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Near infrared (NIR) phosphors have been booming as promising candidates for agriculture due to the adjustable spectrum and excellent match with the dyes of the plants. Here, Mn4+ activated double perovskite LaMg 2/3 Mn 1/3 O 3 NIR phosphor was prepared, which showed high match with the absorption spectra of phytochrome P FR. Concentration of Mg2+ was decreased to create octahedron vacancy into the lattice to improve the luminescence performance. Structure and luminescence variation of the phosphors LaMg 2/3- x Nb 1/3 O 3 :Mn4+ along with the increased vacancy concentration were carried out. Relative sensitivity S r of the optimized LaMg 0.57 Nb 0.33 O 3 :Mn4+ reaches 3.109 % and exhibits great application potential in temperature sensor. Both the NIR light emitting diode (LED) and white LED were fabricated by using this double perovskite NIR phosphor and applied to the cultivation of dragon fruit as light compensation. The dragon fruits matured faster than those without any light compensation. These results confirm the great application potential of this double perovskite NIR phosphor in temperature sensor and plant cultivation. [ABSTRACT FROM AUTHOR]

Near infrared (NIR) phosphor has continued booming in plant cultivation due to the excellent match with the phytochrome P FR and P R. Herein, the garnet NIR phosphor Gd 3 Ga 5 O 12 :Cr3+ is prepared and energy transfer engineering is created by co-doping with Bi3+. Enhanced luminescence improvement is observed in the Bi3+ co-doped samples and the energy transfer between Bi3+ and Cr3+ is confirmed. Optimized Gd 2.96 Bi 0.04 Ga 4.96 Cr 0.04 O 12 exhibits abnormal thermal quenching behavior and the integral emission intensity reaches 102% of that at room temperature. The relative sensitivity S r and absolute sensitivity S a were estimated to be 0.19% K−1 and 0.252 K−1, respectively. This garnet NIR phosphor is coated to the blue chip to fabricate the NIR light emitting diodes for dragon fruit tree cultivation as light compensation during the night. The spectrum of the device covers well of all the absorption spectra of chlorophyll B and phytochrome P FR , exhibiting huge application of this garnet NIR phosphor in plant cultivation. • Energy transfer induced luminescence enhancement of Cr3+. • Abnormal thermal quenching of this NIR phosphor. • NIR LED application in the cultivation of dragon fruit. [ABSTRACT FROM AUTHOR]

Cr3+ doped near infrared (NIR) phosphors have remained exploding in the area of bioimaging, food detection and plant cultivation. Herein, the spinel ZnGa 2 O 4 :Cr3+ NIR phosphor was prepared and the defect was introduced into the matrix via substituting the bivalent Zn2+ with the trivalent Ga3+. Structure variation and the microstructure of the phosphors were investigated and the state of the elements was confirmed. The existence of the defect in the lattice was verified by X-ray photoelectron spectroscopy and thermoluminescence. By substituting Zn2+ with Ga3+ both the emission intensity and the thermal stability were improved. Thermal stability improvement was explored as the result of the defect level in the lattice. The emission intensity of the optimized Zn 0.98 Ga 2.02 O 4+δ :Cr3+ kept 77.3% at 423 K than that at room temperature. This work provides a strategy to enhance the luminescence efficiency and thermal stability simultaneously of Cr3+ doped NIR phosphors. • Simple strategy to introduce defects • Defect engineering induced thermal stability improvement • Good thermal stability of optimized Zn 0.98 Ga 2.02 O 4 :Cr3+ [ABSTRACT FROM AUTHOR]