Solvothermal synthesis of Cr2O3 nanocubes via template-free route (original) (raw)
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Authors personal copy Saleh Mani et al Cr2O3 nanoparticles 2011
Monodispersed spherical particles of chromium (III) oxide, a-Cr 2 O 3 , were successfully synthesized from a diluted solution of KCr(SO 4 ) 2 Á 12H 2 O using the Aqueous Chemical Growth (ACG) technique. The spherical a-Cr 2 O 3 particles obtained were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Raman spectroscopy for structural, surface morphological, chemical, and physical properties, as a function of deposition time. The XRD and Raman spectroscopy showed that aging had no apparent effect on the structure of the obtained uniform fine (in the range of micronnano-level)-spherical particles of a-Cr 2 O 3 . The use of SEM demonstrated that aging had a clear influence on the size and the particles size distribution. Accordingly, the time dependence of the average diameter of a-Cr 2 O 3 spherical particles follows the d 3 law as required for diffusion-limited Ostwald ripening.
Cr2O3 Nanoparticles: Synthesis, Characterization, and Magnetic Properties
Nanochemistry Research, 2020
In this paper, semi-solid precursor of chromium was prepared from the reaction of Cr(NO3)3 and oxalic acid at the presence of NaOH. Then, Cr2O3 nanoparticles were prepared by solid-state thermal decomposition of this precursor at 500 and 600 ºC at standard atmospheric pressure for 3 h. The as-prepared Cr2O3 nanoparticles were characterized by Fourier transform infrared (FT-IR), ultraviolet-visible (UV-Vis) spectroscopy, X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The sharp vibration bands in FT-IR spectra and high intensity peaks in XRD patterns confirmed the preparation of pure, single rhombohedral phase and crystalline Eskolaite structure of Cr2O3 nanoparticles. A broad absorption peak appeared at UV-Vis spectra indicates the d3 electronic transition of Cr3+. The TEM images show that the particles are similar and a little agglomerated with the average crystal size of < 100 nm. The VSM results predict that the as-prepared Cr2O3 nanoparticles are weak ferromagnetic and paramagnetic.
Chromia (Cr2O3) nanoparticles have been successfully synthesized via the facile solvothermal process, by using CrO3 in butanol and propanol as solvents. The functional groups of the samples were tested by the Fourier Transform Infrared (FTIR) spectroscopy. The as-synthesized nanoparticle sizes are calculated and confirmed to be 34 and 40 nm, by using X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). The morphology of the samples was observed by the Scanning Electron Microscopy (SEM). The measured band gap energies (Eg= 4.04 and 3.66 eV) higher than that of bulk Cr2O3 and increased with decreasing particles size, which indicated that the particles had been successfully synthesized in the nano region, and measured by UltraViolet visible (UV-vis) absorption spectroscopy. The broad visible emission at ~397 nm, in the photoluminescence spectroscopy revealed the high purity and perfect crystallinity of the samples.)
