scholarly journals SYNTHESIS AND DIELECTRIC PROPERTIES OF NANOCRYSTALLINE BASRTIO3

2012 ◽  
Vol 05 ◽  
pp. 188-195
Author(s):  
M. Golmohammad ◽  
A. Nemati ◽  
M. A. Faghihi Sani
Keyword(s):  
Grain Size ◽  
Sol Gel ◽  
Simultaneous Thermal Analysis ◽  
Nanocrystalline Powders ◽  
Grain Size Effect ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transition Electron Microscopy ◽  
Titanium Tetrabutoxide ◽  
Transition Electron

Ba 0.7 Sr 0.3 TiO 3 was prepared via simple sol-gel method by using titanium tetrabutoxide, barium and strontium carbonates, citric acid and ethylene glycol as starting materials. Simultaneous Thermal Analysis (STA) was used to examine thermal behavior of xerogel. The crystallite size of BST was about 21nm calculated by X-Ray diffraction (XRD) and confirmed by transition electron microscopy (TEM). Using these nanocrystalline powders, BST pellets were prepared and sintered in various temperatures. The grain size effect on electrical properties was studied and found that as the grain size decreased, the dielectric constant decreased too.

Ionic conductivity in nanocrystalline Gd doped ceria

2008 ◽  
Vol 1122 ◽  
Author(s):  
Gianguido Baldinozzi ◽  
David Simeone ◽  
Dominique Gosset ◽  
Mickael Dollé ◽  
Georgette Petot-Ervas
Keyword(s):  
Grain Size ◽  
Ionic Conductivity ◽  
Sol Gel ◽  
Doped Ceria ◽  
Narrow Size Distribution ◽  
Conductivity Measurements ◽  
X Ray Diffraction ◽  
X Ray ◽  
Grain Sizes ◽  
The Impact

AbstractWe have synthesized Gd-doped ceria polycrystalline samples (5, 10, 15 %mol), having relative densities exceeding 95% and grain sizes between 30 and 160 nm after axial hot pressing (750 °C, 250 MPa). The samples were prepared by sintering nanopowders obtained by sol-gel chemistry methods having a very narrow size distribution centered at about 16 nm. SEM and X-ray diffraction were performed to characterize the sample microstructures and to assess their structures. We report ionic conductivity measurements using impedance spectroscopy. It is important to investigate the properties of these systems with sub-micrometric grains and as a function of their composition. Therefore, samples having micrometric and nanometric grain sizes (and different Gd content) were studied. Evidence of Gd segregation near the grain boundaries is given and the impact on the ionic conductivity, as a function of the grain size and Gd composition, is discussed and compared to microcrystalline samples.

Heterogeneity Effects in X-Ray Analysis*

1961 ◽  
Vol 5 ◽  
pp. 335-354 ◽  
Author(s):  
Fernand Claisse ◽  
Claude Samson
Keyword(s):  
Grain Size ◽  
Size Effect ◽  
Mathematical Treatment ◽  
Grain Size Effect ◽  
Light Elements ◽  
X Ray Diffraction ◽  
Limited Region ◽  
X Ray ◽  
Grain Sizes ◽  
Heterogeneity Effects

AbstractA fundamental quantitative treatment of the heterogeneity effects in X-ray fluorescence has been made. The theory predicts that the grain-size effect appears only in a limited region of grain sizes which depends on the wavelength of the primary radiation and the nature of the compounds in the mixture. With monochromatic radiation, the fluorescence intensity showed increase or decrease by a factor of a few units as grain size is decreased, A factor as large as 12, the theoretical value, has been observed in one particular experiment. Usually the grain-size effect can be eliminated by intensive grinding. For the light elements fine grinding is disastrous if long wavelengths are used. By an appropriate choice of the wavelength it is possible to eliminate the effect even without grinding. The mathematical treatment also predicts, but less rigorously, a grain-size effect in X-ray diffraction.The effect on the fluorescence intensities by changes in the chemical composition of the grains that contain the fluorescent element is predicted by the theory.These findings are discussed in relation to the analysis of elements when polychromatic beams are used.

Structural and Chemical Characterization of Tungsten Gate Stack for 1 Gb Dram

2000 ◽  
Vol 611 ◽  
Author(s):  
O. Gluschenkov ◽  
J. Benedict ◽  
L.A. Clevenger ◽  
P. DeHaven ◽  
C. Dziobkowski ◽  
...  
Keyword(s):  
Side Wall ◽  
Chemical Characterization ◽  
X Ray Diffraction ◽  
Gate Stack ◽  
X Ray ◽  
Transition Electron Microscopy ◽  
Tungsten Crystal ◽  
Material Interaction ◽  
Transition Electron

ABSTRACTMaterial interaction during integration of tungsten gate stack for 1 Gb DRAM was investigated by Transition Electron Microscopy (TEM), X-ray Diffraction analysis (XRD) and Auger Electron Spectroscopy (AES). During selective side-wall oxidation tungsten gate conductor undergoes a structural transformation. The transformation results in the reduction of tungsten crystal lattice spacing, re-crystallization of tungsten and/or growth of grains. During a highly selective oxidation process, a relatively small but noticeable amount of oxygen was incorporated into the tungsten layer. The incorporation of oxygen is attributed to the formation of a stable WO x (x<2) composite.

