Structural and magnetic properties control of Pr$_{0.7}$Ba$_{0.3}$MnO$_3$ with Sr-doping

Structural and magnetic properties of Sr-doped Pr$_{0.7}$Ba$_{0.3}$MnO$_3$ polycrystallines prepared by solid state reaction are presented. Samples were in monoclinic structure $P$2$_1$/$n$ without structural phase transition when Ba was gradually replaced by Sr. Parameters $a$, $b$, and $c$ of a unit cell monotonously decrease with increasing Sr content, while $\beta$ angle has increased from 89.981$^\circ$ to 90.007$^\circ$. The $X$-ray absorption spectra show the co-existence of Mn$^{3+}$ and Mn$^{4+}$ ions in materials and the number of Mn$^{4+}$ ions increases in the presence of Sr. The thermal magnetization data indicate that the Curie temperature shifts toward room temperature from 190, 210, 232 to 267 K with increasing Sr content $x$ from 0 to 0.3.