Theoretical Calculation of Bond Energy, Self-Reduction Phenomenon, and Photoluminescence Properties of Eu/Ce Single-Doped and Codoped Ba2CaB2Si4O14 Phosphors

The self-reduction of Eu3+ to Eu2+ and Ce4+ to Ce3+ can first be found by doping rare earth ions RE (RE = Eu, Ce) in Ba2CaB2Si4O14 (BCBSO). The Eu2+/Eu3+ codoped BCBSO and Ce4+/Ce3+ codoped BCBSO and Eu/Ce codoped BCBSO were synthesized by a high-temperature solid-phase method in air and reducing atmospheres, respectively. By comparing the photoluminescence spectra in air and reducing atmospheres, the self-reduction phenomenon of Eu3+ and Ce4+ in the BCBSO were verified adequately. The theoretical method of the bond energy was used to analyze the occupancy and self-reduction of Eu or Ce ions. The experimental results are in agreement with the theoretical ones. The color tuning phosphors were achieved in BCBSO:Eu and BCBSO:Ce. The codoped system BCBSO:Eu, Ce was studied and it was found that the position and shape of the emission spectra changed with the change in the excitation wavelength, and the change in the corresponding color could be seen from the CIE chromaticity coordinates. Its emission peak shifts from 481 to 595 nm with the increase in the Ce3+ concentration in the codoped system under the excitation of 365 nm. Based on the fluorescence lifetime, the energy transfer process between Eu2+–Ce3+ is proved, and its emission color can be adjusted to a certain extent.