Combined magnetic and structural investigation of nano crystalline iron oxides: The interplay between crystal size and phase composition during FeS2 oxidation

2007 ◽  
Vol 308 (2) ◽  
pp. 250-268 ◽  
Author(s):  
Erik Eneroth
Keyword(s):  
Phase Composition ◽  
Iron Oxides ◽  
Crystal Size ◽  
Structural Investigation ◽  
Nano Crystalline

Aluminium influence on iron oxides: XVIII. The effect of Al substitution and crystal size on magnetic hyperfine fields of natural goethites

Clay Minerals ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 455-464 ◽  
Author(s):  
J. Friedl ◽  
U. Schwertmann
Keyword(s):  
Iron Oxides ◽  
Room Temperature ◽  
Crystal Size ◽  
Tropical Soil ◽  
Iron Ores ◽  
Hyperfine Fields ◽  
Al Substitution ◽  
Subtropical Soils ◽  
Crystallization Conditions ◽  
The Mean

AbstractTwo sets of natural Al-substituted goethites from contrasting surface environments (24 tropical and subtropical soils vs. ten lake iron ores from Finland) were characterized by Mössbauer spectra obtained at room temperature and 4.2 K. A negative correlation between Bhf and Al substitution (R2 = 0.751) was found by combining the data of all the samples, which was slightly improved (R2 = 0.779) by taking the mean coherence length perpendicular to 111 (MCL111) into account. The effect of Al on lowering Bhf was, however, stronger for the tropical soil goethites than for those of the lake ores. This is parallelled by a corresponding difference in the unit-cell decrease per unit Al substitution. These differences are believed to result from the crystallization conditions in the two different environments.

Nano-Crystalline Barium Hexaferrite Powders Prepared by Mechanical Alloying Using Acetate Precursor

2008 ◽  
Vol 368-372 ◽  
pp. 610-612 ◽  
Author(s):  
M. Honarvar Nazari ◽  
Abolghasem Ataie ◽  
S.A. Seyyed Ebrahimi
Keyword(s):  
Heat Treatment ◽  
Magnetic Properties ◽  
Phase Composition ◽  
Mechanical Alloying ◽  
Thermal Behavior ◽  
Crystallite Size ◽  
Barium Hexaferrite ◽  
Subsequent Heat Treatment ◽  
Molar Ratios ◽  
Nano Crystalline

Nano-crystalline barium hexaferrite powders have been prepared by mechanical alloying of nFe2O3+Ba(CH3COO)2 with Fe/Ba molar ratios of 10-12 and subsequent heat treatment. Thermal behavior, phase composition, morphology and magnetic properties of samples were studied using DTA/TGA, XRD, SEM and VSM, respectively. Nano-crystalline Ba-hexaferrite with a mean crystallite size of 46 nm and magnetic properties as high as Ms = 73.9 A.m2/kg and Hci = 334.2 kA/m was formed for mixture of 5.5Fe2O3+Ba(CH3COO)2 which was milled for 48 h and then annealed at 1100 °C.

Structural Investigation of Ti-N Films

1985 ◽  
Vol 54 ◽  
Author(s):  
M. Asplund ◽  
A. S. Korhonen ◽  
J. M. Molarius ◽  
E. Nykänen ◽  
M. S. Sulonen
Keyword(s):  
Phase Composition ◽  
Nitrogen Content ◽  
Crystallographic Texture ◽  
Structural Investigation ◽  
Pure Titanium ◽  
Structure And Properties ◽  
Major Phase ◽  
Ion Plating ◽  
Wide Range ◽  
Diffraction Peaks

ABSTRACTTi-N films were deposited by reactive ion plating on various substrates. The N/Ti-ratio was systematically varied in order to produce films of varying structure and properties from pure titanium to overstoichiometric TiN. Broad diffraction peaks typical of PVD Ti-N films were found. Metastable ct-titanium was observed over a wide range up to about 50 at. % N. No marked differences in the phase composition or in the crystallographic texture could be found in the films deposited on the various substrates. The hardness of the films was observed to increase with increasing nitrogen content, reaching a maximum around 35 – 40 at. % N corresponding to a mixed ε-Ti2N and δ-TiN structure. Extended annealing at 773 K did not result in any major phase transformations. After annealing at 1173 K, α-Ti could no longer be found in nitrogen-rich films. Also ε-Ti2 N transformed to δ-TiN after annealing at 1173 K for 2 h.

