Synthesis and Characterization of Hexagonal Shaped Nanocrystalline Zinc Oxide Powders

2014 ◽  
pp. 204-217 ◽  
Author(s):  
M. Ahmad ◽  
E. Ahmed ◽  
N. R. Khalid ◽  
M. J. Jackson ◽  
W. Ahmed
Keyword(s):  
Grain Size ◽  
Elevated Temperatures ◽  
Combustion Process ◽  
Combustion Method ◽  
X Ray Diffraction ◽  
Wurtzite Phase ◽  
X Ray ◽  
Oxide Powders ◽  
Heat Treated ◽  
Zno Powders

Nanocrystalline ZnO powders are synthesized using a quick, simple and inexpensive combustion method. Glycine and zinc nitrate, used as fuel and oxidant/cation sources respectively, were mixed together at room temperature to form a slurry or gel. A series of experiments were performed to synthesize nanoparticles for different fuel to oxidant ratios. The rate of heating and stirring greatly influenced the combustion process. The as-synthesized powder was heat treated at elevated temperatures for varying time to remove adsorbed impurities from the surface of the ZnO nanoparticles. Both the as-synthesized and heat treated powders were characterized using a variety of analytical techniques. The hexagonal wurtzite phase of the ZnO powder was revealed from x-ray diffraction measurements. A decrease in the x-ray diffraction density (Dx) and the bulk density (D) resulted in an increase in percentage porosity (%P) of as-synthesized and heat treated ZnO powders. The range of fuel to oxidant ratios used in the present work indicates that they had a strong influence on the grain size of ZnO powders. The average grain size estimated by using the Scherer formula indicated an approximate value of 6-21 nm for the as-synthesized and heat treated samples.

Synthesis and Characterization of Hexagonal Shaped Nanocrystalline Zinc Oxide Powders

2012 ◽  
Vol 2 (2) ◽  
pp. 61-76 ◽  
Author(s):  
M. Ahmad ◽  
E. Ahmed ◽  
N. R. Khalid ◽  
M. J. Jackson ◽  
W. Ahmed
Keyword(s):  
Grain Size ◽  
Elevated Temperatures ◽  
Combustion Process ◽  
Combustion Method ◽  
X Ray Diffraction ◽  
Wurtzite Phase ◽  
X Ray ◽  
Heat Treated ◽  
Average Grain Size ◽  
Zno Powders

Nanocrystalline ZnO powders are synthesized using a quick, simple and inexpensive combustion method. Glycine and zinc nitrate, used as fuel and oxidant/cation sources respectively, were mixed together at room temperature to form a slurry or gel. A series of experiments were performed to synthesize nanoparticles for different fuel to oxidant ratios. The rate of heating and stirring greatly influenced the combustion process. The as-synthesized powder was heat treated at elevated temperatures for varying time to remove adsorbed impurities from the surface of the ZnO nanoparticles. Both the as-synthesized and heat treated powders were characterized using a variety of analytical techniques. The hexagonal wurtzite phase of the ZnO powder was revealed from x-ray diffraction measurements. A decrease in the x-ray diffraction density (Dx) and the bulk density (D) resulted in an increase in percentage porosity (%P) of as-synthesized and heat treated ZnO powders. The range of fuel to oxidant ratios used in the present work indicates that they had a strong influence on the grain size of ZnO powders. The average grain size estimated by using the Scherer formula indicated an approximate value of 6-21 nm for the as-synthesized and heat treated samples.

scholarly journals SÍNTESIS DE YAIO3 (YAP) POLICRISTALINO POR EL MÉTODO DE COMBUSTIÓN EN SOLUCIÓN

2018 ◽  
Vol 27 (1) ◽  
pp. 61
Author(s):  
A. Lazo ◽  
C. Paucarchuco ◽  
H. Loro
Keyword(s):  
Combustion Process ◽  
Orthorhombic Phase ◽  
Combustion Method ◽  
X Ray Diffraction ◽  
Solution Combustion ◽  
X Ray ◽  
Structure And Morphology ◽  
Palabras Clave ◽  
Diffraction Peaks ◽  
Ray Patterns

