Phase transitions in strained ferroelectric KxNa1-xNbO3 thin films

Here, we propose to study the dynamics of ferroelectric phase transitions in KxNa1-xNbO3 (KNNO) thin films. Our experiment aims at determining the mechanism triggering the transition from the low-temperature monoclinic to the high-temperature orthorhombic phase in KNNO. Note that both phases show a ferroelectric polarization vector with different strength and orientation. We will use a pulsed nanosecond laser synchronized to the storage ring to heat the sample and successively probe the crystalline phase by time-resolved X-ray diffraction. In the proposed experiment we will determine the dynamics of the thermally induced phase transition depending at different laser fluences (i.e., maximally induced temperature) and different starting temperatures.