Strengthening of CP-Ti by Rolling at Room Temperature

2010 ◽  
Vol 667-669 ◽  
pp. 737-741
Author(s):  
Jian Hua Jiang ◽  
Yi Ding ◽  
Ai Dang Shan
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Mechanical Test ◽  
Commercial Purity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transition Electron Microscopy ◽  
Microstructure Observation ◽  
Cp Ti ◽  
Transition Electron

The effects of asymmetric and symmetric rolling at room temperature on mechanical properties and microstructure of the commercial purity Ti were investigated by means of mechanical test, optical microscopy, X-ray diffraction and transition electron microscopy. The results show that through asymmetric and symmetric rolling processes the ultimate tensile strength is substantially increased from 450 MPa to 960 MPa. Microstructure observation illustrates this variation in mechanical property is caused by the grain refinement and work hardening.

scholarly journals Synthesis of ZnO-CdO Nanocomposites

2013 ◽  
Vol 1 (1) ◽  
pp. 11-14
Author(s):  
N. Sahu ◽  
◽  
R. K. Duchaniya ◽  
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Low Cost ◽  
Sol Gel ◽  
Particle Size Analysis ◽  
Synthesis Process ◽  
Size Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron

The ZnO-CdO nanocomposite was prepared by sol-gel method by using their respective nitrates. It is a simple and low cost method to prepare nanocomposites. The drying temperature and drying period of prepared gel was varied during the synthesis process. The prepared samples were characterized by using scanning electron microscope (SEM), particle size analysis (PSA), X-ray diffraction (XRD) and photoluminescence spectroscopy (PL) to get surface morphology, idea of getting particle of nanosized range so that further characterizations can be done, to study the optical property of synthesized nanocomposite and measure the band gap . The grain size determined by Scherrer’s formula was found to be between 30-50 nm.

The Obtaining of Porous Strong Ceramics from Nano-Hydroxyapatite

2008 ◽  
Vol 3 (4) ◽  
pp. 40-46
Author(s):  
Dmitriy Yu. Trufanov ◽  
Andrey V. Nomoev ◽  
Molon D. Buyatuev ◽  
Dashima Zh. Bazarova ◽  
Deleg Sangaa ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Grain Size ◽  
Porous Ceramics ◽  
X Ray ◽  
Transition Electron Microscopy ◽  
Gas Penetration ◽  
Transition Electron ◽  
Scanning Electron

The present paper describes the possibility of strong porous ceramics preparation from hydroxyapatite nanopowders. The as-dried hydroxyapatite nanopowders were uniaxially compacted and sintered. The sintered ceramics and nanopowders were analyzed by methods of transition electron microscopy, scanning electron microscopy and X-ray phase diffraction. The ceramics gas-penetration and hardness were measured. The methods of pore control were tested. The ceramics samples with open equally dispersed pores were received; the pores and grain size is about micron and less. The results are useful for making medical implantate and membrane ceramics with controlled pores size.

Luminescence properties of R2MoO6:Eu3+ (R = Gd, Y, La) phosphors prepared by Pechini sol-gel process

2005 ◽  
Vol 20 (10) ◽  
pp. 2676-2681 ◽  
Author(s):  
Maolin Pang ◽  
Xiaoming Liu ◽  
Jun Lin
Keyword(s):  
Grain Size ◽  
Sol Gel ◽  
Luminescent Properties ◽  
Luminescence Properties ◽  
X Ray Diffraction ◽  
Powder Morphology ◽  
X Ray ◽  
Average Grain Size ◽  
Sem Study ◽  
Sol Gel Process

R2MoO6:Eu3+ (R = Gd, Y, La) phosphors were prepared by the Pechini sol-gel process. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), reflectance spectra, photoluminescence (PL) spectra, and lifetimes were used to characterize the resulting phosphors. The results of XRD indicate that all of the R1.96Eu0.04MoO6 (R = Gd, Y, La) phosphors crystallized completely at 800 °C. Y1.96Eu0.04MoO6 and Gd1.96Eu0.04MoO6 are of isomorphous monoclinic (α) structure, while La1.96Eu0.04MoO6 preferentially adopts the tetragonal (γ) form. FE-SEM study reveals that the samples mainly consist of aggregated particles with an average grain size ranging from 100 to 250 nm. The luminescent properties of R2MoO6:Eu3+ (R = Gd, Y, La) phosphors are largely dependent on their structure, grain size, and powder morphology. The isomorphous Y2MoO6:Eu3+ and Gd2MoO6:Eu3+ phosphors show very similar luminescence properties, which differ greatly from that of the La2MoO6:Eu3+ phosphor.

