Efficient deep-red-emitting CaMg2La2W2O12:Mn4+, Nd3+ phosphor toward indoor plant cultivation LED lighting

This study presents the synthesis and characterization of efficient deep-red-emitting CaMg 2 La 2 W 2 O 12 :Mn 4+ , Nd 3+ (CMLW:Mn 4+ , Nd 3+ ) phosphors for application in light-emitting diodes (LEDs) designed for indoor plant cultivation. The phosphors were prepared via a high-temperature solid-state reaction and exhibited an orthorhombic structure with optimal luminescence properties at Mn 4+ (0.90 %) and Nd 3+ (0.60 %) doping concentrations. The enhanced performance of CMLW:0.90 %Mn 4+ , 0.60 %Nd 3+ over its Nd 3+ -free counterpart originates from three synergistic mechanisms: (1) Nd 3+ substitution for larger La 3+ induces lattice shrinkage, shortening the Mn 4+ -O 2- bond length and enhancing the crystal-field strength, thereby increasing the radiative transition probability of 2 E g → 4 A 2g emission at 708 nm; (2) Nd 3+ co-doping suppresses concentration quenching by increasing the critical distance between Mn 4+ ions, as evidenced by prolonged lifetime and higher optimal Mn 4+ concentration; (3) The optimal Nd 3+ concentration improves lattice rigidity while avoiding defect formation observed at higher doping levels. The resulting phosphor demonstrates intense deep-red emission matching the phytochrome P FR absorption band, excellent thermal stability (73.66 % intensity at 453 K), and a high internal quantum efficiency (IQE) of 86.80 %. A prototype LED device exhibits stable deep-red emission and a luminous efficacy of 0.10 lm/W under 365 nm excitation. These results position CMLW:Mn 4+ , Nd 3+ phosphor as a promising candidate for indoor plant cultivation LEDs.