Progress in Solid State Chemistry最新文献

The series $R{T}_2{X}_8$ (R = La–Nd, Sm, Eu, Yb, Ca and Sr; T = Fe, Co, Ni, Ru, Rh and Ir; X = Al, Ga and In) belong to a class of quasi-skutterudite intermetallic compounds which crystallize in the orthorhombic CaCo₂Al₈-type structure with space group $Pbam$ (No. 55). A new member of the series CePd₂Al₈ crystallizes in a monoclinic structure of its own type with space group C2/m (No. 12). While this family of compounds are still largely unexplored, recent studies have revealed the evolution of interesting electronic and magnetic ground states in certain members of the series. Due to an increasing interest in the study of compounds with cage-like structures owing to their promising properties for thermoelectric applications and the search for heavy fermion superconductivity, it is therefore imperative to put into perspective the observations and important results in previous studies on the $R{T}_2{X}_8$ series. Besides the macroscopic properties such as specific heat, transport properties and magnetization, other important results from techniques such as neutron scattering, X-ray absorption spectroscopy and Mössbauer spectroscopy are also presented for some of the compounds.

Environmental pollution is one of the significant area under discussion that the world is facing nowadays and it is increasing day by day and leading to serious and dangerous consequence to this world. Electrical energy storage (EES) plays a very important part in everyday life because of our reliance on various transportable devices. Nano- and atomic-level two-dimensional (2D) materials have broad applications in optoelectronic devices. This review deals with the cutting edge of EES devices, highlights advances to overcome present restrictions, and helps us to go further to get future advanced EES technology based devices, whose uniqueness symbolizes an exact hybridization of batteries and capacitors. The essential features of 2D materials are illustrated, and their energy storage systems are also reviewed. Secondly, energy storage performances of 2D materials-based batteries and supercapacitors (SC) will also be highlighted. At last, a few efficient schemes for boosting their performance based on 2D materials are also explained. The prospect and challenges of the 2D-material-based energy storage at commercial level are also provided.

The photoluminescent phosphor materials nowadays are extremely important source of light to fulfill the technological demand over the conventional light source for eco-friendly environment. This review brings the morphological and optical properties of the chemically engineered rare earth doped photoluminescent materials at one platform. The recent developments have been incorporated and different processes involved in the morphological changes of these materials are discussed. The optical properties of different mono-, di- and tri-rare earth doped phosphors have been analyzed and evaluated using various sensitizers and surface modifiers. The photoluminescence intensity of the materials is greatly affected by changing the morphology of the phosphors via some sensitizers and surface modifiers. The large photoluminescence intensity thus obtained has been summarized due to change in the morphology. The future aspects of change in the morphological properties of the chemically engineered rare earth doped phosphors have been also proposed.

Fullerene derivatives with amino acids, peptides and proteins have wide perspectives in biomedical applications. Thus, development and up-scaling of synthesis procedures, as well as investigation of the physico-chemical and biological properties of these derivatives, are extremely important. The present paper systematizes the current literature data on synthesis, physico-chemical properties and application of fullerene derivatives with amino acids, peptides and proteins in biomedicine. Experimental and theoretical data presented in the review give a comprehensive overview of these substances and can be valuable for specialists in the fields of nanotechnology, nanomaterials and bionanomedicine.

A comprehensive structural comparison of 56 Te⁶⁺-, Mo⁶⁺-, and W⁶⁺-containing oxides with the double perovskite stoichiometry (A₂BB′O₆) is presented. This work shows that much like d⁰ Mo⁶⁺- and W⁶⁺-containing perovskites, p⁰ Te⁶⁺-containing compositions are strongly affected by the tolerance factor and identities of the A- and B-cations. To make this comparison more complete, the ambient temperature crystal structures of five A₂BTeO₆ (A = Ca²⁺, Sr²⁺, or Ba²⁺; B = Zn²⁺ or Cd²⁺) perovskites were determined via powder diffraction and their vibronic and electronic structures were probed via infrared and diffuse reflectance spectroscopy. The new structural information reported here coupled with a thorough review of relevant literature demonstrates that Te⁶⁺, with its sigma bonding preference and lack of allowed orbital mixing gives rise to additional structure types that are not commonly observed in the Mo⁶⁺ or W⁶⁺ analogues. Analysis of double perovskites containing the hexavalent cations comparing the tolerance factor to the difference in ionic radii of the cations with octahedral coordination is presented. Additionally, examination of the Coulombic repulsions between the B and Te⁶⁺ cations plotted as a function of difference in the twelve- and seven-coordinate ionic radii for the A- and B-cations respectively provides new insight on why A₂BTeO₆ and A₂BWO₆ (A = B = Sr²⁺ or Ba²⁺) adopt perovskite structures with non-cooperative octahedral tilting distortions, while cooperative octahedral distortions are observed when the A and B sites are occupied by smaller cations like Ca²⁺ and Cd²⁺.

