scholarly journals CoFe2O4-TiO2Hybrid Nanomaterials: Synthesis Approaches Based on the Oil-in-Water Microemulsion Reaction Method

2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
Arturo Adrián Rodríguez-Rodríguez ◽  
Sagrario Martínez-Montemayor ◽  
César Cutberto Leyva-Porras ◽  
Francisco Enrique Longoria-Rodríguez ◽  
Eduardo Martínez-Guerra ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Core ◽  
Hybrid Nanoparticles ◽  
Magnetic Domains ◽  
Spinel Type ◽  
Reaction Method ◽  
Light Region ◽  
Oil In Water ◽  
Vis Spectroscopy ◽  
Nanomaterials Synthesis

CoFe2O4nanoparticles decorated and wrapped with TiO2nanoparticles have been prepared by mixing well-dispersed CoFe2O4with amorphous TiO2(impregnation approach) and growing amorphous TiO2over the magnetic core (seed approach), respectively, followed by thermal treatment to achieve TiO2crystallinity. Synthesis strategies were based on the oil-in-water microemulsion reaction method. Thermally treated nanomaterials were characterized in terms of structure, morphology, and composition, to confirm hybrid nanoparticles formation and relate with the synthesis approaches; textural, optical, and magnetic properties were evaluated. X-ray diffraction revealed coexistence of cubic spinel-type CoFe2O4and tetragonal anatase TiO2. Electron microscopy images depicted crystalline nanoparticles (sizes below 25 nm), with homogeneous Ti distribution for the hybrid nanoparticles synthesized by seed approach. EDX microanalysis and ICP-AES corroborated established chemical composition. XPS evidenced chemical states, as well as TiO2predominance over CoFe2O4surface. According to BET measurements, the hybrid nanoparticles were mesoporous. UV-Vis spectroscopy showed optical response along the UV-visible light region. Magnetic properties suggested the breaking order of magnetic domains due to modification with TiO2, especially for mediated seed approach sample. The properties of the obtained hybrid nanoparticles were different in comparison with its individual components. The results highlight the usefulness of designed microemulsion approaches for the straightforward synthesis of CoFe2O4-TiO2nanostructured hybrids.

scholarly journals Diatom Mediated Production of Fluorescent Flower Shaped Silver-Silica Nanohybrid

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7284
Author(s):  
Piya Roychoudhury ◽  
Aleksandra Golubeva ◽  
Przemysław Dąbek ◽  
Michał Gloc ◽  
Renata Dobrucka ◽  
...  
Keyword(s):  
High Surface ◽  
Nitrate Solution ◽  
Volume Ratio ◽  
Cost Effective ◽  
Silver Nitrate Solution ◽  
Hybrid Nanoparticles ◽  
Sem Images ◽  
Light Region ◽  
Vis Spectroscopy ◽  
Sio2 Particles

Fabrication of flower-like nanostructures are gaining attention because of their high surface/volume ratio and extensive adsorption capacity. In the present investigation, flower-shaped, autofluorescent silver-silica (Ag-SiO2) hybrid nanoparticles have been fabricated exploiting diatoms as a source of nanosilica. Two different species of Gedaniella including G. flavovirens and G. mutabilis showed their efficacy in synthesizing fluorescent Ag-SiO2 nanoflowers (NFs) and nanospheres (NSs) against 9 mM silver nitrate solution, respectively. The biogenic nanoconjugate (Ag-SiO2) was characterized by Uv-vis spectroscopy, energy dispersive X-ray spectroscopy (EDS), scanning (SEM) and transmission (TEM) electron microscopy. Production of Ag-SiO2 hybrid nanoparticle was confirmed by observing both Ag and Si signals from a single nanoparticle in an EDS study. The broad and single absorption band at ~420 nm in Uv-vis spectroscopy confirmed proper miscibility and production of hybrid nanoparticles. The Ag-SiO2 nanohybrids revealed autofluorescent property under the blue light region (excitation ~450–490 nm). SEM images of particles synthesized by G. flavovirens revealed the production of microscopic flower shaped Ag-SiO2 particles with several layers of petals. A TEM study confirmed that the synthesized Ag-SiO2 NFs are variable in size with 100–500 nm in diameter. Decolorization of methylene blue after exposure to Ag-SiO2 particles confirmed catalytic activity of synthesized nanostructures. This eco-friendly method provides a new dimension in nanobiotechnology for biogenesis of such hierarchical nanostructure in a cost-effective way.

