Potassium Titanyl Phosphate and Its Isomorphs: Growth,Properties, and Applications

Potassium titanyl phosphate (KTP) and its isomorphs have received enormous attention in the last 2 decades. In particular, KTP assumes importance due to its large nonlinear optic and electrooptic coefficients together with the broad thermal and angular acceptance for second harmonic generation. This article provides an overview of the material aspects, structural, physical, and chemical properties and device feasibility of the KTP family of crystals. Some of the current areas of research and development along with their significance in understanding the physical properties as well as device applications are addressed. Optical waveguide fabrication processes and characteristics with their relevance to the present-day technology are highlighted. Studies performed so far have enabled us to understand the fundamental aspects of these materials and what needs to be pursued vigorously is the exploitation of their device applications to the maximum extent.     

The structure and magnetic properties of amorphous magnetic thin films

A review of the structural and magnetic properties of amorphous ferromagnetic and ferrimagnetic thin films is presented. An attempt is made to report structural information on atomic and microstructural scales, and to stress its relevance to the magnetic properties of these materials. The more obvious microstructural features of deposited films are not present in the other important type of amorphous magnetic material prepared by rapid quenching from the melt, and present opportunities for differences in structure dependent magnetic properties. In the main, three classes of amorphous magnetic films are considered. Ferromagnetic transition metal (TM) films which are metastable only at temperatures well below room temperature are discussed. Their importance lies in the fact that they clearly represent the most fundamental amorphous phase. Ferromagnetic transition metal-metalloid (TM-Me) alloys have potential applications as magnetically soft materials. These alloys are, perhaps, the most studied amorphous magnetic materials both in deposited thin film and rapidly quenched ribbon forms. Finally, amorphous rare earth-transition metal (RE-TM) films are reviewed. They exhibit a wide variety of magnetic properties encompassing both extremely low and very high coercivities and also perpendicular magnetic anisotropy. The possible application of these materials in various types of device has encouraged much detailed research into their magnetic properties. This has highlighted the importance of preparation conditions and microstructure in defining their properties.     

A Review of Research Trends in Microwave Processing of Metal-Based Materials and Opportunities in Microwave Metal Casting

Microwave processing of materials has emerged as a new method for processing of a variety of materials in the recent years. Microwaves have been used effectively with significant advantages, particularly in food processing and chemical synthesis. They are also found to be efficient for processing polymers, ceramics, polymeric composites, and ceramic composites. The physics of interaction of microwaves with characteristically different materials is not yet explored well; consequently, there are challenges in microwave processing of metal-based materials. Industrial processing of bulk metal is yet to be popular in spite of the fact that the feasibility of metal powder sintering was demonstrated a few decades ago. This article provides a summary of fundamental aspects of microwave processing of metal-based materials and their interaction with metallic materials. The processing challenges have been surveyed; developments in terms of techniques and tooling have been analyzed. Possible effects of microwave processing on metallic materials, in particular metal powders, bulk metals, bulk metal-metal powder systems, and sheet metals have been presented. Future research aspects of microwave processing of metallic materials with reference to metal casting have been identified.     

The role of virtual photons in nanoscale photonics

The fundamental theory of processes and properties associated with nanoscale photonics should properly account for the quantum nature of both the matter and the radiation field. A familiar example is the Casimir force, whose significant role in nanoelectromechanical systems is widely recognised; the correct representation invokes the creation of short‐lived virtual photons from the vacuum. In fact, there is an extensive range of nanophotonic interactions in which virtual photon exchange plays a vital role, mediating the coupling between particles. This review surveys recent theory and applications, also exhibiting novel insights into key electrodynamic mechanisms. Examples are numerous and include: laser‐induced inter‐particle forces known as optical binding; non‐parametric frequency‐conversion processes especially in rare‐earth doped materials; light‐harvesting polymer materials that involve electronic energy transfer between their constituent chromophores. An assessment of these and the latest prospective applications concludes with a view on future directions of research.     

