Microwave Absorption of BaLa0.5Fe11.5O19/SiO2 Nano-Powders

2010 ◽  
Vol 105-106 ◽  
pp. 380-382
Author(s):  
Zhi Dong Han ◽  
Qing Rui Zhao ◽  
Li Min Dong ◽  
Ze Wu ◽  
Xian You Zhang
Keyword(s):  
Sol Gel ◽  
Sio2 Nanoparticles ◽  
Nano Particles ◽  
Powder Size ◽  
X Ray Diffraction ◽  
Microwave Absorbing Properties ◽  
Diffraction Peaks ◽  
Microwave Absorbing ◽  
Xrd Patterns ◽  
Nano Size

Nano-size BaM hexaferrites (BaLa0.5Fe11.5O19) were synthesized in the presence of SiO2 nano- particles by sol-gel method. The X-ray diffraction (XRD) patterns of ferrites annealed at above 900°C manifested that all the species had hexagonal crystal structure and no diffraction peaks of SiO2 found. Compared with BaLa0.5Fe11.5O19 powders, those synthesized in the presence of SiO2 nano-particles presented in smaller powder size, as proved by scanning electron microscopy (SEM). As a result, SiO2 nanoparticles promoted the formation of more homogeneous and finer ferrite crystal while the structure of hexaferrites consisted with that synthesized without SiO2 nano-particles. Microwave absorbing properties were evaluated. As a result, BaLa0.5Fe11.5O19/SiO2 showed good microwave absorbing properties with the maximum absorption more than 20dB.

Structure and Magnetic Properties of BaLa0.5Fe11.5O19/ SiO2

2008 ◽  
Vol 368-372 ◽  
pp. 626-628 ◽  
Author(s):  
Zhi Dong Han ◽  
Li Min Dong ◽  
Ze Wu ◽  
Xian You Zhang
Keyword(s):  
Magnetic Properties ◽  
Saturation Magnetization ◽  
Sol Gel ◽  
Sio2 Nanoparticles ◽  
Nano Particles ◽  
Powder Size ◽  
Hexagonal Crystal ◽  
Method Effects ◽  
Diffraction Peaks ◽  
Xrd Patterns

The paper aims at synthesizing La substituted BaM hexaferrites (BaLa0.5Fe11.5O19) in the presence of SiO2 nano-particles by sol-gel method. Effects of SiO2 nano-particles on the structure and particle size of hexaferrites are investigated by XRD and SEM. Magnetic properties of BaFe12O19, BaLa0.5Fe11.5O19 and BaLa0.5Fe11.5xO19/SiO2 are compared by vibrating sample magnetometer (VSM). The XRD patterns of BaLa0.5Fe11.5O19/SiO2 calcined at 1000°C manifest that all the species have hexagonal crystal structure and no diffraction peaks of SiO2 are found. Compared with BaLa0.5Fe11.5O19 powders, those synthesized in the presence of SiO2 nanoparticles present in smaller powder size, as proved by SEM. The results of VSM reveal that BaLa0.5Fe11.5O19 possesses much higher saturation magnetization than BaFe12O19. BaLa0.5Fe11.5xO19/SiO2 also shows higher saturation magnetization than BaFe12O19, but lower than BaLa0.5Fe11.5O19 because of addition of nano-SiO2.

Photocatalytic Oxidation of Hexanol over Titanium Dioxide Supported on Mesoporous Silica

2015 ◽  
Vol 1112 ◽  
pp. 176-179
Author(s):  
Nur Umisyuhada Mohd Nor ◽  
Hendrik O. Lintang ◽  
Salasiah Endud ◽  
Leny Yuliati
Keyword(s):  
Photocatalytic Activity ◽  
Mesoporous Silica ◽  
Photocatalytic Oxidation ◽  
Sol Gel ◽  
Impregnation Method ◽  
X Ray Diffraction ◽  
Diffraction Peaks ◽  
Loading Amount ◽  
Xrd Patterns ◽  
Mcm 41

