Preparation and Characterization of Cr&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; Nano-Powders by Sol-Gel Method

Zhu, Chun Cheng; Yan, Hong; Zhang, Jian Guang; Zhou, Bai Bin

doi:10.4028/0-87849-456-1.2111

Cited by 1 publication

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“…Chromium oxide nanoparticles have been synthesized by a large number of physical and chemical techniques that include hydrothermal reduction, 6 solution combustion synthesis, 7 sonochemical reaction, 8 laser-induced pyrolysis, 9 hydrazine reduction and thermal treatments, 10 supercritical alcohol synthesis, 11 condensation−polymerization, 12 precipitation−gelation, 13 gas condensation, 14 microwave plasma chemistry, 15 and sol−gel methods. 16 The major drawbacks of most of these fabrication methods are a wide particle-size distribution, a low yield, and agglomeration of the particles. The fabrication methods also tend to be complex and require chemically harsh conditions and/or high processing temperatures.…”

Section: Introductionmentioning

confidence: 99%

Radiation-Induced Formation of Chromium Oxide Nanoparticles: Role of Radical Scavengers on the Redox Kinetics and Particle Size

Alrehaily

Wren

2015

J. Phys. Chem. C

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The formation of Cr 2 O 3 nanoparticles by gamma irradiation of dichromate solutions was investigated in the presence of radical scavengers, t-butanol, nitrous oxide and dissolved oxygen.The concentrations of Cr VI and Cr III species and the chemical composition and sizes of particles that were formed were measured as a function of irradiation time. A mechanism is proposed that is consistent with the observed effects of scavengers on the kinetics of reduction of Cr VI in solution to solid Cr III , and the final size of Cr 2 O 3 nanoparticles that are formed. The chromium reduction occurs in three stages: Stage I involves homogeneous aqueous reduction of Cr VI (aq) to Cr III (aq) followed by spontaneous condensation of Cr(OH) 3 , providing nucleation sites onto which Cr VI and Cr III co-precipitate and form mixed Cr VI /Cr III oxide/hydroxide particles. In Stage II the aqueous reduction of Cr VI (aq) and Cr III (aq) reaches steady state but the adsorption of Cr VI continues, growing the mixed Cr VI /Cr III oxide/hydroxide particles. Stage 3 involves the solidstate conversion of Cr VI and Cr III and the particles slowly convert from a mixed Cr VI /Cr III oxide/hydroxide to Cr(OH) 3 and then to Cr 2 O 3 . Adding a radical scavenger in solution affects the kinetics of particle formation and growth at different stages differently. This information can be used to tailor the final sizes of particles.

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