IN two previous notes1, Prof. Max Born and I have shown that one can obtain a theory of superconductivity by taking account of the fact that the interaction of the electrons with the ionic lattice is appreciable only near the boundaries of Brillouin zones, and particularly strong near the corners of these. This leads to the criterion that the metal should be superconductive if a set of corners of a Brillouin zone is lying very near the Fermi surface, considered as a sphere, which limits the region in the momentum space completely filled with electrons.

On the theory of superconductivity

Impurity doping is a promising method to impart new properties to various materials. Due to their unique optical, magnetic, and electrical properties, rare-earth ions have been extensively explored as active dopants in inorganic crystal lattices since the 18th century. Rare-earth doping can alter the crystallographic phase, morphology, and size, leading to tunable optical responses of doped nanomaterials. Moreover, rare-earth doping can control the ultimate electronic and catalytic performance of doped nanomaterials in a tunable and scalable manner, enabling significant improvements in energy harvesting and conversion. A better understanding of the critical role of rare-earth doping is a prerequisite for the development of an extensive repertoire of functional nanomaterials for practical applications. In this review, we highlight recent advances in rare-earth doping in inorganic nanomaterials and the associated applications in many fields. This review covers the key criteria for rare-earth doping, including basic electronic structures, lattice environments, and doping strategies, as well as fundamental design principles that enhance the electrical, optical, catalytic, and magnetic properties of the material. We also discuss future research directions and challenges in controlling rare-earth doping for new applications.

Rare-Earth Doping in Nanostructured Inorganic Materials.

Ceria (CeO2) is an exciting alternative noble metal catalyst, because it has ability to release and absorb oxygen in the redox system, and function as an oxygen buffer In this study, heterostructured catalysts consisting of CeO2/Y2O3 nanocomposites were successfully synthesized by hydrothermal method in the presence of sodium hydroxide as a reducing agent from cerium nitrate and yttrium nitrate as a precursor which was then evaluated for its photocatalytic activity in the degradation of Rhodamine B (RhB) synthetic dye Scanning electron microscopy (SEM) imparts the surface morphology and size of the prepared sample Elemental compositions and the purity of the nanoparticles are proved by energy dispersive X-ray Spectroscopy (EDX) CeO2/Y2O3 nanoparticles were made up of CeO and YO bonds which are confirmed by Fourier transform infrared spectroscopy (FTIR) Synthesis temperature and pressure, during hydrothermal reactions, plays a critical role in controlling the shape, size, oxygen vacancy concentration, and low temperature reducibility in CeO2 based nanocomposites The lattice constants and oxygen vacancy concentrations of ceria nanoparticles also depend upon the concentration of hydroxide ion which leads to better morphology at low temperature and pressure Hydrogenation of p-nitrophenol to p-aminophenol with a reducing agent is conveniently carried out in aqueous medium by using this binary metal oxide catalyst Further, the photocatalytic performance of the synthesized nanoparticles was monitored by photocatalytic degradation of Rhodamine B synthetic dye under UV light irradiation To get maximum photocatalytic degradation (PCD) efficiency, we have used H2O2 for the generation of excess reactive oxygen species (ROS) In addition, the antibacterial activity of nanoparticles against bacteria was also examined The observed antibacterial activity results are comparable with the results obtained using the standard antibiotic

Facile synthesis of heterostructured cerium oxide/yttrium oxide nanocomposite in UV light induced photocatalytic degradation and catalytic reduction: Synergistic effect of antimicrobial studies

New insights into structural and magnetic properties of Ce doped ZnO nanoparticles

Porous Ce-doped ZnO hollow sphere with enhanced photodegradation activity for artificial waste water

In the present study Zinc Oxide (ZnO) nanoparticles and Rare Earth (RE) ion Cerium (Ce) doped ZnO nanoparticles were synthesized by chemical precipitation technique. The synthesized nanoparticles were characterized by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscope (TEM), photoluminescence spectroscopy (PL), UV–visible spectroscopy and ferromagnetism behavior at room temperature. The XRD and EDX analysis revealed that Ce doped ZnO pattern matched with the ZnO pattern i.e. they exhibited hexagonal wurtzite structure and Ce ions were successfully incorporated into the ZnO nanoparticles. TEM images illustrated the average diameter of synthesized nanoparticles. The average diameter of ZnO and Ce doped ZnO nanoparticles was around 20 nm. PL measurements revealed that ZnO nanoparticles and Ce doped ZnO nanoparticles had an UV emission and a green emission while the Ce ions doping induced a red shift in the UV emission with broadening in the green emission. Direct type of transition of band gaps was confirmed by transmission spectra occurring at 3.5 and 3.2 eV respectively for ZnO nanoparticles and Ce doped ZnO nanoparticles i.e. decrease of band gap energy with doping of Ce ions in ZnO nanoparticles. The magnetization study on the Ce doped ZnO nanoparticles exposed outstanding ferromagnetism property at room temperature.

Effect of Ce doping on the structural, optical and magnetic properties of ZnO nanoparticles

Synthesis of graphene oxide and its reduction by green reducing agent

Factors affecting morphological and electrical properties of Barium Titanate: A brief review

Extensive burning of fossil fuels to fulfill the intensifying demands of energy has led to raising the concentration of carbon dioxide in atmosphere, which is a major component responsible for global warming. Imitating the natural photosynthesis, photoreduction of CO2 seems to be one of the most promising solutions to this critical problem. Among the different photocatalysts, ZnO had been thoroughly examined for CO2 reduction owing to its low cost and eco-friendliness. Combining ZnO with carbon-based nanomaterials is being progressively investigated to improve the photocatalytic efficiency. This article is organized to explore the latest advancements in ZnO/carbon nanocomposites for photocatalytic CO2 reduction systems. The article begins with the fundamentals of photocatalysis, and the basic mechanism of CO2 reduction over semiconductor materials is also reviewed. Then, it surveys literature and underlines the recent developments of ZnO/carbon-based hybrid nanomaterials, covering activated carbon, graphene-based materials, carbon nanotubes, carbon dots and recently developed morphologies. More specifically, synthesis routes and mechanisms of CO2 reduction enhancement are thoroughly discussed. Finally, a summary along with some new valuable recommendations are also presented. 

Anuradha Sharma

Papers

Effect of Ce doping on the structural, optical and magnetic properties of ZnO nanoparticles

Synthesis of graphene oxide and its reduction by green reducing agent

Factors affecting morphological and electrical properties of Barium Titanate: A brief review

Insight into ZnO/carbon hybrid materials for photocatalytic reduction of CO2: An in-depth review

Carbon Nano-structures and functionalized associates: adsorptive detoxification of organic and inorganic water pollutants