Photoluminescence property of vanadates M2V2O7 (M: Ba, Sr and Ca)

We investigated the photoluminescent properties including the internal quantum efficiency (η) for the M2V2O7 (M: Ba, Sr, and Ca) as a new vanadate phosphor system. In the M2V2O7, the broad band emission spectra from 400 to 800 nm derived from the charge transfer transition in the VO4 tetrahedra were observed. The emission band of these compounds consisted of two maxima Em1 and Em2 corresponding to 3T1–1A1 and 3T2–1A1 transitions, respectively. These two maxima red-shifted with the decreasing ionic radius of M-site, as a result, the luminescent colour was varied from green (M: Ba) to yellowish orange (M: Ca). The η for the Ba2V2O7, Sr2V2O7 and Ca2V2O7 were 25%, 8% and 0.9%, respectively. This enhancement of η in the M2V2O7 could be due to following structural features: the stronger V–V and weaker V–M correlations.