Charge Density, Urbach Energy Tail Band, and Electronic Properties in Cr Substituted BaSnO ₃ Perovskite

BaSnO 3 (BSO) and Cr‐substituted BaSnO 3 (1%, 3%, and 5%) perovskite samples were successfully synthesized by a chemical precipitation method. X‐ray diffraction analysis confirmed the formation of a cubic perovskite structure in both unsubstituted and Cr‐substituted BSO samples. The charge density distribution within the unit cell was visualized using the maximum entropy method (MEM), providing insight into the electronic structure and interatomic bonding. Urbach energy tails (BSO EU = 0.26 and BSOCr5 EU = 0.68 eV) demonstrate the presence of structural disorder in the prepared perovskite samples. 119 Sn Mössbauer spectra underpin tetravalent tin in both samples. Density functional theory calculations show that unsubstituted BSO is a wide‐bandgap, non‐magnetic semiconductor, while Cr substitution introduces Cr‐3d states that reduce the bandgap. The central substituted site is the most stable for Cr and shows strong spin polarization. However, this remains localized in the absence of defects. An oxygen vacancy near Cr significantly enhances and stabilizes this spin polarization, leading to more pronounced magnetic behavior. Together, our experimental results and DFT calculations show that Cr substitution effectively tunes the electronic structure, disorder, and magnetic behavior of BaSnO 3 , making it promising for optoelectronic applications.