Determination of Illite-Smectite Structures Using Multispecimen X-ray Diffraction Profile Fitting

In recent years, several profile-shape functions have been successfully used in X-ray powder diffraction studies. Here, a new profile function for approximating the X-ray diffraction peaks is proposed. This model, based on a Gaussian function multiplied by a correction factor in the form of a series expansion in Hermite polynomials, can be employed in the cases where there are peak asymmetries. The function has been tested by using samples of α-Al2O3and 9-YSZ (yttria-stabilized zirconia), yielding generally satisfactory results.

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Quantitative X-Ray Structure Determination of Superlattices and Interfaces

MRS Proceedings ◽

10.1557/proc-229-41 ◽

1991 ◽

Vol 229 ◽

Cited By ~ 6

Author(s):

Ivan K. Schuller ◽

Eric E. Fullerton ◽

H. Vanderstraeten ◽

Y. Bruynseraede

Keyword(s):

General Procedure ◽

Structural Refinement ◽

X Ray Diffraction ◽

Diffraction Profile ◽

X Ray ◽

Superlattice Structure ◽

Wide Range ◽

Fitting Algorithm ◽

Superlattice Structures

AbstractWe present a general procedure for quantitative structural refinement of superlattice structures. To analyze a wide range of superlattices, we have derived a general kinematical diffraction formula that includes random, continuous and discrete fluctuations from the average structure. By implementing a non-linear fitting algorithm to fit the entire x-ray diffraction profile, refined parameters that describe the average superlattice structure, and deviations from this average are obtained. The structural refinement procedure is applied to a crystalline/crystalline Mo/Ni superlattices and crystalline/amorphous Pb/Ge superlattices. Roughness introduced artificially during growth in Mo/Ni superlattices is shown to be accurately reproduced by the refinement.

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An expert system for the structural characterization of kaolinites

Clay Minerals ◽

10.1180/claymin.1990.025.3.01 ◽

1990 ◽

Vol 25 (3) ◽

pp. 249-260 ◽

Cited By ~ 40

Author(s):

A. Plançon ◽

C. Zacharie

Keyword(s):

Expert System ◽

Defect Structure ◽

Defect Structures ◽

X Ray Diffraction ◽

Diffraction Profile ◽

X Ray ◽

Diffraction Patterns ◽

Xrd Patterns

AbstractUntil recently, the determination of the defect structures (previously referred to incorrectly as “crystallinity”) of kaolinites has been obtained in one of two ways: (1) measurement of the Hinckley index, or (2) by comparing calculated X-ray diffraction patterns based on a model of the defect structure (including types of defects and abundances) with experimental diffraction profiles. The Hinckley method is simple and easy to perform but contains no real information about the defect structure. Calculated XRD patterns are based on real defects but these calculations are time consuming and require some skill in application. Another approach is proposed: an expert system which will accurately describe the defect structure of kaolinites based on a few measurements taken from a normal powder diffraction profile. This system has been verified for nine kaolinite samples for which the defect structure was previously determined by comparison of calculated and observed diffraction profiles. The expert system reproduced the correct defect structure for each of the samples.

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Determination of minor quantities of linezolid polymorphs in a drug substance and tablet formulation by powder X-ray diffraction technique

Powder Diffraction ◽

10.1017/s0885715617000069 ◽

2017 ◽

Vol 32 (2) ◽

pp. 78-85 ◽

Cited By ~ 6

Author(s):

Mengying Sun ◽

Xiurong Hu ◽

Xinbo Zhou ◽

Jianming Gu

Keyword(s):

Limit Of Detection ◽

Drug Product ◽

Multidrug Resistant ◽

Tablet Formulation ◽

Drug Substance ◽

X Ray Diffraction ◽

X Ray ◽

Profile Fitting ◽

Full Profile

Linezolid (LZD) is one of the first commercially available synthetic oxazolidinone antibiotics and is widely used for the treatment of multidrug-resistant Gram-positive bacterial infection. LZD was found to have five polymorphic forms. The most stable and commercialized polymorphs are known as forms II and IV. Trace content of form II in LZD form IV will cause to transition LZD form IV to II rapidly. Powder X-ray diffraction (PXRD) methods were evaluated for the determination of the polymorphic content of the drug substance and drug product. The estimated limit of detection values of the single peak method for LZD polymorph form II in drug substance and tablet formulation were 0.4 and 0.6%, respectively, while the limit of detection value of Rietveld Refinement (full-profile fitting) evaluated LZD polymorph form II in drug substance was 0.2%. The results clearly show that levels <1 wt.% (in active pharmaceutical ingredients) and 2 wt.% (in tablets) LZD form II in form IV can be detected and quantified by PXRD. Validation of the analytical method proved that the method is repeatable, sensitive, and accurate.

