Liquid Alumina: Detailed Atomic Coordination Determined from Neutron Diffraction Data Using Empirical Potential Structure Refinement

Landron, C.; Hennet, Louis; Jenkins, Tim; Greaves, G.N.; Coutures, Jean-Pierre; Soper, A. K.

doi:10.1103/physrevlett.86.4839

Cited by 163 publications

(140 citation statements)

References 26 publications

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“…These pyramids also appear in liquid Al 2 O 3 [31], while all known bulk crystalline phases of alumina contain only four-and sixfold coordinated Al atoms.…”

Section: Discussionmentioning

confidence: 99%

Structural and electronic properties of Σ7 grain boundaries in α-Al2O3

et al. 2015

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“…These pyramids also appear in liquid Al 2 O 3 [31], while all known bulk crystalline phases of alumina contain only four-and sixfold coordinated Al atoms.…”

Section: Discussionmentioning

confidence: 99%

Structural and electronic properties of Σ7 grain boundaries in α-Al2O3

et al. 2015

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“…In order to study the liquid state, we used the aerodynamic levitation technique combined with CO2 laser heating. This technique was pioneered about 15 years ago by Neville Greaves with teams from the University of Aberystwyth (UK) and the CNRS-CEMHTI in Orléans (France) [9,10].…”

Section: Introductionmentioning

confidence: 99%

Neutron diffraction of calcium aluminosilicate glasses and melts

Hennet

Drewitt

Neuville

et al. 2016

Journal of Non-Crystalline Solids

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. AbstractThe combination of neutron diffraction with aerodynamic levitation and laser heating, pioneered by Neville Greaves and co-workers about 15 years ago, is an important tool for studying the structure of liquid melts. Since the first work on liquid Al2O3 published in 2001, the technique has been largely improved and experiments are now routinely performed at neutron sources, providing interesting structural information on various materials.In this paper, the structure of glass-forming compounds in the system CaO-Al2O3-SiO2 was measured by applying neutron diffraction with aerodynamic levitation. Results obtained in the liquid state above the melting point and from the glass at room temperatures are presented. Various compositions were studied by increasing the silica content and by changing the ratio CaO/Al2O3. As observed using other methods, the main structural changes relate to modification of the Al-O short range order.

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“…The effect is typically larger for lower field strength cations, and Ti 4+ has a similar field strength to Al 3+ , for which there is a large drop in average coordination number, from 6.0 to 4.4 in molten alumina [27][28][29], upon melting the stable Corundum form. In the case of Al 2 O 3 , several other crystalline polymorphs exist, within which Al exists in both tetrahedral and octahedral coordination to oxygen [30].…”

Section: Introductionmentioning

confidence: 99%

Structure of molten titanium dioxide

et al. 2014

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The x-ray structure factor of molten TiO 2 has been measured for the first time, enabled by the use of aerodynamic levitation and laser beam heating, to a temperature of T = 2250(30) K. Ti-O coordination number in the melt is close to n TiO = 5.0(2), with modal Ti-O bond length r TiO = 1.881(5) Å, both values being significantly smaller than for the high temperature stable Rutile crystal structure (n TiO = 6.0, r TiO = 1.959 Å). The structural differences between melt and crystal are qualitatively similar to those for alumina, which is rationalized in terms of the similar field strengths of Ti 4+ and Al 3+. The diffraction data are used to generate physically and chemically reasonable structural models, which are then compared to the predictions based on various classical molecular dynamics (MD) potentials. New interatomic potentials, suitable for modelling molten TiO 2 , are introduced, given the inability of existing MD models to reproduce the diffraction data. These new potentials have the additional great advantage of being able to predict the density and thermal expansion of the melt, as well as solid amorphous TiO 2 , in agreement with published results. This is of critical importance given the strong correlation between density and structural parameters such as n TiO . The large thermal expansion of the melt is associated with weakly temperature dependent structural changes, whereby simulations show that n TiO = 5.85(2) -(3.0(1) x 10 -4 )T (K, 2.75 Å cut-off). The TiO 2 liquid is structurally analogous to the geophysically relevant high pressure liquid silica system at around 27 GPa. We argue that the predominance of 5-fold polyhedra in the melt implies the existence of as yet undiscovered TiO 2 polymorphs, based on lowerthan-octahedral coordination numbers, which are likely to be metastable under ambient conditions. Given the industrial importance of titanium oxides, experimental and computational searches for such polymorphs are well warranted.

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Liquid Alumina: Detailed Atomic Coordination Determined from Neutron Diffraction Data Using Empirical Potential Structure Refinement

Cited by 163 publications

References 26 publications

Structural and electronic properties of Σ7 grain boundaries in α-Al2O3

Structural and electronic properties of Σ7 grain boundaries in α-Al2O3

Neutron diffraction of calcium aluminosilicate glasses and melts

Structure of molten titanium dioxide

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