The stereochemistry of 5s² (E) lone pair of divalent Sn (Sn^II designated by M*) and the lone pair triplet around the fluorine ions are examined complementarily with stereo-chemical approach and ab initio quantum investigations focusing on the electron localization and pertaining electronic structure properties, obtained within Density Functional Theory (DFT) and derived Electron Localization Function (ELF) mapping. The review completes a series of former ones focusing on the stereochemical role played by electron lone pairs LP. We start by examining LP-free Sn^IVF₄ then develop on Sn^IIF₂E in its three crystal varieties (α, β, γ). The investigation then extends to study two mixed-valence fluorides: Sn₂^IISn^IVF₆E₂ and Sn^IISn^IVF₆E. The lone pair presence is readily detected in the crystalline network by its sphere of influence characterized by a radius rE, and M*-E directions; all distances are also detailed and assessed. The observations point to significant modifications of the structure which are also analyzed with the electronic density of states DOS projected over the different atomic constituents. Within the selected fluorides details of Sn^II various coordination numbers (CN) generally indicate one-sided coordination; specifically: CN = 4 + 1 SnF₄E triangular bipyramid, CN = 5 + 1 SnF₅E distorted octahedron (square pyramid with E roughly symmetric of its F apex) and CN = 6 octahedron [SnE]F₆. In the latter, the rotation speed of E (which increases with Z number due to relativistic effects) and the size of the F polyhedron make it favorable enough to E rotating around Sn²⁺ with the particularity of its transformation into a large cation [SnE]²⁺ with a size comparable to Ca²⁺, Sr²⁺ or Ba²⁺.

Bond relaxation from one equilibrium to another under perturbation matters uniquely the performance of a substance and thus it has enormous impact to materials science and engineering. However, the basic rules for the perturbation-bond-property correlation and efficient probing strategies for high-resolution detection stay yet great challenge. This treatise features recent progress in this regard with focus on the multifield bond oscillation notion and the theory-enabled phonon spectrometrics. From the perspective of Fourier transformation and the Taylor series of the potentials, we correlate the phonon spectral signatures directly to the transition of the characteristic bonds in terms of stiffness (frequency shift), number fraction (integral of the differential spectral peak), structure fluctuation (linewidth), and the macroscopic properties of the substance. A systematic examination of the spectral feature evolution for group IV, III-V, II-VI crystals, layered graphene nanoribbons, black phosphor, (W, Mo)(S₂, Se₂) flakes, typical nanocrystals, and liquid water and aqueous solutions under perturbation has enabled the ever-unexpected information on the perturbation-bond-property regulations. Consistency between predictions and measurements of the crystal size-resolved phonon frequency shift clarifies that atomic dimer oscillation dictates the vibration modes showing blueshift while the collective vibration of oscillators formed between a certain atom and its nearest neighbors governs the modes of redshift when the sample size is reduced. Theoretical matching to the phonon frequency shift due to atomic undercoordination, mechanical and thermal activation, and aqueous charge injection by solvation has been realized. The reproduction of experimental measurements has turned out quantitative information of bond length, bond energy, single bond force constant, binding energy density, vibration mode activation energy, Debye temperature, elastic modulus, and the number and stiffness transition of bonds from the mode of references to the conditioned upon perturbation. Findings prove not only the essentiality of the multifield lattice oscillating dynamics but also the immense power of the phonon spectrometrics in revealing the bond-phonon-property correlation of solid and liquid substance.

Band gap engineering of TiO₂ has attracted many researchers looking to extend its applicability as a functional material. Although TiO₂ has been commercialised in applications that utilise its special properties, its band gap should be modified to improve its performance, especially as an active photo catalyst. Reduction of TiO₂ under a hydrogen atmosphere is a promising method which can increase the visible-light absorption efficiency of TiO₂ and enhance its electrochemical and other properties related to electronic band structure. In this second review paper, the production and influence of O vacancies $\left(V_O\right)$ and other defects, such as interstitial cations, under vacuum and hydrogen are reviewed for the common phases of TiO₂. The particular modification TiO_2–x in which O is randomly removed from the crystal structure is considered in detail. Despite early evidence that hydrogen is absorbed into the bulk of TiO₂, the action of hydrogen has become controversial in recent years, with claims that surface disorder is responsible for the enhanced photoactivity induced by exposure to hydrogen. The many published experimental and density-functional-theory modelling studies are surveyed with the aims of determining what is agreed or contested, and relating defect structure to band structure. It is concluded that further work is needed to clarify the mechanisms of defect production and defect diffusion, as well as the origins of the numerous sample colours observed following treatment in vacuum or hydrogen.

Chalcogenide lone pair semiconducting materials are important materials due to their prospective applications in thermoelectrics, phase change memories, topological insulators etc. Investigating these lone pair semiconductors for versatile applications, different electronic properties were studied by researchers world-wide. Analyses of these semiconducting materials in bulk and thin films for electronic properties like dark and photo-conductivity, photosensitivity, carrier concentration, carrier type, relaxation time and thermopower are the major constituents while accepting them for applications. This review stresses on the electronic properties of several binary, ternary and quaternary lone pair chalcogenide systems. The electronic properties are generally discussed on the basis of chemical ordering in system. A brief discussion on some theoretical background of conduction mechanism has also been incorporated for new researchers in this field. Potential applications of chalcogenide semiconducting materials have been outlined.