scholarly journals Isolation and Characterization of Microcrystalline Cellulose and Preparation of Nano-Crystalline Cellulose from Tropical Water Hyacinth

2018 ◽  
Vol 31 (1) ◽  
pp. 180 ◽  
Author(s):  
Mohammed H. Abdul Latif ◽  
Yasir Fathi Mahmood
Keyword(s):  
Microcrystalline Cellulose ◽  
Water Hyacinth ◽  
Crystal Size ◽  
Crystallinity Index ◽  
Crystalline Cellulose ◽  
Gravimetric Analysis ◽  
Average Crystal Size ◽  
Isolation And Characterization ◽  
Nano Crystalline ◽  
Stretching Vibration

Because of the conservation problems causes by the existence of water hyacinth (W.H) as an watery plant in water bodies of Iraq, our study aimed to make  use of (W.H) by isolation of microcrystalline cellulose, and a new method of preparation of Nano crystalline cellulose. Microcrystalline cellulose was produced using base bleaching method by sodium hypochlorite [NaOCl] to remove unorganized region of cellulose and lignin to create particles comprising of micro crystal and preparing of Nano crystalline cellulose from microcrystalline cellulose by acid hydrolysis and ultrasonic treatment. The Nano crystalline and microcrystalline cellulose characterized by AFM, FTIR, XRD and TGA. FT-IR spectra of microcrystalline cellules and Nano crystalline cellulose show peaks at (1076.28, 1058.92) cm-1 and (1118.71, 1112.93) cm-1 refer to the stretching vibration of   C–O and stretching vibration intermolecular ester bonding.         The AFM image shows that isolated microcrystalline cellulose have a diameter of (141.37 nm) and the prepared Nano crystalline have a diameter of (87.39 nm). The Thermo gravimetric analysis of cellulose showed a high decomposition temperature at (283°C) for microcrystalline cellulose and (253)°C for Nano crystalline cellulose .The thermal stability of microcrystalline cellulose was more than Nano crystalline cellulose XRD result possessed a segal crystallinity index of 92.8 % and a average crystal size of 41.7 A ° for Nano crystalline cellulose and a Segal Crystallinity Index of 86.4 % and a average crystal size of 55.3°A    of microcrystalline cellulose.   

Concentration of iron oxides from soil clays by 5 m NaOH treatment: the complete removal of sodalite and kaolin

Clay Minerals ◽  
1991 ◽  
Vol 26 (4) ◽  
pp. 463-472 ◽  
Author(s):  
Balwant Singh ◽  
R. J. Gilkes
Keyword(s):  
Iron Oxide ◽  
Iron Oxides ◽  
Crystal Size ◽  
Complete Removal ◽  
Complete Dissolution ◽  
Al Substitution ◽  
Soil Clays ◽  
Naoh Treatment ◽  
Very High

AbstractThe Kämpf & Schwertmann (1982) procedure for concentrating iron oxides in soil clays by dissolution of kaolin and gibbsite by boiling for 1 h in 5 m NaOH may not dissolve all kaolin, and also results in the precipitation of sodalite. For the complete dissolution of kaolin in kaolin-rich soil clays a boiling time of 2 h in 5 m NaOH was required. The large amounts of sodalite produced were not removed by the prescribed single wash in 0·5 m HCl. Oxalate soluble Al contents of iron oxide concentrates were sometimes very high and dithionite Fe contents were very low both in concentrates containing sodalite, and in those for which sodalite was not detected by XRD, but where a previously unsuspected amorphous sodalite-like phase may have been present. Complete removal of precipitated sodalite was achieved by two extractions with 0·5 m HCl at 25°C for 20 min. This modified procedure does not alter the Al-substitution and crystal size of goethite, hematite and maghemite as determined by XRD measurements.

Microstructure and phase composition evolution of nano-crystalline carbon films: Dependence on deposition temperature

2002 ◽  
Vol 91 (5) ◽  
pp. 3336-3344 ◽  
Author(s):  
A. Hoffman ◽  
A. Heiman ◽  
H. P. Strunk ◽  
S. H. Christiansen
Keyword(s):  
Phase Composition ◽  
Deposition Temperature ◽  
Carbon Films ◽  
Nano Crystalline
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