Effect of Particle Size and Sintering Procedure on Microstructure, Dielectric, Ferroelectric and Mechanical Properties of SrBi₄Ti₄O₁₅

Abstract

Bismuth layered-perovskite compounds such as SrBi₄Ti₄O₁₅ (SBTi) ceramics are prepared by solid state reaction. The SBTi ceramics are sintered by microwave and conventional sintering techniques. In this study, the effect of ball milling on different sintering processes, microstructure as well as on dielectric, ferroelectric and mechanical properties of SBTi ceramics is emphasized. The powder has been milled to produce nanocrystalline powders using a planetary ball mill. Different samples have been prepared by varying the milling time from 5 to 20 h, keeping the milling speed fixed at 300 rpm. The X-ray diffraction results show that crystalline powders with a single perovskite structure can be obtained when calcined at 700°C for 4 h. It has been observed that the average grain size, dielectric and ferroelectric properties are dependent on the duration of ball milling. The dielectric constant and loss tangent of the conventional sintered samples range between (140 and 165), and (0.05 and 0.07) respectively and those of the microwave sintered samples range between (155 and 175), and (0.04 and 0.06) respectively when measured at 1 MHz frequency. The microwave sintering process has been found to improve the homogeneity of the grains and morphology. The microwave sintering of the SBTi ceramics leads to higher densification (98% of the theoretical density), fine microstructure and good mechanical and ferroelectric properties in much shorter duration of time than that of conventional sintering process.

Keywords:

• SBTi ceramics
• Ball milling
• Dielectric properties
• Ferroelectric properties
• Mechanical properties