In order to improve the efficiency of TiO2, material with large surface area such as mesoporous silica is usually used as a support. In this study, the TiO2 was dispersed on mesoporous silica, MCM-41 by an impregnation method, meanwhile the bulk TiO2 was prepared by sol gel method. The X-ray diffraction (XRD) patterns showed that the intensities of diffraction peaks for MCM-41 decreased with the increase of the TiO2 loading, suggesting that the higher loading amount of TiO2 might lead to less ordered structure of MCM-41. The successful addition of TiO2 on MCM-41 was also confirmed from the fluorescence spectra, which the emission intensities of TiO2 and MCM-41 increased and decreased, respectively, with the increase of TiO2 loading on the MCM-41. The activities were compared between the bulk and dispersed TiO2 for photocatalytic oxidation of hexanol. Both bulk and dispersed TiO2 on MCM-41 showed good photocatalytic activity, while the MCM-41 did not show photocatalytic activity. Since the efficiency of photocatalyst can be defined by its respective turnover number (TON), the comparison between bulk and dispersed TiO2 on MCM-41 was made based on their TON values. It was revealed that the dispersed TiO2 on the MCM-41 with 5 wt% of TiO2 loading was the most efficient photocatalyst among all the samples.

Effect of Calcinations on Characterizations of Fabricated Nano Manganese Ferrite

2013 ◽  
Vol 634-638 ◽  
pp. 2150-2154 ◽  
Author(s):  
Rita Sundari ◽  
Tang Ing Hua ◽  
M. Rusli Yosfiah
Keyword(s):  
Sol Gel ◽  
Volatile Components ◽  
Manganese Ferrite ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Reflectance Analysis ◽  
Transmission Electron Microscope Analysis ◽  
Electron Microscope Analysis ◽  
Nano Size

A citric acid anionic surfactant has been applied for nano manganese ferrite (MnFeO3) fabrication using sol gel method. The calcinations have been varied for 300, 600 and 800oC. The UVDR (UV-Vis Diffused Reflectance) analysis shows a high absorptive band gap after 400 nm for the 600oC calcinated MnFeO3. The DTA (Differential Thermal Analysis) profiles exhibit remarkably trapped volatile matters (H2O, CO2, and NO2) in the fabricated MnFeO3 under sol gel heat treatment at 100oC and the peaks disappeared as the calcination increased to 600oC. As the temperature elevated from 100 to 300oC, the absorption peaks of volatile components are disappeared as demonstrated clearly by the FTIR (Fourier Transform Infrared) spectra of the fabricated material, which 3393 cm-1 corresponded to OH group, 1624 cm-1 to CO group, and 1384 cm-1 to NO group. The XRD (X-Ray Diffraction) spectra show clearly the alteration process from amorphous to crystalline structure as the calcinations increased from 300 to 600oC. In addition, the TEM (Transmission Electron Microscope) analysis exhibits parts of the fabricated MnFeO3 found in cubic nano size of 15-40 nm under interested calcinations and the result is in agreement with that obtained by XRD investigation.

PREPARATION OF SOME NANO SIZE COLOSSAL MAGNETO RESISTANCE MATERIALS BY THE SOL-GEL ROUTE

2003 ◽  
Vol 17 (01) ◽  
pp. 19-24 ◽  
Author(s):  
K. PADMAVATHI ◽  
V. RAJAKUMARI ◽  
M. VITHAL ◽  
V. PRASD ◽  
S. V. SUBRAMANYAM ◽  
...  
Keyword(s):  
Single Phase ◽  
Sol Gel ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Resistivity Measurements ◽  
Temperature Range ◽  
Ionic Size ◽  
Colossal Magneto Resistance ◽  
Magneto Resistance ◽  
Nano Size

A series of colossal magneto resistance materials having compositional formula Re 0.67 Sr 0.33 MnO 3 (Re = Nd, Gd, … etc.) were prepared by the sol-gel method, using Ethylene glycol as a gelating reagent. The materials were characterized by the powder X-ray diffraction technique and are found to be single phase with orthorhombic structure. The particle size of all the materials were calculated using the well known Shearer formula and are found to be in the range of 20–45 nm. In order to determine the transition temperature (T c ), the DC electrical resistivity measurements were also carried out over a temperature range 80–300 K using the four probe method and it has been observed that the T c values are found to increase with increasing ionic size. Finally the magneto resistance measurements were also undertaken in the temperature range 80–300 K and it has been found that the MR values of these materials are better when compared with those prepared by the solid state reaction method.

