scholarly journals Lithium diffusion pathways in metastable ramsdellite-like Li2Ti3O7 from high-temperature neutron diffraction

2016 ◽  
Vol 293 ◽  
pp. 37-43 ◽  
Author(s):  
Dennis Wiedemann ◽  
Suliman Nakhal ◽  
Alexandra Franz ◽  
Martin Lerch
Keyword(s):  
High Temperature ◽  
Neutron Diffraction ◽  
Lithium Diffusion

The role of π-bonding on the high temperature structure of the double perovskites Ba2CaUO6and BaSrCaUO6

2015 ◽  
Vol 44 (36) ◽  
pp. 16036-16044 ◽  
Author(s):  
Emily Reynolds ◽  
Gordon J. Thorogood ◽  
Maxim Avdeev ◽  
Helen E. A. Brand ◽  
Qinfen Gu ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Neutron Diffraction ◽  
Temperature Structure ◽  
Double Perovskites ◽  
Phase Transition Behavior ◽  
X Ray ◽  
Progressive Loss ◽  
Octahedral Tilting

High temperature synchrotron X-ray and neutron diffraction powder diffraction studies of the uranium perovskites Ba2CaUO6and BaSrCaUO6reveal unusual phase transition behavior associated with the progressive loss of cooperative octahedral tilting.

scholarly journals The inverse perovskite BaLiF3: single-crystal neutron diffraction and analyses of potential ion pathways

2018 ◽  
Vol 74 (6) ◽  
pp. 643-650 ◽  
Author(s):  
Dennis Wiedemann ◽  
Falk Meutzner ◽  
Oscar Fabelo ◽  
Steffen Ganschow
Keyword(s):  
High Temperature ◽  
Neutron Diffraction ◽  
Scattering Length ◽  
Temperature Structure ◽  
Luminescent Materials ◽  
Lithium Ions ◽  
Ion Migration ◽  
Mobile Species ◽  
Tolerance Factors ◽  
Migration Pathways

Doped barium lithium trifluoride has attracted attention as component for scintillators, luminescent materials and electrodes. With lithium and fluoride, it contains two possibly mobile species, which may account for its ionic conductivity. In this study, neutron diffraction on oxide-containing BaLiF3 single-crystals is performed at up to 636.2°C. Unfortunately, ion-migration pathways could not be mapped by modelling anharmonic ion displacement or by inspecting the scattering-length density that was reconstructed via maximum-entropy methods. However, analyses of the topology and bond-valence site energies derived from the high-temperature structure reveal that the anions can migrate roughly along the edges of the LiF6 coordination octahedra with an estimated migration barrier of ∼0.64 eV (if a vacancy permits), whereas the lithium ions are confined to their crystallographic positions. This finding is not only valid for the title compound but for ion migration in all perovskites with Goldschmidt tolerance factors near unity.

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