scholarly journals Fast quantitative analysis of the amorphous content with the Rietveld method

2014 ◽  
Vol 70 (a1) ◽  
pp. C949-C949
Author(s):  
Jordi Ibanez ◽  
Jose Fernandez-Turiel ◽  
Josep Elvira ◽  
Marta Rejas ◽  
Soledad Alvarez
Keyword(s):  
Rietveld Method ◽  
Internal Standard ◽  
Basic Research ◽  
Rietveld Analysis ◽  
Glassy Matrix ◽  
Fly Ashes ◽  
Amorphous Phases ◽  
Amorphous Content ◽  
Processing Times ◽  
Volcanic Ashes

The characterization of the mineralogy and chemical composition of multi-phase mixtures is of chief importance in many different contexts, from industry to basic research. In the case of industrial processes, it is often necessary to perform fast and reliable quantitative phase analyses (QPAs) in large amounts of samples that contain amorphous phases. Rietveld refinement from powder x-ray diffraction (XRD) data is widely employed for this purpose. The quantification of the amorphous content with the Rietveld method is usually performed by spiking the samples with an internal standard, and this implies increased processing times. Alternatively, in samples exhibiting the typical, broad XRD signal from the amorphous (glassy) matrix, a poorly-crystalline structure can be used to represent the amorphous phase during the Rietveld analysis [1]. This procedure provides highly consistent data, but is limited because the particular crystal structure used for the QPAs is strongly sample dependent. Recently, it has been shown that fast Rietveld QPAs of coal fly ashes can be carried out with no sample spiking by initially calibrating the XRD signal from the glass [2]. In this work, we evaluate the usefulness of the calibration Rietveld-based approach on two different types of samples: fly ashes from coal combustion plants, and volcanic ashes. While the mineralogy of the fly ashes considered here is relatively simple (they mainly contain quartz, mullite and glass), the volcanic ashes contain sizable amounts of crystalline compounds with both simple and complex structures, including quartz, feldspars, biotite, pyroxene or iron oxides. We show that the calibration approach provides a suitable method to assess in a fast and consistent manner the amount of crystalline and amorphous phases in both types of samples. This method may be extended to industrial characterization processes involving large numbers of complex samples, reducing considerably the analytical times.

scholarly journals Multi-Scale Minero-Chemical Analysis of Biomass Ashes: A Key to Evaluating Their Dangers vs. Benefits

2021 ◽  
Vol 13 (11) ◽  
pp. 6052
Author(s):  
Paola Comodi ◽  
Azzurra Zucchini ◽  
Umberto Susta ◽  
Costanza Cambi ◽  
Riccardo Vivani ◽  
...  
Keyword(s):  
Raw Materials ◽  
Average Diameter ◽  
Rietveld Analysis ◽  
Fly Ashes ◽  
Amorphous Content ◽  
Multi Scale ◽  
Italian Law ◽  
Polycyclic Aromatic ◽  
Mineralogical Study ◽  
The One

A multi-methodic analysis was performed on five samples of fly ashes coming from different biomasses. The aim of the study was to evaluate their possible re-use and their dangerousness to people and the environment. Optical granulometric analyses indicated that the average diameter of the studied fly ashes was around 20 µm, whereas only ~1 vol% had diameters lower that 2.5 µm. The chemical composition, investigated with electron probe microanalysis, indicated that all the samples had a composition in which Ca was prevalent, followed by Si and Al. Large contents of K and P were observed in some samples, whereas the amount of potentially toxic elements was always below the Italian law thresholds. Polycyclic aromatic hydrocarbons were completely absent in all the samples coming from combustion plants, whereas they were present in the fly ashes from the gasification center. Quantitative mineralogical content, determined by Rietveld analysis of X-ray powder diffraction data, indicated that all the samples had high amorphous content, likely enriched in Ca, and several K and P minerals, such as sylvite and apatite. The results obtained from the chemo-mineralogical study performed make it possible to point out that biomass fly ashes could be interesting materials (1) for amendments in clayey soils, as a substitution for lime, to stimulate pozzolanic reactions and improve their geotechnical properties, thus, on the one hand, avoiding the need to mine raw materials and, on the other hand, re-cycling waste; and (2) as agricultural fertilizers made by a new and ecological source of K and P.