Synthesis and Characterization of Nanocrystalline PZT Powders by a Simple Sol-Gel Method

2012 ◽  
Vol 512-515 ◽  
pp. 147-152
Author(s):  
Shao Peng Zhang ◽  
Xiao Hui Wang ◽  
Long Tu Li
Keyword(s):  
Grain Size ◽  
Lead Zirconate Titanate ◽  
Sintering Temperature ◽  
Ferroelectric Properties ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Gel Method ◽  
X Ray ◽  
Sol Gel Method ◽  
Average Grain Size

Nanocrystalline lead zirconate titanate (PZT) powders with composition at the morphotropic phase boundary (MPB) were synthesized by a simple aqueous based sol-gel method, using lead nitrate, zirconium nitrate and tetrabutyl titanate as the starting materials. The sol could be easily transformed into gel, firstly heated at 120°C for 10h, then at 180°C for 24h. The thermal decomposition process of the gel was investigated by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) techniques. The effect of citrate addition amount on the calcining temperature was discussed. The results reveal that pure perovskite phase PZT powders can be obtained at a calcining temperature as low as 600°C. The average grain size of the powders was determined by transmission electron microscope and X-ray diffraction. The influences of calcining temperature and the pH value of the solution on the grain size were investigated. The sintering temperature and electrical properties of the ceramics derived by nano-powders were compared with those prepared by the conventional ceramic processing. The result shows that using the nanopowder, the sintering temperature could be reduced by about 100°C and the ferroelectric properties were enhanced.

Insight into the Structural, Electrical, and Magnetic Properties of Al-Substituted BiFeO3 Synthesised by the Sol–Gel Method

2020 ◽  
Vol 75 (3) ◽  
pp. 249-256
Author(s):  
Mukhtar Ahmad ◽  
Rizwan Ali ◽  
Atiq ur Rehman ◽  
Akbar Ali ◽  
Ishrat Sultana ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Grain Size ◽  
Sol Gel ◽  
Random Access ◽  
X Ray Diffraction ◽  
Sem Images ◽  
X Ray ◽  
Electrical And Magnetic Properties ◽  
Auto Combustion ◽  
Ferroelectric Random Access Memories

AbstractMultiferroics with chemical formula BiAlxFe1−xO3 (x = 0, 0.1, 0.2, and 0.3) and substituted by Al are synthesised using sol–gel auto-combustion. The materials are sintered at 500 °C for 5 h. In the ongoing study, the crystal structure of BiAlxFe1−xO3 was investigated by X-ray diffraction. After confirming the rhombohedral single-phase crystal structure, various characterisation techniques, such as scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, elemental mapping images, electrical properties, Fourier transform infrared spectroscopy, and vibrating sample magnetometry (VSM), were used to investigate the synthesised samples. The grain size estimated from SEM images decreased as Al contents increased. Elemental composition was confirmed by EDX spectra. Direct current electrical resistivity increased whereas drift mobility decreased with increasing Al contents. The VSM results of Al-doped BiFeO3 (BFO) demonstrate that BFO crystals with size >60 nm show anti-ferromagnetic behaviour, which is evident in the present study. The increase in Al doping results in an increase in coercivity, as grain size and coercivity are inversely related with each other. This is because of the replacement of Fe3+ by Al3+ ions, which weakens the sub-lattice interactions. It has been observed that BFO materials with such parameters are favourable for ferroelectric random access memories where data can be written electrically and read magnetically.

Sol-Gel Deposition and Luminescence Properties of Spherical Phosphors Ca2Y8(SiO4)6O2:Eu3+

2008 ◽  
Vol 368-372 ◽  
pp. 378-380
Author(s):  
Xiu Mei Han ◽  
J. Lin ◽  
M. Yu ◽  
C.K. Lin ◽  
Xi Wei Qi ◽  
...  
Keyword(s):  
Grain Size ◽  
Charge Transfer ◽  
Diffraction Analysis ◽  
Charge Transfer Band ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Red Emission ◽  
X Ray ◽  
Average Grain Size ◽  
Sol Gel Process

Spherical SiO2 particles were coated with Ca2Y8(SiO4)6O2:Eu3+ phosphor layers through a sol-gel process. The results of XRD (X-ray diffraction) analysis indicated that the phosphors crystallized completely at 1000oC. AFM study revealed that the average grain size is 500 nm. In Ca2Y8(SiO4)6O2:Eu3+ spherical phosphors , the Eu3+ showed its characteristic red emission at 612 nm(5D0-7F2) upon excitation into its charge transfer band of Eu3+-O2- at 242nm.

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