PROCEEDING OF THE 1ST INTERNATIONAL CONFERENCE ON ADVANCED RESEARCH IN PURE AND APPLIED SCIENCE (ICARPAS2021): Third Annual Conference of Al-Muthanna University/College of Science
The nanoparticles were synthesized from chromium oxide using Roselle extract in two methods, the first by (simple chemical method) and the second by (sol-gel method). These technologies are a new, environmentally friendly and cheap. Roselle contains plant materials and biomolecules (phenols, alkalis, vitamins, amino acids, quinones, etc.) that convert chromium chloride hexahydrate (CrCl3.6H2O) into chromium nanoparticles. The plant extracts also act as diluents, stabilizers and anti-caking agents Chromium oxide (Cr2O3) nanoparticles were prepared by sol-gel method. Nano powders are annealing at different. X-ray diffraction (XRD) analysis showed that the size of the crystals decreased from (16.12) nm by the simple chemical method to (13.8) nm of Cr2O3 using sol-gel (200),(13.5)nm using solgel(400),(13.3)nm of Cr2O3 using sol0gel(600). The (Scanning electron microscopy (SEM) showed that the nanoparticles of Cr2O3 NPs with (36.38) nm in a simple chemical method while the (SEM) in sol-gel method (200) showed that the nanoparticles of Cr2O3 NPs using Roselle extract are spherical or semispherical in shape) with a particle size of (89.83) nm in scale 200nm, the results no similar any source. Ultraviolet-visible (UV-Vis) showed value the band gap from of 2.9 eV of Cr2O3 NPs in a simple chemical method, while in a sol-gel method of Cr2O3 NPs was (3, 3.2, 3.35, 3.5) ev at different temperatures, In this research were obtain on high pure, small particle size, and large energy gap of chromium oxide NPs in a sol-gel method better than of chromium oxide NPs in a simple chemical method. The study revealed that the Chromium oxide nanoparticles synthesized using Roselle extracts could be used as antibacterial agent for human pathogenic bacteria. The aim of this research is to obtain chromium oxide (Cr2O3) nanoparticles using inexpensive and available materials, in Simple method.
Structural, Optical and Magnetic Studies of Cr2O3 Nanoparticles Prepared by Microwave-Assisted
2021
In this paper, quasi-rectangular Cr2O3 nanoparticles were prepared by microwave-assisted solution using Cr(NO3)2.6H2O and salicylic acid at the presence of NaOH in optimum conditions for the power of 360 W, the temperature of 50 oC and the time duration of 30 min. The as-prepared chromium precursor was annealed in an air atmosphere at two different temperatures, 500 oC and 600 oC, for 3 h. Quasi-rectangular Cr2O3 nanoparticles were prepared and characterized by Fourier transform infrared (FT-IR), and ultraviolet–visible (UV-Vis) spectroscopy, X-ray diffraction analysis (XRD), Transmission electron microscopy (TEM) and Vibrating sample magnetometer (VSM). The sharp peaks in FT-IR spectra and high intensity peaks in XRD patterns confirm that the single and pure phase existence of the Cr2O3 nanoparticles with an average nanoparticle size of 25 nm. The optical band gap (Eg) values of the as-prepared Cr2O3 nanoparticles calculated were in the range of 1.6 and 1.8 eV, respectively. The TE...
Characterization of Cr2O3 nanoparticles prepared by using different plant extracts
Academia Journal of Agricultural Research, 2018
Chromium oxide nanoparticles were synthesized using auto-combustion/sol-gel method by employing green chemistry. This method is environmentally friendly and less expensive than other methods. Natural extracts of different plants were used as substitutes for materials used as a fuel for the process of ignition. Prepared Powders were characterized using X-ray diffraction (XRD). The as-burnt powder of Cr2O3 nanoparticles, which showed the presence of crystalline Rhombohedral with unit cell parameters was conformed with standard data. The crystallite size observed was in the range of 29 to 35 nm. Scanning electron microscopy (SEM) showed that the nanoparticles were spherical or semi-spherical in shape. Vis-UV spectrometry showed that Cr2O3 nanoparticles have a high absorbance at λ between 310 and 500 nm and that the energy gap varies between 3 and 3.05 eV for the three samples prepared in green chemistry. The results of the present study showed that silver nanoparticles synthesized by plant extracts had effective antibacterial activities on the test isolates as indicated by the diameter of inhibition zone. It was from 12 to 18 mm for Gram's negative bacteria, and from 10 to 16 mm for Gram's positive bacteria. The study revealed that the Chromium oxide nanoparticles synthesized using plant extracts could be used as antibacterial agent for human pathogenic bacteria.
