Novel red colour emitting Ca_0.995Mg₂(SO₄)₃:0.5Eu²⁺ phosphor under ultraviolet, blue, and green excitation for plant growth LEDs

Abstract

In the recent few years, Eu 2+ -and Mn 4+ -activated phosphors are widely used as potential colour converters for indoor plant cultivation lighting application due to their marvellous luminescence characteristics as well as low cost. In this investigation, we synthesized novel red colour-emitting Ca (2Àx) Mg 2 (SO 4 ) 3 :xmol% Eu 2+ (x = 0-1.0 mol%) phosphors via a solid-state reaction method in a reducing atmosphere. The photoluminescence (PL) excitation spectra of synthesized phosphors exhibited a broad excitation band with three excitation bands peaking at 349 nm, 494 nm, and 554 nm. Under these excitations, emission spectra exhibited a broad band in the red colour region at $634 nm. The PL emission intensity was measured for different concentrations of Eu 2+ . The maximum Eu 2+ doping concentration in the Ca 2 Mg 2 (SO 4 ) 3 host was observed for 0.5 mol%. According to Dexter theory, it was determined that dipole-dipole interaction was responsible for the concentration quenching. The luminous red colour emission of the sample was confirmed using Commission international de l'eclairage colour coordinates. The results of PL excitation and emission spectra of the prepared phosphors were well matched with excitation and emission wavelengths of phytochrome P R . Therefore, from the entire investigation and obtained results it was concluded that the synthesized Ca 0.995 Mg 2 (SO 4 ) 3 :0.5mol %Eu 2+ phosphor has huge potential for plant cultivation application.