Synthesis, Characterization and Properties of PANI/(La-Nd Doped BaFe12O19) Composites

2017 ◽  
Vol 727 ◽  
pp. 327-334
Author(s):  
Yan Wang ◽  
Jun Wang ◽  
Xiao Fei Zhang ◽  
Ya Qing Liu
Keyword(s):  
Sol Gel ◽  
Network Analyzer ◽  
X Ray Diffraction ◽  
Sem Images ◽  
Structure Morphology ◽  
Xrd Patterns ◽  
Hexagonal Platelet ◽  
Peak Value ◽  
Properties Of Composites

La-Nd co-doped barium hexaferrites, Ba0.7(LamNdn)0.3Fe12O19 (D-BaM), were successfully prepared by sol-gel method. PANI / D-BaM composites were synthesized by in-situ polymerization in solution. The structure, morphology and properties of samples have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), four-probe conductivity tester and vector network analyzer. The XRD patterns showed that the crystal structure of all the samples exist as M-type phases. The SEM images revealed that the particles presented a hexagonal platelet-like morphology. The magnetic properties could be improved by substitutions of La and Nd ions. The saturation magnetization (Ms) and coercive force (Hc) increased with the change of La / Nd ratio to the maximum at La / Nd = 3:1. The doped particles have also been embedded in conductive PANI to prepare electromagnetic materials, and the conductivity kept on the order of 10-2. The microwave absorbing properties of composites at 30 MHz-6 GHz improved obviously, the peak value of reflection loss could reach-7.5 dB.

The effect of silver concentration and calcination temperature on structural and optical properties of ZnO:Ag nanoparticles

2015 ◽  
Vol 29 (01) ◽  
pp. 1450254 ◽  
Author(s):  
M. Shayani Rad ◽  
A. Kompany ◽  
A. Khorsand Zak ◽  
M. E. Abrishami
Keyword(s):  
Calcination Temperature ◽  
Sol Gel ◽  
Visible Emission ◽  
X Ray Diffraction ◽  
Ag Nps ◽  
Zno Nps ◽  
Calcination Temperatures ◽  
Transmission Electron ◽  
Xrd Patterns ◽  
Average Size

Pure and silver added zinc oxide nanoparticles ( ZnO -NPs and ZnO : Ag -NPs) were synthesized through a modified sol–gel method. The prepared samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy. In the XRD patterns, silver diffracted peaks were also observed for the samples synthesized at different calcination temperatures of 500°C, 700°C, 900°C except 1100°C, in addition to ZnO . TEM images indicated that the average size of ZnO : Ag -NPs increases with the amount of Ag concentration. The PL spectra of the samples revealed that the increase of Ag concentration results in the increase of the visible emission intensity, whereas by increasing the calcination temperature the intensity of visible emission of the samples decreases.

The Effect of Ti Addition on the Microstructure and Fracture Toughness of Bn-Al Composite Materials Synthesized by Vacuum Infiltration

2013 ◽  
Vol 58 (2) ◽  
pp. 509-512 ◽  
Author(s):  
W. Chao ◽  
X. Xiangxin ◽  
C. Xiaozhou ◽  
Y. He ◽  
Ch. Gongjin
Keyword(s):  
Fracture Toughness ◽  
Composite Materials ◽  
Vacuum Infiltration ◽  
X Ray Diffraction ◽  
Al Composite ◽  
Vacuum Atmosphere ◽  
Diffraction Peaks ◽  
Xrd Patterns ◽  
Ti Content ◽  
Ti Addition

