Structural and electrical characterization of PLZT 22/20/80 relaxor films obtained by PLD and RF-PLD

Thin films of Pb0.67La0.22(Zr0.2Ti0.8)O3 (PLZT 22/20/80) have been grown by pulsed laser deposition (PLD) and by PLD assisted by radiofrequency (RF) discharge in oxygen. All obtained films were polycrystalline, with perovskite cubic structure, but significant differences have been found in their phase content and surface morphology, as evidenced by XRD and AFM investigations. Films grown by RF-assisted PLD are (1 0 0)-oriented and have less amorphous phase, about two times larger grains and a more compact structure. Other significant differences have been found in the measured dielectric nonlinearities from the capacitance, loss and quasi-static field methods. These nonlinearities were connected with the movements of domain walls and/or domain switching, depending on field amplitude. Films obtained by RF-PLD show lower variation of dielectric properties with ac signal amplitude. This variation is about 1.2 times lower for RF-PLD films compared to PLD films. A high value of capacitance tunability (about 10% at a bias field of 80 kV/cm and ac signal frequency 20 MHz) was obtained for both films type, though, RF-PLD-deposited films have much lower dielectric loss, 2.5% instead of 4% at 1 kHz.