Enhanced dielectric response of Gd2Ti2O7 nanoparticles in SiO2 matrix

Dielectric properties of Gd2Ti2O7 nanopaticles in SiO2 matrix are remarkably different in comparison with the Gd2Ti2O7 single crystal. Gd2Ti2O7–SiO2 nanocomposite exhibits significant increase in the dielectric constant (ɛ′) for smaller Gd2Ti2O7 nanopaticles (GdT900). ɛ′(T) behavior suggests diffuse phase transition (DPT) near room temperature (RT). The estimated value of the diffuseness exponent (γ) related to DPT is 1.35 for GdT900, indicating an incomplete DPT. The dielectric relaxation near DPT has been associated with the thermally activated oxygen vacancies. The P(E) loops for GdT900 near RT are slim with low values of remnant polarization (Pr ∼0.15 μC/cm2) and coercive field (Ec ∼ 0.85 kV/cm). Nyquist plot for GdT900 indicates that Gd2Ti2O7 nanopaticles play dominant role in electrical conduction. The frequency activated behavior of ac conductivity in the DPT regime suggests that the conduction is due to hopping of bound charge carriers like small polarons.