Holes trapped near Mg²⁺ and Al³⁺ impurities in SrTiO₃

From SrTiO3 doped with Al or Mg, ESR signals are identified arising from holes captured in O2-p(π) orbitals near Al3+ or Mg2+ ions substitutional on Ti4+ sites. These centers are involved in photochromic processes in SrTiO3. © 1976.