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X-ray powder diffraction profile fitting in quantitative determination of two polymorphs from their powder mixture

International Journal of Pharmaceutics ◽

10.1016/0378-5173(92)90008-p ◽

1992 ◽

Vol 81 (2-3) ◽

pp. 169-177 ◽

Cited By ~ 20

Author(s):

V.P. Tanninen ◽

J. Yliruusi

Keyword(s):

Quantitative Determination ◽

Powder Diffraction ◽

Powder Mixture ◽

Diffraction Profile ◽

X Ray ◽

Profile Fitting ◽

Fitting In

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Hydration behavior by X-ray diffraction profile fitting of smectite-bearing minerals in a Plio-Pleistocene mudrock from Eugene Island, Gulf of Mexico

Marine and Petroleum Geology ◽

10.1016/j.marpetgeo.2018.12.008 ◽

2019 ◽

Vol 102 ◽

pp. 86-100 ◽

Cited By ~ 2

Author(s):

Ruarri J. Day-Stirrat ◽

L. Taras Bryndzia ◽

Anja M. Schleicher ◽

Rieko Adriaens ◽

Ronny Hofmann ◽

...

Keyword(s):

Gulf Of Mexico ◽

X Ray Diffraction ◽

Diffraction Profile ◽

X Ray ◽

Profile Fitting

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A new kaolinite order index based on XRD profile fitting

Clay Minerals ◽

10.1180/0009855064140220 ◽

2006 ◽

Vol 41 (4) ◽

pp. 811-817 ◽

Cited By ~ 31

Author(s):

P. Aparicio ◽

E. Galán ◽

R. E. Ferrell

Keyword(s):

Silica Gels ◽

X Ray Diffraction ◽

X Ray ◽

Amorphous Phases ◽

Structural Order ◽

Profile Fitting ◽

Overlapping Peaks ◽

Highly Correlated

AbstractThe determination of kaolinite order-disorder by X-ray diffraction is problematic due to overlapping peaks from associated kaolin minerals and X-ray amorphous phases. This paper presents a new index (Aparicio-Gala´n-Ferrell index — AGFI), measured on 02land 11lreflections after decomposing individual peaks in the complex diffraction band in an effort to reduce interferences. The new index was tested with three kaolins, of varying structural order, and their admixtures containing different percentages of quartz, feldspar, illite, smectite, chlorite, halloysite and Fe hydroxides and silica gels. The AGFI is highly correlated with the percentage of low-defect kaolinite and the Hinckley Index. It is not as prone to interference by associated minerals and X-ray amorphous phases as other indices. The AGFI can be used to determine kaolinite order-disorder in a wide variety of kaolins and kaolinitic rocks; the only prerequisite is that the kaolinite content should be >10 wt.% in order for the results to be reproducible.

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The Determination of Low Levels of Quartz in Commercial Kaolins by X-ray Diffraction

Powder Diffraction ◽

10.1017/s0885715600018261 ◽

1992 ◽

Vol 7 (2) ◽

pp. 71-76 ◽

Cited By ~ 8

Author(s):

N.J. Elton ◽

P.D. Salt ◽

J.M. Adams

Keyword(s):

United States ◽

Data Collection ◽

The United States ◽

X Ray Diffraction ◽

X Ray ◽

Respirable Fraction ◽

Profile Fitting ◽

Potential Problems ◽

Low Levels

AbstractLegislation in the United States and Canada requires labelling of products containing ≥ 0.1 wt.% crystalline silica. Kaolin clays are used in a variety of industries and usually contain low levels of total (i.e., respirable plus non-respirable) quartz, even after beneficiation. X-ray diffraction procedures have been developed here which are suitable for the quantification of total quartz in commercial kaolins with accuracy sufficient to satisfy the legislation. Separation and analysis of the respirable fraction is not addressed in this paper; however, the procedures described would be applicable to such samples if sufficient were available. Use of the 50.1° 2θrather than the 26.6° 26 (CuKα) quartz peak avoids most of the potential problems of overlap with reflections from other accessory minerals. It is shown that profile fitting techniques and optimised experimental procedures allow the determination of quartz in bulk samples to ± 0.03 wt.% (95% confidence) at the 0.1 wt.% level, and ± 0.1 wt.% at the 1.0 wt.% level, with tolerable data collection times.

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