Electroceramic materials for high-energy store capacitors

Abstract

Dielectric materials such as electroceramics have a wide use in electronical devices, like capacitors. Lead zirconate titanate (PZT) is the most used electroceramic. However, lead toxicity has raised concerns about its use, due to its capacity to endanger the health and the environment. For this reason, since the early 2000s there has been substantial research on lead-free electroceramics that could present electrical properties similar to those of PZT. Materials based in BaTiO3 (BTO) have attracted great interest as possible substitutes of PZT. Like PZT, BTO presents dielectric behaviour and perovskite structure. However, its electrical properties are not as good as the ones described for PZT. For this reason, numerous researchers have studied derivatives of BTO in which doping elements improve its electrical behaviour. In this project, Ba1−xSrxTiO3 (BST) is proposed as an alternative to PZT. To do so, various BST compositions have been prepared through solid-state reaction. Characterisation by XRD confirmed the synthesis of single-phase BST compounds and the variation of unit cell parameters, which correspond with the introduction of Sr in the perovskite structure of BTO. In addition, distribution of elements across the material was analysed with EDS. The morphology of the ceramics was studied with SEM. Moreover, the dielectric behaviour of BST compounds was characterised by EIS. It was observed that BST compounds with Sr content ranging between 50 % and 70 % do not present phase transition at temperatures between 313 K and 473 K. In addition, BST low dielectric loss, along with its limited permittivity variability in the studied temperature range, confirm BST feasibility as a candidate to be used in capacitors