Mössbauer Investigation of γ-Fe2O3 Nanocrystals in Silica Matrix Prepared by the Sol-gel Method

2002 ◽  
Vol 57 (3-4) ◽  
pp. 154-158 ◽  
Author(s):  
C. Cannas ◽  
G. Concas ◽  
F. Congiu ◽  
A. Musinu ◽  
G. Piccaluga ◽  
...  
Keyword(s):  
Particle Size ◽  
Low Temperature ◽  
Sol Gel ◽  
Average Particle Size ◽  
Volume Ratio ◽  
Silica Matrix ◽  
Blocking Temperature ◽  
Average Particle ◽  
Gel Method ◽  
Sol Gel Method

A series of Fe2O3-SiO2 nanocomposites (25 weight % of Fe2O3) has been prepared using a sol-gel method. Samples showing different features were obtained by varying the evaporation conditions acting on the surface / volume ratio of the starting sol. The samples were investigated using Mössbauer spectroscopy at low temperature. The Fe2O3 nanoparticles have been identified as maghemite ( γ-Fe2O3) particles. The samples show a superparamagnetic behavior with a blocking temperature that depends on the average particle size.

Morphology and Optical Studies of (1-x)ZnAl2O4 – xSiO2 Thin Films Prepared by Sol-Gel Method

2014 ◽  
Vol 895 ◽  
pp. 63-68 ◽  
Author(s):  
Mohd Syafiq Zulfakar ◽  
Huda Abdullah ◽  
Wan Nasarudin Wan Jalal ◽  
Sahbudin Shaari ◽  
Zainuddin Zalita
Keyword(s):  
Thin Film ◽  
Particle Size ◽  
Band Gap ◽  
Optical Band Gap ◽  
Sol Gel ◽  
Average Particle Size ◽  
Average Crystallite Size ◽  
Average Particle ◽  
Gel Method ◽  
Sol Gel Method

The effect of morphological structures and optical band gap of (1-x)ZnAl2O4xSiO2samples with compositions ofx= 0.00, 0.05, 0.10 and 0.15 were prepared by sol-gel method. Spin coating technique was used to deposited the (1-x)ZnAl2O4xSiO2as a thin film and to investigate the structural and optical band gap. The produced thin film samples were annealed at 450 °C for 1h. Field emission scanning electron microscope (FESEM) was used to investigate the surface morphology of the samples. The average particle size for (1-x)ZnAl2O4xSiO2is about 331.23 nm. The particle size are tend to increase as the composition of SiO2increased. XRD analysis shows the formation of cubic structure phase and dominant peak has been observed with Miller Indices (311) plane. The average crystallite size,Dwas calculated with average size about 8 13 nm. The optical band gap was calculated for (1-x)ZnAl2O4xSiO2samples and it was found within range of 3.34 to 3.94 eV.

scholarly journals Size Effects on Magnetic Properties ofNi0.5Zn0.5Fe2O4Prepared by Sol-Gel Method

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Min Zhang ◽  
Zhenfa Zi ◽  
Qiangchun Liu ◽  
Peng Zhang ◽  
Xianwu Tang ◽  
...  
Keyword(s):  
Particle Size ◽  
Magnetic Measurements ◽  
Sol Gel ◽  
Domain Wall Motion ◽  
Blocking Temperature ◽  
Particle Sizes ◽  
X Ray Diffraction ◽  
Gel Method ◽  
Sol Gel Method ◽  
Cation Redistribution

Ni0.5Zn0.5Fe2O4particles with different particle sizes have been synthesized by sol-gel method. X-ray diffraction results show that all the samples are pure cubic spinel structure with their sizes ranging from 9 to 96 nm. The lattice constant significantly decreases with further increasing annealing temperature. The magnetic measurements show superparamagnetic nature below the particle size of 30 nm, while others show ferrimagnetic nature above the corresponding blocking temperature. The blocking temperature increases with the increase in particle size, which can be explained by Stoner-Wohlfarth theory. The saturation magnetization increases as the particle size increases, which can be explained by the cation redistribution on tetrahedral A and octahedral B sites and the domain wall motion. The variation of coercivity as a function of particle size is based on the domain structure.

