Phys. Rev. Lett. 96, 147602 (2006) [4 pages]Frustration of Tilts and A-Site Driven Ferroelectricity in KNbO3-LiNbO3 AlloysReceived 8 February 2006; revised 7 March 2006; published 12 April 2006 Density functional calculations for K0.5Li0.5NbO3 show strong A-site driven ferroelectricity, even though the average tolerance factor is significantly smaller than unity and there is no stereochemically active A-site ion. This is due to the frustration of tilt instabilities by A-site disorder. There are very large off centerings of the Li ions, which contribute strongly to the anisotropy between the tetragonal and rhombohedral ferroelectric states, yielding a tetragonal ground state even without strain coupling. © 2006 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevLett.96.147602
DOI:
10.1103/PhysRevLett.96.147602
PACS:
77.84.Dy, 71.15.Nc, 77.80.−e
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