Search

LiF crystal doped with magnesium (Mg), copper (Cu) and phosphorous (P) was grown in the form of multicrystalline sheet using Edge-defined film-fed growth (EFG) technique for dosimetry application. These crystals were grown in argon gas atmosphere using graphite crucible and stainless steel die. Dosimetry peak was observed at 210 °C for as-grown crystal. As reported earlier LiF:Mg, Cu, P is a highly sensitive material but losses its sensitivity if annealed at temperature above 240 °C. In this paper, the effect of annealing temperature on thermoluminescence glow-curve structure, maximum peak temperature, peak height and integrated area of the glow peak of EFG grown samples was investigated in detail. Annealing temperature range from 220 °C to 500 °C was considered for the study. Experimental results of the obtained glow curve show that with increase in annealing temperature, glow peak shift towards higher temperature region with substantial increase in TL intensity. Annealing at 500 °C for 10 min gave maximum TL intensity with main dosimetry peak positioned at 233 °C. Change in the defect structure with different pre-annealing temperature was analysed using trapping parameters. [ABSTRACT FROM AUTHOR]

Abstract: The Rhodamine 6G (R6G) dye sample synthesized by thermal evaporation method is irradiated by 120 MeV Ag+9 ions at different fluences from 1 × 1011 ion/cm2 to 3 × 1012 ion/cm2. These samples are characterized by X-ray diffraction (XRD), ultraviolet–visible (UV–Vis) absorption spectroscopy and photo-conductivity measurements. In XRD, it is observed that amorphous nature of dye films increases with fluence and hence aggregates of dye molecules spread homogeneously on the substrate after irradiation. The absorption spectroscopy and photoconductivity results show maximum absorption and minimum photoresistivity at lowest fluence. The properties of the dye films such as increase in amorphous nature, increase in absorption peak area and marginal increase in photoconductivity are favorable for Dye-sensitize solar cell (DSSC) applications. [Copyright &y& Elsevier]

This work focuses on the synthesis and characterization of Tb doped LiCaAlF 6 phosphor for its OSL dosimetry properties. The phosphor has been prepared by melting method. XRD shows the formation of LiCaAlF 6 with enrichment of CaF 2. The excess availability of Ca2+ions are advantageous in incorporation of Tb dopant. The photoluminescence studies show the increase in the luminescence intensity after Tb doping by showing strong emission corresponding to 5D 4 → 7F J (J = 6, 5, 4, 3) transitions with a prominent green emission transition 5D 4 → 7F 5 at 540 nm. Further, Tb ion exist in Tb3+ and Tb4+ state as observed from XPS. The incorporation of Tb4+ ion is difficult to achieve and its presence in the host might also increase the of number of trapping states. The OSL studies of LiCaAlF 6 : Tb show high intensity under blue light stimulation for beta irradiation in the dose range 0.05–10Gy. The OSL sensitivity of LiCaAlF 6 : Tb phosphor is found to be ∼8 times higher to that of commercially available Al 2 O 3 : C. The phosphor has shown dose linearity in the range of 0.05–10Gy and minimum detectable dose (MDD)∼6.95 μGy. The enhanced sensitivity may be attributed to the additional defect centers due to excess CaF 2 with mixed oxidation state of Tb3+ and Tb4+ ions. The enhancement of OSL signal of LiCaAlF 6 : Tb in comparison to Al 2 O 3 :C has been discussed based on charge compensation mechanism. These results indicate that LiCaAlF 6 : Tb phosphor prepared via melting method in Ar gas atmosphere shows good OSL properties and has potential application in radiation dosimetry. • Synthesis of Tb doped LiCaAlF 6 phosphor using melting method in argon atmosphere. • XPS results confirm the co-existence of mixed oxidation state i.e., Tb3+ and Tb4+. • PL spectra confirm the existence of Tb3+ associated defects in LiCaAlF 6 phosphor. • The OSL sensitivity LiCaAlF 6 : Tb phosphor is found to be ∼1.5 times higher than commercially available Al 2 O 3 :C phosphor. • Insight into Tb3+/Tb4+ incorporation in LiCaAlF 6 host and its impact on trapping centers and Tb distribution. [ABSTRACT FROM AUTHOR]