Effect OF SrTiO3 addition on the thermal stability OF Ba2TiSi2O8 matrix in the radio frequency range

ABSTRACT The dielectric properties of the Ba 2 TiSi 2 O 8 (BTS) ceramic matrix added with strontium titanate (SrTiO 3 ) at varying concentrations were investigated in this work using Impedance Spectroscopy (IS). The Rietveld refinement method was employed to analyze the presence of a secondary phase, (Ba 0.3 Sr 0.7 )TiO 3 , in the composites, while scanning electron microscopy (SEM) was used to examine the morphologies of the synthesized composites. According to the IS results, it was observed that the relative dielectric permittivity ( ε′ᵣ ) of the composites increases with the addition of SrTiO 3 , a fact attributed to the formation of the new phase (Ba 0.3 Sr 0.7 )TiO 3 ( ε′ᵣ ∼ 623). The Nyquist plot was utilized to study the dielectric behavior, and the grain and grain boundary effects in the ceramic samples were numerically modeled using an equivalent circuit (CPE). The activation energy (E a ) of the ceramic composites was determined to range from 1.76 to 1.92 eV. Additionally, the temperature coefficient of capacitance (TCC) values for the composites doped with 10% and 15% strontium titanate (SrTiO 3 , by mass) showed within the range of ±1500 ppm.°C -1 . The BTS-STO system, which has not been explored previously, overcomes the thermal instability of pure STO (typical TCC > ±2000 ppm/°C) and similar compounds such as (Ba,Sr)TiO 3 .