Determination of Iron in Humates

Clark, Norman Ashwell; Sieling, Dale H.

doi:10.1021/ac50102a010

Cited by 6 publications

(2 citation statements)

References 5 publications

(2 reference statements)

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“…X-ray powder diffraction has been used for quantitative phase analysis since the mid-1930s (Clark & Reynolds, 1936). By contrast, there has been, to the best of our knowledge, only one application of neutron powder diffraction to phase analysis, namely a study of austenite in maraging steel by Windsor, Sinclair, Faulkner, Rainey & Slattery (1984).…”

Section: Introductionmentioning

confidence: 99%

Quantitative phase analysis from neutron powder diffraction data using the Rietveld method

Hill¹,

Howard²

1987

J Appl Crystallogr

1,167

606

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The weight of a phase in a mixture is proportional to the product of the scale factor, as derived in a multicomponent Rietveld analysis of the powder diffraction pattern, with the mass and volume of the unit cell. If all phases are identified and crystalline, the weight fraction W of phase p is given by Wp = Sp( Z M IO p/~ S,( Z M IO,, iwhere S, Z, M and V are, respectively, the Rietveld scale factor, the number of formula units per unit cell, the mass of the formula unit and the unit-cell volume. This is the basis of a method providing accurate phase analyses without the need for standards or for laborious experimental calibration procedures. The method is demonstrated by measurements on binary mixtures of rutile, corundum, silicon and quartz.

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Section: Introductionmentioning

confidence: 99%

Quantitative phase analysis from neutron powder diffraction data using the Rietveld method

Hill¹,

Howard²

1987

J Appl Crystallogr

1,167

606

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“…X-ray powder diffraction methods have been a tool for quantitative analysis of crystalline phases since the first suggestions of Hull (1919). One of the earliest applications based on the addition of an internal standard is that of Clark & Reynolds (1936); later Alexander & Klug (1948) provided a sound theoretical foundation to the internal standard method [-see Klug & Alexander (1974) for a thorough review]. Recently, the capability of routinely step scanning and integrating diffraction peaks by computer controlled devices has led to renewed interest in this field because improved precision is attainable through photon counting.…”

Section: Introductionmentioning

confidence: 99%

The reference intensity ratio,I/I_c, for computer simulated powder patterns

Hubbard¹,

Evans²,

Smith³

1976

J Appl Crystallogr

264

110

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A scale factor 7, to convert from the relative to the absolute/relative intensity scale, is readily calculated during computer simulation of powder patterns. Previously used scale factors are related to 7. The Reference Intensity Ratio, I/Ic (c = corundum), is obtained from ~, e, and 7 for the sample and for corundum. Comparing calculated and experimental I/lc values confirms that microabsorption and primary extinction can be serious experimental aberrations possibly limiting the accuracy to several wt.% in quantitative analysis by powder diffraction.

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