scholarly journals Li Conductivity of Nanocrystalline Li4Ti5O12 Prepared by a Sol-Gel Method and High-Energy Ball Milling

2009 ◽  
Vol 289-292 ◽  
pp. 565-570 ◽  
Author(s):  
W. Iwaniak ◽  
J. Fritzsche ◽  
M. Zukalová ◽  
R. Winter ◽  
Martin Wilkening ◽  
...  
Keyword(s):  
Particle Size ◽  
Crystallite Size ◽  
Sol Gel ◽  
High Energy ◽  
Average Particle ◽  
Li Ion Batteries ◽  
Gel Method ◽  
Sol Gel Method ◽  
Li Ion ◽  
20 Nm

Spinel-type structured Li4+xTi5O12 (0 6 x 6 3 ) is actually one of the most promising anode materials for Li ion batteries. In its nanostructured form it is already used in some commercially available Li ion batteries. As was recently shown by our group (Wilkening et al., Phys. Chem. Chem. Phys. 9 (2007) 1239), Li diffusivity in microcrystalline Li4+xTi5O12 with x = 0 is rather slow. In the present contribution the Li conductivity in nanocrystalline samples of the electronic insulator Li4Ti5O12 prepared by different routes is investigated using impedance spectroscopy. The mean crystallite size of the samples is about 20 nm. The ionic conductivity of nanocrystalline Li4Ti5O12 obtained by mechanical treatment is higher by about two orders of magnitude compared to that found for a material which was prepared following a sol-gel method. The latter resembles the behaviour of the microcrystalline sample with an average particle size in the μm range rather than that of a nanocrystalline ball milled one with a mean crystallite size of about than 20 nm. The larger conductivity of the ball milled sample is ascribed to a much higher defect density generated when the particle size is reduced mechanically.

Barium Zirconium Titanate Powders Prepared by Sol–Gel Method

2011 ◽  
Vol 412 ◽  
pp. 86-89 ◽  
Author(s):  
Xiao Ling Deng ◽  
Dong Jiao Guo ◽  
Wei Cai ◽  
Chun Lin Fu
Keyword(s):  
Sol Gel ◽  
Average Particle Size ◽  
Average Particle ◽  
Gravimetric Analysis ◽  
Zirconium Titanate ◽  
Thermal Gravimetric ◽  
Gel Method ◽  
Sol Gel Method ◽  
Barium Zirconium Titanate ◽  
Xrd Patterns

Barium zirconium titanate, Ba (Zr0.20Ti0.80)O3(BZT) powders were prepared by sol-gel method. These powders were characterized by thermal gravimetric and differential thermal gravimetric analysis (TG-DTA), X-ray diffraction (XRD). The grain size and lattice constant were determined. The decomposition of the precursors was monitored by TG-DTA. XRD patterns reveal that BZT powders heat-treated at 800°C present single phase with perovskite type cubic structure. The average particle size of the BZT powders is about 25 nm.

scholarly journals Structure and dielectric behaviour of Sr-modified Bi4Si3O12 thin films prepared via sol gel method

2018 ◽  
Vol 12 (1) ◽  
pp. 36-44 ◽  
Author(s):  
Abbas Sadeghzadeh-Attar ◽  
Saeid Hajijafari-Bidgoli ◽  
Mohammad Bafandeh
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Dielectric Loss ◽  
Annealing Temperature ◽  
Sol Gel ◽  
Average Particle Size ◽  
Average Particle ◽  
Sem Images ◽  
Gel Method ◽  
Sol Gel Method

Bismuth silicate (Bi4Si3O12, BSO) nanostructured films containing 0,1,2, and 3mol% Sr were prepared via sol-gel method and annealed at different temperatures up to 700?C. The effects of Sr content on the structure and morphology of prepared films were investigated. SEM images showed that surfaces of the prepared films were dense, smooth and homogeneous. The average particle size was changed from 30 to 35 nm as the annealing temperature was increased from 500 to 700?C. Variation of the dielectric constant and dielectric loss as a function of frequency and annealing temperature for the synthesized thin films with different content of Sr were also studied. The dielectric constant and dielectric loss decrease with Sr addition, and reach the minimum for the sample containing 2mol% Sr. These changes could be attributed to the crystal structure and formation of secondary phases.

