Dielectric properties enhancement in epitaxial BCZT thin films with nanoscale strain domains

Full text: Lead-free (Ba_1−xCa_x)(Zr_yTi₁₋y)O₃ (BCZT) bulk materials exibit similar piezoelectric and ferroelectric properties with lead-based materials such as Pb(Zr_xTi_1-x)O₃ (PZT). These superior properties are due to the existence of a triple point of morphotropic phase boundary (MPB) were the enhancement of electrical or mechanical responses appears. We report on the electrical and structural properties of epitaxial strained thin films of BCTZ with composition around MPB. The BCTZ thin films were deposited using pulsed laser deposition method (PLD) on SrTiO3, LaAlO3 and GdScO3 substrates. The thin films structural features and induced microstrain due to the lattice misfit between the pseudocubic lattice parameter of BCTZ and the used substrates were studied by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). The dielectric properties (relative permittivity of about 2200 and tangent loss ~ 1-1.5% at frequency of 10 KHz) have been obtained by dielectric spectroscopy. The local piezoelectric properties (d33~280 pm/V), polarization dynamics and switching characteristics of the samples were investigated by piezoresponse force microscopy technique (PFM). (author)