Nanocrystalline α-Fe2O3: A Superparamagnetic Material for w-LED Application and Waste Water Treatment

2021 ◽  
Author(s):  
Mahesh Gaidhane ◽  
Deepak Taikar ◽  
Pravin Gaidhane ◽  
Kalpana Nagde
Keyword(s):  
Photocatalytic Activity ◽  
Waste Water Treatment ◽  
Sol Gel ◽  
Average Particle Size ◽  
Emission Spectra ◽  
Broad Emission Band ◽  
Average Particle ◽  
X Ray ◽  
Prepared Material ◽  
Cie Chromaticity

Abstract Nanocrystalline α-Fe2O3 is synthesized by sol-gel technique. The prepared nanomaterial was characterized by X-ray diffraction (XRD), SEM, TEM, Fourier Transform Infrared (FTIR) spectroscopy, Vibrating Sample Magnetometry (VSM) and photoluminescence (PL) techniques. X-ray powder diffraction analysis confirmed the formation of α-Fe2O3. Electron microscopy showed spherical morphologies with an average particle size of 30-40 nm. The magnetic property of the prepared material was studied by VSM at room temperature. VSM study shows superparamagnetic nature of the synthesized nanoparticles. Photoluminescence (PL) emission spectra show intense broad emission band centered at 570 nm with 393 nm excitation indicating its usefulness for w-LED application. The CIE-chromaticity color coordinates of prepared material were calculated. The photocatalytic activity of the α-Fe2O3 nanoparticles was analyzed and the nanopowder exhibited good photocatalytic activity for the removal AO7 from its aqueous solution.

Pb2+ and Ce3+ Doped SrZnO2: New Blue Luminescent Phosphors

2006 ◽  
Vol 916 ◽  
Author(s):  
Alp Manavbasi ◽  
Jeffrey C LaCombe
Keyword(s):  
Sol Gel ◽  
Average Particle Size ◽  
Broad Band ◽  
Emission Spectra ◽  
Broad Emission Band ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Broad Emission ◽  
Diffraction Patterns ◽  
Individual Particles

AbstractTwo new blue emitting phosphors, SrZnO2:Pb2+ and Ce3+ were synthesized by adipic acid and sucrose templated sol-gel routes, respectively. The resulting phosphor particles were fine, nanocrystalline and pure. The optimum activator concentrations were found to be 1 mol% Pb2+ and 12 mol% Ce3+. Two excitation bands centered at 283 and 317 nm, plus a weak shoulder at 275 nm were observed for Pb2+ doped samples, however only one broad excitation band with a maximum at 294 nm was observed for Ce3+ doped samples fired at 1000 °C for 2h. The emission spectra of SrZnO2:Pb2+ showed a very broad band extending from 374 to 615 nm with a maximum at ~455 nm which was ascribed to the 3P1 ¡æ 1S0 transition on the Pb2+ ions allowed by the strong spin-orbit (SO) coupling. Similarly, SrZnO2:Ce3+ showed a broad emission band extending from 374 to 609 nm and centered at 467 nm. This broad emission was attributed to the 5d1 ¡æ 4f1 transition of Ce3+ ions. The lower level 2F5/2 of the 4f1 is populated but the level 2F7/2 is almost empty at room temperature where all measurements were taken. The luminescence properties of Ce3+, K+ co-doped SrZnO2 revealed that the characteristic band locations remained the same and the ratio of emission to excitation intensities were constant. X-ray diffraction patterns showed that the SrZnO2 phase started to form at 900 °C (after 2 hrs), and the single-phase SrZnO2 obtained at 1000 °C. SEM micrographs of both phosphors have a rounded and filled morphology for individual particles with an approximate diameter of 50-250 nm. Dynamic light scattering studies revealed that average particle size is around 1 ¥ìm for both phosphors.

scholarly journals Synthesis of cuprous oxide nanocubes combined with chitosan nanoparticles and its application to p-nitrophenol degradation

2021 ◽  
Vol 22 (48) ◽  
Author(s):  
Tran Thi Bich Quyen ◽  
Ngo Nguyen Tra My ◽  
Do Thi Thuy Ngan ◽  
Duy Toan Pham ◽  
Doan Van Hong Thien
Keyword(s):  
Photocatalytic Activity ◽  
Cuprous Oxide ◽  
Treatment Time ◽  
Average Particle Size ◽  
Chitosan Nanoparticles ◽  
Synthetic Approach ◽  
Average Particle ◽  
X Ray ◽  
Nitrophenol Reduction ◽  
Nitrophenol Degradation

