Effect of intermediate layer and electrode materials on dielectric and flexoelectric properties of double-layer BST films with parallel structure

BST films were prepared on Pt/Ti/SiO2/Si substrates by spin-coating method and double-layer BST films with parallel structure were designed in order to improve their dielectric and flexoelectric properties. The best dielectric constant 409 and dielectric loss 0.0104 of the single-layer BST film are obtained at 800 °C annealing temperature. The dielectric constant of double-layer BST films with parallel structure almost doubled to about 800. The maximum of equivalent piezoelectric constant of the single-layer BST film is 107 pC/N, while the values reach 198 and 251 pC/N, respectively, for BST1/ZrO2/BST2 and BST1/MgO/BST2 parallel structure films. The flexoelectric properties of BST1/MgO/BST2 films are better than those of BST1/ZrO2/BST2 films. When LSCO is applied as the inner electrode, the dielectric properties of the double-layer BST films are better than those applied Au electrode. The curves of transverse flexoelectric signal of the former are smoother than those of the latter.