Isothermal relaxation due to random local phase transformation in pbzr0.993ti0.007o3 single crystal

In a PbZr0.993Ti0.007O3 single crystals of the perovskite structure an isothermal structural transformation has been found. One of phase transitions appearing in this compound between the paraelectric, ferroelectric and antiferroelectric states disclosed a time dependent character. Only on cooling there is a temperature range in the intermediate ferroelectric phase inside which spontaneous transformation from the ferroelectric (R3m) to antiferroelectric (Pbam) state takes place in time at constant temperature. By means of three different experimental methods (dielectric, X-ray and optical) it was established that the transformation was completed after about 30 minutes. X-ray diffraction proved that this transition was of structural type and optical observation excluded this phenomenon to be related with a domain structure rearrangement. Nature of phase transitions in the investigated crystal is discussed from the point of view of martensitic transformation.