Host excitation-induced red emission from Pr~(3+) in strontium barium niobate thin film

摘要

Optical quality Sr_xBa_(1-x)Nb_2O_6 (SBN) thin films doped with Pr~(3+) ions were successfully grown on fused quartz substrates using a pulsed laser deposition technique. Both as-grown and annealed samples were studied at either room temperature or at 10 K. Luminescence measurements show that most 4f~2→4f~2 emissions from Pr~(3+) centers were efficiently quenched in the films. Strong red emission from ~1D_2 to ~3H_4 at ～610nm accompanied by weak emission to other ~3H_j multiplets could be observed only by UV excitation into the SBN conduction band. At 10 K, the main emission peak splits into four components. In addition, a broadband SBN-host luminescence was identified at ～ 560 nm in the annealed sample, associated with the charge-transfer vibronic exciton. As an interstitial ion, Pr~(3+) may occupy a 15-, 12-, 9- or 6-fold cage surrounded by oxygen and was found to occupy all four possible sites in SBN thin films. This behavior is different from Eu~(3+) - SBN where Eu~(3+) only occupies a 6-fold site.