XRD and Photoluminescence Studies of Pure and In2O3 Doped ZnO Nanophases

2005 ◽  
Vol 480-481 ◽  
pp. 393-398 ◽  
Author(s):  
N. Boulares ◽  
K. Guergouri ◽  
Nouar Tabet ◽  
A. Lusson ◽  
F. Sibieude ◽  
...  
Keyword(s):  
Grain Size ◽  
Spinel Phase ◽  
Lattice Parameter ◽  
Solar Furnace ◽  
X Ray Diffraction ◽  
Drastic Reduction ◽  
Grain Sizes ◽  
Oxide Powders ◽  
Excitonic Emission ◽  
Photoluminescence Studies

ZnO oxide is a promising material for optoelectronics because of its wide and direct gap (Eg=3.4 eV). Pure and doped zinc oxide powders of various grain sizes have been synthesized by vaporisation-condensation method using a solar furnace. The initial powders contained from 0 to 5 In2O3 mol % . X-ray diffraction technique (XRD) has been used to measure the lattice parameter and the grain size as a function of the composition, the results show the appearance of the spinel phase Zn5In2O8 in the micopowders and the decrease of the grain size of nanopowders as the In concentration increases for all considered compositions. The photoluminescence spectra revealed the presence of two main transitions at 3.31 and 3.36 eV, a shift of the excitonic peaks towards the lower energies, a drastic reduction of the exciton bound to donor emission from the doped material and a large broadening of the excitonic emission in In doped nanopowder.

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.

Elaboration, Structure and Mössbauer Spectroscopy of Nanostructured Fe100−xSix Powders Elaborated by Mechanical Alloying

SPIN ◽  
2017 ◽  
Vol 07 (02) ◽  
pp. 1750002 ◽  
Author(s):  
M. Hemmous ◽  
A. Guittoum
Keyword(s):  
Magnetic Field ◽  
Solid Solution ◽  
Mechanical Alloying ◽  
Hyperfine Magnetic Field ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
Grain Sizes ◽  
The Mean ◽  
Xrd Studies

We have studied the effect of the silicon concentration on the structural and hyperfine properties of nanostructured Fe[Formula: see text]Six powders ([Formula: see text], 20, 25 and 30[Formula: see text]at.%) prepared by mechanical alloying. The X-ray diffraction (XRD) studies indicated that after 72[Formula: see text]h of milling, the solid solution bcc-[Formula: see text]-Fe(Si) is formed. The grain sizes, [Formula: see text]D[Formula: see text] (nm), decreases with increasing Si concentration and reaches a minimum value of 11[Formula: see text]nm. We have found that the lattice parameter decreases with increasing Si concentration. The changes in values are attributed to the substitutional dissolution of Si in Fe matrix. From the adjustment of Mössbauer spectra, we have shown that the mean hyperfine magnetic field, [Formula: see text]H[Formula: see text] (T), decreases with increasing Si concentration. The substitutional dependence of [Formula: see text]H[Formula: see text] (T) can be attributed to the effect of p electrons Si influencing electrons d of Fe.

On the Structure and Some Properties of LaCo Co-substituted NiZn Ferrites Prepared Using the Standard Ceramic Technique

2016 ◽  
Vol 35 (4) ◽  
pp. 417-423 ◽  
Author(s):  
Xiaofei Niu ◽  
Xiansong Liu ◽  
Xin Huang ◽  
Kai Huang ◽  
Yuqi Ma ◽  
...  
Keyword(s):  
Grain Size ◽  
Power Loss ◽  
Low Frequency ◽  
Secondary Phase ◽  
Lattice Parameter ◽  
Initial Permeability ◽  
High Resistivity ◽  
X Ray Diffraction ◽  
Ferrite Sample ◽  
Higher Power

