Spectroscopic and computer modelling studies of mixed-cation superionic fluorites

Netshisaulu, T. T.; Chadwick, Alan V.; Ngoepe, Phuti E.; Catlow, C. Richard A.

doi:10.1088/0953-8984/17/41/026

Cited by 8 publications

(4 citation statements)

References 13 publications

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“…Simultaneously, the pseudo Debye-Waller factor associated with the Pb-F scattering is fairly high. Both facts have been previously observed [14] in pure β-PbF 2 and interpreted on the basis of F − migration from lattice to interstitial sites around Pb, with the simultaneous creation of F vacancies. These effects are thought to originate the superionic conduction observed above 695 K in pure β-PbF 2 [15,16].…”

Section: Discussionsupporting

confidence: 69%

Formation of nanostructures in Eu³⁺doped glass–ceramics: an XAS study

Pellicer‐Porres¹,

Segura²,

Martı́nez-Criado³

et al. 2012

J. Phys.: Condens. Matter

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We describe the results of x-ray absorption experiments carried out to deduce structural and chemical information in Eu(3+) doped, transparent, oxyfluoride glass and nanostructured glass-ceramic samples. The spectra were measured at the Pb and Eu-L(III) edges. The Eu environment in the glass samples is observed to be similar to that of EuF(3). Complementary x-ray diffraction experiments show that thermal annealing creates β-PbF(2) type nanocrystals. X-ray absorption indicates that Eu ions act as seeds in the nanocrystal formation. There is evidence of interstitial fluorine atoms around Eu ions as well as Eu dimers. X-ray absorption at the Pb-L(III) edge shows that after the thermal treatment most lead atoms form a PbO amorphous phase and that only 10% of the lead atoms remain available to form β-PbF(2) type nanocrystals. Both x-ray diffraction and absorption point to a high Eu content in the nanocrystals. Our study suggests new approaches to the oxyfluoride glass-ceramic synthesis in order to further improve their properties.

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Section: Discussionsupporting

confidence: 69%

Formation of nanostructures in Eu³⁺doped glass–ceramics: an XAS study

Pellicer‐Porres¹,

Segura²,

Martı́nez-Criado³

et al. 2012

J. Phys.: Condens. Matter

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“…Ionic conductivities between 10 −3 and 10 −4 S cm −1 at 400 K have been reported for the solid solution with composition 0.33 x 0.7, which are higher than those exhibit by CdF 2 (σ ∼ 10 −7 S cm −1 at 400 K) and β-PbF 2 (σ ∼ 3 × 10 −5 S cm −1 at 400 K) [1,17,6,22,21]. These superionic solid solutions have attracted considerable attention because of their potential applications in solid-state batteries [18,6,5,10]. 4 Author to whom any correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 93%

The structural inhomogeneity of lead–cadmium fluoride systems and its implications

Picinin

Silva

Rino

2009

J. Phys.: Condens. Matter

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In this paper we present a detailed study of structural and dynamical properties of the CdF(2)-PbF(2) systems. Particular attention is devoted to the processes involving the phase separation, a phenomenon of fundamental importance in the correct description of some dynamical properties, as introduced in our previous works. We show here, that the phase separation trend is observed in the undercooled melt, whether by cooling the liquid below its melting point, or by heating a homogeneous glass at temperatures above T(g). The degree of phase separation depends on the procedure employed to obtain the crystalline materials, and the simplest way to determine this property is by performing an isothermal treatment in the undercooled melt region. The local fluorine environments Q((n)), corresponding to fluorine surrounded by nPb and 4-nCd neighbors, is used as a probe in the average local composition. We demonstrate that the increase in the structural inhomogeneity around the composition with x = 0.35 is the factor which leads to a better fluorine conducting property for the Cd(0.35)Pb(0.65)F(2) solid solution, in addition to providing a correct determination of the melting temperature of the Cd(x)Pb(1-x)F(2) compositions.

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“…The initial work on energy devices focused on mixed-metal fluorites in the fast-ion phase for application in batteries. Static and molecular dynamics calculations and extended X-ray absorption fine structure spectroscopy (EXAFS) measurements were used to study how the temperature and composition of mixed-metal fluorites affect the defect and ion transport mechanisms [15,16]. Furthermore, light-scattering techniques and calculations on lanthanide-doped BaF 2 and CaF 2 provided insight into the changes in ion transport owing to various dopants [17,18].…”

Section: Energy Storagementioning

confidence: 99%

Materials modelling in the University of Limpopo

Ngoepe,

Chadwick,

Sithole

et al. 2024

Interface Focus.

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This article provides insights into building research capacity in computational modelling of materials at the University of Limpopo (UL), formerly University of the North, in South Africa, through a collaboration with a consortium of universities in the United Kingdom (UK) through the support of the National Research Foundation (NRF), formerly the Foundation for Research and Development, and the Royal Society (RS). A background that led to the choice of building research capacity at historically disadvantaged universities in South Africa, including the UL, is given. The modus operandi of the collaboration between the UL and several UK universities on computational modelling of materials is outlined, together with the scientific highlights that were achieved in themes of minerals, energy storage and alloy development. The capacity built in terms of human capital and institutions set up is shared, which is followed by a discussion of the continuing research activities after the formal NRF–RS collaboration ceased with more alignment to industrial applications with national and international support. We conclude by highlighting the success of the project in capacity-building and consolidating the Materials Modelling Centre with developments of high-performance computing in South Africa and the African continent. We comment on the lessons learned regarding successful capacity-building programmes.

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Spectroscopic and computer modelling studies of mixed-cation superionic fluorites

Cited by 8 publications

References 13 publications

Formation of nanostructures in Eu³⁺doped glass–ceramics: an XAS study

Formation of nanostructures in Eu³⁺doped glass–ceramics: an XAS study

The structural inhomogeneity of lead–cadmium fluoride systems and its implications

Materials modelling in the University of Limpopo

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Spectroscopic and computer modelling studies of mixed-cation superionic fluorites

Cited by 8 publications

References 13 publications

Formation of nanostructures in Eu3+doped glass–ceramics: an XAS study

Formation of nanostructures in Eu3+doped glass–ceramics: an XAS study

The structural inhomogeneity of lead–cadmium fluoride systems and its implications

Materials modelling in the University of Limpopo

Contact Info

Product

Resources

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Formation of nanostructures in Eu³⁺doped glass–ceramics: an XAS study

Formation of nanostructures in Eu³⁺doped glass–ceramics: an XAS study