scholarly journals Some considerations related to the use of the Scherrer equation in powder X-ray diffraction as applied to heterogeneous catalysts

2016 ◽  
Vol 2 (1-4) ◽  
pp. 33-37 ◽  
Author(s):  
J. S. J. Hargreaves
Keyword(s):  
Heterogeneous Catalysts ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scherrer Equation

The Synthesis of Cu0.81Ni0.19 Intermetallics by Mechanical Alloying

2012 ◽  
Vol 496 ◽  
pp. 379-382
Author(s):  
Rui Song Yang ◽  
Ming Tian Li ◽  
Chun Hai Liu ◽  
Xue Jun Cui ◽  
Yong Zhong Jin
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Grain Size ◽  
Mechanical Alloying ◽  
Milling Time ◽  
Elemental Powder ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scherrer Equation ◽  
Scanning Electron

The Cu0.81Ni0.19 has been synthesized directly from elemental powder of nickel and copper by mechanical alloying. The alloyed Cu0.81Ni0.19 alloy powders are prepared by milling of 8h. The grain size calculated by Scherrer equation of the NiCu alloy decreased with the increasing of milling time. The end-product was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM)

Morphological Characterization of Shape-Controlled TiO2 Anatase through XRPD Analysis

2016 ◽  
Vol 230 (9) ◽  
Author(s):  
Mauro Coduri ◽  
Michela Maisano ◽  
Maria Vittoria Dozzi ◽  
Elena Selli
Keyword(s):  
Morphological Characterization ◽  
Morphological Investigation ◽  
X Ray Diffraction ◽  
Preferential Growth ◽  
Rietveld Refinements ◽  
X Ray ◽  
Tio2 Anatase ◽  
Shape Controlled ◽  
Scherrer Equation

AbstractPreferential growth of anatase crystallites along different directions is known to deeply affect their photocatalytic properties, especially with respect to the exposure of the reactive {001} facets. Its extent can be easily quantified through simple geometric calculations, on the basis of crystal sizes extracted for specific directions by means of X-Ray Diffraction data analysis. Nevertheless, the actual results depend on the method employed for such a quantification. Here we report on a comparative morphological investigation, performed by employing the Scherrer equation and the line profile from Rietveld refinements, on shape-controlled anatase photocatalysts produced by employing HF as capping agent. Compared to the Rietveld-based method, the use of the Scherrer equation produces a systematic underestimation of crystallite dimensions, especially concerning the [100] direction, which in turn causes the percentage of exposed {001} crystal facets to be underestimated. Neglecting instrumental-related effects may further reduce the estimate.

scholarly journals Quinone-modified metal-organic frameworks MIL-101(Fe) as heterogeneous catalysts of persulfate activation for degradation of aqueous organic pollutants

2019 ◽  
Vol 79 (12) ◽  
pp. 2357-2365 ◽  
Author(s):  
Huaisu Guo ◽  
Weilin Guo ◽  
Yang Liu ◽  
Xiaohua Ren
Keyword(s):  
Photoelectron Spectroscopy ◽  
Heterogeneous Catalysts ◽  
Electrochemical Impedance ◽  
Metal Organic Framework ◽  
Optimum Conditions ◽  
X Ray Diffraction ◽  
Heterogeneous Fenton ◽  
X Ray ◽  
Metal Organic ◽  
Persulfate Activation

Abstract In this work, quinone-modified metal-organic framework MIL-101(Fe)(Q-MIL-101(Fe)), as a novel heterogeneous Fenton-like catalyst, was synthesized for the activation of persulfate (PS) to remove bisphenol A (BPA). The synthetic Q-MIL-101(Fe) was characterized via X-ray diffraction, scanning electron microscope, Fourier transform infrared, electrochemical impedance spectroscopy, cyclic voltammetry and X-ray photoelectron spectroscopy. As compared to the pure MIL-101(Fe), Q-MIL-101(Fe) displayed better catalytic activity and reusability. The results manifested that the Q-MIL-101(Fe) kept quinone units, which successfully promoted the redox cycling of Fe3+/Fe2+ and enhanced the removal efficiency. In addition, the reaction factors of Q-MIL-101(Fe) were studied (e.g. pH, catalyst dosage, PS concentration and temperature), showing that the optimum conditions were [catalyst] = 0.2 g/L, [BPA] = 60 mg/L, [PS] = 4 mmol/L, pH = 6.79, temperature = 25 °C. On the basis of these findings, the probable mechanism on the heterogeneous activation of PS by Q-MIL-101(Fe) was proposed.

