Spectroscopic Characterization of a Lead–Lead Dioxide Automobile Battery

Here we combine small angle neutron scattering measurements (SANS) with X-ray diffraction analysis (XRD) and infrared spectroscopy (IR) measurements to obtain information about nanoparticles formed in a series of lead-lead dioxide samples mixed with various CuO concentrations. New vitreous systems with the xCuO???(100?x)[4PbO₂???Pb] composition where x?=?0, 30, and 70?mol% CuO were prepared by the melt-quenching method using CuO mixed in suitable proportion with the active electrodes of a disassembled car battery as the starting materials. The X-ray diffraction patterns permit the identification of the metallic Pb phase and the presence of oxidic nanoparticles of the lead and copper ions. By doping with higher CuO contents, the SANS curves have a concave shape indicating inhomogeneities and tendency of phase separation due to formation of nanoparticles of the lead and copper ions in recycled host matrix. The studied samples can be considered as polydispersed systems. The matrix is the solvent and the soluble phase is formed from the oxidic lead and/or copper particles with sizes smaller than 69?Å dispersed either inside the host matrix grains or between the host matrix grains. The formation of the nanoparticles in the host matrix and the knowledge of the type of nanoparticles have a decisive role in applications for the construction of essential components of the automobile batteries.     

Incorporating Rare-Earth Terbium(III) Ions into Cs2AgInCl6:Bi Nanocrystals toward Tunable Photoluminescence

The incorporation of impurity ions or doping is a promising method for controlling the electronic and optical properties and the structural stability of halide perovskite nanocrystals (NCs). Herein, we establish relationships between rare-earth ions doping and intrinsic emission of lead-free double perovskite Cs₂AgInCl₆ NCs to impart and tune the optical performances in the visible light region. Tb³⁺ ions were incorporated into Cs₂AgInCl₆ NCs and occupied In³⁺ sites as verified by both crystallographic analyses and first-principles calculations. Trace amounts of Bi doping endowed the characteristic emission (⁵D₄→⁷F_6-3) of Tb³⁺ ions with a new excitation peak at 368 nm rather than the single characteristic excitation at 290 nm of Tb³⁺. By controlling Tb³⁺ ions concentration, the emission colors of Bi-doped Cs₂Ag(In_1−xTb_x)Cl₆ NCs could be continuously tuned from green to orange, through the efficient energy-transfer channel from self-trapped excitons to Tb³⁺ ions. Our study provides the salient features of the material design of lead-free perovskite NCs and to expand their luminescence applications.     

Unraveling Epitaxial Habits in the NaLnF4 System for Color Multiplexing at the Single‐Particle Level

We report an epitaxial growth technique for scalable production of hybrid sodium rare‐earth fluoride (NaLnF₄) microcrystals, including NaYF₄, NaYbF₄, and NaLuF₄ material systems. The single crystalline nature of the as‐synthesized products makes them strong upconversion emission. The freedom of combining a lanthanide activator (Er³⁺ or Tm³⁺) with a sensitizer (Yb³⁺) at various doping concentrations readily gives access to color multiplexing at the single‐particle level. Our kinetic and thermodynamic investigations on the epitaxial growth of core–shell microcrystals using NaLnF₄ particle seeds suggest that within a certain size regime it is plausible to exert precise control over shell thickness and growth orientation under hydrothermal conditions.     

Hydrothermal synthesis of TiO2 nanorods: formation chemistry,growth mechanism,and tailoring of surface properties for photocatalytic activities

