Improve the dielectric properties of PrSrNi0.8Mn0.2O4 compounds by longer mechanical milling

Abstract

Structural and dielectric properties of PrSrNi0.8Mn0.2O4 ceramics elaborated by a rapid method combining mechanical milling and heat treatment were studied for the first time. The raw materials are milled at different times (tmil = 0, 5, 10, 20 and 30 h) and annealed at 1300 °C for 8 h to produce a revealed PrSrNi0.8Mn0.2O4 single phase, exhibiting tetragonal structure with space group I4/mmm. This result was confirmed by using the TEM/ED pattern for sample milled at 30 h using the [001] orientation. The corresponding lattice images show a well-ordered compound, indicating the absence of stacking faults and the growth of the crystallites. Giant dielectric response was observed in these ceramics, and only one dielectric relaxation was found on the curve of a dielectric constant as a function of the temperature. The dielectric loss drops with increasing milling time. For 30 h milling it is divided by 100 at room temperature for low frequencies compared with 5 h milling. An equivalent circuit [R-C][R-CPE] was used to fit the experimental data and provide the activation energy of the thermally activated relaxation. Using the same nominal composition, the milling time has a major effect on the dielectric constant by significantly reducing the losses.