For the first time, cuprous oxide nanocubes (Cu2O NCBs) were successfully combined with chitosan nanoparticles (CS NPs) to generate Cu2O NCBs/CS NPs composites material with highly optical property and photocatalytic activity using a simple and eco-friendly synthetic approach at room temperature for 30 min. The synthesized Cu2O NCBs NPs/CS NPs were determined characterizations by Ultraviolet-visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), X – ray Diffraction (XRD),  Transmission Electron Microscope (TEM) and Energy-dispersive X-ray spectroscopy (EDX). Results show that the Cu2O NCBs/CS NPs composites have an average particle size of ~3-5 nm; in which, Cu2O has the form of nanocubes (Cu2O NCBs) with size ~3-4 nm and chitosan nanoparticles with spherical shape (CS NPs) with size ~4-5 nm. In addition, the percent (%) composition of elements present in Cu2O NCBs/CS NPs composites material have been obtained respective: Cu (23.99%), O (38.18%), and C (33.61%). Moreover, Cu2O NCBs/CS NPs composites material was also investigated for photocatalytic activity applied in p-nitrophenol degradation. The obtained results showed that the catalytic capability of Cu2O NCBs/CS NPs for p-nitrophenol reduction reached the highest efficiency >55% in the treatment time of 25 min, and this efficiency was higher than that result of using ZnO@chitosan nanoparticles (ZnO@CS NPs) catalyst under the same conditions for comparison.

Photocatalytically Active Cotton Fabrics Produced with Anatase Synthesized Using a Low-Temperature Sol-Gel Process

2018 ◽  
Vol 762 ◽  
pp. 408-412
Author(s):  
Raivis Eglītis ◽  
Gundars Mežinskis
Keyword(s):  
Photocatalytic Activity ◽  
Uv Light ◽  
Sol Gel ◽  
Average Particle Size ◽  
Synthesis Method ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Sol Gel Process ◽  
Anatase Nanoparticles ◽  
Pre Treatment

In this work two different hydrosols were used to impregnate a commercially available cotton fabric with anatase nanoparticles to give it photocatalytic activity. To increase the activity, different pre-treatment methods were applied. The nanoparticle size was determined using dynamic light scattering and x-ray diffraction and the fabrics were examined using scanning electron microscopy. Photocatalytic activity was measured using the degradation of methyl-orange while irradiating the samples with UV light. The synthesis method allowed to produce anatase with an average particle size of 32 to 37 nm depending on the synthesis method used.

scholarly journals Oxide Nanomaterials Based on SnO2 for Semiconductor Hydrogen Sensors

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
George Fedorenko ◽  
Ludmila Oleksenko ◽  
Nelly Maksymovych
Keyword(s):  
Tin Dioxide ◽  
Sol Gel ◽  
Average Particle Size ◽  
Fast Response ◽  
Average Particle ◽  
Hydrogen Sensors ◽  
Measuring Range ◽  
X Ray ◽  
Response And Recovery ◽  
Good Repeatability

Nanosized tin dioxide with an average particle size of 5.3 nm was synthesized by a sol-gel method and characterized by IR spectroscopy, TEM, X-ray, and electron diffraction. The obtained SnO2 can be used as initial material for creation of gas-sensitive layers of adsorption semiconductor sensors. Addition of palladium into the initial nanomaterial allows to improve response to hydrogen of such sensors in comparison with sensors based on undoped SnO2 and provides fast response and recovery time, a wide measuring range of hydrogen content in air ambient, and good repeatability of the sensor signal. Such promising properties could make useful the sensors based on these nanomaterials for devices intended to determine hydrogen in air.

Multiferroic Bismuth Ferrite Nanoparticles: Rapid Sintering Synthesis, Characterization, and Optical Properties

2010 ◽  
Vol 152-153 ◽  
pp. 81-85
Author(s):  
Xiong Wang ◽  
Yin Lin ◽  
Jin Guo Jiang
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
Optical Properties ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Average Particle Size ◽  
Average Particle ◽  
X Ray ◽  
Bifeo3 Nanoparticles ◽  
Rapid Sintering

The homogeneous multiferroic BiFeO3 nanoparticles with average particle size of 85 nm have been successfully synthesized by a simple sol-gel route. The prepared sample was characterized by a variety of techniques, such as X-ray diffractometry, thermogravimetric analysis and differential thermal analysis, differential scanning calorimeter analysis, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The obtained results shows that rapid sintering and subsequently quenching to room temperature are the two vital important factors for the preparation of pure BiFeO3. The magnetic phase transition (TN = 369 °C) and the ferroelectric phase transition (TC = 824.5 °C) were determined, revealing the antiferromagnetic and ferroelectric nature of the as-prepared BiFeO3 nanoparticles. The optical properties of the nanopowders were investigated. The strong band-gap absorption at 486 nm (2.55 eV) of the BiFeO3 nanoparticles may bring some novel applications.

