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dc.contributor.authorMullens, Bryce
dc.contributor.authorSaura-Múzquiz, Matilde
dc.contributor.authorMarlton, Frederick
dc.contributor.authorAvdeev, Maxim
dc.contributor.authorBrand, Helen E. A.
dc.contributor.authorMondal, S.
dc.contributor.authorVaitheeswaran, G.
dc.contributor.authorKennedy, Brendan James
dc.date.accessioned2023-12-11T07:02:10Z
dc.date.available2023-12-11T07:02:10Z
dc.date.issued2023en_AU
dc.identifier.urihttps://hdl.handle.net/2123/31975
dc.description.abstractSynchrotron X-ray powder diffraction methods have been used to obtain accurate structures of the lanthanoid tantalates, LnTaO4, at room temperature. Three different structures are observed, depending on the size of the Ln cation: P21/c (Ln = La, Pr), I2/a (Ln = Nd-Ho), and P2/c (Ln = Tb-Lu). BVS analysis indicated that TaV is six-coordinate in these structures, with four short bonds and two longer bonds. Synchrotron X-ray powder diffraction methods were also used to observe the impact of Ta doping on the orthoniobates, Ln(Nb1-xTax)O4 (Ln = Pr, Nd, Sm, Gd, Tb, Dy, Ho, Yb and Lu). Where both the niobate and tantalate oxide were isostructural (fergusonite structure, space group I2/a), complete solid solutions were prepared. In these solid solutions, the unit cell volume decreases as the Ta content increases. The subtle interaction evident between the LnO8 and BO6 sublattices in the fergusonite-type oxides was not observed in the related pyrochlore oxides. A combined synchrotron X-ray and neutron powder diffraction study of the series Ho(Nb1-xTax)O4 was used to determine accurate atomic positions of the anions, and hence, bond lengths. This revealed a change in the (Nb/Ta)-O bond lengths, reflective of the difference in the valence orbitals of Nb(4d) and Ta(5d). Examination of the partial density of states demonstrates differences in the electronics between Nb and Ta, leading to a difference in the bandgap. This study highlights the importance of the long B-O contacts in the fergusonite structures, and its potential impact on the I2/a to I41/a phase transition.en_AU
dc.language.isoenen_AU
dc.publisherElsevieren_AU
dc.relation.ispartofJournal of Alloys and Compoundsen_AU
dc.subjectScheeliteen_AU
dc.subjectLanthanoid tantalatesen_AU
dc.subjectCrystal structureen_AU
dc.subjectSynchrotron X-ray diffractionen_AU
dc.subjectRietvelden_AU
dc.titleBeyond the Ionic Radii: A Multifaceted Approach to Understand Differences between the Structures of LnNbO4 and LnTaO4 Fergusonitesen_AU
dc.typeArticleen_AU
dc.identifier.doi10.1016/j.jallcom.2022.167399
dc.type.pubtypeAuthor accepted manuscripten_AU
usyd.facultySeS faculties schools::Faculty of Science::School of Chemistryen_AU
usyd.citation.volume930en_AU
usyd.citation.spage167399en_AU
workflow.metadata.onlyNoen_AU


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