Near-infrared(NIR)phosphor-converted light-emitting diodes(pc-LEDs)hold great promise for versa-tile applications such as non-destructive analysis,machine vision and biological imaging.Currently,exploring effi-cient broadband tunable NIR-Ⅰ-emitting phosphors applicable for NIR pc-LEDs has been an ongoing focus among material researchers.Herein,we firstly synthesize two kinds of NIR-emitting perovskite-type Sr3MgTa2O9∶Cr3+and Ba3MgTa2O9∶Cr3+phosphors via the solid-state reaction,both of which possess the characteristic of broadband emis-sion bands covering the NIR-Ⅰ spectral range from 700 nm to 1 000 nm.Fine regulating Ba2+/Sr2+dopant ratio in(Sr1-mBam)3MgTa2O9∶Cr3+solid-solution phosphors further achieves the continuously adjustable NIR luminescence with the emission peak position tuning from 786 nm to 848 nm,due to the weakened crystal field environment of crys-tallographic Mg2+site which is occupied by Cr3+ion.The representative Sr0.4Ba0.6MgTa2O9∶0.015Cr3+phosphor exhibits high internal quantum efficiency(82.1%)and favorable thermal stability(I423 K/I298 K=73.6%),which is competitive with some other emerging Cr3+-doped NIR-emitting phosphors.Finally,a prototype NIR pc-LED by uti-lizing Sr0.4Ba0.6MgTa2O9∶0.015Cr3+phosphor and a blue LED chip achieves the ideal NIR output with satisfactory lu-minous efficacy of 63.28 lm/W,exhibiting its enormous potential for practical applications in the fields of veins imag-ing and night vision.The present study develops a series of novel NIR-emitting perovskite-type phosphors with excel-lent luminescent properties based on the mineral-type structural prototype and cationic substitution strategy,which will provide a basis for design of Cr3+-doped broadband tunable NIR-Ⅰ-emitting phosphors.
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