Problems and Solutions in Quantitative Analysis of Complex Mixtures by X-Ray Powder Diffraction

1987 ◽  
Vol 31 ◽  
pp. 295-308 ◽  
Author(s):  
David L. Bish ◽  
Steve J. Chipera
Keyword(s):  
Quantitative Analysis ◽  
Amorphous Materials ◽  
Rietveld Method ◽  
Internal Standard ◽  
Preferred Orientation ◽  
Complex Mixtures ◽  
Calibration Data ◽  
Cell Parameters ◽  
Amorphous Phases ◽  
Standard Data

AbstractIn spite of the wide availability of automated diffractometers and advanced data reduction software, numerous traditional problems still exist that make highly precise and accurate quantitative analyses of complex mixtures difficult. The problems include particle statistics, primary extinction, microabsorption, preferred orientation, overlapping and broad reflections, variation in standard data with composition, availability of pure standards, and detection of amorphous and trace phases. Our analyses of rocks use the matrix flushing method on < 5μm particle-size material mixed with a 1.0-μm corundum internal standard to minimize the first four effects. Integrated intensities are used, and we employ several peaks from each phase whenever possible. We overcame overlap problems through iterative calculations using integral, multiple peaks or with profile refinement. Use of observed and calculated diffraction patterns for every phase enables us to predict the effects of composition and preferred orientation on RIRs. This allows us to correct for these effects if reference intensity ratios (RIRs) are known as a function of composition and orientation. Detection of amorphous phases is a significant problem, and standard mixtures reveal that amounts of amorphous components below 30% are difficult to detect. The poor detection limit and the nature of the diffraction band from amorphous phases make internal standard or spiking methods the best approach for analyzing samples containing amorphous materials. The Rietveld method of quantitative analysis has the potential to minimize all of the above problems. This method requires a knowledge of the crystal structures of all component crystalline phases, but no calibration data are necessary, structural and cell parameters can be varied during the refinement process, so that compositional effects can be accommodated and precise cell parameters can be obtained for every phase. Since this method fits the entire diffraction pattern and explicitly uses all reflections from every phase, complex, overlapped patterns can be easily analysed. In addition, this method presents the opportunity to correct for preferred orientation and microabsorption during data analysis.

Quantitative Analysis of Cement-Based Materials and Sulfate Attack Products by XRD-Rietveld Analysis

2013 ◽  
Vol 357-360 ◽  
pp. 1362-1369 ◽  
Author(s):  
Hua Li ◽  
Jia Ping Liu ◽  
Wei Sun
Keyword(s):  
Quantitative Analysis ◽  
Calcium Hydroxide ◽  
Rietveld Method ◽  
Internal Standard ◽  
Rietveld Analysis ◽  
Sulfate Attack ◽  
Practical Significance ◽  
Cement Pastes ◽  
Cement Based Materials ◽  
Mixed Samples

XRD-Rietveld method has been adopted for quantitative analysis of phases in cement powder, phases in mixed samples of cement and pure calcium hydroxide, and sulfate attack products in cement pastes, based on the TOPAS software. The results show that, Rietveld analysis values show good agreement with the actual levels of mixed samples, and the accuracy degree of Rietveld method is at least as well as that of TG/DSC method which is commonly used in quantitative analysis of calcium hydroxide. By adding appropriate internal standard substance, XRD-Rietveld analysis method can be effectively used in quantitative analysis of sulfate attack products in cement-based materials. This work has practical significance on the study of sulfate attack of cement-based material.

scholarly journals Quantitative Rietveld analysis of the crystalline and amorphous phases in coal fly ashes

Fuel ◽  
2013 ◽  
Vol 105 ◽  
pp. 314-317 ◽  
Author(s):  
J. Ibáñez ◽  
O. Font ◽  
N. Moreno ◽  
J.J. Elvira ◽  
S. Alvarez ◽  
...  
Keyword(s):  
Rietveld Analysis ◽  
Fly Ashes ◽  
Amorphous Phases ◽  
Coal Fly Ashes

A study to assess the performance of an “X-ray powder diffraction with Rietveld” approach for measuring the crystalline and amorphous components of inhalable dust collected on aerosol sampling filters

2019 ◽  
Vol 34 (3) ◽  
pp. 251-259 ◽  
Author(s):  
P. Stacey
Keyword(s):  
Rietveld Method ◽  
Internal Standard ◽  
Relative Difference ◽  
Wood Dust ◽  
Aerosol Sampling ◽  
Amorphous Content ◽  
Quartz Fibre ◽  
External Standard Method ◽  
External Standard ◽  
Inhalable Dust

