BaMgF4-Eu2+ thin films were prepared from trifluoroacetate precursor solutions by a sol-gel method and their violet luminescence was investigated. A (Ba,Eu)MgF4 phase was obtained by heating the spin-coated precursor films at temperatures of 550-650°C. The reduction of Eu3+, which originated from Eu(CH3COO)3·4H2O in the precursor, to Eu2+ in the heat-treated films was evidenced by the strong, broadband 4f-5d excitation at 290 nm and emission at 420 nm in photoluminescence measurements. The intensity of violet luminescence of Eu2+ depended on the heating temperature, heating time and the Eu concentration. The strongest violet emission was observed with the BaMgF4-Eu (15 mol%) film that was heated at 650°C for 10 min under the present experimental conditions.
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