Evidence of two different crystalline phases of isotactic trans-1,4-poly(1,3-pentadiene). An application of the Rietveld method

1986 ◽  
Vol 19 (1) ◽  
pp. 235-239 ◽  
Author(s):  
Sergio Brueckner ◽  
Giuseppe Di Silvestro ◽  
William Porzio
Keyword(s):  
Rietveld Method ◽  
Crystalline Phases

scholarly journals CRYSTALLINE PHASE REACTIVITY IN THE SYNTHESIS OF FLY ASH-BASED GEOPOLYMER

2011 ◽  
Vol 11 (1) ◽  
pp. 90-95 ◽  
Author(s):  
Lukman Atmaja ◽  
Hamzah Fansuri ◽  
Anggaria Maharani
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Power Plant ◽  
Ambient Temperature ◽  
Alkaline Solution ◽  
Crystalline Phase ◽  
Rietveld Method ◽  
Initial Reaction ◽  
Crystalline Phases ◽  
Significant Change

Aluminosilicate, alkaline solution and fly ash from a power plant have been used to synthesize geopolymer at ambient temperature. SiO2/Al2O3 mole ratio of the starting materials was varied by the addition of pure, insoluble corundum and quartz. The geopolymer exhibited some differences in the ratio of initial reaction mixtures and that of final products. The corundum gave no influence to the compressive strength while the quartz at SiO2/Al2O3=4.0-6.0 produced significant change in the strength. The highest compressive strength achieved was 65 MPa. XRD using analysis Rietveld method proved that quartz has been found both in starting materials as well as in the geopolymer indicating the involvement of crystalline phases, to some extent, in geopolymerization process.

Quantification of phases with partial or no known crystal structures

2006 ◽  
Vol 21 (4) ◽  
pp. 278-284 ◽  
Author(s):  
Nicola V. Y. Scarlett ◽  
Ian C. Madsen
Keyword(s):  
Crystal Structures ◽  
Rietveld Method ◽  
Amorphous Material ◽  
Internal Standard ◽  
Crystalline Phases

Quantification of mixtures via the Rietveld method is generally restricted to crystalline phases for which structures are well known. Phases that have not been identified or fully characterized may be easily quantified as a group, along with any amorphous material in the sample, by the addition of an internal standard to the mixture. However, quantification of individual phases that have only partial or unknown structures is carried out less routinely. This paper presents methodology for quantification of such phases. It outlines the procedure for calibration of the method and gives detailed examples from both synthetic and mineralogical systems. While the method should, in principle, be generally applicable, its implementation in the TOPAS program from Bruker AXS is demonstrated here.

Determination of the crystallized fractions of a largely amorphous multiphase material by the Rietveld method

2001 ◽  
Vol 34 (2) ◽  
pp. 114-118 ◽  
Author(s):  
X. Orlhac ◽  
C. Fillet ◽  
P. Deniard ◽  
A. M. Dulac ◽  
R. Brec
Keyword(s):  
Rietveld Method ◽  
Amorphous Material ◽  
Effective Means ◽  
Site Occupancy ◽  
Internal Standard ◽  
Ceramic Materials ◽  
Contrast Effects ◽  
Crystalline Phases ◽  
Cell Parameters ◽  
High Level

The Rietveld method has proved to be a very effective means to characterize and quantify the crystalline phases and the amorphous phase in glass ceramic materials using X-ray powder diffraction data. The technique was applied to a borosilicate glass of the type used for high-level nuclear-waste containment, in order to measure the proportions of the crystallized phases after heat treatment and, thus, to qualify the thermal stability of the glass. Six crystalline phases were analysed in this way in an almost entirely (>95 wt%) amorphous material after adding a known proportion of an internal standard (TiO2). The quantitative analyses were corrected to allow for microabsorption effects resulting from grain-size and absorption-contrast effects. In addition to the quantitative data, unit-cell parameters and site-occupancy refinements revealed solid-solution and substitution phenomena in the crystal.

scholarly journals QUANTIFICAÇÃO DE MULLITA PROVENIENTE DE RESÍDUOS DE CAULIM DA REGIÃO AMAZÔNICA: USO DO MÉTODO DE RIETVELD

Química Nova ◽  
2020 ◽  
Author(s):  
Marlice Martelli ◽  
Eric Mochiutti ◽  
João Lima ◽  
Roberto Neves
Keyword(s):  
Rietveld Method ◽  
Internal Standard ◽  
Amazon Region ◽  
Synthesis Process ◽  
X Ray Diffraction ◽  
Crystalline Phases ◽  
X Ray ◽  
Mineral Phases ◽  
Precursor Material ◽  
Quantitative Analyses

QUANTIFICATION OF MULLITE FROM KAOLIN WASTES FROM THE AMAZON REGION: USE OF THE RIETVELD METHOD. Mullite is used to obtain a refractory material, there are several factors that influence the synthesis process of mullite: the preparation of the mixture, the precipitation and the reaction of SiO2 and Al2O3. For the synthesis of mullite, samples of kaolin processing residues were used as precursor material, because it presents SiO2 and Al2O3 in its composition. This work aimed to identify, by X-ray diffraction, and quantify the mineral phases present in samples of kaolin processing residues from the Amazon region calcined at 1300, 1400 and 1500 ºC, using the Rietveld method. The method allowed the refinement of the complex crystalline structures and was applied to the data supply for quantitative analyses with satisfactory results of good accuracy. The results of the quantification of crystalline and non-crystalline phases (with internal standard) in the samples calcined at 1500 ºC presented approximate values of mullite (62%), cristobalite (32%) and non-crystalline phases (6%), for both samples, indicating that the refinement model applied is optimal. These results obtained from the quantification of the phases by the method of Rietveld are presenting coherent and satisfactory values, in comparison with the theoretical ones by the phase diagram Al2O3 and SiO2

Quantitative Determination of the Crystalline Phases of the Ceramic Materials Utilizing the Rietveld Method

2010 ◽  
Vol 660-661 ◽  
pp. 164-169 ◽  
Author(s):  
C.T. Kniess ◽  
P.B. Prates ◽  
J.C. de Lima ◽  
N.C. Kuhnen ◽  
Humberto Gracher Riella ◽  
...  
Keyword(s):  
Quantitative Determination ◽  
Rietveld Method ◽  
Bottom Ash ◽  
Ceramic Materials ◽  
X Ray Diffraction ◽  
Crystalline Phases ◽  
Coal Bottom Ash ◽  
Lattice Design ◽  
Simplex Lattice

Ceramic materials have properties defined by their chemical and micro-structural composition. The quantification of the crystalline phases is a fundamental stage in the determination of the structure, properties and applications of a ceramic material. Within this context, this study aims is the quantitative determination of the crystalline phases of the ceramic materials developed with addition of mineral coal bottom ash, utilizing the X ray diffraction technique, through the method proposed by Rietveld. For the formulation of the ceramic mixtures a {3,3} simplex-lattice design was used, giving ten formulations of three components (two different types of clays and coal bottom ash). The crystalline phases identified in the ceramic materials after sintering at 1150oC during two hours are: quartz, tridimite, mullite and hematite. The proposed methodology utilizing the Rietveld method for the quantification relating to crystalline phases of the materials was shown to be adequate and efficient.

Sign in / Sign up

Export Citation Format

Share Document