R.N. Dubey

Synthesis and detailed kinetic analysis of Sr4Al14O25:Eu2+ phosphor under black light irradiation

Black light source (360 nm) is used to undertake detailed kinetic analysis of strontium aluminate (Sr4Al14O25:Eu2+) with a long-lasting afterglow. Thermally stimulated luminescence studies were carried out to obtain different trapping parameters such as order of kinetics, frequency factor(s) and activation energy (E). The non-shifting T m property in the measured glow curves is used to describe the order of kinetics. Decay studies are also used to verify the order of kinetics. Double peak structure is obtained with peaks at 487 and 423 K. Glow curve deconvolution function using a computerized package is applied to find the associated trapping parameters. McKeevers T m–T stop method is applied to determine the trap distribution and to approximate energies. The depth of the traps is found to be varying within 0.50 and 1.36 eV. Photoluminescence studies reveal the emission characteristics and mechanism. The emission peak is obtained at 487 nm.

Study Of Effect Of Anthracene Doping On EB‐PAni

Anthracene doped emeraldine base polyaniline (EB‐PAni) compounds were prepared through emulsion polymerization reaction. The difference of two orders of magnitude was observed in room temperature conductivity (σ) of bare and doped EB‐PAni. For bare EB‐PAni σ = 1.13×10−3 Sm−1 and σ = 15.0×10−5 Sm−1 for doped EB‐PAni with highest dopant concentration. UV‐VIS absorption studies indicate that with increasing dopant concentration the intensity of absorption at 600 nm increases. This is attributed to the change in population of quinoid imine units in the polymer backbone. Two significant changes were observed in the FTIR spectrum of bare and doped EB‐PAni. First is appearance of a peak at 1140.0 cm−1 in doped compounds, attributed to vibration mode of the ‐NH+= structure. It suggests oxidation of polymer backbone. And second is decrease in intensity in the peak at 1294.8 cm−1 in doped EB‐PAni, which is attributed to decrease in π electron delocalization across the polymer backbone. Therefore doping of anthracen...