Titanium dioxide (TiO₂) is one of the best semiconductor photocatalysts with optical band gap of 3.2 eV. The optical band gap and photocatalytic properties could be further tuned by tailoring shape, size, composition, and morphology of the nanostructures. Hydrothermal synthesis methods have been applied to produce well-controlled nanostructured TiO₂ materials with different morphologies and improved optoelectronic properties. Among various morphologies, one-dimensional (1D) TiO₂ nanostructures are of great importance in the field of energy, environmental, and biomedical because of the directional transmission properties resulting from their 1D geometry. Particularly, TiO₂ nanorods (NRs) have gained special attention because of their densely packed structure, quantum confinement effect, high aspect ratio, and large specific surface area that could specially improve the directional charge transmission efficiency. This results in the effective photogenerated charge separation and light absorption, which are really important for potential applications of TiO₂-based materials for photocatalytic and other important applications. In this review, hydrothermal syntheses of TiO₂ NRs including the formation chemistry and the growth mechanism of NRs under different chemical environments and effects of various synthesis parameters (pH, reaction temperature, reaction time, precursors, solvents etc.) on morphology and optoelectronic properties have been discussed. Recent developments in the hydrothermal synthesis of TiO₂ NRs and tailoring of their surface properties through various modification strategies such as defect creation, doping, sensitization, surface coating, and heterojunction formation with various functional nanomaterials (plasmonic, oxide, quantum dots, graphene-based nanomaterials, etc.) have been reported to improve the photocatalytic activities. Furthermore, applications of TiO₂ NRs/tailored TiO₂ NRs as superior photocatalysts in degradation of organic pollutants and bacterial disinfection have been discussed with emphasis on mechanisms of action and recent advances in the fields.     

一种通过纳米粒子的组装制备基于二氧化铈中孔材料的简易方法

用HF或者HCl作联合剂,三嵌段共聚物表面活性剂作模板剂,通过二氧化铈纳米粒子(或者过渡金属掺杂的二氧化铈纳米粒子)组装形成具有热稳定和晶化孔壁的基于二氧化铈的中孔材料。焙烧该合成的超分子模板中孔结构的材料可以形成具有高比表面的基于二氧化铈的中孔材料,这些中孔材料用不同的光谱技术表征。通过D₂-OH交换测得的二氧化铈表面的羟基在组装过程和中孔材料的稳定性方面至关重要。联结剂中的卤素离子(F和Cl离子)可以替代中孔材料的表面羟基,从而影响这些中孔材料的结构稳定性和光学活性,而用具有3 d的过渡金属在组装前掺杂二氧化铈纳米粒子可以显著地提高中孔材料的光学活性,这种提高主要归结为通过掺杂可以促使能量转移的提高。     

Review on Undoped/Doped TiO2 Nanomaterial; Synthesis and Photocatalytic and Antimicrobial Activity

This review covers the various synthetic methods of doped and undoped TiO₂ nanomaterials, ranging from single‐doped and co‐doped to multidoped with transition‐metal ions, rare earth metal ions, and other metals and nonmetals ions. The effects of doping on the physiochemical propertiesas well as the photocatalytic and antimicrobial activities of TiO₂ nanomaterial are discussed. The results from the literature show that doping of TiO₂ shifts the absorption edge to the visible region as a result of the decrease in the bandgap due to the formation of new energy levels in the bandgap. The dopent also acts as a trapping center for electrons and holes, thereby reducing the recombination rate of charge carriers and increasing the photocatalytic and antimicrobial activity of TiO₂ nanomaterials. All multidoped TiO₂ nanomaterials show higher activity than their undoped, single‐doped, and co‐doped counterparts.     

Confining Excitation Energy in Er3+‐Sensitized Upconversion Nanocrystals through Tm3+‐Mediated Transient Energy Trapping

A new class of lanthanide‐doped upconversion nanoparticles are presented that are without Yb³⁺ or Nd³⁺ sensitizers in the host lattice. In erbium‐enriched core–shell NaErF₄:Tm (0.5 mol %)@NaYF₄ nanoparticles, a high degree of energy migration between Er³⁺ ions occurs to suppress the effect of concentration quenching upon surface coating. Unlike the conventional Yb³⁺‐Er³⁺ system, the Er³⁺ ion can serve as both the sensitizer and activator to enable an effective upconversion process. Importantly, an appropriate doping of Tm³⁺ has been demonstrated to further enhance upconversion luminescence through energy trapping. This endows the resultant nanoparticles with bright red (about 700‐fold enhancement) and near‐infrared luminescence that is achievable under multiple excitation wavelengths. This is a fundamental new pathway to mitigate the concentration quenching effect, thus offering a convenient method for red‐emitting upconversion nanoprobes for biological applications.     

