Rare Earth Dy3+ Activated MgSrAl10O17 Phosphors for Luminescence

MgSrAl10O17:xDy3+ nanophosphors were fabricated by combustion method for different concentrations (x = 0, 0.0005, 0.001, 0.005, 0.01 and 0.02 mol) of Dysprosium (Dy). The synthesized nanophosphors were characterized by XRD, SEM, TEM, FTIR, PL and TL. The XRD (X-ray diffraction) showed crystalline hexagonal structure with preferred orientation of (107) plane. SEM (Scanning electron microscope) result shows the formation of nanosheets in irregular shape. TEM (transmission electron microscope) study revealed the nanoparticles within average diameter size of 30 nm. The FTIR ( fourier transform infrared spectrum) shows absorption peaks in numerous regions. TL (thermo-luminescence) properties included TL glow curves and TL response for different concentrations of Dy after exposure of 700 Gy gamma rays. TL intensity was found to increase with increase in concentration of dopant Dy and was found to show best result for x=0.02. Further PL (photoluminescence) characterization ofMgSrAl10O17:0.02 Dy3+ phosphor exhibits two main emission peaks at 484 and 575 nm due to Dy3+ ion, when excited with 350 nm wavelength.

Thermo-luminescence Response of Carbon Nanotubes and Some Other Familiar TL Materials Using Medical LINAC

Strain and impurity defects in carbon nanotubes (CNTs) particularly their potentiality as a new TL material has been studied over the years. In this research, our main objective is to explore the suitability of using CNTs and its composites in the area of TL dosimeter. For this purpose, a study was carried out between the TL responses of the dosimeters TLD-100, TLD-7000 and NaI-LiF pellets. To carry out this research, equivalent irradiations were performed with these pellets using clinical linear accelerator (LINAC) under 6 MV X-ray photon beam. The dose range was from 0.5 to 5 Gy. During irradiation, the dose rate was kept constant at 300 MU/min. TLD reader was used to readout the samples in a flowing N2 atmosphere to reduce surface oxidation.During readout, pre-heat temperature was set initially at 50 °C, acquired temperature rate 10 °C/s and maximum annealed temperature was 300 °C. Response of TLD-100 under varying dose was typically linear for any doses but other dosimeters TLD-7000 showed supra-linearity beyond 2 Gy and NaI-LiF pellets showed sub-linearity response after 2 Gy. The TL glow peak of CNTs indicated that it was lying somewhere away from 300 °C.

The Luminous mechanism of Eu2+ and Dy3+ co-doped long persistent luminous fiber

Fiber-forming polymer polyethylene terephthalate chips were blended with Eu2+ and Dy3+ co-doped SrAl2O4 (SAOED) to afford luminous fiber with long and persistent afterglow. A dynamical model was set up to study the afterglow process in order to correlate the afterglow characteristics with the trap levels of SAOED and luminous fiber. The results indicated that the illustration of initial afterglow for luminous fiber was obviously lower than that of SAOED, but its decay process was moderately slow and therefore longer than that of SAOED. Compared with SAOED, the thermo-luminescence peak of the fiber shifted to the higher temperature, and its intensity was lower than that of SAOED. With the time extension of delay time after excitation, the depth of trap level for luminous fiber in our studies did not show any significant change. The afterglow decay behavior can be best fit by using I = I0/(1 + bt)2; the fitting showed that the afterglow decay process followed the second order dynamics.