AbstractZn0.5Ni0.5-xCoxFe2-yLayO4 ferrites (with x=0, 0.02 and y=0, 0.02) were prepared by an industrial method using the standard ceramic technique and sintered at 1,250°C in air. X-ray diffraction (XRD) was used to obtain the phase formation of the NiZn ferrites. The microstructure of ferrites was investigated by scanning electron microscopy (SEM). The XRD reveals that lattice parameter (a) is decreased and a secondary phase (LaFeO3) is formed in the La–Co co-substituted NiZn ferrite sample, meanwhile, the grain size (D) of this sample decreased obviously by observing SEM photographs. Vibrating sample magnetometry (VSM), B-H analyzer, impedance analyzer and electrometer were carried out in order to characterize some properties of the ferrites. This investigation indicates that, La–Co co-substituted NiZn ferrite sample has higher power loss (Pcv) than other samples at low frequency with an increase in coercive field (Hc) and magnetocrystalline anisotropy (K1), a decrease in initial permeability (μi) and saturation magnetization (Ms). However, at high frequency, the power loss of La–Co co-substituted sample is low, which is attributed to high resistivity (ρ), small grain size (D), less number of Fe2+ ions and low porosity (P).

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.

Preparation and Photoelectrochemical Properties of SrTiO3 Thin Films on Nickel Substrate by Hydrothermal Method

2007 ◽  
Vol 121-123 ◽  
pp. 1297-1300
Author(s):  
G.T. Wang ◽  
J.P. Tu ◽  
W.K. Zhang ◽  
X.L. Wang ◽  
H. Huang
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Saturated Vapor ◽  
Photoelectrochemical Properties ◽  
Vapor Pressures ◽  
Nickel Substrate ◽  
X Ray Diffraction ◽  
Xrd Pattern ◽  
Ni Substrate ◽  
Grain Sizes

Well-crystallized nanopolycrystalline thin films of cubic strontium titanate, SrTiO3, have been prepared on the TiNi-deposited Ni substrate in Sr(OH)2 aqueous solutions at temperatures between 130 and 200°C under saturated vapor pressures. The microstructure and morphology of the films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The photoelectrochemical properties of SrTiO3 thin films on TiNi-deposited Ni substrate were investigated on a three-electrode assembly. The grain sizes increased from 30 nm to 300 nm and the relative crystal intensity in XRD pattern increased with the reaction temperature. Its photocurrent increasesdfirst with the grain size, then decreased. When the grain size of the film is about 200 nm, the photocurrent is highest.

scholarly journals Crystallographic and optical studies on Cr doped ZnS nanocrystals

Cerâmica ◽  
2014 ◽  
Vol 60 (355) ◽  
pp. 425-428 ◽  
Author(s):  
M. R. Bodke ◽  
Y. Purushotham ◽  
B. N. Dole
Keyword(s):  
Grain Size ◽  
Fourier Transforms ◽  
Chemical Species ◽  
Lattice Parameter ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
Cubic Form ◽  
Zns Nanocrystals ◽  
Cr Concentration ◽  
Co Precipitation

Chromium doped ZnS nanocrystals with pure and 10% compositions were synthesized by chemical co-precipitation route. Samples were characterized by X-ray diffraction (XRD) technique, Fourier transforms infrared spectroscopy (FTIR) and UV-Visible spectrometer. Lattice parameter 'a' decreases and grain size increases with increasing Cr concentration. XRD study shows that both the samples have cubic structure. Grain size increases due to ionic radius. The functional groups and chemical species of Cr doped ZnO samples were determined using FTIR data. UV-Vis study revealed that red shift is clearly observed in absorption band. Surface morphology of pure and 10% Cr doped samples was investigated by SEM technique and it is confirmed that images exibit cubic form of the samples. Using EDS, percentage of chemical compositions of material recorded.

Morphological and structural evolutions of nonequilibrium titanium-nitride alloy powders produced by reactive ball milling

1992 ◽  
Vol 7 (4) ◽  
pp. 888-893 ◽  
Author(s):  
M. Sherif El-Eskandarany ◽  
K. Sumiyama ◽  
K. Aoki ◽  
K. Suzuki
Keyword(s):  
Electron Microscopy ◽  
Titanium Nitride ◽  
Gas Flow ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Nitrogen Gas ◽  
X Ray ◽  
Grain Sizes ◽  
Transmission Electron

Nonequilibrium titanium-nitride alloy powders have been fabricated by a high energetic ball mill under nitrogen gas flow at room temperature and characterized by means of x-ray diffraction, scanning electron microscopy, transmission electron microscopy, and differential scanning calorimetry. Initial hcp titanium is completely transformed to nonequilibrium-fcc Ti–N after 720 ks of the milling time. The fcc Ti–N phase is stable at relatively low temperature and transforms at 855 K to Ti2N and δ phases. At the final stage of milling, the particle- and grain-sizes of alloy powders are 1 mm and 5 nm, respectively, and the lattice parameter is 0.419 nm.

