BiAlO 3 is a perovskite ferroelectric with a high Curie temperature above 520°C. However, it is difficult to prepare pure perovskite phase by the conventional method. In this experiment, BaTiO 3 has been selected as host to incorporate BiAlO 3 , and the nominal binary system of (1-x)BaTiO 3 -xBiAlO 3 has been investigated with regard to its Curie temperature (T c ) and dielectric relax behaviors. It was found that the pure perovskite phase can be retained below x00.08. However, the value of T c in the system doesn't follow the normal Vegard's law, on the contrary, shows the decreasing trend with the increase of x. According to the compared experiments about Bi 3+ and Al 3+ doping in BaTiO 3 , it can be safely concluded that the combined substitution of Bi 3+ and Al 3+ played the dominant role to decrease the T c and increase the relaxor behavior in (1-x) BaTiO 3 -xBiAlO 3 system.

Perovskite-type dense ceramics (La0.9Bi0.1)AlO3 (LBAO) have been prepared through a solid-state reaction route. LaAlO3 is indeed a paraelectric, whereas a significant ferroelectric relaxor behavior is obtained in LBAO. The variations of ferroelectric hysteresis loops versus the applied field or frequency indicate the nature of the ferroelectric domain switching. A broad dielectric anomaly coupled with the shift in dielectric maxima toward a higher temperature with increasing frequency has been observed in LBAO, and the indicator of degree of diffuseness γ is about 1.86. Moreover, the dielectric relaxation, which follows the Vogel–Fulcher relationship with TVF = 706.9 K, f0 = 1.85 × 109 Hz, and Ea = 0.09 eV, further supports spin-glass-like characteristics. Compared with LaAlO3, the abnormal contraction of crystal cell is observed in LBAO, which does not follow the normal Vegard’s law. This can be attributed to the covalent hybridization of the Bi3+ ions with the surrounding O2- ions. The large local displacements at the off-centered Bi position lead to the formation of polarized nanoclusters in the paraelectric matrix and the reorientation of these unstable polarized nanoclusters further results in ferroelectric relaxor behavior.

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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.