Incommensurate-Commensurate Phase Transition of BaZnGeO4Studied by Electron Microscopy and Diffraction

Abstract

BaZnGeO 4 undergoes several successive phase transitions from I to V phase. The modulated structure in the incommensurate phases (III and IV) and the commensurate-incommensurate phase transition between the IV and V phases were studied by electron microscopy. The direction of the modulation wave vector slightly deviates from the c * direction, and the tilt angle changes with temperature. The modulated structure does not change into the discommensuration (DC) arrays around the III ′ phase, but the DC's appear in the IV phase near the C-IC phase transition temperature. The electron microscope images clearly revealed that the stripples and antistripples composed of the three DC's were formed and moved in the DC lattice during the C-IC phase transition.