A study focusing on the influence of multiple cationic substitutions in Dion-Jacobson (n = 2) layered perovskite oxides.

Multiple cation substitutions within the 'A' sites of the perovskite blocks of the (n = 2) Dion-Jacobson (DJ) layered perovskite, CsANb2O7, have resulted in Cs(Pr1/3Nd1/3Sm1/3)Nb2O7 (RE3) along with two new compositionally complex perovskites, Cs(Pr1/4Nd1/4Sm1/4Eu1/4)Nb2O7 (HE4) and Cs(Pr1/5Nd1/5Sm1/5Eu1/5Bi1/5)Nb2O7 (HE5). The structural characterization of the oxides synthesized by the high-temperature solid state reactions confirms the possibility of obtaining isostructural polar (S.G. P21am) materials. The extent of orthorhombic strain as deduced from the a and b parameters has been found to follow the order, HE4 > RE3 > HE5. Significant results include the anomalies observed around 802 K and 870 K for RE3 and HE4 in the variable temperature permittivity data along with the matching ferroelectric to paraelectric transitions (around 773 K and 873 K) in the high temperature powder X-ray diffraction measurements for the respective phases. The oxide, HE5, having a minimal orthorhombic distortion also displayed an anomaly close to 660 K.