Doping Mn Induced Modification on the Crystal Structure, Morphology and Optical Properties of Mechanically Activated SrTiO₃ Powders

Abstract

Mechanically activated strontium titanate (SrTiO₃) powders with various manganese dioxide (MnO₂) doping levels (1.5, 3 and 6 wt%) were prepared by solid state method. Due to the possibility of manganese ion incorporation in SrTiO₃ at Ti⁴⁺ and/or Sr²⁺ sites a detailed analysis of the influence of dopants on the microstructure, morphology and optical properties of perovskite oxide was conducted. The investigation showed that manganese was incorporated into the lattice and surface layers of SrTiO₃ particles with the presence of manganese segregation and inhomogeneities. Optical measurements indicated a shift of the absorption edge to higher values of wavelengths where the lowest value of the band gap (3.10 eV) was for the longest activation time (120 min) and the highest weight percentage of dopant (6 wt%). In the case of lower concentration (1.5 wt%), there was a significant relative contribution of the substitution of Sr²⁺ ions by Mn²⁺ ions, while the substitution of Ti⁴⁺ ions by Mn⁴⁺ ions dominated samples with an increased concentration.

GRAPHICAL ABSTRACT

Keywords:

• Mn-doped SrTiO₃ powders
• Mechanical activation
• Structural and optical properties