Nanophase Copper Ferrite Using an Organic Gelation Technique

1996 ◽  
Vol 457 ◽  
Author(s):  
D. Sriram ◽  
R. L. Snyder ◽  
V. R. W. Amarakoon
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Crystallite Size ◽  
Polyacrylic Acid ◽  
Size Analysis ◽  
Copper Ferrite ◽  
Carboxylic Group ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nano Size

ABSTRACTNanocrystalline copper ferrite (Cu0.5Fe2.5O4) was synthesized using a forward strike gelation method with polyacrylic acid (PAA) as a gelating agent. The dried gel was calcined at a low temperature of 400 °C to get the final powder. The effect of pH and the ratio of the cation to the carboxylic group in the initial gel were studied with respect to both the phases and the crystallite size of the final powders synthesized. Phase and crystallite size analysis were done using x-ray diffraction and TEM. Saturation magnetization results were obtained using a SQUID magnetometer. The reactions occurring in the nano-size copper ferrite, in air as a function of temperature, were tracked using adynamic high temperature x-ray diffraction (HTXRD) system.

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 X-ray diffraction analysis of kaolin M1 and M2 via the Williamson–Hall and Warren–Averbach methods

2021 ◽  
pp. 174751982098472
Author(s):  
Lalmi Khier ◽  
Lakel Abdelghani ◽  
Belahssen Okba ◽  
Djamel Maouche ◽  
Lakel Said
Keyword(s):  
Grain Size ◽  
High Temperature ◽  
Low Temperature ◽  
Diffraction Analysis ◽  
Mechanical Resistance ◽  
X Ray Diffraction ◽  
Integral Breadth ◽  
X Ray ◽  
Mullite Phase

Kaolin M1 and M2 studied by X-ray diffraction focus on the mullite phase, which is the main phase present in both products. The Williamson–Hall and Warren–Averbach methods for determining the crystallite size and microstrains of integral breadth β are calculated by the FullProf program. The integral breadth ( β) is a mixture resulting from the microstrains and size effect, so this should be taken into account during the calculation. The Williamson–Hall chart determines whether the sample is affected by grain size or microstrain. It appears very clearly that the principal phase of the various sintered kaolins, mullite, is free from internal microstrains. It is the case of the mixtures fritted at low temperature (1200 °C) during 1 h and also the case of the mixtures of the type chamotte cooks with 1350 °C during very long times (several weeks). This result is very significant as it gives an element of explanation to a very significant quality of mullite: its mechanical resistance during uses at high temperature remains.

Structural chemistry of NaCoPO4

1996 ◽  
Vol 52 (3) ◽  
pp. 440-449 ◽  
Author(s):  
R. Hammond ◽  
J. Barbier
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Large Family ◽  
X Ray Diffraction ◽  
Tetrahedral Framework ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Tetrahedral Sites ◽  
Bond Valence Analysis

Sodium cobalt phosphate, NaCoPO4, occurs as two different polymorphs which transform reversibly at 998 K. The crystal structures of both polymorphs have been determined by single-crystal X-ray diffraction. The low-temperature form α-NaCoPO4 crystallizes in the space group Pnma with cell parameters: a = 8.871 (3), b = 6.780 (3), c = 5.023 (1) Å, and Z = 4 [wR(F 2) = 0.0653 for all 945 independent reflections]. The α-phase contains octahedrally coordinated Co and Na atoms and tetrahedrally coordinated P atoms, and is isostructural with maracite, NaMnPO4. The structure of high-temperature β-NaCoPO4 is hexagonal with space group P65 and cell parameters: a = 10.166 (1), c = 23.881 (5) Å, and Z = 24 [wR(F 2) = 0.0867 for 4343 unique reflections]. The β-phase belongs to the large family of stuffed tridymites, with the P and Co atoms occupying tetrahedral sites and the Na atoms located in the cavities of the tetrahedral framework. The long c axis corresponds to a 3 × superstructure of the basic tridymite framework (c ≃ 8 Å) and is caused by the displacement of the Na atoms, tetrahedral tilts and strong distortions of the CoO4 tetrahedra. A bond-valence analysis of these phases reveals that the polymorphism in NaCoPO4 is due in part to over-/underbonding of the Na atom in the low-/high-temperature structures, respectively.

