scholarly journals Effect of Pressure on Synthesis of Pr-Doped Zirconia Powders Produced by Microwave-Driven Hydrothermal Reaction

2006 ◽  
Vol 2006 ◽  
pp. 1-8 ◽  
Author(s):  
A. Opalinska ◽  
C. Leonelli ◽  
W. Lojkowski ◽  
R. Pielaszek ◽  
E. Grzanka ◽  
...  
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Hydrothermal Reaction ◽  
Quantitative Description ◽  
Thermal Inertia ◽  
X Ray Diffraction ◽  
Synthesis Conditions ◽  
Short Time ◽  
Zirconia Powders

A high-pressure microwave reactor was used to study the hydrothermal synthesis of zirconia powders doped with 1 mol%Pr. The synthesis was performed in the pressure range from 2 to 8 MPa corresponding to a temperature range from 215C∘to 305C∘. This technology permits a synthesis of nanopowders in short time not limited by thermal inertia of the vessel. Microwave heating permits to avoid contact of the reactants with heating elements, and is thus particularly well suited for synthesis of doped nanopowders in high purity conditions. A mixture ofZrO2particles with tetragonal and monoclinic crystalline phases, about 15 nm in size, was obtained. The p/T threshold of about 5-6 MPa/265–280C∘was necessary to obtain good quality of zirconia powder. A new method for quantitative description of grain-size distribution was applied, which is based on analysis of the fine structure of the X-ray diffraction line profiles. It permitted to follow separately the effect of synthesis conditions on the grain-size distribution of the monoclinic and tetragonal phases.

CdS Powders Obtained by Chemical Bath Deposition

2011 ◽  
Vol 672 ◽  
pp. 109-112
Author(s):  
Violeta Popescu ◽  
George Liviu Popescu ◽  
Emil Indrea ◽  
Dan Teofil Silipas
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Chemical Bath Deposition ◽  
Cadmium Chloride ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ft Ir ◽  
Made In

We studied the influence of the mixing on the properties of CdS powders obtained by Chemical Bath Deposition. The powders were obtained from baths containing cadmium chloride, thiourea, and ammonia. The obtained powders were characterized using FT-IR, in order to evaluate the purity of the obtained powder. Granulometric studies were made in order to establish the grain size distribution of the particles, and X ray diffraction in order to determine the structure of nanostructured CdS.

Xrd and Hrem Studies of Nanocrystalline Cu and Pd

1990 ◽  
Vol 206 ◽  
Author(s):  
G. W. Nieman ◽  
J. R. Weertman ◽  
R. W. Siegel
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Long Range ◽  
Grain Size Distribution ◽  
High Resolution Electron Microscopy ◽  
X Ray Diffraction ◽  
Distribution Width ◽  
Lattice Strains ◽  
Resolution Electron ◽  
Grain Size Distributions

ABSTRACTConsolidated powders of nanocrystalline Cu and Pd have been studied by x-ray diffraction (XRD) and high resolution electron microscopy (HREM) as part of an investigation of the mechanical behavior of nanocrystalline pure metals. XRD line broadening measurements were made to estimate grain size, qualitative grain size distribution and average long range strains in a number of samples. Mean grain sizes range from 4-60 nm and have qualitatively narrow grain size distributions. Long range lattice strains are of the order of 0.2-3% in consolidated samples. These strains apparently persist and even increase in Cu samples after annealing at 0.35 Tm (498K) for 2h, accompanied by an apparent increase in grain size of e2x. Grain size, grain size distribution width and internal strains vary somewhat among samples produced under apparently identical processing conditions. HREM studies show that twins, stacking faults and low-index facets are abundant in as-consolidated nanocrystalline Cu samples. Methodology, results and analysis of XRD and HREM experiments are presented.

Contribution to a Technological Characterization of Kaolins from Cuba and Brazil

2006 ◽  
Vol 530-531 ◽  
pp. 720-727
Author(s):  
Guillermo Ruperto Martín Cortés ◽  
Wildor Theodoro Hennies ◽  
Francisco Rolando Valenzuela-Díaz
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
Simple Description ◽  
X Ray ◽  
The Republic

This paper studies the main well-know technological types of kaolins clays from the Republic of Cuba and compares it with one from Brazil. A simple description from the Cuban geology and from the involved kaolins deposits is showed. The basic characterization of each kind of kaolin, includes, chemical analyzes, grain size distribution, scanning electronic microscopy, X-ray diffraction and X-ray fluorescence for chemicals. For special assays it had conformed, by a simple axis hand press up to 5 t, test bodies, which had been burnt to the temperatures of 950, 1250 and 1450°C. These results include refractory and contraction results.

scholarly journals Study of the Nanometric Grain Size Distribution in Iron Compacts Obtained by Mechanical Milling

2006 ◽  
Vol 503-504 ◽  
pp. 1007-1012 ◽  
Author(s):  
Jordi Llumà ◽  
Josep Antonio Benito ◽  
Antoni Roca ◽  
Jose María Cabrera ◽  
Jose Manuel Prado
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Iron Powder ◽  
Grain Size Distribution ◽  
Mechanical Milling ◽  
X Ray Diffraction ◽  
Average Hardness ◽  
Transmission Electron ◽  
Two Temperatures ◽  
Average Size

A study has been carried out on the grain size distribution of cylindrical compacts obtained by consolidation of iron powder severely deformed by mechanical milling. Consolidation has been performed in two consecutive steps: cold and hot conditions. The hot one was done at two temperatures, namely 425 and 475°C. After milling, the iron powder has a grain size of 8 nm (± 4 nm) with an average hardness of 800 HV. After hot compaction the grain size increases up to 50 nm, especially at 475°C where a small fraction of grains reach larger values than the average. The grain size was evaluated by two different techniques, X-Ray Diffraction and Transmission Electron Microscopy. Results showed some differences between both methods. The advantage of using TEM is that grain size distribution, and not only the average size, can be obtained. Small discs were also obtained from the compacted specimen in order to fracture them on a “ball on three balls” equipment. The fracture behaviour of the samples was then studied by SEM.

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