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International
Tables for Crystallography Volume D Physical properties of crystals Edited by A. Authier © International Union of Crystallography 2006 |
International Tables for Crystallography (2006). Vol. D. ch. 3.1, p. 366
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![[Figure 3.1.5.10]](/figures/Dafig3o1o5o10.gif)
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Figure 3.1.5.10
(a) `Soft' optical phonon frequency versus temperature in LaP5O14, showing displacive character of the phase transition. Large acousto-optic interaction prevents the optical phonon frequency from reaching zero at the transition temperature, despite the second-order character of the transition. (b) Lanthanum pentaphosphate structure, showing linked `ribbons' of phosphate tetrahedra. |