In this paper, we studied the effect of Ti addition on the microstructure and fracture toughness of Boron nitride- Aluminum (BN-Al) composite materials that were synthesized by vacuum infiltration. The BN-Al composite materials were fabricated by preheating the [Ti+BN] preforms at 1700º for 1 hour before Al alloys were infiltrated into the preforms in a vacuum atmosphere at 1100º for 2 hours. X-ray diffraction (XRD) patterns showed that the diffraction peaks of titanium diboride (TiB2) appeared when the [Ti+BN] preforms were preheated. It is thought that metal Al protected are visible and this could be achieved by the generation of TiB2 when Al infiltrated into the preform from fractography. The matching fracture toughness of the [Ti+BN] preforms gradually improve when Ti content was increased.

scholarly journals Photocatalytic CO2 Reduction and Thermal Properties of Alumina/Silica Coated TiO2 Nanoparticles

2020 ◽  
Vol 2 (2) ◽  
pp. 47
Keyword(s):  
Tio2 Nanoparticles ◽  
Sol Gel ◽  
Co2 Reduction ◽  
Chemical Deposition ◽  
X Ray Diffraction ◽  
Vacuum Oven ◽  
Al2o3 Layer ◽  
Crystal Properties ◽  
Naoh Solution ◽  
Diffraction Peaks

In this study, the surface of TiO2 was coated with SiO2 and Al2O3 layers by sol-gel and chemical deposition methods. Firstly, the TiCl4 was magnetically stirred for 1 h in deionized water, and then the NaOH solution was drop wised to the solution and stirred 2h. Finally, the obtained TiO2 was washed, filtered, and dried in a vacuum oven. The surface of TiO2 was coated with SiO2 and Al2O3 layers subsequently by chemical deposition methods. The morphological, thermal, and crystal properties of products were determined via SEM, TGA, and XRD machines. The X-ray diffraction peaks displayed that the TiO2 nanoparticles were synthesized without any extra peaks. Moreover, the SiO2 and Al2O3 coated TiO2 particles contain extra SiO2 and Al2O3 peaks, indicating that the surface of TiO2 was coated via SiO2 and Al2O3. The SEM results displayed that TiO2 and SiO2 and Al2O3 coated TiO2 were spherical in shape, and the size distribution was found to be around 20-50 nm and 200-300 nm, respectively. The photocatalytic and UV–vis analyses were used to determine the CO2 reduction and optical properties of particles. The results showed that the absorption peaks were broad to longer wavelength with a coating of SiO2 and Al2O3. The CO2 reduction performance of TiO2 has been enhanced via coating SiO2 and Al2O3 layer.

Synthesis and Characterization of Cadmium with Titanium Oxide (Cd-TiO2) Nanocomposite: Testing its Antibacterial Effect

2021 ◽  
Vol 12 (4) ◽  
pp. 2523-2529
Author(s):  
Daniel Sam N ◽  
Anish C I ◽  
Sabeena G ◽  
Rajaduraipandian S ◽  
Manobala ◽  
...  
Keyword(s):  
Sol Gel ◽  
Gram Negative Bacteria ◽  
X Ray Diffraction ◽  
Sem Images ◽  
Gram Negative ◽  
X Ray ◽  
Weight Percentage ◽  
Inhibition Concentration ◽  
Xrd Patterns

Sol gel methods were used for the study of the antimicrobial activity of Cd-TiO2 against gram-negative and positive bacteria. These Cd-TiO2 have been characterized by various optical and techniques. They have been exhibited by X-ray diffraction, scanning electron microscopy, ultraviolet spectroscopy, and infrared spectroscopy. The structures of the various XRD patterns indicate that the product has a structure. The particle size of Cd-TiO2 is 35nm. The SEM images confirm the spherical appearance of the sample. The energy X-ray spectra have been confirmed as well and then C, O, Ti, Cd, Pt element are present in Cd-TiO2. The weight percentage of Cadmium is 5.8%, Ti is 51.03%, C is 5.13% and O is 31.75% in Cd-TiO2. BET image shows that the major pore size distribution of Cd-TiO2 is ranged from 2.24 nm. The Cd-TiO2 that the antibacterial activity when tested against the pathogens only gram-negative bacteria such as Pseudomonas. The zone of minimum inhibition concentration was measured in a range of 20mm in 25μl and 30mm in 100μl.

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