Synthesis of Bi3+ and Eu3+ co-doped Na4CaSi3O9 blue-red light tunable emission phosphors for inducing plant growth

Sunlight is an important factor in plant growth. In this regard, both blue and red lights provide significant contributions. Blue-red light dual-emission phosphors, which can be achieved by regulating energy transfer between two independent luminous centers, have recently been investigated extensively. In this study, Bi3+ and Eu3+ co-doped Na4CaSi3O9 (NCSO: Bi3+, Eu3+) phosphors are successfully synthesized via a high-temperature solid-phase method at approximately 900 C-degrees for a few hours. X-ray powder diffraction is used to verify the crystal structure, phase purity, and structural refinement of the NCSO-based phosphors. Upon light excitation at 299 nm, the phosphors show blue-red dual emission. The blue emission (300-500 nm) may have originated from the P-3(1) -> S-1(0) transition of Bi3+, whereas the red emission (575-725 nm) is attributable to the D-5(0) -> F-7(J) (J = 1, 2, 3 and 4) transition of Eu3+ ions. Energy transfer from Bi3+ to Eu3+ is systematically investigated and the thermal stability of the phosphors is analyzed using temperature-dependent spectroscopy. The emission spectra of NCSO: Bi3+, Eu3+ are consistent with the absorption spectra of chlorophyll a, chlorophyll b, phytochrome P-R, and phytochrome P-FR. These results indicate that the obtained phosphors exhibit significant potential for inducing plant growth.