Se presenta el método de combustión en solución y su aplicación para la síntesis de YAlO3 (YAP), fueron usados como combustibles para la reacción de combustión y síntesis la urea y glicina, del YAP. Usando las técnicas de difracción de rayos X (XRD) por el método del polvo y microscopia electrónica de barrido (MEB) fueron analizadas la parte estructural y morfológica de las muestras obtenidas. Los difractogramas de Rayos X muestran una excelente correspondencia con lo reportado en la literatura para este material. Se suministran también los resultados de las muestras de material YAlxCrx‐1O3, dopado con Cr3+ con x = 0.001, 0.01, que exhiben picos de difracción dominantes debidos a la fase ortorrómbica de YAlO3 Palabras clave.- YAP, YAlO3, Combustion method. ABSTRACT The solution‐combustion process is presented, as well as its application to the synthesis of YAlO3 (YAP). Urea and glycine were used as fuel for the combustion reaction and synthesis of the YAP. The structure and morphology of the obtained sample were analyzed using the X‐ray diffraction (XRD) powder method and scanning electron microscopy (SEM). The X‐ray patterns showed an excellent agreement with data reported in the literature for this material. Results are also given for samples of YAlxCrx‐1O3 doped with Cr3+, with x = 0.001, 0.01, which showed dominant diffraction peaks due to the orthorhombic phase of YAlO3. Keywords.- YAP, YAlO3, combustion method.

Heat Treatment of Nanocrystalline Al2O3-Zr02

1996 ◽  
Vol 457 ◽  
Author(s):  
Bridget M. Smyser ◽  
Jane F. Connelly ◽  
Richard D. Sisson ◽  
Virgil Provenzano
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Grain Size ◽  
Monoclinic Phase ◽  
Phase Distribution ◽  
Critical Size ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Heat Treated

ABSTRACTThe effects of grain size on the phase transformations in nanocrystalline ZrO2-Al2O3 have been experimentally investigated. Compositions from 10 to 50 vol% Al2O3 in ZrO2 were obtained as a hydroxide gel. The powders were then calcined at 600 °C for 17 hours and heat treated at 1100 °C for 24 and 120 hours and at 1200 °C for 2 hours. The phase distribution and grain size were determined using x-ray diffraction and transmission electron microscopy. The initial grain size after calcining was 8–17 nm. It was determined that the critical ZrO2 grain size to avoid the tetragonal to monoclinic phase transformation on cooling from 1100 °C was between 17 and 25 nm. Samples containing 50% Al2O3 maintained a grain size below the critical size for all times and temperatures. The 30% Al2O3 samples showed the same behavior in all but one heat treatment. The remainder of the samples showed significant grain growth and at least partial transformation to the monoclinic phase.

EFFECTS OF HEAT TREATMENT ON TRIBOLOGICAL BEHAVIOR OF ELECTROLESS Ni–B COATING AT ELEVATED TEMPERATURES

2017 ◽  
Vol 24 (Supp01) ◽  
pp. 1850014 ◽  
Author(s):  
ARKADEB MUKHOPADHYAY ◽  
TAPAN KUMAR BARMAN ◽  
PRASANTA SAHOO
Keyword(s):  
Heat Treatment ◽  
Elevated Temperatures ◽  
Tribological Behavior ◽  
Wear Behavior ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Treated ◽  
Pin On Disc ◽  
Mixed Layers ◽  
Electroless Ni

The present work investigates the effects of heat treatment on friction and wear behavior of electroless Ni–B coatings at elevated temperatures. Coating is deposited on AISI 1040 steel specimens and subjected to heat treatments at 350[Formula: see text]C, 400[Formula: see text]C and 450[Formula: see text]C. Coating characterization is done using scanning electron microscope, energy dispersive X-Ray analysis and X-Ray diffraction analysis. Improvement in microhardness is observed for the heat treated deposits. Further, the effect of heat treatment on the tribological behavior of the coatings at room temperature, 100[Formula: see text]C, 300[Formula: see text]C and 500[Formula: see text]C are analyzed on a pin-on-disc setup. Heat treatment at 350[Formula: see text]C causes a significant improvement in the tribological behavior at elevated temperatures. Higher heat treatment temperatures cause deterioration in the wear resistance and coefficient of friction. The wear mechanism at 100[Formula: see text]C is observed to be predominantly adhesive along with abrasion. While at 300[Formula: see text]C, abrasive wear is seen to be the governing wear phenomenon. Formation of mechanically mixed layers is noticed at both the test temperatures of 100[Formula: see text]C and 300[Formula: see text]C for the coatings heat treated at 400[Formula: see text]C and 450[Formula: see text]C test temperature. The predominant wear mechanisms at 500[Formula: see text]C are abrasive and fatigue for as-deposited and heat treated coatings, respectively.

