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1. Equation (3.13) should read E N = 2 27βε 3 00 ε 3 0 instead of E N = 2 27βε 3 00 . 2. Equation (3.22) should read:3. Sentence after Eq. (3.22) on page #16 should read:"In the limit of small concentration of the dielectric material in the mixture (q 1) and when ε f /ε d 1, the last two terms in the Eq. (3.22) can be neglected and the renormalized electric field E * in Eq. (3.20) become equal to the electric field E 0 ." instead of: "In the limit of small concentration of the dielectric material in the mixture (q 1) and when ε f /ε d 1, the last three terms in the Eq. (3.22) can be neglected and the renormalized electric field E * in Eq. (3.20) become equal to the electric field E 0 ." 4. Equation for the matrix G ts on page #16 should read G ts = 3n t n s − δ ts instead of G ts = 3n + ns − δ ts . 5. Sentence after equation for the matrix G ts on page #16 should read: "where n = ( r − r i )/| r − r i | and δ ts is the Kroneker symbol." instead of: "where n = ( r − r i )/| r − r i | and δ is the Kroneker symbol. Where ϕ and θ are the azimuthal and polar angles of the vector r − r i ."

Using pulsed-laser deposition, a two-step growth technique was applied to epitaxial SrTiO3 (STO) thin films on LaAlO3 substrates providing a way to obtain an effective strain relaxation in these films otherwise strained due to lattice mismatch between film and substrate. By changing the thickness of a first layer, deposited at a temperature as low as 100°C before the deposition of the main layer at 750°C, different strain relaxation states of the films could be systematically realized. With a 10-nm-thick first layer, an almost full strain relaxation at the deposition temperature of the main layer was achieved, suggesting a strong impact of this method on strain relaxation. The in-plane dielectric measurements displayed that the ferroelectric transition temperature increases with strain relaxation during the growth. This trend is correct and compatible with the theoretical prediction of the behavior of strained STO derived from Landau theory.

The nonlinear response of ferroelectric BaxSr1−xTiO3 films to microwave electric field intensity up to ∼3×106 V/m was studied. Two techniques were used for this investigation: (i) 10 GHz pulsed power measurements, and (ii) 4 GHz intermodulation distortion (IMD) measurements. The nonlinear distortion of the resonant curve under microwave pulsed power and generation of the third-order IMD products in microwave resonators using ferroelectric film planar capacitors were measured. The use of microwave pulses and continuous signals enabled the separation of the nonlinear dielectric response from the heating response of the ferroelectric films and the microwave nonlinear parameters of the ferroelectric films to be determined. It is shown that up to a specified value of microwave voltage amplitude the nonlinear response of BaxSr1−xTiO3 film capacitors can be predicted from the small signal capacitance–voltage characteristics. Formulas to estimate power handling capability connected with the field dielectric nonlinearity and the film overheating are derived for the tunable microwave devices based on ferroelectric films.

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A model of the quasi-Debye loss mechanism in SrTiO3 and Ba0.6Sr0.4TiO3 perovskite ferroelectrics at microwave frequencies is presented. The field dependence and the size of the field-induced quasi-Debye loss contribution in SrTiO3 and Ba0.6Sr0.4TiO3 systems have been evaluated in the simple approximation of the isotropic phonon spectra of these materials. Good agreement between experimental and simulated results for the field dependence of dielectric loss for SrTiO3 ferroelectric material is observed for the weak dc fields [tunability n=ε(0)∕ε(E)⪡2]. A significant feature in the field dependence of dielectric loss at microwave frequencies, a pronounced maximum, is predicted for SrTiO3 at higher values of the bias field (n≅2) whereas in Ba0.6Sr0.4TiO3 the field dependence of the loss is found to be monotonic. The influence of the quasi-Debye loss contribution on microwave performance of SrTiO3 and Ba0.6Sr0.4TiO3 ferroelectric materials is analyzed. It is concluded that the contribution of this mechanism is large enough to affect the performance of tunable microwave devices based on SrTiO3 ferroelectric materials, whereas in the case of Ba0.6Sr0.4TiO3 ferroelectrics the contribution of the quasi-Debye loss mechanism is found to be relatively small.

Structural and dielectric properties of epitaxial SrTiO3 (STO) thin films on LaAlO3 substrates fabricated by a two-step growth technique using pulsed laser deposition were investigated by in situ and ex situ observations in terms of strain relaxation from the lattice mismatch between the film and the substrate. In a first step, a very thin STO layer of less than 10nm was deposited at low temperature. The main part of the film was deposited in a second step at high temperature, as commonly used for epitaxial growth. In situ reflection high-energy electron diffraction observations showed that almost full strain relaxation was realized before the deposition of the second layer, whereas the normally grown film was not fully relaxed even when the film thickness exceeded 300nm. The relaxation process of the two-step-grown film took place through the crystallization of the first layer with substantial misfit dislocation formation, which is therefore fundamentally different from that of the normally grown film. Since the normally grown film possesses compressive strain due to less strain relaxation, the two-step-grown film showed larger permittivity and larger tuning compared to the normally grown film. The estimation of the extrinsic loss contribution from the measured loss tangent implied that the two-step growth technique could suppress the extrinsic loss due to a redistribution of defects in the film. The first layer leads to two effects: (i) strain relaxation and (ii) lower loss of the film.

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