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In this paper, an aqueous-based approach is introduced for facile, fast, and green synthesis of gradient-alloyed Fe-doped ZnSe(S)@ZnSe(S) core:shell quantum dots (QDs) with intense and stable emission. Co-utilization of co-nucleation and growth doping strategies, along with systematic optimization of emission intensity, provide a well-controllable/general method to achieve internally doped QDs (d-dots) with intense emission. Results indicate that the alloyed ZnSe(S)@ZnSe(S) core:shell QDs have a gradient structure that consists of a Se-rich core and a S-rich shell. This gradient structure cannot only passivate the core d-dots by means of the wider band gap S-rich shell, but also minimizes the lattice mismatch between alloyed core-shell structures. Using this novel strategy and utilizing the wider band gap S-rich shell can obviously increase the cyan emission intensity and also drastically improve the emission stability against chemical and optical corrosion. Furthermore, the cytotoxicity experiments indicate that the obtained d-dots are nontoxic nanomaterials, and thus they can be considered as a promising alternative to conventional Cd-based QDs for fluorescent probes in biological fields. Finally, it is demonstrated that the present low-toxicity and gradient-alloyed core:shell d-dots can be used as sensitive chemical detectors for Pb ions with excellent selectivity, small detection limit, and rapid response time.

The purpose of this investigation is to study dc conductivity in glass systems with a combination of 40P 2 O 5 _xV 2 O 5 _(35-x)MoO 3 _5CaO_20Li 2 O. The specimens were prepared by the conventional melt-quenching technique. The dependence of the dc conductivity on temperature and the initial concentration of samples was evaluated, and it was observed that it increases with an increase in temperature for all samples. As the vanadium oxide percentage increased, the dc conductivity also increased, and the activation energy decreased almost uniformly. Variations of activation energy and conductivity are compatible with theoretical concepts. The conductivity of these samples is mixed electronic-ionic conduction, but because of variation in the transition metal oxide concentration, electronic conductivity is more effective as a result of small polaron hopping. Also, the differential scanning calorimetry measurements of these glasses (a heating rate of 10 °C Min −1 ) were investigated, and glass transition temperatures (T g ) were determined for each chemical composition. It was shown that the enhancement of MoO 3 concentration leads to a decrease in T g values.

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