Comparative study of phase structure and dielectric properties for K0.5Bi0.5TiO3BiAlO3 and LaAlO3BiAlO3

In this work, two perovskite‐type compounds, K0.5Bi0.5TiO3 and LaAlO3, have been selected as host material to incorporate with BiAlO3 using a solid‐state reaction route. The phase evolution and dielectric properties for both systems have been investigated in detail. For the K0.5Bi0.5TiO3BiAlO3 system, it is interesting to find that when using Bi2O3, Al2O3, K2CO3, and TiO2 as starting materials, the formed compounds are K0.5Bi0.5TiO3K0.5Bi4.5Ti4O15 and Al2O3 only plays a dopant role. There are two distinct dielectric peaks appearing in the patterns of temperature dependence of dielectric constant, corresponding to the phase‐transition points of perovskite‐type K0.5Bi0.5TiO3 and Aurivillius‐type K0.5Bi4.5Ti4O15, independently. In comparison, using Bi2O3, Al2O3, and La2O3 as starting materials, the pure perovskite phase LaAlO3BiAlO3 can be obtained. Compared to the inherent paraelectric behavior in LaAlO3, the diffuse phase‐transition phenomena can be observed in the LaAlO3BiAlO3 binary system, which corresponds well to the Vogel–Fulcher (VF) relationship. Moreover, compared to pure LaAlO3, the synthesized LaAlO3BiAlO3 compound shows enhanced dielectric properties, which are promising in application as gate dielectric materials.