Effect of Sintering Temperature and Polarization on the Dielectric and Electrical Properties of La0.9Sr0.1MnO3 Manganite in Alternating Current

Abstract

The electrical characterization ofa La0.9Sr0.1MnO3 compound sintered at 800, 1000 and 1200 °C was investigated by means of the impedance-spectroscopy technique. As the results, the experimental conductivity spectra were explained in terms of the power law. The AC-conductivity study reveals the contributions of different conduction mechanisms. Indeed, the variation in the frequency exponents (‘s1’ and ‘s2’) as a function of the temperature confirms the thermal activation of the conduction process in the system. It proves, equally, that the transport properties are governed by the non-small-polaron-tunneling and the correlated-barrier-hopping mechanisms. Moreover, the values of the frequency exponents increase under the sintering-temperature (TS) effect. Such an evolution may be explained energetically. The jump relaxation model was used to explain the electrical conductivity in the dispersive region, as well as the frequency-exponent values by ionic conductivity. Under electrical polarization with applied DC biases of Vp = 0.1 and 2 V at room temperature, the results show the significant enhancement of the electrical conductivity. In addition, the dielectric study reveals the evident presence of dielectric relaxation. Under the sintering-temperature effect, the dielectric constant increases enormously. Indeed, the temperature dependence of the dielectric constant is well fitted by the modified Curie–Weiss law. Thus, the deduced values of the parameter (γ) confirm the relaxor character and prove the diffuse phase transition of our material. Of note is the high dielectric-permittivity magnitude, which indicates that the material is promising for microelectronic devices.

Narrowing of band gap and decrease in dielectric loss in La1-xSrxMnO3 for x = 0.0, 0.1, and 0.2 manganite nanoparticles

“…where t represents the thickness of the sample, ɛ o the permittivity of free space, and A the area of the electrode surface (Hizi et al, 2022). The frequency-dependent dielectric constant for all compositions of x is displayed in Figure 7A.…”

“…Transition metals, such as manganese (Mn), play a vital role in charge transport when it undergoes transition via partial replacement of Sr 2+ (1.44 Å) with La 3+ (1.36 Å) (Turky et al, 2016), improving electrical properties that are connected to dielectric losses in the desired material. Typically, tunneling and hooping processes can demonstrate the movement of these charge carriers (Hizi et al, 2022). In polycrystalline material, at high frequency, charge carriers move from one localized state to another across grain boundaries through a process known as hooping, which can reduce the defect density and contribute to an increase in the AC conductivity of the material (Mohanty et al, 2020a).…”