Formation mechanism, thermal and magnetic properties of (Bi$_{1-x}$Sr$_x$)$_{m+1}$Fe$_{m-3}$Ti$_3$O$_{3(m+1)-\delta}$ ($m=4$–$7$) ceramics

Specific features of the formation of Aurivillius phases (Bi$_{1-x}$Sr$_x$)$_{m+1}$Fe$_{m-3}$Ti$_3$O$_{3(m+1)-\delta}$ ($m=4$–$7$, $x=0.0$–$0.7$) with a perovskite-like block having a nanometric thickness ($h$) of $2$–$3$ nm are described. It has been established that the degree of isomorphous substitution in the bismuth sublattice and thermal stability of phases tend to reduce with the increasing $h$. It has been demonstrated that the magnetic ions inside the perovskite-like block can have antiferromagnetic interaction exchange that influences magnetic properties of the Aurivillius phases.