超导强磁场材料的新进展

本文评述了超导强磁场材料的新进展。基础科学和高技术的迅速发展,对超导强磁场材料不断提出新的要求。针对一些特定的应用目标,现行的实用超导材料,如Nb-Ti、Nb_3Sn和V_3Ga等,在改进制备工艺和提高性能两个方面都取得了明显的进展。有关多芯复合导体的微结构研究正在蓬勃地展开。对一些具有潜在应用前景的超导体研究,正预示着它们将成为超导技术中使用价值更高的新型材料。基于所研究的科学问题具有交叉学科的特点,今后组织多学科的力量开展合作研究,必将加速这一领域工作的发展。     

“Small and beautiful” – The novel structures and phases of nano-oxides

Low-dimensional oxide nanostructures supported on well-defined metal surfaces raise scientific interest both on a fundamental level and for potential technological applications. These systems may be regarded as artificially created hybrid materials with novel emergent properties, supporting new concepts of geometrical structure, electronics and magnetism, complex phase diagrams and particular chemical reactivity. The coupling of the oxide nano-phase to the metal support surface by electronic and elastic interactions together with the low dimensionality aspects are at the origin of the particular behaviour of these hybrid structures. By way of prototypical examples, this Prospective article highlights some of the novel properties of nano-oxides and, as a side aspect, comments on the aesthetics of their structural motifs.     

Magnetic properties of lithium ferrite microwave materials

This report presents a comprehensive review of the magnetic properties of lithium ferrite materials. The fundamental properties are considered first. These include crystal structure, magnetization, magnetocrystalline anisotropy, and magnetostriction. The extrinsic magnetic properties, which are related to microwave applications, are then examined. These include coercive force, remanence, and microwave loss. Finally, a systematic review of the effects of substituents, including titanium, zinc, manganese, cobalt, and bismuth, is presented.     

Photothermal methods for determination of thermal properties of bulk materials and thin films

Information on the thermal properties of materials is very important both in fundamental physical research and in engineering applications. The development of materials with desirable heat transport properties requires methods for their experimental determination. In this paper basic concepts of the measurement of parameters describing the heat transport in solids are discussed. Attention is paid to methods utilizing nonstationary temperature fields, especially to photothermal methods in which the temperature disturbance in the investigated sample is generated through light absorption. Exemplary photothermal measuring techniques, which can be realized using common experimental equipment, are described in detail. It is shown that using these techniques it is possible to determine the thermal diffusivity of bulk transparent samples, opaque and semi-transparent plate-form samples, and the thermal conductivity of thin films deposited on thick substrates. Results of the investigation of thermal diffusivity of the ground in the polar region, which is based on the analysis of the propagation of the thermal wave generated by sun-light, are also presented. Based on chosen examples one can state that photothermal techniques can be used for determination of the thermal properties of very different materials.     

Fluorescent Metallic Nanoclusters: Electron Dynamics,Structure, and Applications

Atomically precise Au nanoclusters (NCs) have emerged as fascinating fluorescent nanomaterials and attracted considerable research interest in both fundamental research and practical applications. Due to enhanced quantum confinement, they possess extraordinary optical, electronic, and magnetic properties and therefore are very promising for a wide range of applications, including biosensing, bioimaging, catalysis, photonics, and molecular electronics. Remarkable progress has been reported for the fundamental understanding, synthesis techniques, and applications. In this review, the updated advances are summarized in Au NCs, including synthesis techniques, optical properties, and applications. In particular, we focus on the optical properties and electron dynamic processes. In addition, the progress in other noble metallic NCs is included in this Review, such as Ag, Cu, Pt, and alloy, which have attracted much research interest recently. Finally, an outlook is presented for such fascinating nanomaterials in both aspects of future fundamental research and potential applications.     

Noble Metal Clusters: Applications in Energy,Environment, and Biology

Sub‐nanometer‐sized metal clusters, having dimensions between metal atoms and nanoparticles, have attracted tremendous attention in the recent past due to their unique physical and chemical properties. As properties of such materials depend strongly on size, development of synthetic routes that allows precise tuning of the cluster cores with high monodispersity and purity is an area of intense research. Such materials are also interesting owing to their wide variety of applications. Novel sensing strategies based on these materials are emerging. Owing to their extremely small size, low toxicity, and biocompatibility, they are widely studied for biomedical applications. Primary focus of this review is to provide an account of the recent advances in their applications in areas such as environment, energy, and biology. With further experimental and theoretical advances aimed at understanding their novel properties and solving challenges in their synthesis, an almost unlimited field of applications can be foreseen.     