An empirical Scherrer equation for weakly swelling mixed-layer minerals, especially illite-smectite

Clay Minerals ◽  
1999 ◽  
Vol 34 (4) ◽  
pp. 601-617 ◽  
Author(s):  
M. Jaboyedoff ◽  
B. Kübler ◽  
Ph. Thélin
Keyword(s):  
Mixed Layer ◽  
Diffraction Peak ◽  
X Ray Diffraction ◽  
X Ray ◽  
Peak Broadening ◽  
Scherrer Equation ◽  
Xrd Patterns ◽  
Mixed Layering

AbstractThe Scherrer equation links the measured width of an X-ray diffraction peak (Scherrer width, SW) to the number of stacked cells (N) in the direction normal to the diffracting planes. The formula is only valid for one d-value occurring in the coherently diffracting domain. This equation can be modified for weakly swelling mixed-layer minerals. This assumes that the peak broadening caused by the mixed-layering is proportional to the amount of swelling component (S) and that the effects of size and mixed-layering are additive.If two SW can be measured on XRD patterns from samples treated in two different ways (such as air dried or glycolated), N and S can be determined. This equation is applicable to illite-smectite mixed-layer minerals with high illitic content. The results are most accurate for N>30. The use of Scherrer's equation is discussed.

Triazole-directed Fabrication of Polyoxovanadate-based Metal-organic Frameworks as Efficient Multifunctional Heterogeneous Catalysts for Knoevenagel Condensation and Oxidation of Alcohols

2021 ◽  
Author(s):  
Jikun Li ◽  
Chuanping Wei ◽  
Yinfeng Han ◽  
Yu Mei ◽  
Xueli Cheng ◽  
...  
Keyword(s):  
Single Crystal ◽  
Heterogeneous Catalysts ◽  
Knoevenagel Condensation ◽  
Metal Organic Frameworks ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxidation Of Alcohols ◽  
Metal Organic

By introducing 4-amino-1,2,4-triazole (4-NH2-trz), three new polyoxovanadate-based metal-organic frameworks (PMOFs) [Ni3(4-NH2-trz)6][V6O18]•3H2O (1), [Co3(4-NH2-trz)6][V6O18]•3H2O (2) and [Cu3OH(4-NH2-trz)3H2O][VO3]5•H2O (3) have been synthesized and thoroughly characterized by single-crystal X-ray diffraction (SXRD), powder X-ray...

Emerging heterogeneous catalysts for biomass conversion: studies of the reaction mechanism

2021 ◽  
Author(s):  
Longfei Lin ◽  
Xue Han ◽  
Buxing Han ◽  
Sihai Yang
Keyword(s):  
Reaction Mechanisms ◽  
Heterogeneous Catalysts ◽  
Inelastic Neutron Scattering ◽  
Biomass Conversion ◽  
Inelastic Neutron ◽  
Computational Techniques ◽  
X Ray Diffraction ◽  
Isotope Labelling ◽  
X Ray ◽  
X Ray Absorption

This review analyses the reaction mechanisms for the conversion of biomass and derivatives studied by inelastic neutron scattering, synchrotron X-ray diffraction, X-ray absorption spectroscopy, NMR, isotope-labelling and computational techniques.

The Structure of Crystalline 1,2-Polybutadiene and of Other Syndyotactic Polymers

1956 ◽  
Vol 29 (4) ◽  
pp. 1458-1471 ◽  
Author(s):  
G. Natta ◽  
P. Corradini
Keyword(s):  
Heterogeneous Catalysts ◽  
Crystalline Polymer ◽  
Infrared Analysis ◽  
X Ray Diffraction ◽  
Crystalline Materials ◽  
X Ray ◽  
Crystalline Polymers ◽  
Temperature Modification ◽  
Cis And Trans ◽  
First Time

Abstract Systematic x-ray and electron diffraction studies of polymers of 1,3-butadiene prepared by different anionic catalysts have made it possible for us to identify two types of highly crystalline materials. One of us (G. N.) has already reported that our synthesis was carried out with the aid of different highly selective catalysts. The description of the preparation of these catalysts, which have made it possible for the first time to prepare these new polymers, will be separately published by one of us (G. N.) with L. Porri. Infrared analysis carried out by E. Mantica and D. Morero in our Institute has established that one type of these crystalline polymers obtained with heterogeneous catalysts represents a continuous l,4-trans arrangement of the monomer units. X-ray diffraction has shown that this material is dimorphous, having one crystalline modification that is stable at room temperature and another stable above 60° C. The x-ray melting point of a polymer having a molecular weight of the order of 100,000 is around 130° C. The low-temperature modification has an identity period of 4.9 A along the chain axis and a hexagonal packing with a period of a=4.54 A perpendicular thereto, but the symmetry of the crystals, as a whole, is lower. The high temperature modification seems to have the chains in helicoid form. The other crystalline polymer consists essentially of 1,2-monomer units; infrared studies have shown that more than 90 per cent of its double bonds are of the vinyl type and the residual 10 per cent represents a mixture of cis and trans. The higher the proportion of 1,2-units, the more crystalline is the material. Figure 1 shows the infrared absorption curves of two different typical samples of the product. In this article, we limit ourselves to describing the structure of the latter polymer, which, in our opinion, is the more interesting material and which we shall simply call 1,2-polybutadiene. We shall report on the structure of the two modifications of the l,4-trans-polybutadiene in another paper together with the study of the structure of other crystalline polydienes.

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