Recent Advances in Inorganic Nanomaterials Synthesis Using Sonochemistry: A Comprehensive Review on Iron Oxide,Gold and Iron Oxide Coated Gold Nanoparticles

Sonochemistry uses ultrasound to improve or modify chemical reactions. Sonochemistry occurs when the ultrasound causes chemical effects on the reaction system, such as the formation of free radicals, that intensify the reaction. Many studies have investigated the synthesis of nanomaterials by the sonochemical method, but there is still very limited information on the detailed characterization of these physicochemical and morphological nanoparticles. In this comprehensive review, recent advances in the sonochemical synthesis of nanomaterials based on iron oxide nanoparticles (Fe₃O₄NP), gold nanoparticles (AuNP) and iron oxide-coated gold nanoparticles (Fe₃O₄@Au NP) are discussed. These materials are the most studied materials for various applications, such as medical and commercial uses. This review will: (1) address the simple processing and observations on the principles of sonochemistry as a starting point for understanding the fundamental mechanisms, (2) summarize and review the most relevant publications and (3) describe the typical shape of the products provided in sonochemistry. All in all, this review’s main outcome will provide a comprehensive overview of the available literature knowledge that promotes and encourages future sonochemical work.     

Confining Excitation Energy in Er3+-Sensitized Upconversion Nanocrystals through Tm3+-Mediated Transient Energy Trapping

A new class of lanthanide-doped upconversion nanoparticles are presented that are without Yb³⁺ or Nd³⁺ sensitizers in the host lattice. In erbium-enriched core–shell NaErF₄:Tm (0.5 mol %)@NaYF₄ nanoparticles, a high degree of energy migration between Er³⁺ ions occurs to suppress the effect of concentration quenching upon surface coating. Unlike the conventional Yb³⁺-Er³⁺ system, the Er³⁺ ion can serve as both the sensitizer and activator to enable an effective upconversion process. Importantly, an appropriate doping of Tm³⁺ has been demonstrated to further enhance upconversion luminescence through energy trapping. This endows the resultant nanoparticles with bright red (about 700-fold enhancement) and near-infrared luminescence that is achievable under multiple excitation wavelengths. This is a fundamental new pathway to mitigate the concentration quenching effect, thus offering a convenient method for red-emitting upconversion nanoprobes for biological applications.     

Structural studies of magnetic nanoparticles doped with rare-earth elements

Magnetic nanoparticles and those doped with rare-earth metal ions having spinel structure were synthesized, possessing the average particles size of 11.3-13.4 nm. According to Mössbauer spectroscopy data it can be concluded that prepared iron oxide nanoparticles are γ-Fe₂O₃. For materials containing rare-earth elements the decrease of octahedral component surface was observed in comparison to non-doped material, what can be explained by Eu³⁺, Sm³⁺ и Gd³⁺ ions occupying the octahedral position.     

Chemical processing for inorganic fluoride and oxyfluoride materials having optical functions

Chemical processing such as a sol–gel method can offer interesting and useful routes for designing and synthesizing inorganic metal fluoride and oxyfluoride materials for applications in optics and photonics. In our series of studies during the last decade, a variety of fluoride materials including alkaline earth fluorides (MgF₂, CaF₂, SrF₂ and BaF₂), rare-earth fluorides (LaF₃, NdF₃, GdF₃, etc.), rare-earth oxyfluorides (LaOF, EuOF, GdOF, Sm₄O₃F₆, Er₄O₃F₆, etc.) and complex fluorides (SrAlF₅, BaMgF₄, BaLiF₃, LiGdF₄, etc.) have been prepared, using trifluoroacetic acid as a fluorine source, in the form of nanoparticles, thin films and oxide/fluoride nanocomposites. They can be utilized as anti-reflective coatings, luminescent materials, VUV materials, IR materials, and so forth. This article summarizes fundamentals and possible applications of optically useful inorganic fluoride and oxyfluoride materials, with emphasis on porous single-layer anti-reflective coatings and visible photoluminescence of doped Eu³⁺ or Eu²⁺ ions. Furthermore, our recent results on LaF₃:Ce³⁺ and LaOF:Ce³⁺ are originally reported here.     

