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

The micro-structures and vibrational modes of complex double perovskite oxides xLaAlO 3 – (1-x)Ba(Mg 1/2 W 1/2 )O 3 [LA-BMW] have been characterized for different values of x (0.10, 0.25, 0.50, 0.75 and 0.90). The materials are synthesized by the solid state reaction technique. The Rietveld refinement of the XRD patterns shows rhombohedral (161) phase for LaAlO 3 and cubic  (225) phases for Ba(Mg 1/2 W 1/2 )O 3 . XRD patterns show that with increasing the doping concentration ‘x’, rhombohedral phase gradually increases and cubic phase gradually decreases. A meticulous comparison of crystal structures and vibrational degrees of freedom in the light of change in doping concentration ‘x’ for LA-BMW has been carried out for accurate identification of crystal symmetry and distortions. From room-temperature comparative Raman spectra of the samples, different vibrational phonon modes have been assigned using group theoretical analysis together with experimental literature survey.

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Micro-Structure and Vibrational Mode of Complex Double Perovskite Oxides xLaAlO3 – (1-x)Ba(Mg1/2 W1/2 )O3

Linear and nonlinear optical properties of copper and gold nanoclusters in fused silica glasses synthesized by 200 KeV Cu+ and 1.5 MeV Au+ ion implantation at a dose of 3x1016 ions/cm2 have been studied. UV-Vis spectroscopy has revealed prominent linear absorption bands at characteristic surface plasmon resonance (SPR) frequency signifying appreciable formation of copper and gold colloids in glass matrices. Third-order optical properties of the nanocluster-glass composite materials have been studied by Z-Scan and Anti Resonant Interferometric Nonlinear Spectroscopy (ARINS) techniques. The sign of the nonlinear refraction is readily obtained from Z-scan signature. The ARINS technique utilizes the dressing of two unequal-intensity counter-propagating pulsed beams with differential nonlinear phases, which occur upon traversing the sample. This difference in phase manifests itself in the intensity-dependent transmission. The nonlinear refractive index, nonlinear absorption coefficient and the real (and imaginary) parts of the third-order optical susceptibility have been extracted from ARINS data. Results of the investigation of the nonlinear refraction using the above two techniques and the possible mechanisms responsible for the nonlinear optical responses are presented in the current paper.

https://iopscience.iop.org/article/10.1088/1742-6596/185/1/012010/pdf

Anti-Resonant Interferometric Nonlinear Spectroscopy (ARINS) study of metal nanocluster-glass composites

The Optical and dielectric mechanism of complex double perovskite oxides xLaAlO3 – (1-x)Ba(Mg1/2W1/2)O3 [LA-BMW] have been characterized for different values of x (0.10, 0.25, 0.50, 0.75 and 0.90). UV–Visible absorption optical spectra show that with increase in concentration x, the band gap of the corresponding sample slowly decreases from 5.59eV to 4.75eV systematically. The dielectric data have been measured using a LCR meter (Hioki-3532-50, Japan) in the frequency range from 50 Hz to 4.8 MHz as a function of temperature varying from 300 K to 723 K. The dielectric data shows that room temperature conductivity increases with increase in the doping concentration x. A comparative study has been carried out to corelate structural variation with change in band gap which in turn effects the electrical properties of the samples.

Optical and dielectric mechanism of complex double perovskite oxides xLaAlO3 – (1-x)Ba(Mg1/2 W1/2)O3

Europium-doped luminescent barium samarium tantalum oxide Ba2SmTaO6 (BST) has been investigated by first-principles calculation, and the crystal structure, electronic structure, and optical properties of pure BST and Eu-doped BST have been examined and compared. Based on the calculated results, the luminescence properties and mechanism of Eu-doped BST has been discussed. In the case of Eu-doped BST, there is an impurity energy band at the Fermi level, which is formed by seven spin up energy levels of Eu and act as the luminescent centre, which is evident from the band structure calculations.

Understanding the photoluminescence characteristics of Eu3+-doped double-perovskite by electronic structure calculation

Since the inception of lasers, nonlinear optics has been a rapidly growing field of research in recent decades. It is based on the study of effects and phenomena related to the interaction of intense coherent light radiation with matter. In other words, nonlinear optics (NLO) is the branch of optics that describes the behaviour of light in nonlinear media, that is, the media in which the dielectric polarization P responds nonlinearly to the electric field E of the light. This nonlinearity is typically and only observed at very high light intensities (values of the electric field comparable to interatomic electric fields, typically 108 V/m) such as those provided by pulsed lasers. Such high powers of laser beams made it possible, for the first time, to observe that the effect of light on a medium can indeed change its optical properties, e.g. refractive index or absorption. When this happens, the light itself also gets affected by this change in a non-linear way; for example, the non-linear response of the material can convert the laser light into new colours, both harmonics of the optical frequency and sum and difference frequencies. Typically, only a laser light is sufficiently intense to modify the optical properties of a material system. In fact, the beginning of the field of nonlinear optics is taken to be the discovery of second-harmonic generation by Fraken et al. in 1961 [1], shortly after the demonstration of the first working laser by Maiman in 1960 [2]. The nonlinear effect comes essentially from ‘quantum confinement’ effect. In an unconfined (bulk) semiconductor, an electron-hole pair is typically bound within a characteristic length, called the ‘exciton Bohr radius’. This is estimated by replacing the positively charged atomic core with the hole in the Bohr formula. If the electron and hole are constrained further, then properties of the semiconductor change. Besides confinement in all three dimensions i.e. ‘Quantum Dot’ other quantum confined semiconductors include (1) quantum wires, which confine electrons or holes in two spatial dimensions and allow free propagation in the third (2) quantum wells which confine electrons or holes in one dimension and allow free propagation in two dimensions. Nonlinear optical effect in semiconductor quantum dots was observed in the minuscule crystals of semiconductor material composed of various compounds of chemicals such as cadmium, zinc, tellurium, selenium, sulphur, etc. of sizes less than 500 nanometers. These semiconductor nanoparticles or ‘quantum dots’ have been found to react to electricity or light by emitting their own light across the visible range of wavelengths from 470 to 730 nm.

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Binita Ghosh

Papers

Micro-Structure and Vibrational Mode of Complex Double Perovskite Oxides xLaAlO3 – (1-x)Ba(Mg1/2 W1/2 )O3

Anti-Resonant Interferometric Nonlinear Spectroscopy (ARINS) study of metal nanocluster-glass composites

Optical and dielectric mechanism of complex double perovskite oxides xLaAlO3 – (1-x)Ba(Mg1/2 W1/2)O3

Understanding the photoluminescence characteristics of Eu3+-doped double-perovskite by electronic structure calculation

Optical Nonlinearities of Colloidal Metal Quantum Dot - Glass Composites for Nanophotonics