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 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 3P1 → 1S0 transition of Bi3+, whereas the red emission (575–725 nm) is attributable to the 5D0 → 7FJ (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 PR, and phytochrome PFR. These results indicate that the obtained phosphors exhibit significant potential for inducing plant growth.