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Structure, microstructure and low-temperature dielectric properties of undoped SrTiO3 (STO) thin films prepared by sol–gel and deposited on Si/SiO2/TiO2/Pt substrates are studied. The effect of annealing temperature and of buffer layers on properties of STO films is analysed. Dielectric permittivity ε′, relative tunability nr and polarization P are lowest for STO films prepared without buffer layers and annealed at 750 °C and are highest for films prepared with buffer layers and annealed at 900 °C. The increase of c/a ratio for films with buffer layer and of the grain size for films annealed at higher temperature is used to explain the improved dielectric response. The dielectric permittivity of STO films prepared by low-cost sol–gel technique with optimized deposition conditions is found to be comparable to that of STO films fabricated by more sophisticated and expensive methods such as pulsed laser deposition. [ABSTRACT FROM AUTHOR]

Abstract: The structure–property relations of Mg-doped SrTiO3 (ST) sol–gel thin films deposited on Pt/TiO2/SiO2/Si substrates have been investigated in order to determine the effect that Mg dopants have on the dielectric properties of SrTiO3. It has been predicted that Mg-doped SrTiO3 should exhibit a dielectric anomaly similar to that observed recently in Bi doped SrTiO3 but, to date, no polar state has been reported. It has been suggested that this may relate to the low solubility of Mg on the A-site in bulk ceramics (<0.05at.%). However, for Sr1−x Mg x TiO3 (SMT) (x ⩽0.30) films annealed at 750°C, all Mg ions were accommodated in the perovskite lattice and for SMT films annealed at 900°C, the solubility limit of Mg was x =0.10, above which a Mg-rich ilmenite second phase was observed. Irrespective of the higher solid solubility limit of Mg in the ST lattice for sol–gel ST films compared to equivalent ceramics, no ferroelectric or relaxor phase transition was observed, refuting previous predictions for this dopant. [Copyright &y& Elsevier]