Preparation and characterization of nano TiO2/micron Cr2O3 composite particles
Journal of Alloys and Compounds, 2011
Nano-TiO 2 /micro-size Cr 2 O 3 composite particles were first prepared by hydrolysis of Ti(OBu) 4 in an abundant acidic aqueous solution without calcinations at room temperature. XPS analysis shows that the element C, O, Ti and Sn existed on the surfaces of the composite particles. Observation by field emission scanning electronic microscope shows TiO 2 particles of 10-15 nm covers on Cr 2 O 3 powder surfaces to form nanometer/micron composite particles. UV-vis spectra show a red shift of the absorption edge and a significant increase of absorption intensity in the visible region. These results confirm that TiO 2 of anatase type can be synthesized on the surface of Cr 2 O 3 .
Synthesis and Characterization of Chromium Oxide Nanoparticles
Chromium oxide nanoparticles (NPs) have been rapidly synthesized by precipitation method using ammomia as precipitating agent and are characterized by using X-ray Diffraction (XRD), Thermo Gravimetric Analysis (TGA), UV-Visible absorption (UV), Infrared Spectoscopy (IR), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). XRD studies show that chromium oxide NP is formed as Cr 2 O 3 and it has hexagonal structure. The shape and particle size of the synthesized Cr 2 O 3 NPs is determined by SEM and TEM. The images showed that the size of NPs of Cr 2 O 3 varied from 20 nm to 70 nm with average crystalline size 45 nm. UV-Visible absorption and IR spectoscopy confirm the formation of nanosized Cr 2 O 3 . TGA verifies that the Cr 2 O 3 NPs are thermally stable upto 1000 °C.
Synthesis of Cr2O3/TiO2 Nanocomposite and its Application as the Blocking Layer in Solar Cells
Journal of Environmental Analytical Chemistry, 2018
In this study, Cr 2 O 3 /TiO 2 nanoparticles were synthesized using sol-gel method. TiO 2 as one of the most important semiconductor materials with a variety of applications in many fields including photocatalysis and solar cells combined with Cr 2 O 3 as a mineral material and one of the basic oxides used as pigments to improve properties such as mechanical strength, thermal stability form the Cr 2 O 3 /TiO 2 nanocomposite showing attractive applications in photocatalysis and solar cells. To this end, its application in solar cells has been investigated to testify its performance. The results were promising in the case of solar cell. Cr 2 O 3 /TiO 2 nanocomposite solution formed a compact layer with low defects and grain boundaries while it was sprayed as blocking layer (TiO 2) in superstrate structure CZTS solar cells (Glass/FTO/TiO 2 /In 2 S 3 /CZTS/carbon). Compared to individual TiO 2 blocking layer, the asdeposited layer showed better quality and performance. X-Ray was used to confirm synthesized nanoparticles and their morphology was investigated by Field-Emission Scanning Electron Microscopy (FE-SEM).
Cr3+ Doped Al2O3 Obtained by Non-Hydrolytic Sol-Gel Methodology
Journal of the Brazilian Chemical Society
This paper reports the synthesis and characterization of Cr 3+-doped alumina by the sol-gel non-hydrolytic methodology. The resulting sample was treated at different temperatures. X-ray diffraction revealed that the ruby phase emerged in the sample treated at 1100 o C, which was later confirmed by absorption bands correspondent to Cr 3+ ions allowed transitions at 4 A 2 → 4 T 1 , 4 T 2 , and forbidden at 4 A 2 → 2 T 1 , 2 E, observed by diffuse reflectance UV-Vis. The luminescence spectroscopy showed the intensity band at 694 nm in red region, characterized of the Cr 3+ ion. The peaks at 702 and 705 nm correspond to N 1 and N 2 lines, respectively, which arose from the second and fourth nearest-neighbor exchange-coupled pairs of chromium(III) ion, respectively, ascribed to high chromium(III) concentration. The Cr 3+ cluster formation was observed in electron paramagnetic resonance signal as discussed in this work. Nuclear magnetic resonance evidenced that the 27 Al symmetry changed in the samples treated between 900 and 1100 o C.