Understanding the Effect of the Preparation Process on the Electrochemical Properties of 0.25Li2MnO3∙0.75LiNi1/2Mn1/2O2 by Rietveld Refinement Method

2011 ◽  
Vol 391-392 ◽  
pp. 648-653
Author(s):  
Fang Lian ◽  
Dong Li ◽  
Peter Axmann ◽  
Margret Wohlfahrt-Mehrens
Keyword(s):  
Electrochemical Properties ◽  
Rietveld Refinement ◽  
Local Environment ◽  
Preparation Process ◽  
X Ray Diffraction ◽  
Electrochemical Lithiation ◽  
Refinement Method ◽  
End Products ◽  
Initial Charge ◽  
Diffraction Patterns

0.25Li2MnO3•0.75LiNi1/2Mn1/2O2solid solution was prepared via a two-step calcination technique. No appreciable difference between the end products can be detected from the X-ray diffraction patterns including the superstructure reflections. However, the material prepared from preheating the precursor at 450°C for 4h in N2 delivers a high first charge capacity of 287mAhg-1between 2.5and 4.8V at 0.5C, while the samples obtained from preheating the precursor for 10h in air exhibit a low capacity of 199 mAhg-1and an undetectable plateau around 4.5V in the initial charge curve. With an aim to identify the influence of preparation process on the structural and electrochemical properties, Rietveld refinement method was performed on the detailed structure testing with the model integrating R m layered rock salts and Fd m cubic ones. The end products prepared from precalcining the precursor in N2 shows low proportion of Fd m domain about 8.0% and larger Li-O slab space in dominating R m rock salts. By contrast, the samples obtained from prolonging the process-prheating time to 10h in air consists of 12.7% Fd m cubic rock salts and 87.3% R m layered ones. The observations indicate that the samples obtained from different precursor-preheating process appear a variation in the local environment of Li+ insertion/extraction, which give an evidence on their electrochemical lithiation/delithiation process shown in the CV curves.

Structural and electrochemical properties of Ti–Ru–Fe–O alloys prepared by high energy ball-milling

1998 ◽  
Vol 13 (5) ◽  
pp. 1171-1176 ◽  
Author(s):  
S-H. Yip ◽  
D. Guay ◽  
S. Jin ◽  
E. Ghali ◽  
A. Van Neste ◽  
...  
Keyword(s):  
Electrochemical Properties ◽  
High Energy ◽  
X Ray Diffraction ◽  
Long Term Stability ◽  
Ternary Metal ◽  
Oxide Phases ◽  
Energy Ball ◽  
Diffraction Patterns ◽  
B2 Structure

The structural and electrochemical properties of the Ti–Ru–Fe–O system have been studied over the whole ternary metal compositional range, keeping constant the oxygen content at 30 at.%. The phase diagram was explored systematically by varying the composition of the material along one of the following axes: (i) constant Ru content of 16 at. %; (ii) constant Ti/Ru ratio of 2; (iii) constant Ti/Fe ratio of 1.6. For O/Ti ratios equal or below unity, the most prominent peaks observed in the x-ray diffraction patterns belong to a B2 structure. For O/Ti ratio larger than unity, stable titanium oxide phases are formed, which coexist with a cubic Fe-like or hcp-Ru like phases depending on the Fe/Ru ratio. Powder compositions with stoichiometry close to Ti2RuFeO2 are of interest due to good electrocatalytic properties, long-term stability, and low Ru content.

Portland Cement for the Cementing of Oil Wells Developed with the Aid of the Rietveld Refinement Method

2014 ◽  
Vol 805 ◽  
pp. 350-355
Author(s):  
Danielle Nascimento Silva Oliveira ◽  
Gelmires Araújo Neves ◽  
Ulisses Targino Bezerra ◽  
Alexsandra C. Chaves ◽  
B. Silveira Lira
Keyword(s):  
Linear Programming ◽  
Portland Cement ◽  
Rietveld Refinement ◽  
Polycrystalline Materials ◽  
Oil Well ◽  
X Ray Diffraction ◽  
X Ray ◽  
Refinement Method ◽  
Low Levels

The use of the Rietveld refinement method has been highlightened as essential in the characterization of polycrystalline materials. With the aid of this method, combined with the application of the X-ray diffraction, it was possible to develop a type of cement that can temporarily substitute the Portland cement for Oil well. This cement was developed from the mixture of Portland cements commonly found in the market. The cements were passed through various sieves, then characterized by X-ray diffraction, being identified the main phases (C3A, C4AF, C3S and C2S) and quantified by the Rietveld refinement method. With the values obtained in the quantification of the phases, a new cement was made through the method of linear programming. From the results, it was possible to conclude that the developed cement presented a composition (levels of the main phases) that satisfies the requirements of NBR 9831, mainly in relation to the low levels of C3A.

scholarly journals Rietveld Refinement on X-Ray Diffraction Patterns of Bioapatite in Human Fetal Bones

2003 ◽  
Vol 84 (3) ◽  
pp. 2021-2029 ◽  
Author(s):  
Carlo Meneghini ◽  
Maria Chiara Dalconi ◽  
Stefania Nuzzo ◽  
Settimio Mobilio ◽  
Rudy H. Wenk
Keyword(s):  
Rietveld Refinement ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns

scholarly journals Investigation into the crystallization of molecular sieve DNL-6

