Dielectric properties of solution derived KTa0.6Nb0.4O3 thin films on polycrystalline alumina substrates were investigated in radio frequency and in microwave frequency range. The relaxorlike behavior of dielectric properties was unambiguously confirmed by the fit to the Vogel–Fulcher law. The room temperature values of permittivity and dielectric losses, measured at 10 kHz, are 2430 and 0.08, respectively. The corresponding values, measured at 14.5 GHz, are 590 and 0.52.
COBISS.SI-ID: 22594599
Thin films of potassium sodium niobate (K0.5Na0.5)NbO3 on Pt (111)/TiO2/SiO2/Si substrates have been prepared by chemical solution deposition. The stoichiometric sols were synthesized from corresponding alkali metal ethoxides or acetates and niobium ethoxide in 2-methoxyethanol. The thin film quality is affected by choice of alkali metal precursors. Thin films prepared from the acetate-based sol upon heating to 670?C crystallize in pure perovskite phase. The dielectric permittivity of the 350 nm thick KNN film at 1 kHz is 570 and the dielectric loss factor is 0.07.
COBISS.SI-ID: 22155559
KTa0.6Nb0.4O3 thin films on alumina substrates were prepared from acetate-alkoxide derived precursor with 1 h or 24 h of reflux and heating at 900°C. Perovskite films were obtained from the 24 h-refluxed solutions. The 240 nm thick films had room temperature dielectric permittivity value of 1690, dielectric loss value of 0.04 and tunability (C0V / C30V) value of 2.6, measured at 1 MHz with the voltage amplitude of 300 mV. The films, prepared from the 1 h-refluxed solutions, were multi-phase and had inferior dielectric properties.
COBISS.SI-ID: 23108135
Our aim was to obtain a reliable quantitative composition of alkali perovskites at nanoscale, with KTaO3 as the case study, by a combination of two analytical methods of transmission electron microscopy: energy-dispersive X-ray and electron energy-loss spectroscopy. Because of the volatile nature of alkali-based compounds, special attention was paid to optimization of acquisition parameters. Compositional inhomogeneities, which were identified in the as-calcined and KTaO3 powder sample, were found to affect the subsequently produced ceramic, which showed compositional deviations of up to 5%.
COBISS.SI-ID: 24363047
The (1-x)K0.5Na0.5NbO3 – xSrTiO3 thin films, x = 0.05 – 0.25, were prepared in order to study the influence of the SrTiO3 on the phase composition, microstructure and dielectric properties of the films. Increasing the SrTiO3 content decreased the monoclinic distortion, characteristic for pure K0.5Na0.5NbO3 due to the formation of a solid solution. The grain size, the dielectric permittivity and the dielectric loss factor were reduced with increasing SrTiO3 content. The RT permittivity and losses of the films with x = 0.005 were about 300 and 0.01 at 100 kHz.
COBISS.SI-ID: 24341031