Piezoelectric and ferroelectric materials are used in numerous applications, such as actuators, sensors, ultrasonic transducers and energy storage devices, where conversion between mechanical and electrical signals is needed. Over the last few decades, materials based on $\rm{Pb(Zr,Ti)O_3}$ dominate the market of piezoelectric devices. That material has excellent functional properties, but it is harmful to the environment and humans due to its high content of lead. The development of new piezoelectric materials is therefore oriented towards environmental-friendly lead-free materials, such as $\rm{(K,Na)NbO_3}$-based ones.
The aim of this work was to study the local piezoelectric and ferroelectric properties of the polycrystalline $\rm({K_{0.5}Na_{0.5})_{0.99}Sr_{0.01}NbO_3}$ thin films. I have done all the experiments by atomic force microscope. At first, I determined the sample topography, surface roughness and local piezoelectric response in vertical direction. The surface roughness was 3 nm (scanned on the area of 2 μm x 2 μm). The average value of the local piezoelectric response d$_{33}$ was 42 pm/V. Further, I measured the local hysteresis loop of phase shift in dependence of electric field whom I reoriented polarization. With reorienting polarization in particular point, I proved that the sample is local ferroelectric.
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