The invention provides a near-
infrared fluorescent material activated by Sm < 2 + > as well as a preparation method and application of the near-
infrared fluorescent material. The
chemical composition of the fluorescent material is Si < 2-x > Al < x > N < 2 + y > O < 1-y >: Mz, Smm, Lnn, m in the formula is one or more elements of Ba, Sr, Ca and Mg; ln is one or more elements of Bi, Yb, Eu, Nd, Gd, Tb, Dy, Ho, Er, Tm and Pr; 0 < = x < = 0.2, 0.1 < = y < = 0.5, 0 < = z < = 0.5, 0 < = m < = 0.15, and 0 < = n < = 0.1. The
luminescent material provided by the invention has a brand new
chemical composition, takes Sm < 2 + > as an activation center, and shows a near-
infrared luminescence behavior in a gap occupation manner. The fluorescent material can be excited by light within the
wavelength range of 300-600 nm, so that narrow-band near-infrared light of 681 nm is emitted, and therefore, the fluorescent material can convert
ultraviolet light, purple
blue light and
green light into near-infrared light. The near-infrared fluorescent material provided by the invention has the advantages of convenient synthesis method and stable chemical properties, and is suitable for the fields of
biological imaging,
plant growth illumination,
white light LEDs, temperature sensors and the like.