Chirality at nanoscale for bioscience

In the rapidly expanding fields of nanoscience and nanotechnology, there is considerable interest in chiral nanomaterials, which are endowed with unusually strong circular dichroism. In this review, we summarize the principles of organization underlying chiral nanomaterials and generalize the recent advances in the main strategies used to fabricate these nanoparticles for bioscience applications. The creation of chirality from nanoscale building blocks has been investigated both experimentally and theoretically, and the tunability of chirality using external fields, such as light and magnetic fields, has allowed the optical activity of these materials to be controlled and their properties understood. Therefore, the specific recognition and potential applications of chiral materials in bioscience are discussed. The effects of the chirality of nanostructures on biological systems have been exploited to sense and cut molecules, for therapeutic applications, and so on. In the final part of this review, we examine the future perspectives for chiral nanomaterials in bioscience and the challenges posed by them.

In this review, we summarize the principles of fabrication on chiral nanomaterials and generalize the recent achievements for the bioscience applications.     

Interaction of loparite concentrate with ammonium hydrodifluoride

Results obtained in a study of the interaction between the loparite concentrate and ammonium hydrodifluoride are reported. It was found that the reactions of the main components of the concentrate with NH₄HF₂ yield complex ammonium fluorometallates. It was shown that water leaching of the fluorinated product makes it possible to transfer niobium and tantalum into solution together with fluoroammonium salts of titanium and silicon and to concentrate rare-earth elements in the insoluble residue in the form of complex salts of general formula NaLnF₄.     

Optical and spectroscopic investigation on Calcium Borotellurite glass system

In this work, the glass formation in Calcium Borotellurite (CBTx) system and their optical properties were studied. Six glass samples were prepared by melt-quenching technique and the samples obtained are transparent, lightly yellowish, without any visible crystallites. The results showed that TeO₂ addition increases the density, the electronic polarizability and, consequently, the refractive index. The increase of electronic polarizability and optical basicity suggest that TeO₂ addition increases the non-bridging oxygen (NBO) concentration. The increase of TeO₂ shifts the band edge to longer wavelength owing to increase in non-bridging oxygen ions, resulting in a linear decrease of optical energy gap. The addition of TeO₂ increases the temperature coefficient of the optical path length (dS/dT) in room temperature, which are comparable to phosphate and lower than Low Silica Calcium Alumino Silicate (LSCAS) glasses. The values of dS/dT present an increase as a function of temperature for all the samples measured. The results suggest that CBTx is a good candidate for rare-earth doping and several optical applications.     

Nano-titanium oxide doped with gold,silver, and palladium — synthesis and structural characterization

Nano-titania doped with noble metals (Au/TiO₂, Ag/TiO₂, Pd/TiO₂) has been synthesized by mild hydrolysis of the mixture of metal salts or complexes and titanium isopropoxide ((iPr-O)₄Ti). After thermal decomposition of the obtained precursors, nanomaterials were formed. Morphological characterization of the nanomaterials was provided by scanning electron microscopy (SEM) and stereological analysis, determining the BET specific surface area, and BJH nanoporosity (pore volume, pore size). It has been found that the structure of nanomaterials (size of nanoparticles and agglomerates) depended strongly on the method of the (iPr-O)₄Ti hydrolysis. A minor dependence on the kind of solvents and precursors of noble metals was observed. The presence of doping metal nanoparticles was confirmed by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). Nanomaterial phases were identified by X-ray diffraction (XRD). According to the XRD patterns, Ag/TiO₂ and Pd/TiO₂ products with doping metals in their oxidized form contain Ag-Ti and Pd-Ti phases. Peaks of the metal oxides Ag₂O and PdO are absent in the XRD patterns. The average size of TiO₂ nanoparticles is situated in the region of 20–60 nm, whereas metals are present as about 10–15 nm sized particles and fine nanoparticles.     

