ИСТИНА

In present paper the effect of ammonia contained in water fluid on synthesis and properties of gahnite (ZnAl2O4) doped with (0.4-4 mol%) europium was investigated. It is revealed that the synthesis of oxide in water-ammoniac fluid proceeds with formation of single-phase product that has a smaller size of crystal, than in case of synthesis in water fluid. The gahnite synthesized in water-ammoniac fluid has intensive luminescence bands of oxygen vacancies. In its structure the bound nitrogen is detected. However, during synthesis in water fluid the europium ions are more effectively incorporated into structure of nascent gahnite. The europium ions form complexes with oxygen vacancies. The excitation efficiency of Eu3+ ions luminescence in absorption band of oxygen vacancies is increased with the content of Eu3+ in gahnite. After annealing on air of gahnite samples synthesized in fluid of various compositions the changes of their luminescence differ. It has been supposed that in the gahnite synthesized in a fluid of various compositions the environment around Eu3+ ions differs outside the first coordination sphere. It is concluded that ammonia participates in processes of gahnite formation and provokes increasing of nucleation rate and is remained in its structure.