Metal nanoparticles (MNPs) hold great technological promise because of the possibility of engineering their electronic and optical properties through material design. One of the effective methods to fabricate MNPs is ion implantation. In this review, recent results on the nonlinear optical properties of nanoparticles (including copper, silver, gold, and bismuth nanoparticles) doped in various bases have been discussed. Some specific optical nonlinear properties, such as nonlinear refraction, two-photon absorption, and optical limiting, for femtosecond, picosecond, and nanosecond laser pulses have also been covered. In addition to ion implantation, we have summarized several other methods for the preparation of composite materials, and Z-scan has been used to study the nonlinear optical properties of these materials.

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Nonlinear optical properties of metal nanoparticles: a review

Crystalline ceramics are intensively investigated as effective materials in various nuclear energy applications, such as inert matrix and accident tolerant fuels and nuclear waste immobilization. This paper presents an analysis of the current status of work in this field of material sciences. We have considered inorganic materials characterized by different structures, including simple oxides with fluorite structure, complex oxides (pyrochlore, murataite, zirconolite, perovskite, hollandite, garnet, crichtonite, freudenbergite, and P-pollucite), simple silicates (zircon/thorite/coffinite, titanite (sphen), britholite), framework silicates (zeolite, pollucite, nepheline /leucite, sodalite, cancrinite, micas structures), phosphates (monazite, xenotime, apatite, kosnarite (NZP), langbeinite, thorium phosphate diphosphate, struvite, meta-ankoleite), and aluminates with a magnetoplumbite structure. These materials can contain in their composition various cations in different combinations and ratios: Li-Cs, Tl, Ag, Be-Ba, Pb, Mn, Co, Ni, Cu, Cd, B, Al, Fe, Ga, Sc, Cr, V, Sb, Nb, Ta, La, Ce, rare-earth elements (REEs), Si, Ti, Zr, Hf, Sn, Bi, Nb, Th, U, Np, Pu, Am and Cm. They can be prepared in the form of powders, including nano-powders, as well as in form of monolith (bulk) ceramics. To produce ceramics, cold pressing and sintering (frittage), hot pressing, hot isostatic pressing and spark plasma sintering (SPS) can be used. The SPS method is now considered as one of most promising in applications with actual radioactive substances, enabling a densification of up to 98-99.9% to be achieved in a few minutes. Characteristics of the structures obtained (e.g., syngony, unit cell parameters, drawings) are described based upon an analysis of 462 publications.

Ceramic Mineral Waste-Forms for Nuclear Waste Immobilization

In this contribution, we report synthesis of luminescent Ag nanoclusters (NCs, 1 nm average diameter) directly conjugated to an enzyme, bovine pancreatic α-chymotrypsin (CHT). The structural characterization of Ag−CHT nanobioconjugates was done using steady-state UV−vis absorption/photoluminescence spectroscopy and high-resolution transmission electron microscopy. By use of the spherical jellium model, the emission energy of CHT-conjugated Ag NCs was correlated with the number of atoms in the cluster and was found to be almost consistent with the experimental result. To establish the conformational changes of the enzyme before and after the conjugation of Ag NCs, circular dichroism studies were performed. The functional integrity of the enzyme conjugated to Ag NCs was investigated by monitoring the enzymatic activity of Ag−CHT conjugates by using UV−vis absorption spectroscopy and compared with the unbound enzyme under similar experimental conditions. To confirm the conjugation of Ag NCs to CHT, we carrie...

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Structural and Functional Characterization of Luminescent Silver−Protein Nanobioconjugates

Novel highly efficient and thermally stable Ca2GdTaO6:Eu3+ red-emitting phosphors with high color purity for UV/blue-excited WLEDs

The investigation on the modification of NaY zeolite on LaHY and AEHY (AE refers Ca and Sr and the molar ratio of Ca and Sr is 1:1) zeolites was proformed by XRD, N2-physisorption (BET), XRF, XPS, NH3-TPD, Py-IR, hydrothermal stability, and catalytic cracking test. These results indicate that HY zeolite with ultra low content Na can be obtained from NaY zeolite through four exchange four calcination method. The positioning capability of La3+ in sodalite cage is much better than that of AE2+ and about 12 La3+ can be well coordinated in sodalite cages of one unit cell of Y zeolite. Appropriate acid amount and strength favor the formation of propylene and La3+ is more suitable for the catalytic cracking of cyclohexane than that of AE2+. Our results not only elaborate the variation of the strong and weak acid sites as well as the Bronsted and Lewis acid sites with the change of exchanged ion content but also explore the influence of hydrothermal aging of LaHY and AEHY zeolites and find the optimum ion exchange content for the most reserved acid sites. At last, the coordination state and stabilization of ion exchanged Y zeolites were discussed in detail.

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The effect of positioning cations on acidity and stability of the framework structure of Y zeolite

Linear and nonlinear optical absorption in copper nanocluster-glass composites

Electronic structure and electrical conduction by polaron hopping mechanism in A2LuTaO6 (A= Ba, Sr, Ca) double perovskite oxides

Dielectric relaxation and conduction mechanism in Ba2GdTaO6

The crystal structures of the double-perovskite oxide A2SmTaO6 series (AST, A = Ba, Sr, Ca) synthesized by solid-state reaction technique are determined from X-ray powder diffraction data. Rietveld refinements of the X-ray diffraction data of the samples show that Ba2SmTaO6 (BST) crystallizes in cubic phase and Sr2SmTaO6 (SST) and Ca2SmTaO6 (CST) crystallize in monoclinic phase. Fourier transform infrared spectra show two primary modes of the samples at around 370 and 600 cm−1. The vibrational properties of the samples are studied by Raman spectroscopy taken at 488-nm wavelength. Group-theoretical study is performed to assign the different vibrational modes of the samples in accordance with structural symmetry. The observed shifts of some vibrations in the SST and CST w.r.t. BST upon changing the A cation are tentatively explained. Dielectric spectroscopy is applied to investigate the ac electrical conductivity of AST in different temperatures between 303 and 673 K and in a frequency range of 42 Hz–1 MHz. The complex impedance plane plots show that the relaxation (conduction) mechanism in these materials is purely a bulk effect arising from the semiconductive grains. The relaxation mechanism of the samples is modeled by Cole–Cole equation. The frequency-dependent conductivity spectra are found to follow the power law.

Binita Ghosh

Papers

Linear and nonlinear optical absorption in copper nanocluster-glass composites

Electronic structure and electrical conduction by polaron hopping mechanism in A2LuTaO6 (A= Ba, Sr, Ca) double perovskite oxides

Dielectric relaxation and conduction mechanism in Ba2GdTaO6

Dielectric Relaxation and Collective Vibrational Modes of Double-Perovskites A2SmTaO6 (A = Ba, Sr and Ca)

Enhanced nonlinear optical responses in metal-glass nanocomposites