Spinel-type ferrite nanoparticles: Synthesis by the oil-in-water microemulsion reaction method and photocatalytic water-splitting evaluation

2019 ◽  
Vol 44 (24) ◽  
pp. 12421-12429 ◽  
Author(s):  
Arturo Adrián Rodríguez-Rodríguez ◽  
Maira Berenice Moreno-Trejo ◽  
Miguel Jesús Meléndez-Zaragoza ◽  
Virginia Collins-Martínez ◽  
Alejandro López-Ortiz ◽  
...  
Keyword(s):  
Water Splitting ◽  
Ferrite Nanoparticles ◽  
Spinel Type ◽  
Reaction Method ◽  
Photocatalytic Water Splitting ◽  
Oil In Water ◽  
Nanoparticles Synthesis

Effect of Temperature on the Magnetic Permeability of Hexagonal Ferrites

2018 ◽  
Vol 781 ◽  
pp. 36-40
Author(s):  
Olga Dotsenko ◽  
Kirill Frolov ◽  
Dmitry Wagner ◽  
Veronika Dotsenko ◽  
Dmitry Aksentev
Keyword(s):  
Magnetic Properties ◽  
High Temperature ◽  
High Frequency ◽  
Solid State Reaction Method ◽  
Nonlinear Dependence ◽  
Effect Of Temperature ◽  
Hexagonal Ferrites ◽  
Temperature Synthesis ◽  
Reaction Method ◽  
High Temperature Synthesis

In this study, Co0,7Zn1,3W powders were synthesized and investigated at the microwave region. The solid-state reaction method and self-propagating high-temperature synthesis were used to production of the two kinds of hexaferrite powders. The high-frequency magnetic properties under temperature effect have been studied. It is show, that there is a nonlinear dependence on temperature within the 0 – +40 °C temperature range.

scholarly journals Influence of mechanical activation and heat treatment on magnetic properties of nanostructured mixture Ni85.8Fe10.6Cu2.2W1.4

2019 ◽  
Vol 55 (1) ◽  
pp. 85-93 ◽  
Author(s):  
M.M. Vasic ◽  
A.S. Kalezic-Glisovic ◽  
R. Milincic ◽  
Lj. Radovic ◽  
D.M. Minic ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Thermal Treatment ◽  
Mechanical Activation ◽  
Powder Mixture ◽  
Structural Characteristics ◽  
Volume Density ◽  
Magnetic Domains ◽  
Microstructural Changes ◽  
Mass Magnetization ◽  
Stress Relieving

The mechanical activation of the Ni85.8Fe10.6Cu2.2W1.4 powder mixture in the time intervals of 30-210 min in combination with thermal treatment at 393-873 K resulted in microstructural changes, forming the nanostructured mixture of the same composition but improved magnetic properties. The best result were achieved for mechanical activation during 120 min and thermal treatment at temperatures close to the Curie temperature (693K), enhancing the mass magnetization of the starting powder mixture by about 57%. The microstructural changes, which include the structural relaxation, decrease in free volume, density of dislocation and microstrain, improve structural characteristics of material, enabling better mobility of walls of magnetic domains and their better orientation in applied magnetic field and consequently enabling better mass magnetization of the material. With longer time of milling, the growing stress introduced in the sample undergoes easier relief, relocating stress-relieving processes toward lower temperatures.

Characterization of Antiferromagnetism in Double Perovskites Ba2FeMoO6 Prepared by Solid State Method

2019 ◽  
Vol 891 ◽  
pp. 224-229
Author(s):  
Naphat Albutt ◽  
Vanussanun Aitviriyaphan ◽  
Thanapong Sareein ◽  
Sudarath Suntaropas ◽  
Panakamon Thonglor ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Solid State ◽  
Solid State Reaction ◽  
Double Perovskite ◽  
Solid State Reaction Method ◽  
Double Perovskites ◽  
Solid State Method ◽  
Reaction Method ◽  
State Method

The magnetic properties of Ba2FeMoO6 (BFMO) double perovskite are investigated. BFMO samples were prepared by solid state reaction method through compression. Magnetic properties are influenced by electron environments of the Fe3+ and Mo5+ ions within the perovskite structure. BFMO sintered at 800 oC exhibited the largest hysteresis loop at 50 K. In addition, the values of Ms and Mr indicate ferromagnetic behaviour in BFMO ceramics sintered at 800 oC for different times up to 10 hours. Using the Curie-Weiss law fitting to investigate μeff~30μB high spin of Fe and Mo, and negative θ present the antiferromagnetic characteristics of the BFMO sample.

scholarly journals Antibacterial Activity of TiO2- and ZnO-Decorated with Silver Nanoparticles

2019 ◽  
Vol 3 (2) ◽  
pp. 61 ◽  
Author(s):  
Van Thang Nguyen ◽  
Viet Tien Vu ◽  
The Huu Nguyen ◽  
Tuan Anh Nguyen ◽  
Van Khanh Tran ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Antibacterial Activity ◽  
Zno Nanoparticles ◽  
Visible Region ◽  
Light Irradiation ◽  
Hybrid Nanoparticles ◽  
Diffusion Method ◽  
Oxide Nanoparticles ◽  
Vis Spectroscopy ◽  
Xrd Patterns

