Structural phase transitions in insulating and metallic La2CuO4

Structural phase transitions

Structural phase transitions can be studied by a variety of techniques; macroscopic fields, X-ray, light and neutron diffraction, and resonance methods. The information which can be obtained by these different techniques about the order parameter and susceptibility at structural phase transitions is described and compared. Landau theory coupled with the 'sot~ mode' concept provides a simple pic...

Caged clusters in Al11Ir4: Structural transition and insulating phase

Using pair potentials fitted to an ab initio database, combined with replica-exchange simulated annealing, we show that the complex, quasicrystal-related Al11Ir4 compound contains a nonstandard version of the “pseudo-Mackay” icosahedral cluster, with nonicosahedral inner Al10Ir and/or Al9Ir clusters that exist in various orientations and account for partial occupancies in the reported structure...

Structural phase transformations in metallic grain boundaries.

Structural transformations at interfaces are of profound fundamental interest as complex examples of phase transitions in low-dimensional systems. Despite decades of extensive research, no compelling evidence exists for structural transformations in high-angle grain boundaries in elemental systems. Here we show that the critical impediment to observations of such phase transformations in atomis...

Structural Distortions in the Paramagnetic Insulating ” Phase of La 0

We report x-ray scattering studies of polarons and tilt ordering in the hightemperature, paramagnetic insulating phase of LM.7C%.3MnOq. The temperature dependence of scattering due to individual and correlated polarons was measured, and the latter was found to disappear at -400 K. The scattering due to tilt ordering, which was observed by tuning the incident photon energy near the La L1 edge, w...

Structural Phase Transitions in Ag2Se (Naumannite)