Crystal structure and two types of Eu3+-centered emission in Eu3+ doped Ca2V2O7

The dependence of Ca2V2O7:Eu3+ photoluminescence on the crystal structure was discussed experimentally and theoretically. The important chemical parameters, especially, standard deviation of the bond environmental factor were calculated firstly. Two broad excitation bands with the peaks at 311 and 400 nm covering from 250 to 475 nm and two different types of f-f transition-emission of Eu3+ can be found. Detailed discussion demonstrated that two different emission mechanisms exist in Ca2V2O7:Eu3+: (1) was from the Eu13+ ions occupying the Ca1 sites and (2) was from the Eu23+ ions in the Ca2 sites. The energy transfer was in two ways: one was from O-V1 charge transfer (CT) to Eu2 and another was from O-V2 CT to Eu1.