@conference{
author = "Vojisavljević, Katarina and Pečnik, Tanja and Uršič, Hana and Malič, Barbara",
year = "2017",
abstract = "The interest for the lead-free materials rapidly increased after 2003, when the
legislation against the use of lead-based piezoelectric materials in electronics had
passed. Among the numerous lead-free materials, special attention was paid to some
compositions of potassium sodium niobate solid solutions, K0.5Na0.5NbO3 (KNN)
obtained by a partial replacement of A- and B- site atoms from the perovskite KNN
crystal lattice with dopants, which in the form of ceramic showed excellent
piezoelectric and ferroelectric properties. Driven by the miniaturization and
integration into sensors and energy harvesters, great efforts have been also made in
processing of high quality KNN thin films.
In this contribution, the effects of the A-site doping of KNN films with Sr
(KNN-xSr) on the microstructure and electrical properties were investigated for the
first time. For that purpose, liquid precursors of (K0.5Na0.5)1-xSrxNbO3 (KNN-xSr, x
= 0, 0.005, 0.01) thin-films, were prepared from potassium and sodium acetates,
niobium ethoxide and an appropriate amount of strontium nitrate in 2-
methoxyethanol solvent with 5 mol% of potassium acetate excess. The
approximately 250 nm thick KNN-xSr thin films on Pt(111)/TiOx/SiO2/Si substrates
were obtained through repeated spin-coating and pyrolysis steps, followed by the
rapid thermal annealing at 650 °C.
All KNN films crystallized in pure perovskite structure with (100) preferential
orientation, which became more pronounced in doped films, as confirmed by the
Lotgering factor. The addition of 1 mole% Sr dopant, however, effectively reduced
the leakage current density to 4.2·10-8 A/cm2 at the electric field of 100 kV/cm and
contributed to the well-saturated ferroelectric hysteresis loop of the film. The major
drawback of this film was in the low piezoelectric response (a few pm/V measured
by piezoresponse force microscopy) and inability to switch ferroelectric polarization
by electric field, which can be related to the defects, such as oxygen vacancies. To
overcome the problem, an improved synthesis of the KNN-1Sr films with 1 mole%
Mn was introduced. The reasons for decrease in the leakage current density and
improvement of piezoelectric response will be discussed.",
publisher = "Institute for Multidisciplinary Research, University of Belgrade",
journal = "4th Conference of Serbian Society for Ceramic Materials",
title = "ENHANCED LOCAL PIEZOELECRTIC RESPONSE IN Mn- DOPED (K0.5Na0.5)0.99Sr0.01NbO3 FILMS",
pages = "64-64",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_2314"
}