scholarly journals Influence of Homogenization and Micro/Nano Source of Starting Powders on Format Ion of the Single YAP Phase

2016 ◽  
Vol 61 (4) ◽  
pp. 1753-1760 ◽  
Author(s):  
D. Michalik ◽  
T. Pawlik ◽  
J. Plewa ◽  
M. Sopicka-Lizer
Keyword(s):  
Low Cost ◽  
Diffraction Method ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Small Areas ◽  
Oxide Powders ◽  
Heat Treated ◽  
Interesting Task

Abstract Manufacturing high purity polycrystalline YAlO3 (YAP) ceramics could replace monocrystalline YAP thus recently it is an interesting task for low cost producers of scintillators. The paper presents influence of different source of initial oxide powders (micro/nano powders of Y2O3 and Al2O3) and the method of their homogenization on the formation of a YAP phase. The solid state reaction method was used to prepare YAP powder or ceramic pellets. After preheating, all samples in the form of powders and pellets were heat-treated in the temperature range of 1050-1650 °C. DTA method was applied for examination of the phase crystallization in the tested system. X-ray diffraction method (XRD) was used for characterization of the phase composition. X-ray microanalysis (EDS) was used to control homogeneity in the small areas. Morphology of the resultant samples are presented on SEM pictures. The results show a significant influence of the starting powders on the homogeneity, purity and temperature of formation of the main phase.

Structural and Magnetic Properties of Ultrafine Magnesium Ferrite Nanoparticles

2014 ◽  
Vol 938 ◽  
pp. 128-133 ◽  
Author(s):  
P.M. Md Gazzali ◽  
V. Kanimozhi ◽  
P. Priyadharsini ◽  
G. Chandrasekaran
Keyword(s):  
Combustion Process ◽  
Average Crystallite Size ◽  
Combustion Method ◽  
Spherical Particles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Infra Red ◽  
History Of ◽  
Ft Ir ◽  
Constituent Elements

Nanoparticles of MgFe2O4 with average crystallite size of ~ 8 nm have been synthesized employing non-aqueous combustion method. Structural properties of the nanoparticles are analyzed with the help of X-Ray Diffractometry (XRD), Scanning Electron Microscopy (SEM), Energy dispersive X-Ray analysis (EDX), Fourier Transform Infra-Red spectroscopy (FT-IR). X-Ray Diffraction pattern and FT-IR spectra reveal the formation of spinel structure of MgFe2O4 nanoparticles. The SEM micrographs of the sample show the formation of clusters of spherical particles with pores revealing the history of synthesis as combustion process. The constituent elements and chemical composition are analyzed using EDX spectrum. Magnetic study done using Vibrating Sample Magnetometer (VSM) reveals that the prepared nanoparticles remain unsaturated within the field of 15 kOe and have a very low coercivity of 20 Oe.

scholarly journals Effect of Heat Treatment on Structural and Magnetic Properties of Li-Ni Ferrite Prepared via Sol-Gel Auto-Combustion Method

2021 ◽  
Author(s):  
Jiali Song ◽  
Zhi Wang ◽  
Yu Gao
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Annealing Temperature ◽  
Sol Gel ◽  
Combustion Method ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
Auto Combustion ◽  
Ft Ir

Abstract Nanocrystalline Li 0.35 Ni 0.3 Fe 2.35 O 4 ferrites were prepared at different annealing temperature by sol-gel auto-combustion method. The effects of the annealing temperature on the structure and magnetic properties of the synthesized Li-Ni ferrites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectra (FT-IR) and Squid-VSM. Rietveld refinement of the X-ray diffraction data confirmed the occurrence of phase transition from α-spinel to β-spinel, from which the ideal cation occupation and lattice parameter can be obtained. The grain size increased significantly with annealing temperature. The variation of saturation magnetization can be well explained in terms of the occupation of ions in tetrahedron and octahedron. The coercivity initially increased and later decreased significantly from 115 to 37 Oe with the increase of annealed temperature which could be attributed the fact that the 600℃-annealed grain size is close to transition size from single to multidomain region.

scholarly journals Evaluation of Dislocation Densities in Various Microstructures of Additively Manufactured Ti6Al4V (Eli) by the Method of X-ray Diffraction

