Abstract:
A new full color emitting single phase phosphor in Bi3+ and Eu3+ ion co-doped La3TaO7 weberite system was developed via a conventional high temperature ceramic method. Phase, structural and luminescence characteristics of the developed phosphor were evaluated with different concentrations of Bi3+ and Eu3+ ions. The structural studies show that the samples are crystallized into orthorhombic weberite type structure with Cmcm space group. Photoluminescence studies reveal that the Bi3+ and Eu3+ ions co-doped La3TaO7 phosphors show broad excitations in the n-UV region (270 nm, 336 nm, 394 nm), and displays broad bluish-green emission due to the 1S0 to 3P1 and 1P1 transitions of Bi3+ and intense orange-red emission due to 5D0 to 7F0-2 transitions of Eu3+ leading to cover the whole visible spectral region. The lifetime measurements and the overlap of the spectral regions with the variation of Eu3+ concentration with Bi3+ suggest an effective energy transfer from Bi3+ to Eu3+, allowing to fine tune the chromaticity coordinates close to the white point. Further, the energy transfer mechanism existing in this phosphor is established, and it is found to be due to the dipole–quadrupole interaction. These properties make it an irrefutable candidate for single phase phosphor material for WLED application.