This work was undertaken in preparation for a survey to assess the exposure of carpenters to hazardous dust working in construction. Inhalable dust, in this industry, was expected to contain both crystalline mineral and amorphous phases (wood dust). The Rietveld method was applied to provide a simultaneous multicomponent analysis. To assess its performance, mixtures of aerosolised calcite, gypsum, quartz, kaolinite, and wood dust were collected onto quartz fibre filters (n = 41) using the Button inhalable sampler. Results obtained using Rietveld were compared with loaded mass and those from external standard calibrations. The measured content of a component in 14 samples was used as an internal standard by Rietveld to determine amorphous content (wood). The performance of the Rietveld and external standard methods was similar. The 95% confidence interval for the absolute differences between the two methods was 15%. Only one relative difference of more than 15% had a mass loading >0.5 mg. An approach for assessing the limits of detection with relative intensity ratios was applied and gave comparable values with the usual method using calibration coefficients from the external standard method. Rietveld is therefore a potentially useful multicomponent method for the measurement of dust aerosol to help better understand workers' exposures.

Quantitative Rietveld analysis of hydrated cementitious systems

2006 ◽  
Vol 21 (2) ◽  
pp. 111-113 ◽  
Author(s):  
L. D. Mitchell ◽  
J. C. Margeson ◽  
P. S. Whitfield
Keyword(s):  
Internal Standard ◽  
Rietveld Analysis ◽  
Cementitious Materials ◽  
Preferential Orientation ◽  
Hydrated Cement ◽  
Amorphous Content ◽  
System A ◽  
Quantitative Results ◽  
Reflection Geometry ◽  
Cementitious Systems

A study examining the feasibility, and possible necessity, of using transmission data from capillary mounted samples for quantitative analysis of hydrated cement systems was conducted. In order to obtain true quantitative results, the amorphous contents were determined by the addition of an internal standard. The amorphous content of the starting tricalcium silicate was found to be approximately 21–22 wt %, in close agreement with previously published results. The study revealed that the spherical harmonics preferential orientation correction may not be reliable with unmicronized hydrated cement materials in reflection geometry, as chemically unreasonable progressions in Portlandite content with time were observed. The data obtained from capillary measurements, however, exhibited little or no preferential orientation, and appeared to produce the progression of phase contents expected from the reaction. The use of capillaries would appear to be justified in some circumstances to obtain reliable quantitative results from hydrated cementitious materials. In this particular system, a significant fraction of calcium carbonate was present as aragonite, as well as the more usual calcite.

scholarly journals A Multi Scale Minero-chemical Analyses of Biomass Ashes: A Key to Evaluate their Danger vs Benefit

2021 ◽  
Author(s):  
Paola Comodi ◽  
Azzurra Zucchini ◽  
Umberto Susta ◽  
Costanza Cambi ◽  
Riccardo Vivani ◽  
...  
Keyword(s):  
Raw Materials ◽  
Average Diameter ◽  
Rietveld Analysis ◽  
Pozzolanic Reaction ◽  
Fly Ashes ◽  
Amorphous Content ◽  
Italian Law ◽  
Polycyclic Aromatic ◽  
Mineralogical Study ◽  
The One

A multi-methodic analysis was performed on 5 samples of fly ashes coming from different biomasses. The aim of the study was to evaluate their possible re-use and their dangerousness for men and environment. Optical granulometric analyses indicate that the average diameter of the studied fly ashes is around 20 &micro;m, whereas only ~1 vol% has diameter lower that 2.5 &micro;m. The chemical composition, investigated with electron probe microanalysis, indicates that all the samples have a prevalent Ca composition, followed by Si and Al. A large content in K and P was observed in some samples, whereas the content in potentially toxic elements is always below the Italian law thresholds. Polycyclic aromatic hydrocarbons are completely absent in all the samples coming from combustion plants, whereas they are present in the fly ashes from the gasification center. Quantitative mineralogical content, determined by Rietveld analysis of X-ray powder diffraction data, indicates that all the samples have a large amorphous content, likely enriched in Ca, and several K and P minerals, such as sylvite and apatite. The results obtained from the performed chemo-mineralogical study allowed to point out that the biomass fly ashes could be interesting materials (1) as amending in clayey soils, in substitution to lime, to stimulating pozzolanic reaction and improve their geotechnical properties, on the one hand, avoiding to mine raw materials and, on the other hand, re-cycling wastes; (2) as agricultural fertilizes made by a new and ecological source of K and P.