Synthesis and Characterization of Nanosized ZrTiO4 Powders Prepared by the Sol-Gel Method

2006 ◽  
Vol 530-531 ◽  
pp. 401-407 ◽  
Author(s):  
I.C. Cosentino ◽  
F.M. Vichi ◽  
E.N.S. Muccillo ◽  
R. Muccillo
Keyword(s):  
Mercury Porosimetry ◽  
Sol Gel ◽  
Average Particle Size ◽  
Nitrogen Adsorption ◽  
Zirconium Oxychloride ◽  
Average Particle ◽  
Titanium Tetraisopropoxide ◽  
Nanosized Powders ◽  
Gel Method ◽  
Sol Gel Method

Ceramic ZrTiO4 powders were prepared by a modified sol-gel method using zirconium oxychloride and titanium tetraisopropoxide. In situ high temperature X-ray diffraction results show that crystallization of the amorphous gel starts at 400 °C. Singlephase ZrTiO4 nanoparticles were obtained after heat treatment at 450 oC for 1 h. An average particle size of 46 nm has been determined by nitrogen adsorption analysis. After pressing these sinteractive powders, pellets with controlled pore size distribution were obtained by sintering at temperatures as low as 400 oC. The analysis of pores by mercury porosimetry shows an average porosity of 45 %. Pressing and sintering the nanosized powders prepared by that modified sol-gel technique produced pellets that are good candidates to be used in humidity sensing devices.

Low-Temperature Sintering and Enhanced Piezoelectric Properties in KNN-LTS Nanopowder Prepared via a Low-Cost Water-Based Sol-Gel Method

2014 ◽  
Vol 602-603 ◽  
pp. 795-799
Author(s):  
Yu Huan ◽  
Xiao Hui Wang ◽  
Long Tu Li
Keyword(s):  
Electrical Properties ◽  
High Performance ◽  
Low Cost ◽  
Sol Gel ◽  
Average Particle Size ◽  
Lead Free ◽  
Average Particle ◽  
Gel Method ◽  
Sol Gel Method ◽  
Water Based

nanoscale lead-free perovskite powders with a composition of (Na0.52K0.4425Li0.0375)(Nb0.9125Ta0.0375Sb0.05)O3 (KNN-LTS) have been synthesized via a low-cost water-based sol-gel method, to reduce the sintering temperature and enhance the electrical properties. KNN-LTS nanopowders with average particle size of about 20 nm are obtained by citrate precursor sol-gel process, where Nb (OH)5 and Sb2O3 are used to replace the costly mental alkoxides. The sol-gel derived nanopowders can be densified at lower temperature of 940 °C and exhibited excellent electrical properties after sintering at 1020 °C (d33 = 396 pC/N, kp = 50.1% = 1882 and tanδ = 0.02), providing a tremendous potential method for high-performance lead-free ceramics preparation.

DOPANT EFFECTS ON THE STRUCTURAL, OPTICAL AND ELECTRICAL TRANSPORT PROPERTIES IN SrTi1-xCoxO3 NANOPARTICLES SYNTHESIZED BY SOL–GEL METHOD

2010 ◽  
Vol 19 (02) ◽  
pp. 219-227
Author(s):  
DOAN THI THUY PHUONG ◽  
NGUYEN VAN MINH
Keyword(s):  
Transport Properties ◽  
Electrical Transport ◽  
Annealing Temperature ◽  
Dopant Concentration ◽  
Sol Gel ◽  
Average Particle Size ◽  
Average Particle ◽  
Electrical Transport Properties ◽  
Gel Method ◽  
Sol Gel Method