FABRICATION AND CHARACTERIZATION OF AQUEOUS SOL–GEL-DERIVED LaFeO3 THIN FILMS

2000 ◽  
Vol 14 (22n23) ◽  
pp. 801-808 ◽  
Author(s):  
M. RAJENDRAN ◽  
M. GHANASHYAM KRISHNA ◽  
A. K. BHATTACHARYA
Keyword(s):  
Thin Films ◽  
Single Phase ◽  
Annealing Temperature ◽  
Sol Gel ◽  
Average Particle Size ◽  
Optical Transmittance ◽  
Dip Coating ◽  
Correlation Spectroscopy ◽  
Average Particle ◽  
X Ray

A novel all-inorganic aqueous sol–gel process has been developed to fabricate LaFeO3 thin films by dip-coating. Stable, positively charged colloidal sol particles of hydrous lanthanum ferrite with an average particle size (Z av ) of 7 nm were prepared and coated onto quartz plates under controlled conditions. The sols have been characterized using photon correlation spectroscopy (PCS) for Z av and size distribution. The redispersible gel was characterized by thermogravimetric and differential thermal analysis (TG-DTA) and also by isothermal heating followed by X-ray diffraction to identify the reaction sequence to form LaFeO 3. The sol–gel films as deposited were X-ray amorphous on heating up to 500°C, partially crystalline at 600°C, fully crystalline and single phase at 650°C and above. These films were continuous, polycrystalline, single phase, had uniform thickness in the range between 180 to 1000 nm, depending on deposition conditions, and showed about 80% optical transmittance. The optical band gap varied from 2.7 to 3.3 eV as a function of the annealing temperature. The refractive index increased with increase in annealing temperature from 1.55 at 500°C to 1.86 at 800°C.

Facile Synthesis and Characterization of Spinel NiFe2O4 Nanoparticles and Studies of Their Photocatalytic Activity for Oxidation of Alcohols

2020 ◽  
Vol 12 (3) ◽  
pp. 357-365 ◽  
Author(s):  
Xiangrong Ma ◽  
Rui Dang ◽  
Jieying Liu ◽  
Fang Yang ◽  
Huigui Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Photoelectron Spectroscopy ◽  
Average Particle Size ◽  
Average Particle ◽  
X Ray ◽  
Bet Analysis ◽  
Oxidation Of Alcohols ◽  
20 Nm ◽  
Adsorption Desorption

In this paper, we report a novel and facile approach for the synthesis of spinel NiFe2O4 nanoparticles and studies of its photocatalytic activity for oxidation of alcohols. The as-synthesized catalyst was thoroughly characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), elemental mapping, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and N2 adsorption–desorption isotherm (BET) analysis. The TEM image reveals cubic shapes with an average particle size of 10–20 nm. The as-synthesized spinel NiFe2O4 has proved to be an excellent photocatalyst for oxidation of alcohol to the aldehyde with a conversion of 80% and selectivity of 99%. The catalyst has also proved to be noteworthy as it does not loss its catalytic activity even after five cycles of reuse.

scholarly journals Facile Formation of Anatase/Rutile TiO2 Nanocomposites with Enhanced Photocatalytic Activity

Molecules ◽  
2019 ◽  
Vol 24 (16) ◽  
pp. 2996 ◽  
Author(s):  
Jing He ◽  
Yi-en Du ◽  
Yang Bai ◽  
Jing An ◽  
Xuemei Cai ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Tio2 Nanoparticles ◽  
Crystal Surface ◽  
Sol Gel ◽  
Average Particle Size ◽  
Mixed Phase ◽  
Average Particle ◽  
Light Illumination ◽  
Potential Candidate ◽  
Rutile Tio2