Current developments in silicene and germanene

Exploration of the unusual properties of the two‐dimensional materials silicene and germanene is a very active research field in recent years. This paper therefore reviews the latest developments, focusing both on the fundamental materials properties and on possible applications. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

核壳结构磁性复合纳米材料的可控合成与性能

具有核/壳结构的磁性复合纳米材料是十分重要的功能材料,其综合物性受材料微结构的影响,而这很大程度上又取决于复合体系的可控合成.本文综述了近二十年来有关核/壳磁性复合纳米材料的制备、表征及性能研究方面的进展,讨论的体系主要有：铁氧体基永磁/软磁（反铁磁）复合纳米材料、非磁性体包覆磁性核而成的复合纳米材料、用磁性颗粒催化合成的碳基复合纳米材料、基于交换偏置效应而设计的复合纳米材料、核-壳同轴结构的一维复合纳米材料和核/壳/壳三元结构的磁性复合纳米材料等.构建复合体系的组分包括M型永磁铁氧体、3d过渡金属（及其合金、氧化物、碳化物）、多铁化合物、非磁性体（比如绝缘体、半导体、有机分子）和碳材料等,着重分析了复合纳米材料的热稳定性、光致发光性能、光电催化能力、电化学特性、微波吸收性能、磁电阻效应、永磁体性能、高频软磁特性、交换偏置效应及其相关现象.最后,对核/壳结构磁性复合纳米材料的未来发展趋势进行了展望,并在基础研究和改性应用方面提出了一些建议.     

Carbon nanotubes: opportunities and challenges

Carbon nanotubes are graphene sheets rolled-up into cylinders with diameters as small as one nanometer. Extensive work carried out worldwide in recent years has revealed the intriguing electrical and mechanical properties of these novel molecular scale wires. It is now well established that carbon nanotubes are ideal model systems for studying the physics in one-dimensional solids and have significant potential as building blocks for various practical nanoscale devices. Nanotubes have been shown to be useful for miniaturized electronic, mechanical, electromechanical, chemical and scanning probe devices and materials for macroscopic composites. Progress in nanotube growth has facilitated the fundamental study and applications of nanotubes. Gaining control over challenging nanotube growth issues is critical to the future advancement of nanotube science and technology, and is being actively pursued by researchers.     

Review of magnetic properties and magnetocaloric effect in the intermetallic compounds of rare earth with low boiling point metals

The magnetocaloric effect(MCE) in many rare earth(RE) based intermetallic compounds has been extensively investigated during the last two decades, not only due to their potential applications for magnetic refrigeration but also for better understanding of the fundamental problems of the materials. This paper reviews our recent progress on studying the magnetic properties and MCE in some binary or ternary intermetallic compounds of RE with low boiling point metal(s)(Zn, Mg, and Cd). Some of them exhibit promising MCE properties, which make them attractive for low temperature magnetic refrigeration. Characteristics of the magnetic transition, origin of large MCE, as well as the potential application of these compounds are thoroughly discussed. Additionally, a brief review of the magnetic and magnetocaloric properties in the quaternary rare earth nickel boroncarbides RENi_2B_2 C superconductors is also presented.     

