A profile refinement method for nuclear and magnetic structures

Rietveld, H. M.

doi:10.1107/s0021889869006558

Cited by 16,287 publications

(8,427 citation statements)

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“…The diffraction patterns were recorded through the range of 2θ angles between 10° and 100° in steps of 0.01°. The phases present in the sintered samples were identified from the quantitative analyses of the XRD patterns using the Rietveld method, the FULLPROF software, and the crystallographic data from the reference JCPDS files [32,33]. Lattice parameters of hexagonal structure were calculated using the reflections of the most intense peaks from HA and HA10Y XRD patterns.…”

Section: Methodsmentioning

confidence: 99%

Effect of highly dispersed yttria addition on thermal stability of hydroxyapatite

Parente

Savoini

Ferrari

et al. 2013

Materials Science and Engineering: C

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Abstract:The capability of the colloidal method to produce yttria (Y 2 O 3 ) dispersed hydroxyapatite (HA) has been in vestigated as an alternative method to the conventional method of mechanical mixing and sintering for de veloping HA based materials that could exhibit controllable and enhanced functional properties. A water based colloidal route to produce HA materials with highly dispersed Y 2 O 3 has been applied, and the effect of 10 wt.% Y 2 O 3 addition to HA investigated by thermal analysis, X ray diffraction and Fourier transform in frared spectroscopy. These measurements evidence a remarkable effect of this Y 2 O 3 addition on decomposi tion mechanisms of synthetic HA. Results show that incorporation of Y 2 O 3 as dispersed second phase is beneficial because it hinders the decomposition mechanisms of HA into calcium phosphates. This retardation will allow the control of the sintering conditions for developing HA implants with improved properties. Be sides, substitution of Ca 2+ with Y 3+ ions appears to promote the formation of OH − vacancies, which could improve the conductive properties of HA favorable to osseointegration.

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Section: Methodsmentioning

confidence: 99%

Effect of highly dispersed yttria addition on thermal stability of hydroxyapatite

Parente

Savoini

Ferrari

et al. 2013

Materials Science and Engineering: C

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“…The minerals were identified by reference to the ICDD Powder Diffraction File. Quantitative analysis of mineral abundance was carried out using the Siroquant™ processing software (Taylor, 1991), based on the principles developed by Rietveld (1969), using procedures discussed further by Ward et al (1999).…”

Section: Analytical Proceduresmentioning

confidence: 99%

Chemical composition and minerals in pyrite ash of an abandoned sulphuric acid production plant

Oliveira

Ward

Izquierdo

et al. 2012

Science of The Total Environment

162

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The extraction of sulphur produces a hematite-rich waste, known as roasted pyrite ash, which contains significant amounts of environmentally sensitive elements in variable concentrations and modes of occurrence. Whilst the mineralogy of roasted pyrite ash associated with iron or copper mining has been studied, as this is the main source of sulphur worldwide, the mineralogy, and more importantly, the characterization of nanoparticles, in coal-derived roasted pyrite ash remain to be resolved. In this work we provide essential data on the chemical composition and nanomineralogical assemblage of roasted pyrite ash. XRD, HR-TEM and FE-SEM were used to identify a large variety of minerals of anthropogenic origin. These phases result from highly complex chemical reactions occurring during the processing of coal pyrite of southern Brazil for sulphur extraction and further manufacture of sulphuric acid. Iron-rich nanoparticles within the ash may contain high proportions of toxic elements such as As, 2 Se, U, among others. A number of elements, such as As, Cr, Cu, Co, La, Mn, Ni, Pb, Sb, Se, Sr, Ti, Zn, and Zr, were found to be present in individual nanoparticles and nanominerals (e.g. oxides, sulphates, clays) in concentrations up to 5%. The study of nanominerals in roasted pyrite ash from coal rejects is important to develop an understanding on the nature of this by-product, and to assess the interaction between emitted nanominerals, ultra-fine particles, and atmospheric gases, rain or body fluids, and thus to evaluate the environmental and health impacts of pyrite ash materials.

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“…Data were collected in steps of 0.028-2-Theta with total data collection times of 24 h to collect 8 diffractograms from 38 to 538 2-Theta which were then averaged. The diffractograms were evaluated with the Rietveld profile fitting method [36]. The diffraction intensities were calculated on the basis of the crystal structure data of monoclinic hydroxyapatite [37] and the silicon standard.…”

Section: Mineral Analyses: X-ray Diffractionmentioning

confidence: 99%