Dielectric characteristics of Fe-doped LaTiO_{3+: δ} and visible light modulation

Fe-doped La_1-xFe_xTiO_3+δ (x = 0.05, 0.1, and 0.3, 0.4) ceramic samples are prepared via a traditional solid-state reaction route. The low temperature (77 K ≤ T ≤ 360 K) dielectric properties of the samples have been systematically investigated in the frequency range from 100 Hz to 1 MHz. It is clearly observed that extraordinarily high low-frequency dielectric constants appear at room temperature in La_0.6Fe_0.4TiO_3+δ, which is ∼1000 times larger than that of La_0.95Fe_0.05TiO_3+δ. Interestingly, the dielectric characteristics of the samples have obvious light dependence at room temperature within the measured frequency range. The results have demonstrated that visible light improves the dielectric properties of the ceramics by means of I-V and complex impedance analysis.