稀土元素—铁族金悀非晶态薄膜的磁特性及其应用

本文第一部分介绍了Губанов关于非晶态物质具有铁磁性的唯象理论,第二部分介绍近年来有关稀土元素—铁族金属非晶态薄膜的一些研究进展,它包括薄膜的磁、电、磁光等方面的特性,第三部分则介绍这类薄膜的可能应用以及在实验室已取得的一些成就。     

二维有机拓扑绝缘体的研究进展

新材料的发现促进了科学与技术的进步.拓扑绝缘体是近期材料领域新的研究热点,相关研究的进一步深入,不仅加深了人们对材料物理性质的理解,也为其在自旋电子学和量子计算机等领域的潜在应用提供了有价值的参考.近年来,理论工作预测了一系列由金属和有机物构筑的二维有机拓扑绝缘体,本文主要介绍六角对称的金属有机晶格与Kagome金属有机晶格两类典型的二维有机拓扑绝缘体的研究进展,其中重点介绍了理论预测的氰基配位二维本征有机拓扑绝缘体.除了理论计算方面的工作,还简要介绍了关于二维有机拓扑绝缘体材料合成方面的实验工作.二维有机拓扑绝缘体的理论与实验研究不仅拓展了拓扑绝缘体的研究体系,还为寻找新的拓扑绝缘体材料提供了思路.     

Progress in functional studies of transition metal borides

In recent years, transition metal borides (TMBs) have attracted much attention because they are considered as potential superhard materials and have more abundant crystal structures compared with traditional superhard materials. So far, however, no superhard materials have been found in TMBs. A large number of structures and potential new properties in TMBs are induced by the various hybridization ways of boron atoms and the high valence electrons of transition metals, which provide many possibilities for its application. And most TMBs have layered structures, which make TMBs have the potential to be a two-dimensional (2D) material. The 2D materials have novel properties, but the research on 2D TMBs is still nearly blank. In this paper, the research progress of TMBs is summarized involving structure, mechanical properties, and multifunctional properties. The strong covalent bonds of boron atoms in TMBs can form one-dimensional, two-dimensional, and three-dimensional substructures, and the multiple electron transfer between transition metal and boron leads to a variety of chemical bonds in TMBs, which are the keys to obtain high hardness and multifunctional properties of TMBs. Further research on the multifunctional properties of TMBs, such as superconductors, catalysts, and high hardness ferromagnetic materials, is of great significance to the discovery of new multifunctional hard materials.     

Giant magnetostriction materials

One of the significant technical developments in magnetism of the early 1970's was the discovery of a new class of rare earth intermetallic compounds, the RFe₂ Laves phases, which were found to exhibit room temperature magnetostrictive strains approaching 2 × 10⁻³, an order of magnitude larger than any previously known. Since that time both the fundamental and technical properties of these materials have been of intense interest, and they remain the subject of active research even today. The large strains available are useful in such applications as production of high amplitude, low frequency sound waves in water, certain types of strain gages, vibration compensation and compensation for temperature induced strains in large laser mirrors. Because the performance of these materials depends critically on such fundamental properties as the magnetic anisotropy, magnetization and grain orientation of the material, there has been a very strong interplay between fundamental studies and applications. In this article we briefly review the fundamental magnetic and magnetostrictive properties of the RFe₂ Laves phases, focusing especially on the complex behavior of the anisotropy and the success of crystal field theory in explaining it. We also present neutron measurements of magnetic excitation spectra and explain how they provide an understanding of the remarkable success of mean field theory for these systems.     

Nanowhiskerography–a New Method of Security Printing using Scanning Laser Radiation

Based on fundamental research of above-threshold-power laser radiation by C. Townes (laser beam splitting) and G. A. Askaryan (self-focusing and sublimation evaporation), a new highperformance technology for growing nanowhiskers of metal and their oxides, semiprecious crystals, and composite materials based on polycarbonate in open air is developed. Some possibilities of its practical applications are shown.     

Two-dimensional materials for ultrafast lasers

As the fundamental optical properties and novel photophysics of graphene and related two-dimensional(2D) crystals are being extensively investigated and revealed, a range of potential applications in optical and optoelectronic devices have been proposed and demonstrated. Of the many possibilities, the use of 2D materials as broadband, cost-effective and versatile ultrafast optical switches(or saturable absorbers) for short-pulsed lasers constitutes a rapidly developing field with not only a good number of publications, but also a promising prospect for commercial exploitation. This review primarily focuses on the recent development of pulsed lasers based on several representative 2D materials. The comparative advantages of these materials are discussed, and challenges to practical exploitation, which represent good future directions of research, are laid out.