Anatase/rutile mixed-phase TiO2 nanoparticles were synthesized through a simple sol-gel route with further calcination using inexpensive titanium tetrachloride as a titanium source, which effectively reduces the production cost. The structural and optical properties of the prepared materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-vis adsorption. The specific surface area was also analyzed by Brunauer–Emmett–Teller (BET) method. The anatase/rutile mixed-phase TiO2 nanocomposites containing of rod-like, cuboid, and some irregularly shaped anatase nanoparticles (exposed {101} facets) with sizes ranging from tens to more than 100 nanometers, and rod-like rutile nanoparticles (exposed {110} facets) with sizes ranging from tens to more than 100 nanometers. The photocatalytic activities of the obtained anatase/rutile mixed-phase TiO2 nanoparticles were investigated and compared by evaluating the degradation of hazardous dye methylene blue (MB) under ultraviolet light illumination. Compared to the commercial Degussa P25-TiO2, the mixed-phase TiO2 nanocomposites show better photocatalytic activity, which can be attributed to the optimal anatase to rutile ratio and the specific exposed crystal surface on the surface. The anatase/rutile TiO2 nanocomposites obtained at pH 1.0 (pH1.0-TiO2) show the best photocatalytic activity, which can be attributed to the optimal heterojunction structure, the smaller average particle size, and the presence of a specific exposed crystal surface. The enhanced photocatalytic activity makes the prepared anatase/rutile TiO2 photocatalysts a potential candidate in the removal of the organic dyes from colored wastewater.

scholarly journals Effect of Synthesis Method on Antibacterial and Antibiofilm Activity Properties of BaFeO3-δ Perovskite Nanomaterials

2021 ◽  
Author(s):  
eid khalaf ◽  
E. K. Abdel-Khalek ◽  
Ahmed. A. Askar ◽  
M. A. Motawea ◽  
Mohamed A. Aboelnasr ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Average Particle Size ◽  
Synthesis Method ◽  
Rietveld Analysis ◽  
Antibiofilm Activity ◽  
Average Particle ◽  
X Ray ◽  
Valence States ◽  
Fe Ions

Abstract BaFeO3-δ perovskite nanomaterials have been synthesized by two different methods: co-precipitation (Cop) and sol-gel (Sol) methods. Rietveld analysis of the X-Ray diffraction (XRD) shows that the samples are crystallized in rhombohedral perovskite structure with space group R3c. Scanning electron microscope (SEM) of these samples showed the agglomerations of various particles. Dynamic light scattering (DLS) showed that the average particle size of BaFeO3-Cop sample is larger than that of BaFeO3-Sol sample. The amount of oxygen deficient (δ) and the valence states of Fe ions in these samples were determined from Mössbauer spectroscopy. X-ray photoelectron spectroscopy (XPS) shows the elemental compositions and surface electronic states of these samples. The thermal, optical and magnetic properties of these samples depend on the amount of oxygen deficient (δ) and the valence states of Fe ions. Furthermore, the antibacterial and antibiofilm activity of these samples was systematically investigated. The present results suggest that BaFeO3-δ superparamagnetic perovskite can be used as antibacterial and antibiofilm agent.

STRUCTURE AND THICKNESS DEPENDENT OPTICAL PROPERTIES OF NANOCRYSTALLINE HAEMATITE THIN FILMS

2001 ◽  
Vol 15 (02) ◽  
pp. 201-208 ◽  
Author(s):  
M. RAJENDRAN ◽  
M. GHANASHYAM KRISHNA ◽  
A. K. BHATTACHARYA
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Reaction Pathway ◽  
Sol Gel ◽  
Average Particle Size ◽  
Dip Coating ◽  
Correlation Spectroscopy ◽  
Average Particle ◽  
X Ray ◽  
Thermoanalytical Techniques

An aqueous sol-gel process has been developed to deposit nanocrystalline haematite (α- Fe 2 O 3) thin films by dip-coating. Stable, positively charged colloidal sol particles of hydrous iron (III) oxide with an average particle size (Z av ) of 6 nm were prepared and coated onto quartz plates under controlled conditions. The sols were characterised using photon correlation spectroscopy (PCS) for Z av and size distribution. The re-dispersible gel was characterised by thermoanalytical techniques (TG-DTA) and also by isothermal heating followed by X-ray diffraction to identify the reaction pathway to form α- Fe 2 O 3. The films as deposited were X-ray amorphous up to 450°C, nan°Crystalline in the range 450 to 600°C, crystalline and single phase above 600°C. The films were optically transparent, continuous and had uniform thickness in the range between 180 nm to 1000 nm depending on deposition conditions. The optical band gap varied from 2.1 to 2.6 eV as a function of film thickness. The refractive index increased with increase in annealing temperature but decreased with film thickness.

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