Dislocations in Submicron Grain Size and Nanocrystalline Copper

2000 ◽  
Vol 634 ◽  
Author(s):  
T. Ungár ◽  
G. Tichy ◽  
P. G. Sanders ◽  
J. R. Weertman
Keyword(s):  
Grain Size ◽  
Profile Analysis ◽  
Dislocation Model ◽  
X Ray Diffraction ◽  
Strain Anisotropy ◽  
Nanocrystalline Copper ◽  
X Ray ◽  
Gas Condensation ◽  
Grain Sizes ◽  
20 Nm

ABSTRACTUsing the dislocation model of strain anisotropy in X-ray diffraction peak profile analysis it is shown that in nanocrystalline copper produced by inert gas condensation dislocations are present, at least, down to average grain sizes of the order of 20 nm. Based on the analysis of the dislocation contrast factors it is suggested that with decreasing grain size the proportion of Lomer-Cottrell type dislocations increases.

Grain Growth and Mobility in Nanocrystalline Ge Films

2012 ◽  
Vol 1426 ◽  
pp. 359-364
Author(s):  
Siva Konduri ◽  
Max Noack ◽  
Vikram Dalal
Keyword(s):  
Grain Size ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
Deposition Pressure ◽  
High Hydrogen ◽  
Strong Function ◽  
X Ray ◽  
Grain Sizes ◽  
Frequency Plasma ◽  
Hydrogen Mixtures

ABSTRACTIn this paper, we report on deposition and properties of nanocrystalline Ge:H films . The films were grown from germane and hydrogen mixtures using Radio frequency Plasma-enhanced chemical vapor deposition (RF-PECVD) process using ∼45 MHz frequency. The crystallinity of the films was measured using Raman measurements and from x-ray diffraction techniques, it was found that the grain size was a strong function of deposition pressure, temperature and hydrogen/germane ratios. High hydrogen ratios and high powers led to films with smaller grains. Higher pressures and smaller hydrogen/germane ratio led to films with larger grain sizes, as did higher growth temperatures. The mobility of electrons and holes was measured using space charge limited current (SCLC) techniques in n+-n-n+ devices. It was found that nominally undoped films were generally n type with carrier concentrations in the 1E14/cm3 range. Mobility was found to increase with grain size, with 60 nm grains showing mobility in the 2-3 cm2/V-s range.

Auto ignition synthesis of nanocrystalline MgAl2O4 and related nanocomposites

1999 ◽  
Vol 14 (9) ◽  
pp. 3571-3580 ◽  
Author(s):  
S. Bhaduri ◽  
S. B. Bhaduri ◽  
K. A. Prisbrey
Keyword(s):  
Solid Solutions ◽  
Lattice Parameter ◽  
Nanocrystalline Powders ◽  
Ignition Process ◽  
X Ray Diffraction ◽  
Grain Sizes ◽  
Auto Ignition ◽  
Transmission Electron ◽  
Vegard’S Law ◽  
20 Nm

Nanocrystalline powders of various compositions in the Al2O3–MgO binary system were synthesized using a novel “auto ignition” process. The respective nitrates were used as starting materials and urea as fuel. Thermodynamic calculations of the adiabatic temperatures were performed for various compositions from Al2O3-rich to the MgO-rich side of the phase diagram. The combustion temperatures of the different compositions were also determined experimentally. The as-synthesized powders were characterized by x-ray diffraction (XRD) and transmission electron microscopy (TEM). As a result of processing, spinel, alumina, magnesia, and solid solutions/ nanocomposites thereof formed. Grain sizes and the lattice parameter were calculated based on XRD results. Where appropriate, the lattice parameter versus the composition of these solid solutions satisfied Vegard's law. Spinel grains were in the 13–20 nm range, alumina grains were 30–40 nm, and MgO grains were 2–28 nm. The grain sizes calculated from XRD results were in good agreement with the TEM results.

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