| In recent years,near infrared（NIR）spectroscopy has been widely used in emerging fields due to its rapid,non-invasive and reliable advantages,such as food nondestructive testing,medical diagnosis,biomedical imaging,silicon solar cells and night vision technology.These applications rely on the characteristic absorption of chemical components in the near infrared region of the electromagnetic spectrum.Actual application demands of the near infrared light source must have a spectral bandwidth,and luminous intensity is high enough to allow the detector to collect more signal.In addition,the emission wavelength must be long enough,for deeper penetration.Compared with the traditional light source,based on the blue chips,near-infrared fluorescent powder and assembly of the near infrared leds for small volume low energy consumption long life High brightness.Due to its high sensitivity to the surrounding environment,Cr3+ ions are commonly used as emission centers to obtain broadband near-infrared light.In addition,based on the adjustment of Dq,Cr3+ ions provide a considerable wide spectrum of tunability.Therefore,it is of guiding significance and practical value to study the luminescence characteristics of Cr3+ doped oxide near infrared phosphors.Among the various types of near-infrared phosphors currently known,the Cr3+ iondoped gallium（germanium）salt phosphor has been favored by domestic and foreign scholars due to its similar radius and valence state,blue excitation,broadband emission,and tunable wavelength.Such phosphors can be combined with blue light chips to assemble NIR LEDs,which are widely used.This paper focuses on Cr3+ doped gallium germanium salts launched broadband near-infrared fluorescent powder,crystal field on the structure light emitting property morphology etc.Carried on the system research,and the synthesis of broadband near-infrared fluorescent powder combined with blue chip,made the LED light source,a preliminary exploration of its application Mainly from the following three aspects:1.The luminescence properties of a series of broadband NIR phosphors with Cr3+doped NaxCa3-xGa2-xGe4+xO14（0≤x≤2）are studied.The crystal structure was studied by XRD and Rietveld.The strategy of refined fitting is adopted to study the structure.The relationship between the intensity of crystal field and the luminescence property of crystal structure was studied,and the reason of the increase of luminescence intensity after cationic substitution was analyzed.The phosphor and the blue chip are packaged to form a near-infrared light source,and a preliminary analysis of the penetration depth of biological tissues is performed,which provides new ideas and new methods for the application of broadband-emitting near-infrared phosphors in the biological and medical fields.2.The spectral band of the emission spectrum was broadened by the multi-cell occupying strategy,and the Cr（Ⅰ）and Cr（Ⅱ）located at 1064 nm and 1180 nm were determined by Gaussian splitting of the emission spectrum.Cr Ⅰ（1064 nm）and Cr Ⅱ（1180 nm）were assigned to octahedral body position of Cr3+ occupying Sc3+and tetrahedral cell position of Cr4+occupying Ge4+,respectively.In addition,the properties such as fluorescence lifetime and thermal stability of morphologic crystal field are studied.Under the excitation of 470 nm blue light,the emission range of the phosphor is 8001600 nm ultra-broadband emission,and the peak position is at 1110 nm.Finally,the hands,arms and ears were directly irradiated with a self-made NIR-LED light source,and the photos were taken with a near-infrared camera.The imaging effect showed the application prospect of the phosphor in angiography. |
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