Dynamics of crystallization and phase transition in La0.5Sr0.5CoO3 thin films

Dynamics of crystallization and phase transitions were investigated in La0.5Sr0.5CoO3 films with four-probe resistance electrical measurements and x-ray diffraction. Nucleation of crystalline phases from the amorphous phase of La0.5Sr0.5CoO3 was found to start at a temperature of 325 degreesC. It is very interesting to note that the crystallization completes within a very narrow temperature range of 390-420 degreesC, and recrystallization occurs at 560 degreesC. In addition, electron-phonon, electron-grain boundary, and electron-defect interactions, as well as oxygen contents were found to be important factors in various temperature regions during the resistance measurement. The metallic phase La0.5Sr0.5CoO3 films can only be obtained if the films were directly heated to higher than 750 degreesC. The sequence and knowledge of phase transitions observed for La0.5Sr0.5CoO3 are expected to be ubiquitous for perovskite oxide compounds in general. (C) 2002 American Institute of Physics.