Crystal Structure and Effective Dielectric Response of Ba_0.5Sr_0.5TiO₃–MgO Composites Synthesized In Situ Process

Abstract

1 -x)Ba 0.5 Sr 0.5 TiO 3 (BST)-xMgO composite ceramics have been prepared in situ by a citrate-nitrate combustion process, and their crystal structure and effective dielectric response have been investigated systematically. Results reveal that MgO particles homogeneously disperse in BST particles. Rietveld refinement of X-ray diffraction data shows that the amount of the incorporation of MgO into BST lattice is increased with increasing the MgO volume fraction (ƒ M ). It is identified that the incorporation of Mg 2+ into B site gives rise to the formation of F centers in the composites. Related with the incorporation of Mg 2+ into BST lattice, the permittivity of BST in the composite is strongly dependent on ƒ M , which is defined by the relation e BST ¼ a3e b3fM . Also, the high percolation threshold of ƒ M = 0.60 is observed, which is well in agreement with the theoretical predictions of the modified effective medium approximation coupled with the spherical inclusion model.

The anomalous increase in tunability in Ba0.55Sr0.45TiO3‐MgO‐Mg2SiO4 composite ceramics

“…In present work, Mg 2+ content has exceeded the solubility limit in (Ba, Sr)TiO 3 , the main effect should be the composite effect superimposed on doping effect. The solubility limit of Mg 2+ in ferroelectric BST is increased with increasing MgO content, the role of doping effect is very complicated. In this work, we should be more concerned with composite effect.…”

Aluminum‐vacancy‐related dielectric relaxations in AlN ceramics

“…As ESR is a powerful technique for characterizing paramagnetic point defects, to further evidence the existence of the aluminum vacancies, ESR measurements were performed on both pristine and O 2 ‐annealed AlN samples. The results are displayed in Figure .…”

Site‐selective substitution and resulting magnetism in arc‐melted perovskite ATiO3‐δ (A = Ca, Sr, Ba)

“…By XPS and XAS, the ratios of Ti 3+ /Ti 4+ in titanates were verified, and the ratios of Ti 3+ /Ti 4+ increased in the order of CTO_arc < STO_arc < BTO_arc consistent with the order of oxygen vacancy δ values in ICP‐OES. In order to quantify the 3d impurities and Ti 3+ concentration more accurately, electron paramagnetic resonance experiments can be executed hereafter 41 …”