Fundamental aspects of structural phase transitions are discussed in view of XAFS measurements of the local structure below and above Tc. The experimental results show that the local structure and the order parameter have very different temperature dependencies. In particular, while the order parameter is zero above Tc the local structure remains distorted hundreds of degrees above the transition. This means that the local crystal distortions are disordered above Tc and partially disordered below it. This behavior has been observed in pure and mixed crystals and in ferroelectric as well as antiferrodistortive type crystals suggesting that it may be quite general.
|Number of pages||4|
|Journal||Physica B: Condensed Matter|
|State||Published - 1 Mar 1995|
Bibliographical noteFunding Information:
This work was supported in part by DOE Grant No. DE-FG06-90ER45425 and BSF Grant No. 92-00348. Beamline X11-A is supported by DOE Grant No. DE-FG05-89ER45384.