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5355
Author(s):  
Amos Muiruri ◽  
Maina Maringa ◽  
Willie du Preez
Keyword(s):  
Heat Treatment ◽  
Elevated Temperatures ◽  
Direct Metal Laser Sintering ◽  
X Ray Diffraction ◽  
Flow Properties ◽  
X Ray ◽  
Heat Treated ◽  
Dislocation Densities ◽  
Stress Relieving ◽  
As Stress

Dislocations play a central role in determining strength and flow properties of metals and alloys. Diffusionless phase transformation of β→α in Ti6Al4V during the Direct Metal Laser Sintering (DMLS) process produces martensitic microstructures with high dislocation densities. However, heat treatment, such as stress relieving and annealing, can be applied to reduce the volume of these dislocations. In the present study, an analysis of the X-ray diffraction (XRD) profiles of the non-heat-treated and heat-treated microstructures of DMLS Ti6Al4V(ELI) was carried out to determine the level of defects in these microstructures. The modified Williamson–Hall and modified Warren–Averbach methods of analysis were used to evaluate the dislocation densities in these microstructures. The results obtained showed a 73% reduction of dislocation density in DMLS Ti6Al4V(ELI) upon stress relieving heat treatment. The density of dislocations further declined in microstructures that were annealed at elevated temperatures, with the microstructures that were heat-treated just below the β→α recording the lowest dislocation densities.

The Application of X-Ray Diffraction at Elevated Temperatures to Study the Mechanism of Formation of Sodium Tripolyphosphate

1961 ◽  
Vol 5 ◽  
pp. 276-284
Author(s):  
E. L. Moore ◽  
J. S. Metcalf
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Amorphous Phase ◽  
Elevated Temperatures ◽  
Sodium Tripolyphosphate ◽  
X Ray Diffraction ◽  
Mechanism Of Formation ◽  
X Ray ◽  
Temperature Form ◽  
High Temperature Form

AbstractHigh-temperature X-ray diffraction techniques were employed to study the condensation reactions which occur when sodium orthophosphates are heated to 380°C. Crystalline Na4P2O7 and an amorphous phase were formed first from an equimolar mixture of Na2HPO4·NaH2PO4 and Na2HPO4 at temperatures above 150°C. Further heating resulted in the formation of Na5P3O10-I (high-temperature form) at the expense of the crystalline Na4P4O7 and amorphous phase. Crystalline Na5P3O10-II (low-temperature form) appears after Na5P3O10-I.Conditions which affect the yield of crystalline Na4P2O7 and amorphous phase as intermediates and their effect on the yield of Na5P3O10 are also presented.

scholarly journals Stable and Metastable Phase Equilibria Involving the Cu6Sn5 Intermetallic

2021 ◽  
Author(s):  
A. Leineweber ◽  
M. Löffler ◽  
S. Martin
Keyword(s):  
Phase Equilibria ◽  
Electron Backscatter Diffraction ◽  
Metastable Phase ◽  
Stable Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Treated ◽  
Ordered Phases ◽  
Backscatter Diffraction ◽  
Kinetics Of

Abstract Cu6Sn5 intermetallic occurs in the form of differently ordered phases η, η′ and η′′. In solder joints, this intermetallic can undergo changes in composition and the state of order without or while interacting with excess Cu and excess Sn in the system, potentially giving rise to detrimental changes in the mechanical properties of the solder. In order to study such processes in fundamental detail and to get more detailed information about the metastable and stable phase equilibria, model alloys consisting of Cu3Sn + Cu6Sn5 as well as Cu6Sn5 + Sn-rich melt were heat treated. Powder x-ray diffraction and scanning electron microscopy supplemented by electron backscatter diffraction were used to investigate the structural and microstructural changes. It was shown that Sn-poor η can increase its Sn content by Cu3Sn precipitation at grain boundaries or by uptake of Sn from the Sn-rich melt. From the kinetics of the former process at 513 K and the grain size of the η phase, we obtained an interdiffusion coefficient in η of (3 ± 1) × 10−16 m2 s−1. Comparison of this value with literature data implies that this value reflects pure volume (inter)diffusion, while Cu6Sn5 growth at low temperature is typically strongly influenced by grain-boundary diffusion. These investigations also confirm that η′′ forming below a composition-dependent transus temperature gradually enriches in Sn content, confirming that Sn-poor η′′ is metastable against decomposition into Cu3Sn and more Sn-rich η or (at lower temperatures) η′. Graphic Abstract

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