We investigate effects of Co dopant concentration on the structure, as well as optical and electrical transport properties in SrTi 1-x Co x O 3 (x = 0.00, 0.10, 0.20, 0.30, 0.40, 0.50) nanoparticles prepared by sol–gel method with annealing temperature considerably lower than that employed conventionally. The dopant-induced changes are studied by XRD, Raman, Optical absorption and Impedance measurements. The results show an average particle size of about 30 nm, and decreasing lattice parameters. In the Raman spectra, a broad structure in the region 200–500 cm-1 is almost absent and the peaks in the region 600–800 cm-1 show different relative weights with respect to those from SrTiO 3, which is related to structural changes, decreasing gap with increasing dopant concentration in conjuction with increasing grain boundary contribution to the impedance. These results also demonstrate the feasibility of synthesizing the compound with low annealing temperature.

Structural and Morphological Properties of Ag and In Co-Doped ZnO Nanoparticles Synthesized by Sol-Gel Method

2017 ◽  
Vol 17 ◽  
pp. 101-105 ◽  
Author(s):  
V. Porkalai ◽  
B. Sathya ◽  
Durairaj Benny Anburaj ◽  
G. Nedunchezhian ◽  
R. Meenambika
Keyword(s):  
Zno Nanoparticles ◽  
Sol Gel ◽  
Average Particle Size ◽  
Morphological Properties ◽  
Average Particle ◽  
Gel Method ◽  
X Ray ◽  
Sol Gel Method ◽  
Doped Zno ◽  
Co Doped

Zinc oxide has been receiving an enormous attention due to its potential applications in a variety of field such as optoelectronics, spintronics and sensors. Ag and In co-doped ZnO nanoparticles with different doping concentration 0.1M, 0.2M and 0.3M were prepared by sol-gel method via microwave irradiation followed by calcinations at 600°C for 2h. The structure and morphology were examined by X-ray diffraction (XRD), and Scanning Electron Microscope (SEM), respectively. Elemental composition has been estimated by Energy Dispersive X-ray Absorption (EDAX), while chemical properties are studied by Fourier transform infrared spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) . The average particle size of the synthesized ZnO nanoparticles was calculated using the Scherrer formula and is found to be of less than 20 nm. Also the effect on the structure and the morphological properties of ZnO when co-doped with silver and Indium is examined. As the process is simple and low cost, it has the potential to be produced on a large scale.

Effect of Solvent Composition on the Formation of Hydroxyapatite/Silk Fibroin Composites Prepared Using Sol-Gel Method

2013 ◽  
Vol 446-447 ◽  
pp. 408-413
Author(s):  
Suchaya Sriudom ◽  
Hataichanoke Niamsup ◽  
Surin Saipanya ◽  
Ruangsri Watanesk ◽  
Surasak Watanesk
Keyword(s):  
Particle Size ◽  
Silk Fibroin ◽  
Sol Gel ◽  
Volume Ratio ◽  
Structural Features ◽  
Binary Solvent ◽  
Gel Method ◽  
X Ray ◽  
Sol Gel Method ◽  
Calcium Phosphorus

Hydroxyapatite (HA) has been widely utilized in the biomedical applications due to its chemical and structural features that are similar to the natural bones. The addition of organic components enhances the flexibility of the HA-based composites which result in increasing its molding ability into any desirable shapes. In this article, preparation of hydroxyapaptite/silk fibroin (HA/SF) composite using sol-gel method is reported. The optimal condition for preparing the HA/SF composites was determined by judging from their crystallite size, crystallinity and particle size distribution, morphology and calcium/phosphorus (Ca/P) ratio investigated with X-ray diffraction analysis, particle size analyzer, scanning electron microscopy and energy dispersive X-ray spectroscopy, respectively. The HA/SF composite was successfully prepared in the binary solvent of ethanol and water at the optimal volume ratio of 4:1. At this solvent condition, the composites had a uniform rod-liked shape, ranging from 30-70 nanometers. The Ca/P ratios of all composites are close to the theoretical value of about 1.67.

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