Photoluminescence properties of Ba3B′B″2O9 (B′=Mg, Co or Zn and B″=Nb or Ta) ceramics with perovskite structure

► Emission properties of Ba3BNb2O9 are influenced by the order-disorder phase transition. ► Deviation from stoichiometry was demonstrated to result in secondary phase formation. ► Appearance of secondary phases was shown to modify photoluminescence signal.