CHARACTERIZATION AND MICROSTRUCTURE EVOLUTION IN Er-DOPED BaTiO3 CERAMICS

摘要

BaTiO3-ceramics are known as some of the most useful electroceramics with a various applications. In this study the effect of Er2O3 as additive on the microstructure and dielectric properties of doped BaTiO3 was investigated. The samples doped with 0.01 to 1.0 wt% Er2O3 were prepared using by conventional solid state procedure, and were sintered at 1350°C for four hours. The microstructure of sintered specimens was investigated by SEM-5300 and capacitance and dielectric loss measurements have been done using LCR-metra Agilent 4284A in the frequency range from 20Hz to 1MHz. The microstructure study with low additive concentration shows abnormal grain size, with average grain size between 20-60 μm. With the higher dopant concentracion the abnormal grain growth is inhibited and the grain size ranged between 5-15μm. The dielectric constant decrease with increase of dopant concentration and for all of the investigated samples ranged from 650 to 1600 at room temperature. The dissipation losses a linear decrease v.s frequency is mesured for all investigated samples. We applied a fractal method for the microstructure analysis. This method for analysis of the structure of ceramics provides a new approach for describing, predicting and modeling the grain shape and relations between the BaTiO3 ceramic structure and dielectrical properties.