Crystal growth of layered perovskite Sr₂Nb₂O₇ and Sr₂Ta₂O₇ film by the sol-gel technique

High dielectric and low loss capacitor thin films of Sr₂Nb₂O₇ (SN), Sr₂Ta₂O₇ (ST), and their solid solution Sr₂(Nb_x, Ta_1−x)₂O₇ (SNT) were investigated using the sol-gel technique. The SN film grows with the (0n0) orientation in the case of heating at over 700 °C. Heat treatment at a lower temperature results in the polycrystal ST-type structure. The SNT at x < 50% also resulted in the ST type. The dielectric constant for the SN film was 45, within 10% variation at ±0.5 MV/cm. Dielectric loss (tan δ) was 0.3–0.5%. The small variation in dielectric constant and the paraelectricity with low loss are suitable for capacitor applications.