This work emphasizes the use of the silver decorative method to enhance the antibacterial activity of TiO2 and ZnO nanoparticles. These silver-decorated nanoparticles (hybrid nanoparticles) were synthesized using sodium borohydride as a reducing agent, with the weight ratio of Ag precursors/oxide nanoparticles = 1:30. The morphology and optical properties of these hybrid nanoparticles were investigated using transmission electron microscopy (TEM), X-ray diffraction (XRD) patterns, and UV-Vis spectroscopy. The agar-well diffusion method was used to evaluate their antibacterial activity against both Staphylococcus aureus and Escherichia coli bacteria, with or without light irradiation. The TEM images indicated clearly that silver nanoparticles (AgNPs, 5–10 nm) were well deposited on the surface of nano-TiO2 particles (30–60 nm). In addition to this, bigger AgNPs (<20 nm) were dispersed on the surface of nano-ZnO particles (30–50 nm). XRD patterns confirmed the presence of AgNPs in both Ag-decorated TiO2 and Ag-decorated ZnO nanoparticles. UV-Vis spectra confirmed that the hybridization of Ag and oxide nanoparticles led to a shift in the absorption edge of oxide nanoparticles to the lower energy region (visible region). The antibacterial tests indicated that both oxide pure nanoparticles did not exhibit inhibitory effects against bacteria, with or without light irradiation. However, the presence of AgNPs in their hybrids, even at low content (<40 mg/mL), leads to a good antibacterial activity, and higher inhibition zones under light irradiation as compared to those in dark were observed.

scholarly journals Structural and optical properties of AgCl-sensitized TiO2 (TiO2 @AgCl) prepared by a reflux technique under alkaline condition

Cerâmica ◽  
2018 ◽  
Vol 64 (370) ◽  
pp. 190-196 ◽  
Author(s):  
V. A. Mu’izayanti ◽  
H. Sutrisno
Keyword(s):  
Visible Light ◽  
Surface Area ◽  
Alkaline Condition ◽  
Visible Light Region ◽  
X Ray Diffraction ◽  
Structural And Optical Properties ◽  
Light Region ◽  
Vis Spectroscopy ◽  
Xrd Patterns ◽  
Tio2 Rutile

Abstract The AgCl-sensitized TiO2 (TiO2@AgCl) has been prepared from the precursor of TiO2-rutile type which on its surface adsorb chloride anion (Cl-) and various amounts of silver using AgNO3 as starting material: AgNO3/(AgNO3+TiO2) mass ratio of 0.00, 1.14, 3.25, 6.38 and 10.32%. Reflux under alkaline condition was the employed technique. All samples were characterized by X-ray diffraction (XRD) and diffuse reflectance UV-vis spectroscopy. The sample without the addition of AgNO3 was analyzed by scanning electron microscope and surface area analyzer. The morphology of the sample showed a distribution of microspheres of approximately 0.5 to 1.0 µm and the specific surface area was 68 m2/g. XRD patterns indicated that the sample without the addition of AgNO3 contained two types of TiO2: rutile (major) and anatase (minor), whereas the samples with the addition of AgNO3 consisted of one phase of AgCl and two types of TiO2: rutile and anatase. The bandgaps of the samples were in the range of 2.97 to 3.24 eV, which were very close to the bandgap of intrinsic TiO2 powder. The presence of 0.8, 2.6 and 4.4 wt% of AgCl in each sample resulted in an additional bandgap in visible light region of 1.90, 1.94 and 2.26 eV, respectively, whereas the presence of 9.4 wt% of AgCl in the sample resulted in two bandgaps in visible light region of 1.98 and 1.88 eV.

PHOTOCATALYTIC ACTIVITY UNDER VISIBLE LIGHT REGION OF Ca-MODIFIED TiO2NP FILMS PREPARED BY SPARKING OFF Ca-ELECTROPLATED Ti TIPS

2018 ◽  
Vol 25 (Supp01) ◽  
pp. 1840002 ◽  
Author(s):  
NIDCHAMON JUMRUS ◽  
ARISARA PANTHAWAN ◽  
TEWASIN KUMPIKA ◽  
WATTIKON SROILA ◽  
EKKAPONG KANTARAK ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Quartz Substrate ◽  
Ambient Air ◽  
Visible Light Region ◽  
Structural And Optical Properties ◽  
Uniform Size ◽  
Light Region ◽  
Vis Spectroscopy ◽  
Electroplating Process

In this work, calcium (Ca)-modified titanium dioxide (TiO2) nanoparticulate (NP) films were successfully prepared using sparking off Ca-electroplated Ti tips. Aqueous solution of calcium carbonate (CaCO3) was used as electrolyte in the electroplating process. The experiment was carried out using electric current of 0.02[Formula: see text]mA applied to titanium electrodes for 10[Formula: see text]min. The NP films with small and uniform size were deposited on quartz substrate using the sparking process with a high DC voltage of 4[Formula: see text]kV in ambient air. The as-deposited NP films were then annealed at 800∘C, 900∘C and 1000∘C for 3[Formula: see text]h under atmospheric pressure to improve their crystallinity. Morphology, structural and optical properties of the NP films were characterized by SEM, XRD, Raman, XPS and UV-Vis spectroscopy. The effects of annealing temperature on the properties of the as-deposited and annealed NP films were reported. Furthermore, photocatalytic activity against 10 [Formula: see text]M of methylene blue (MB) under visible light region will be discussed.

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