A temperature stable (Ba<inf>1–x</inf>Ce<inf>x</inf>)(Ti<inf>1–x/2</inf>Mg<inf>x/2</inf>)O<inf>3</inf> lead-free ceramic for X4D capacitors

Abstract

A novel dielectric ceramic {(Ba1–xCex)(Ti1–x/2Mgx/2)O3, x = 0.06, BCTM6} with excellent temperature stability (−55 to 65 °C, TCC ≤ ±3.3%, ε′RT ∼ 2242, tan δ < 0.023) was developed for X4D capacitors. Phase structure was found to transfer from tetragonal to cubic phase with increasing x and the solubility limitation of Ce/Mg was determined to be 0.10 by X-ray diffraction (XRD) for (Ba1–xCex)(Ti1–x/2Mgx/2)O3. The formation of 2CeBa•−MgTi’’ dipoles was believed to be responsible for the elimination of oxygen vacancies, leading to the low dielectric loss of BCTM6. An electron paramagnetic resonance (EPR) signal at g ∼ 1.98 suggested the ionization of Ba vacancies in (Ba1–xMgx)(Ti1–yCey)O3 (BMTC), indicative of the amphoteric behavior of Mg2+.