Enhanced dielectric responses of Ba0.6Sr0.4TiO3 thin films onto BaxSr1-xTiO3-buffered stainless steel substrates

Misfit strain, lattice parameter, polarization, permittivity, and tunability of Ba0.6Sr0.4TiO(3) thin films onto BaxSr1-xTiO3-buffered stainless steel (SS) substrates are computed via a modified phenomenological model. When the Ba/Sr ratio of BaxSr1-xTiO3 buffer layer grows, the permittivity and tunability first increase and then decrease with the maximum at x = 0.75. The highest tunability of such films prepared by the sol-gel technique can reach 32.5% at the electric field of 320 kV/cm when x = 0.8. The strains are qualitatively analyzed through combining XRD, Raman, and theoretical calculation. The computed data are generally supported by experimental lattice parameters, permittivities, and tunabilities, which show that polycrystalline BST thin films with smaller compressive strain obtain higher dielectric response, and that inserting buffer layer could regulate the strains and dielectric properties of BST thin films.

Automated summary

Misfit strain, lattice parameter, polarization, permittivity, and tunability of Ba0.6Sr0.4TiO(3) thin films onto BaxSr1-xTiO3-buffered stainless steel (SS) substrates are calculated using a modified phenomenological model. The permittivity and tunability of the films first increase and then decrease with the growth of Ba/Sr ratio in the BaxSr1-xTiO3 buffer layer, reaching a maximum at x = 0.75. The highest tunability achieved for sol-gel prepared films is 32.5% at an electric field of 320 kV/cm when x = 0.8. The strain analysis reveals that BST thin films with smaller compressive strain have higher dielectric response, and inserting a buffer layer can regulate the strain and dielectric properties.