Thermoluminescence Analysis of NIR Persistent Phosphor (LGO:Cr) Synthesized using Sol–Gel and Solid-State Methods

The NIR (near-infrared) persistent phosphor, LiGa 5 O 8 :Cr 3+ (LGO:Cr), is a suitable candidate for bioimaging applications. Understanding the trap characteristics of the LGO:Cr persistent phosphors could enhance their properties. LGO:Cr can be prepared by two different methods: solid-state reaction and sol–gel. In this work, thermoluminescence (TL) analysis of LGO:Cr prepared by the two methods has been performed, revealing that the mode of preparation and irradiation energy play a vital role in using this phosphor. TL analysis found that, for in vivo imaging, LGO:Cr prepared using solid-state synthesis and irradiated with UV rays is better than the LGO:Cr prepared using sol–gel. However, LGO:Cr prepared using sol–gel is better for dosimetry than LGO:Cr prepared using solid-state synthesis provided it has stable fading and a linear dose response. Computerized glow curve deconvolution (CGCD) was performed using a temperature-dependent frequency factor equation. The results showed that the TL curve of LGO:Cr can be described using 13 TL peaks. The activation energy of the trap ranges from 0.6 eV to 1.44 eV, the fraction of empty traps that take part in the retrapping process is about 0.001–0.216, the temperature-dependent frequency factor ranges from 36,000 to 39,300 s −1 °K −2 , and the capture cross-section varies from 2.157 z . 10 - 17 t o 8.789 z . 10 - 18 , where z is the ratio of effective mass to the remaining mass of the electron.