Modification of Asphalt by Montmorillonite

2011 ◽  
Vol 84-85 ◽  
pp. 662-666 ◽  
Author(s):  
Zeng Ping Zhang ◽  
Yong Wen ◽  
Jian Zhong Pei ◽  
Shuan Fa Chen
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Temperature Sensitivity ◽  
Softening Point ◽  
High Speed ◽  
Melt Blending ◽  
X Ray Diffraction ◽  
Nanocomposite Structure ◽  
X Ray ◽  
Temperature Performance

Montmorillonite (MMT) modified asphalts are prepared by melt blending with the help of high-speed shear mixer. The dispersion of MMT layers in the asphalt matrix are characterized by X-ray diffraction (XRD). The effect of different contents of MMT on physical properties of the base asphalt is studied. These properties include penetration, softening point and ductility. The results indicate that MMT/asphalt may form a nanocomposite structure with MMT layers intercalated by the asphalt molecules. MMT can improve the high temperature performance and temperature sensitivity of the base asphalt. And it can slightly reduce the low temperature performances of matrix asphalt. It is found that low temperature performances, high temperature performance and temperature sensitivity of the modified system achieved balance when the content of MMT is 4 wt%.

Displacive Phase Transformation in Vanadium - Substituted Lanthanum Niobate

1983 ◽  
Vol 24 ◽  
Author(s):  
A. T. Aldred ◽  
S.-K. Chan ◽  
M. H. Grimsditch ◽  
M. V. Nevitt
Keyword(s):  
Phase Transformation ◽  
High Temperature ◽  
Low Temperature ◽  
Raman Scattering ◽  
Transformation Temperature ◽  
Complex Oxides ◽  
Temperature Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Order

ABSTRACTThe displacive transformations in complex oxides of the type LaNb1-xVxO4 has been studied by x-ray diffraction and Raman scattering for 0 < x < 0.3. X-ray diffraction results indicate that the transformation from the tetragonal high temperature structure (C4h6) to the monoclinic low-temperature structure (C2h6) is higher than first order and that the transformation temperature Tc is depressed significantly by V substitution. Raman scattering results show that the force constant between the nearest (Nb, V)O4 tetrahedral units behave uniquely compared to others. It softens at Tc as a function of composition and it also softens as a function of temperature as Tc is approached from above.

Applicability of Routine Methods of Crystallite Size Analysis*

1962 ◽  
Vol 6 ◽  
pp. 191-201
Author(s):  
Robert C. Rau
Keyword(s):  
Crystallite Size ◽  
Beryllium Oxide ◽  
Testing Procedure ◽  
Individual Performance ◽  
Size Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Geometry ◽  
Crystallite Sizes ◽  
Performance Results

AbstractSeveral methods for the routine determination of crystallite size by means of X-ray diffraction line-broadening have previously been reported. Although these techniques have proven useful and reliable when utilized with the single X-ray diffractometer and instrumental geometry used to originally develop the methods, it was not known whether other instruments would provide similar reliability. Therefore a study was performed to evaluate the applicability of routine methods of crystallite size analysis to other X-ray diffraction units. A series of six beryllium oxide powder specimens, whose average crystallite sizes ranged stepwise from about 35 to nearly 3000 Å, were used to test a number of X-ray diffractometers. By using a predetermined diffraction geometry for each instrument tested, measured crystallite sizes were found to be quite reproducible and well within the limits of experimental error. The testing procedure, instrumental conditions, and individual performance results are presented in this paper.

