Recent advances in magnetic structure determination by neutron powder diffraction

Rodrı́guez-Carvajal, J.

doi:10.1016/0921-4526(93)90108-i

Cited by 13,866 publications

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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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“…24,25 Examples of the X-ray patterns obtained at room temperature have been provided in Figure 3. The lattice parameters as a function of temperature were used to determine the specific volumes from 100 K up to the melting temperature of each polymorph, which have been plotted in Figure 4.…”

Section: Resultsmentioning

confidence: 99%

“…Peak positions were determined using pseudo-Voigt fitting and lattice parameters were refined using the least-squares option of the FullProf suite package. 24,25 The samples were introduced in Lindemann capillaries with 0.5-mm diameter, which rotated perpendicularly to the X-ray beam during the experiments to improve the averaging over the crystallite orientations. Before data acquisition, each sample was allowed to equilibrate at the temperature of measurement for not less than 10 min, and each acquisition time was at least one hour.…”

Section: Methodsmentioning

confidence: 99%

The Pressure-Temperature Phase Diagram of Metacetamol and Its Comparison to the Phase Diagram of Paracetamol

Huguet

Rietveld

Robert

et al. 2017

Journal of Pharmaceutical Sciences

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Understanding the polymorphic behavior of active pharmaceutical ingredients is important for formulation purposes and for regulatory reasons. Metacetamol is an isomer of paracetamol and it similarly exhibits polymorphism. In the present paper, it has been found that one of the polymorphs of metacetamol is only stable under increased pressure, which has led to the conclusion that metacetamol like paracetamol is a monotropic system under ordinary (= laboratory) conditions and that it becomes enantiotropic under pressure with the I-II-L triple point coordinates for metacetamol T I-II-L = 535±10 K and P I-II-L = 692±70 MPa. However, whereas for paracetamol the enantiotropy under pressure can be foreseen, because the metastable polymorph is denser, in the case of metacetamol this is not possible, as the metastable polymorph is less dense than the stable one. The existence of the stability domain for the less dense polymorph of metacetamol, can only be demonstrated by the construction of the topological phase diagram as presented in this paper. It is a delicate interplay between the specific volume differences and the enthalpy differences causing the stability domain of the less dense polymorph to be sandwiched between the denser polymorph and the liquid. It is a characteristic that metacetamol shares with bicalutamide and fluoxetine nitrate.

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“…The phase identification was carried out using the X'Rayan computer program and X-ray standard patterns in the form of ICDD files (card 19-0701, 19-0683 and 43-1461). The unit-cell refinement and Rietveld structure refinement were made using the FullProf Suite computer program package (Rodriguez-Carvajal 1993).The Rietveld refinement has shown systematic changes in unit cell parameters of studied samples depending on their chemical composition. Dimensions of unit cell parameters of pyromorphite-vanadinite solid solution series increase linearly with the substitution of vanadate ions in the structure of pyromorphite.…”

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The Rietveld refinement studies of pyromorphite-vanadinite and mimetite-vanadinite solid solution series [abstract].

Solecka¹,

Zelek²,

Bajda³

2016

geol

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CC-BY 4.0 License requiring that the original work has been properly cited. study was to examine how lattice parameters of pyromorphite-vanadinite and mimetite-vanadinite solid solutions series change with increasing vanadium content and characterize these pheno mena.Crystallographic studies were conducted on synthetic pyromorphite, mimetite and vanadinite and minerals with intermediate compositions Pb 5 (TO 4 ) 3 Cl, where T = P + V or As + V, of various P/V or As/V ratios. Samples were analyzed by X-Ray diffraction (XRD) using RIGAKU Smartlab X-Ray diffractometer with Cu radiation in a 10° to 110° 2Θ range at a step size of 0.02 2Θ and a rate of 2 s per step. The phase identification was carried out using the X'Rayan computer program and X-ray standard patterns in the form of ICDD files (card 19-0701, 19-0683 and 43-1461). The unit-cell refinement and Rietveld structure refinement were made using the FullProf Suite computer program package (Rodriguez-Carvajal 1993).The Rietveld refinement has shown systematic changes in unit cell parameters of studied samples depending on their chemical composition. Dimensions of unit cell parameters of pyromorphite-vanadinite solid solution series increase linearly with the substitution of vanadate ions in the structure of pyromorphite. Lattice parameter "a" increase in the range of 9.987-10.325 Å, while lattice parameter "c" increase in the range of 7.33-7.343 Å. In case of the mimetite-vanadinite solid solution series, lattice parameter "a" increase (10.251-10.325 Å range), whereas lattice

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Recent advances in magnetic structure determination by neutron powder diffraction

Cited by 13,866 publications

References 28 publications

Effect of highly dispersed yttria addition on thermal stability of hydroxyapatite

Effect of highly dispersed yttria addition on thermal stability of hydroxyapatite

The Pressure-Temperature Phase Diagram of Metacetamol and Its Comparison to the Phase Diagram of Paracetamol

The Rietveld refinement studies of pyromorphite-vanadinite and mimetite-vanadinite solid solution series [abstract].

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