Features of Structural Transitions in La1.875-xSmxSr0.125CuO4

Characteristic features of both structural transitions and related fluctuations in La1.875-xSmxSr0.125CuO4 have been investigated by means of electron diffraction at a temperature range between about 20K and about 600K. It has been experimentally found that when the temperature is lowered a structural transition from an HTT phase to an LTO one takes place in 0 ≤ x≤0.2 and HIT→LTO→Pccn→LTT successive transitions occur in 0.3≤x≤0.4. In addition, a structural-fluctuation enhancement indicating the soft phonon mode was also detected in both the HTT-to-LTO and LTO-to-Pccn transitions.