Abstract
The lattice-dynamical characteristic of the 110°K transition in SrTi has been elucidated by inelastic neutron scattering measurements. The transition is caused by a soft-phonon mode at the [111] zone boundary, confirming the model recently proposed by Fleury, Scott, and Worlock. The square of the frequency of this soft mode is proportional to above the transition temperature . At the transition, this zone boundary becomes a superlattice point, enlarging the unit cell. The results of elastic intensity measurements at the superlattice points at 78°K are consistent with the structure given by Unoki and Sakudo in its space group as well as in the oxygen parameter. This structure is shown to be a logical consequence of the condensed soft mode.
- Received 15 August 1968
DOI:https://doi.org/10.1103/PhysRev.177.858
©1969 American Physical Society