Effect of sintering temperature and ethanol on the dielectric properties of LaFeO3 ceramics

LaFeO3 nanoparticles were prepared by a sol-gel method and chosen as the precursor for the preparation of LaFeO3 ceramics. A series of ceramic samples were fabricated by annealing at different temperatures from 800 to 1300 degrees C and was immersed in ethanol for 1h afterward, so as to study the effect of sintering temperature and ethanol on the dielectric response at room temperature. As sintering temperature increases, the grain becomes larger, while the degree of porosity is reduced as revealed by FE-SEM. The effect of sintering temperature on dielectric permittivity is dependent on the measuring frequency, while the effect on the loss is less frequency-dependent and is mainly determined by its stronger influence on the whole resistance. Owing to the influence of ethanol on the MW polarization at electrode-sample interface and grain boundaries, both dielectric permittivity and loss were increased by different extent after immersing in ethanol for all the samples. The effect is more obvious with smaller grain size and higher degree of porosity, and the highest values and variations of dielectric permittivity and loss were obtained by LaFeO3 ceramics sintered at 800 degrees C with the smallest grain size and highest degree of porosity.