RT Journal Article
T1 Studies of the fergusonite to scheelite phase transition in LnNbO4 orthoniobates
A1 Arulnesan, Shamantini William
A1 Kayser González, Paula
A1 Kimpton, Justin
A1 Kennedy, Brendan
AB Synchrotron X-ray powder diffraction methods have been used to obtain accurate structures of the lanthanoid orthoniobates, LnNbO4 at room temperature. The observed decrease in the unit cell volume in going from Ln = La to Lu correlates with a decrease in the volume of the LnO8 polyhedra due to the changing size of the Ln3+ cation. In all cases the Nb is in a highly distorted six-coordinate geometry with two long, ~2.5 Å, and four short ~1.9 Å Nb–O distances. The importance of the long Nb–O bonds is evident from Bond Valence Sum Calculations. Variable temperature structural studies of three examples, Ln = La, Sm and Gd, showed each transformed to a high temperature tetragonal scheelite type structure in space group I41/a. In the high temperature structure the Nb are tetrahedrally coordinated and it appears that monoclinic – tetragonal transition is best described as a reconstructive transition in which the long Nb–O(1) bond is broken upon heating
PB Elsevier
SN 0022-4596
YR 2019
FD 2019
LK https://hdl.handle.net/20.500.14352/100914
UL https://hdl.handle.net/20.500.14352/100914
LA eng
NO Arulnesan, S. W., Kayser, P., Kimpton, J. A., & Kennedy, B. J. (2019). Studies of the fergusonite to scheelite phase transition in LnNbO4 orthoniobates. Journal of Solid State Chemistry, 277, 229-239.
NO This work was, in part, performed at the powder diffraction beamline at the Australian Synchrotron. BJK acknowledges the support of the Australian Research Council.
NO Australian Research Council
DS Docta Complutense
RD 17 abr 2025