Cubic to amorphous transformation of Se in silica with improved ultrafast optical nonlinearity

Abstract

We report a cubic to amorphous transformation of selenium in silica xerogel with potential industrial application as ultrafast laser safety materials.

Enhanced Ultrafast Nonlinear Optical Response in Ferrite Core/Shell Nanostructures with Excellent Optical Limiting Performance

“…Remarkably, the experimental β values are in the range of 10 −12 –10 −13 cm W −1 , which are comparable to those recently reported in CuO/Graphene hybrids (β ≈ 10 −12 cm W −1 ), reduced graphene oxide (β ≈ 10 −12 cm W −1 ), BiFeO 3 (β ≈ 10 −12 cm W −1 ), Fe 2 O 3 (β ≈ 10 −13 cm W −1 ), SiO 2 ‐Se (β ≈ 4.8 × 10 −13 cm W −1 ), CuS nanoparticles (β ≈ 6 × 10 −13 cm W −1 ), and CuS quantum dots (β ≈ 2.3 × 10 −12 cm W −1 ) . The β values are also comparable to those of CdSe quantum dots (in the size range of 2–3.9 nm) dispersed in hexane, which are in the range of 10 −12 cm W −1 .…”

“…Here, we report ultrafast optical nonlinearities measured in a series of ferrite core/shell nanoparticles, MnFe 2 O 4 /CoFe 2 O 4 and CoFe 2 O 4 /MnFe 2 O 4 , with different core diameter and shell thickness, studied by the open aperture Z‐scan technique. The results show that for 100 fs, 800 nm laser pulses, the core/shell architecture leads to an enhanced optical limiting performance, with optical limiting efficiencies comparable to, or better than, those of benchmark materials reported in the literature . It may be noted that the 800 nm wavelength is rather common for biomedical applications given the minimal absorption of water (and other biological fluids) around this wavelength …”

Complementary combinative strategy of defect engineering and graphene coupling for efficient energy‐functional materials

“…According to transmission electron microscopy (TEM) analysis, the defect‐introduced amorphous aM showed 0D nanocrystal morphology with the size of several tens of nanometers, see Figure S1. As illustrated in the selected area electron diffraction (SAED) patterns, aM did not display diffused ring without distinct diffraction spots, whereas well‐defined diffraction spots were discernible for cM , confirming the crystallization of amorphous aM upon the calcination [11] . As can be seen from Figure 1c, the field emission‐scanning electron microscopy (FE‐SEM) analysis for aMG and cMG clearly demonstrated the composite formation of molybdenum dioxide with 2D rGO nanosheets.…”

Solid-State Fluorescent Selenium Quantum Dots by a Solvothermal-Assisted Sol–Gel Route for Curcumin Sensing

“… 6 − 9 Dependence of ultrafast optical nonlinearity on the cubic and amorphous forms of Se quantum dots is studied in silica xerogels prepared through a simple sol–gel route. 5 Although some progress has been achieved in the synthesis of t-Se nanoparticles 7 , 10 , 11 through green assisted synthesis as well as precursor conversion methods, synthesis of t-Se quantum dots has not been equally explored. Recently, t-Se QDs have been synthesized by ultrasound liquid-phase exfoliation (LPE) of NbSe 2 powders using N -methyl-2-pyrrolidone (NMP) as the dispersant.…”

“…Among them, selenium holds an inimitable position at the boundary of group VI in the periodic table between van der Waals molecular solids (O 2 and S 8 ) and the covalent solid Te. It can exist in several solid modifications: two monoclinic (α and β), the most stable trigonal form, one cubic, and one amorphous modification . Prior studies widely focused on amorphous Se (a-Se) nanoparticles and trigonal Se (t-Se) nanowires due to their ease of formation and stability. − Dependence of ultrafast optical nonlinearity on the cubic and amorphous forms of Se quantum dots is studied in silica xerogels prepared through a simple sol–gel route .…”