2021 ◽  
pp. 1-9
Author(s):  
Maxwell Goldman ◽  
Yining Huang
Keyword(s):  
Hydrothermal Synthesis ◽  
Molecular Sieve ◽  
Local Environment ◽  
Cetyltrimethylammonium Chloride ◽  
X Ray Diffraction ◽  
Reaction Conditions ◽  
Structure Directing Agent ◽  
Dry Gel Conversion ◽  
Intermediate Phases ◽  
Diffraction Patterns

Crystallization of DNL-6, a silicoaluminophosphate (SAPO) based molecular sieve with the RHO topology, was investigated under both the hydrothermal synthesis (HTS) and dry-gel conversion (DGC) conditions. Crystallization of DNL-6 under the HTS conditions is rather fast. But a combination of crystallization under the DGC conditions and reducing reaction temperature slow down the reactions, allowing for intermediates to be captured. Under the DGC conditions, DNL-6 crystallizes through a semi-crystalline layered phase. The nature of this intermediate is aluminophosphate (AlPO) rather than SAPO with most P atoms having a local environment of P(–O–Al)3(OH). The surfactant (cetyltrimethylammonium chloride) used for synthesis appears to be part of the layered intermediate. Si is directly incorporated in the DNL-6 framework via SM II mechanism when the semi-crystalline AlPO phase is transforming to DNL-6 with the assistance of a very small amount of water. Both the structure directing agent and the surfactant play a role in the formation of DNL-6, as they were found within the final synthesized products. SEM data show that hydrothermal synthesis produces a much more crystalline product. The facts that the semi-crystalline layered phase was also observed in the powder X-ray diffraction patterns of the solid samples obtained under the HTS conditions and that the evolution of the local structure around P and Al in the intermediate phases are similar imply that under the reaction conditions employed in the present study, the formation pathways of DNL-6 under the HTS and DGC conditions appear to have some similarities.

Crystal structure of copper(ii) citrate monohydrate solved from a mixture powder X-ray diffraction pattern

2013 ◽  
Vol 29 (1) ◽  
pp. 28-32 ◽  
Author(s):  
Ana Palčić ◽  
Ivan Halasz ◽  
Josip Bronić
Keyword(s):  
Crystal Structure ◽  
Diffraction Pattern ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Indexing Structure ◽  
Pattern Approach ◽  
Structure Solution ◽  
Diffraction Patterns

The crystal structure of copper(ii) citrate monohydrate (C6H4O7Cu2·H2O) has been solved from a mixture powder diffraction pattern. Approach to indexing, structure solution and Rietveld refinement of multiphase diffraction patterns is discussed. Rietveld refinement is carried out employing free-atom refinement and rigid body refinement.

Electrochemical lithiation-induced polymorphism of anthraquinone derivatives observed by operando X-ray diffraction

2015 ◽  
Vol 17 (41) ◽  
pp. 27665-27671 ◽  
Author(s):  
Katharine E. Silberstein ◽  
James P. Pastore ◽  
Weidong Zhou ◽  
Rebecca A. Potash ◽  
Kenneth Hernández-Burgos ◽  
...  
Keyword(s):  
Lithium Ion Batteries ◽  
Molecular Crystals ◽  
Lithium Ion ◽  
X Ray Diffraction ◽  
X Ray ◽  
Organic Molecular Crystals ◽  
Coin Cell ◽  
Electrochemical Lithiation ◽  
Anthraquinone Derivatives ◽  
Diffraction Patterns

Operando X-ray diffraction patterns of organic molecular crystals in lithium-ion batteries provide evidence for polymorphism via a modified coin cell.

scholarly journals Structure properties and dielectric relaxation of Ca0.1Na0.9Ti0.1Nb0.9O3 ceramic

RSC Advances ◽  
2019 ◽  
Vol 9 (44) ◽  
pp. 25358-25367 ◽  
Author(s):  
Hanen Ghoudi ◽  
Souad Chkoundali ◽  
Zeineb Raddaoui ◽  
Abdelhedi Aydi
Keyword(s):  
Solid State ◽  
Dielectric Relaxation ◽  
Rietveld Refinement ◽  
Solid State Reaction ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Diffraction Patterns ◽  
Structure Properties

In this paper, the synthesis of Ca0.1Na0.9Ti0.1Nb0.9O3 (CNTN) ceramic by a solid-state reaction is reported. The results of Rietveld refinement of X-ray diffraction patterns at room temperature showed a pure tetragonal perovskite (P4mm space group).

Structural and anisotropic thermal expansion correlation of Li2ZrO3at different temperatures

2002 ◽  
Vol 35 (5) ◽  
pp. 634-636 ◽  
Author(s):  
Z. K. Heiba ◽  
Karimat El-Sayed
Keyword(s):  
Thermal Expansion ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Lattice Parameters ◽  
Interatomic Distances ◽  
X Ray ◽  
Anisotropic Thermal Expansion ◽  
Refinement Method ◽  
Different Temperatures ◽  
Diffraction Patterns

Structural and thermal expansion studies of Li2ZrO3were carried out by recording X-ray powder diffraction patterns at five temperatures, 82, 198, 300, 423 and 573 K. The Rietveld refinement method was used for the analysis. There were large anisotropic changes in the lattice parameters as a function of temperature, slight changes in the fractional coordinates of the different atoms, and anisotropic changes in the interatomic distances between the different cations. The correlation of these anisotropies with the structure is considered.

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