Vivoagainst High-Dose Herpes Simplex Virus 2 Vaginal and Rectal Challenge

2011 ◽  
Vol 56 (1) ◽  
pp. 358-368 ◽  
Author(s):  
José A. Fernández-Romero ◽  
Ciby J. Abraham ◽  
Aixa Rodriguez ◽  
Larisa Kizima ◽  
Ninochka Jean-Pierre ◽  
...  
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Zinc Acetate ◽  
Sexual Transmission ◽  
High Dose ◽  
Acetate Solution ◽  
Sexual Transmission Of Hiv ◽  
Simplex Virus ◽  
Herpes Simplex Virus 2

ABSTRACTTopical microbicides that block the sexual transmission of HIV and herpes simplex virus 2 (HSV-2) are desperately needed to reduce the incidence of HIV infections worldwide. Previously we completed phase 3 testing of the carrageenan-based gel Carraguard. Although the trial did not show that Carraguard is effective in preventing HIV transmission during vaginal sex, it did show that Carraguard is safe when used weekly for up to 2 years. Moreover, Carraguard hasin vitroactivity against human papillomavirus (HPV) and HSV-2 and favorable physical and rheological properties, which makes it a useful vehicle to deliver antiviral agents such as zinc acetate. To that end, we previously reported that a prototype zinc acetate carrageenan gel protects macaques against vaginal challenge with combined simian-human immunodeficiency virus reverse transcriptase (SHIV-RT). Herein, we report the safety and efficacy of a series of zinc acetate and/or carrageenan gels. The gels protected mice (75 to 85% survival;P< 0.001) against high-dose (106-PFU) HSV-2 vaginal or rectal challenge. In contrast, zinc acetate formulated in HEC (hydroxyethylcellulose; or the Universal Placebo) failed to protect mice against the high-dose vaginal HSV-2 challenge (similar to aqueous zinc acetate solution and the placebo controls). The gels were found to be effective spreading gels, exhibited limited toxicityin vitro, caused minimal damage to the architecture of the cervicovaginal and rectal mucosaein vivo, and induced no increased susceptibility to HSV-2 infection in a mouse model. Our results provide a strong rationale to further optimize and evaluate the zinc acetate/carrageenan gels for their ability to block the sexual transmission of HIV and HSV-2.

scholarly journals Synthesis and structural properties of ZnO films grown by spray pyrolysis of zinc acetate solution

2010 ◽  
Vol 66 (a1) ◽  
pp. s158-s158 ◽  
Author(s):  
Nancy Castillo ◽  
Rodrigo Esparza ◽  
Jesus Velazquez ◽  
Agustin Conde Gallardo ◽  
Miguel Jose Yacaman
Keyword(s):  
Spray Pyrolysis ◽  
Structural Properties ◽  
Zinc Acetate ◽  
Zno Films ◽  
Acetate Solution ◽  
Zinc Acetate Solution

Synthesis Study of Silver-Doped Zinc Oxide for Near-Infrared Shielding Applications

2020 ◽  
Vol 1007 ◽  
pp. 143-147
Author(s):  
Sujittra Kaenphakdee ◽  
Supan Yodyingyong ◽  
Jeerapond Leelawattanachai ◽  
Wannapong Triampo ◽  
Noppakun Sanpo ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Optical Property ◽  
Silver Nitrate ◽  
Zno Nanoparticles ◽  
Zinc Acetate ◽  
Near Infrared ◽  
Visible Region ◽  
Zinc Nitrate ◽  
Precipitation Method ◽  
Doped Zno

Undoped ZnO and Ag-doped ZnO were prepared to use as near-infrared (NIR) shielding by simple precipitation method with zinc acetate and zinc nitrate as Zn precursor and silver nitrate as Ag precursor. The Ag-doped ZnO and undoped ZnO were characterized by XRD, SEM, and UV-vis-NIR spectrophotometer. The NIR reflectance performance reveals that Ag-doping improves the NIR shielding and optical property of pure ZnO. The 10 mol% Ag loading shows the lowest reflection in the visible region of about 15% and the highest reflection in the NIR region of about 50%. It not only shows the best NIR reflection but also exhibits the best thermal insulation. It reduces the inner temperature of the in-lab setup to mimic a house by 7.5°C when compared to the uncoated glass window. It is concluded that 10 mol% Ag-doped ZnO nanoparticles can result in UV-NIR shielding coatings.

Role of Dipping Cycle on Mn Doped ZnO Thin Films Prepared by Successive Ionic Layer Adsorption and Reaction Method

2019 ◽  
Vol 17 (12) ◽  
pp. 987-990
Author(s):  
K. Rathi Devi ◽  
G. Selvan ◽  
M. Karunakaran ◽  
G. Rajesh Kanna ◽  
K. Kasirajan
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Structural Parameters ◽  
Hexagonal Structure ◽  
Zno Thin Films ◽  
Zno Films ◽  
Line Profile Analysis ◽  
X Ray ◽  
Doped Zno ◽  
Mn Doped

In this work, Mn doped Zinc Oxide (ZnO) thin films were coated onto glass substrates by low cost SILAR technique by altering dipping cycle such as 40, 60, 80 and 100. The film thickness was estimated using weight gain method and it revealed that the film thickness increased with dipping cycle. The structural, morphological, elemental and FTIR properties of the coated Mn doped ZnO films were studied using X-ray diffraction (XRD), scanning electron microscope (SEM), EDAX and FTIR spectrophotometer respectively. The prepared films were found to be hexagonal structure with polycrystalline in nature with preferential orientation along (002) plane. X-ray line profile analysis was used to evaluate the micro structural parameters. The crystallite size values are increased with increase of dipping cycle. Morphological results showed that the dipping cycle has a marked effect on morphology of the prepared Mn doped ZnO thin films. EDAX studies showed that the presence of Zinc, Oxygen and Mn content.

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