Quanto: a Rietveld program for quantitative phase analysis of polycrystalline mixtures

2001 ◽  
Vol 34 (3) ◽  
pp. 392-397 ◽  
Author(s):  
Angela Altomare ◽  
Maria Cristina Burla ◽  
Carmelo Giacovazzo ◽  
Antonietta Guagliardi ◽  
Anna Grazia Giuseppina Moliterni ◽  
...  
Keyword(s):  
Rietveld Method ◽  
Internal Standard ◽  
Weight Fraction ◽  
Data Bank ◽  
Quantitative Phase Analysis ◽  
Internal Standard Method ◽  
Amorphous Content ◽  
User Friendly ◽  
Polycrystalline Mixture

Quantitative determination of phase abundance in a multicomponent polycrystalline mixture is a basic goal in materials characterization. Because of several advantages compared with traditional techniques, the Rietveld method has been increasingly applied to this task. Further progress in this direction would be to carry out the analysis automatically. The new Rietveld packageQuantois devoted to the automatic estimation of the weight fraction of each crystalline phase in a mixture. The amorphous content can be estimated by means of the internal-standard method. Corrections for preferred orientation and microabsorption effects are available. A user-friendly graphical interface facilitates interaction. A data bank including several organic and inorganic phases is supplied with the program.

scholarly journals Accuracy in Cement Hydration Investigations: Combined X-ray Microtomography and Powder Diffraction Analyses

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6953
Author(s):  
Inés R. Salcedo ◽  
Ana Cuesta ◽  
Shiva Shirani ◽  
Laura León-Reina ◽  
Miguel A. G. Aranda
Keyword(s):  
Powder Diffraction ◽  
Cement Hydration ◽  
Rietveld Method ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Capillary Porosity ◽  
X Ray ◽  
Amorphous Phases ◽  
Amorphous Content ◽  
Computed Microtomography

Cement hydration is a very complex set of processes. The evolution of the crystalline phases during hydration can be accurately followed by X-ray powder diffraction data evaluated by the Rietveld method. However, accurate measurements of some microstructural features, including porosity and amorphous content developments, are more challenging. Here, we combine laboratory X-ray powder diffraction and computed microtomography (μCT) to better understand the results of the μCT analyses. Two pastes with different water–cement ratios, 0.45 and 0.65, filled within capillaries of two sizes, ϕ = 0.5 and 1.0 mm, were analysed at 50 days of hydration. It was shown that within the spatial resolution of the measured μCTs, ~2 μm, the water capillary porosity was segmented within the hydrated component fraction. The unhydrated part could be accurately quantified within 2 vol% error. This work is a first step to accurately determining selected hydration features like the hydration degree of amorphous phases of supplementary cementitious materials within cement blends.

Rietveld quantitative amorphous content analysis

2001 ◽  
Vol 34 (2) ◽  
pp. 196-202 ◽  
Author(s):  
A. G. De La Torre ◽  
S. Bruque ◽  
M. A. G. Aranda
Keyword(s):  
Content Analysis ◽  
Statistical Analysis ◽  
Systematic Errors ◽  
Rietveld Analysis ◽  
Tricalcium Silicate ◽  
Absorption Coefficients ◽  
Amorphous Content ◽  
Orientation Effects ◽  
Main Component ◽  
Very High

A procedure for Rietveld quantitative amorphous content analysis (RQACA) is outlined, in which the effects of systematic errors in the powder patterns are studied. The method derives the amorphous content from the small overestimation of an internal crystalline standard in a Rietveld refinement of an appropriate mixture. Of several standards studied, Al2O3gave the best results. The statistical analysis of standard mixtures with a known amount of amorphous content indicated that this is a precise and accurate tool. It enables the measurement of the amorphous content with an accuracy close to 1%. Sample preparation and Rietveld analysis need to be optimized in order to minimize the systematic errors. The analysis of samples with phases displaying strong preferred orientation effects gives very high errors in the amorphous content. Samples with different absorption coefficients have also been studied in order to evaluate the importance of microabsorption. This plays an important role but it can be adequately corrected if the absorption coefficients of the standard and the sample are not very different. RQACA has been applied to tricalcium silicate, C3S, which is the main component of Portland cement. The average amorphous content of C3S, after microabsorption correction using two standards of higher and lower absorption coefficients, was found to be 19%.

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