Au-Fe3O4 heterostructures for catalytic,analytical, and biomedical applications

Au-Fe₃O₄ heterostructures including dumbbell-like dimer, core-shell structure, and flower-type nanoparticles (NPs), attract much attention due to their multiple modifiable surfaces and unique properties coming from either Au or Fe₃O₄ nanoparticles. This review focuses on the preparation methods and biomedical applications of these heterogenous NPs in the fields of catalysis, assay, multimodal imaging, and combination therapy.     

Extraction of Rare-Earth Elements in Hydrofluoride Decomposition of Loparite Concentrate

Distribution and existence forms of rare-earth elements in decomposition of the loparite concentrate with ammonium hydrofluoride were studied. It was found that, in the course of the aqueous leaching of the fluorinated concentrate, rare-earth elements fully remain in the insoluble residue as complex salts of general formula NaLnF₄. The process of pyrohydrolysis of the insoluble residue was examined. It was shown that varying the process conditions always results in that a NaLnF4-containing product is obtained. It was found that rare-earth elements can be extracted from the insoluble residue and separated from calcium and thorium, and the conditions for this extraction were determined.     

Tuning magnetic,electronic, and optical properties of Mn-doped NiCr2O4 via microwave method

The main aim of the paper to the synthesis of Mn (x)-doped NiCr₂O₄ nanoparticles by varying Mn content (x = 0.00%, 0.01%, 0.02%, and 0.03%) by microwave method for correlating the effect of NiCr₂O₄ on structural, optical, and magnetic properties of the materials. Understanding the optical, magnetic, and structural properties of huge reservoir factors has essential applications in various aspects of materials science. Our study is to relate the reduction of grain size of Mn content in NiCr₂O₄ host material. The XRD results revealed that there was an apparent decrease in the characteristic peaks of Mn in the MnNiCr₂O₄ nanostructure. Particularly, the peak position of (2 2 0) and (3 1 1) planes was decreased. This decrease in peak position is attributed to the creation of defects or disorders due to the Mn ions in the chromite lattice structure. This inter-site Mn cation migration is responsible for the breaking of long-range cation order and the introduction of defects at both the T-site and O-sublattices site simultaneously.     

Surface Modifications and Optoelectronic Characterization of TiO2‐Nanoparticles: Design of New Photo‐Electronic Materials

TiO₂ nanoparticles are of great current interest for applications in photo‐electronic materials including light‐energy conversion, artificial photosynthetic systems as well as photocatalysis. The success of these applications relies on the exciton recombination dynamics and visible‐light sensitivity of the TiO₂ nanomaterials. Thus, in order to develop the highly efficient photo‐electronic materials absorbing visible light, different low dimensional TiO₂ nanostructures such as nanodiscs, nanofibers and nanochains were synthesized, and thereafter their surfaces were modified by incorporating with Sn‐porphyrins and heteropoly acid. The optoelectronic properties of the surface‐modified nanomaterials were investigated with regard to the optical properties and the surface exciton dynamics by using both steady‐state and ultrafast time‐resolved laser spectroscopic techniques including single nanoparticle photoluminescence technique. These results were correlated with the photo‐electronic properties including photocatalytic activities and solar cell efficiencies, indicating that the electron transfer mechanism in the modified nanostructures may be similar to the “Z‐scheme” of the plant photosynthetic system so that both photocatalytic activity and solar cell efficiencies were synergistically enhanced by using two color illumination.     

Y(P,V)O4:Dy phosphors for white light generation: Emission dynamics and host effect

The structural characteristics and optical spectra of Y(P,V)O₄:Dy³⁺phosphors obtained by solid state reaction, sol-gel and hydrothermal routes have been investigated and compared. The luminescence features of these materials show a complicate dependence on the composition, synthetic method and excitation conditions. The emission performance depends on different effects: host luminescence, energy transfer to the doping ions and host dependence of the Dy³⁺ emission properties. These effects have been rationalized in order to provide useful information for the development of a suitable material for the white light emitting phosphors technology.