X-ray diffraction analyses of 3D MgO-based replicas of diatom microshells synthesized by a low-temperature gas/solid displacement reaction

2005 ◽  
Vol 20 (4) ◽  
pp. 306-310 ◽  
Author(s):  
M. S. Haluska ◽  
I. C. Dragomir ◽  
K. H. Sandhage ◽  
R. L. Snyder
Keyword(s):  
Grain Size ◽  
Low Temperature ◽  
Crystallite Size ◽  
Gas Phase ◽  
Grain Growth ◽  
Annealing Time ◽  
Displacement Reaction ◽  
X Ray Diffraction ◽  
Fourier Methods ◽  
X Ray

The nanostructural features of the gas-phase displacement reaction 2Mg(g)+SiO2→2MgO(s)+{Si}, where SiO2 is in the form of diatom shells were studied via X-ray diffraction and Fourier methods. Diatomaceous powder heated to 700 °C in a sealed graphite cell in the presence of Mg vapor formed MgO via a displacement reaction. Warren-Averbach analysis performed on samples reacted for different times showed an initial sharp MgO grain size distribution which broadened with time. New MgO crystallization was shown to occur until about 60 min, whereafter only MgO grain growth occurred. Median MgO crystallite size increased from 7.5 to 24.9 nm during this period, whereas microstrain decreased dramatically past 60 min annealing time.

Effect of Morphology of MgO on the CO2 Adsorption Capacity for Low Temperature Applications

2017 ◽  
Vol 888 ◽  
pp. 503-507
Author(s):  
Ramarao Poliah ◽  
Srimala Sreekantan
Keyword(s):  
Low Temperature ◽  
Crystallite Size ◽  
Adsorption Capacity ◽  
Hydrothermal Method ◽  
Sol Gel ◽  
Average Diameter ◽  
X Ray Diffraction ◽  
Mgo Nanoparticles ◽  
X Ray ◽  
Adsorption Temperature

MgO nanoparticles, nanoflakes and nanorods were synthesized by sol-gel or hydrothermal method. X-ray diffraction confirmed the formation of cubic MgO in entire samples after calcination. The round particles diameter was in the range of 200-500 nm while the flakes structure were with thickness 100-200 nm. The rods were in average diameter of 150-500 nm. CO2 adsorption capacity was measured by using TGA. MgO flakes with smaller crystallite size demonstrated high CO2 adsorption capacity of 1.738 mmol/g at low adsorption temperature of 50°C.

SYNTHESIS OF DIAMOND FILMS ON MOLYBDENUM SUBSTRATE SURFACE BY COMBUSTION FLAME

2006 ◽  
Vol 20 (25n27) ◽  
pp. 3926-3931 ◽  
Author(s):  
MAMORU TAKAHASHI ◽  
OSAMU KAMIYA ◽  
TADASHI OHYOSHI
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Substrate Surface ◽  
Diamond Films ◽  
Synthesis Temperature ◽  
Interfacial Stress ◽  
X Ray Diffraction ◽  
Thermally Induced ◽  
X Ray ◽  
Combustion Flame

Diamond films were synthesized on a Mo substrate using combustion flame. During the cooling process, most diamond films delaminated. From previous work it was shown that diamond films delaminated at a synthesis temperature less than 1300K (low temperature), and films did not delaminate at synthesis temperature more than 1400K (high temperature). In this study, to clarify the influences on the delamination of the interface, films synthesized at high temperature and low temperature were investigated by SEM and X-ray diffraction. The results show that in the case of low temperature, diamond films were synthesized on the Mo substrate, case of high temperature, Mo 2 C and diamond phases were synthesized on the Mo substrate. Thermally induced interfacial stress occurs due to the thermal expansion mismatch between the synthesized film and the Mo substrate. The interfacial stress by high temperature and low temperature was determined as the cause of the delamination. Thus, the interfacial stress of each synthesized temperature was calculated by a finite element method. The results show that the interfacial stress in the film synthesized by high temperature was smaller than that by the low temperature. As the buffer phases prevent the delamination, synthesized films by high temperature will be useful as hardcoating layer for a metal surface.

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