Influence of Sintering Temperature Strategy on Structural, Dielectric, and Resistive Switching in Bulk Ba_0.7Sr_0.3TiO₃ Ceramics

We introduce a modified sintering approach to investigate the microstructure, dielectric, and resistive switching (RS) properties of bulk Ba_0.7Sr_0.3TiO₃ (BST) ceramics. The ceramics were prepared using a solid-state-reaction method, and then sintered using modified double-step sintering (DS) processes, as well as conventional single-step sintering (CSS) at different peak temperatures (1250°C and 1350°C). To find the phase purity, lattice parameters, and tetragonality of the samples, x-ray diffraction patterns were fitted with the pseudo-Voigt function in the FullProf software. With the help of the software, bond angles and bond lengths were found for all the ceramics. Furthermore, Raman spectrum analysis was performed to confirm the samples' structural variations. The microstructure images of the samples show that the grain size was reduced and the grain size distribution was improved for the DS-processed ceramics as compared to the CSS-processed ceramics. The dielectric properties of the BST ceramic capacitors were investigated in a wide range of frequencies and temperatures. All the BST ceramics displayed humps at near-room temperature, corresponding to tetragonal–cubic phase transitions, and a small shift in transition temperature towards higher temperature regions for the DS ceramics compared with the CSS ceramics was observed due to structural modification by a grain size effect. The metal–insulator–metal (MIM) structures, so-called memristors, were designed with these dielectric ceramics. A bipolar RS behavior was observed in these MIM structures which were confirmed through current–voltage (I–V) characteristics. The improved RS in these structures is the result of the migration and redistribution of cations, such as oxygen ions and oxygen vacancies ,as well as the ferroelectric domain orientation.