Crystal structure of Ln(1/3)NbO(3) (Ln = Nd, Pr) and phase transition in Nd1/3NbO3
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Date
2007-06
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Elsevier
Abstract
The crystal structure of the A-site deficient perovskite Ln1/3NbO3 (Ln=Nd, Pr) at room temperature has been determined, for the first time, as orthorhombic in space group Cmmm using high-resolution neutron powder diffraction. Pertinent features are the alternation of unoccupied layers of A-sites and layers partly occupied by Ln cations, as well as out-of-phase tilting of the NbO6 octahedra around an axis perpendicular to the direction of the cation/vacancy ordering. The phase transition behaviour of Nd1/3NbO3 has also been studied in situ. This compound undergoes a continuous phase transition at around 650°C to a tetragonal structure in space group P4/mmm due to the disappearance of the octahedral tilting. The analysis of spontaneous strains shows that this phase transition is tricritical in nature. © 2007, Elsevier Ltd.
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Keywords
Crystal structure, Perovskites, Phase transformations, Neutron diffraction, Cations, Temperature dependence
Citation
Zhang, Z., Howard, C. J., Kennedy, B. J., Knight, K. S., & Zhou, Q. D. (2007). Crystal structure of Ln(1/3)NbO(3) (Ln = Nd, Pr) and phase transition in Nd1/3NbO3. Journal of Solid State Chemistry, 180(6), 1846-1851. doi:10.1016/j.jssc.2007.03.029