钙钛矿氧化物异质结的光电特性研究进展

光与物质相互作用可以产生各种光学现象,其中光电效应是非常重要的现象之一.文中集中回顾了文章作者在钙钛矿氧化物异质结的光电效应研究中的进展.在钙钛矿氧化物异质结中,分别观测到了传统的纵向光电效应和反常的横向光电效应,并通过对含时的漂移-扩散方程的自洽求解,从理论上分别揭示了钙钛矿氧化物异质结纵向和横向光电效应的动态过程.文章首先介绍了钙钛矿氧化物异质结纵向光电效应的研究进展,接着概述了钙钛矿氧化物异质结横向光电效应研究的进展.最后对氧化物异质结的纵向和横向光电效应的潜在应用前景进行展望.     

1.4μm～1.7μm宽带光放大材料研究

宽带光放大是指在整个硅基光纤最低损耗带1.4μm～1.7μm能够获得有效信号净增益的光放大。研究高效的宽带光放大材料可以大大满足人们提高通信容量和实现光集成的要求。材料体系的研究主要集中在稀土掺杂氧化物薄膜、玻璃材料和有机聚合物材料上。着重从宽带的获得、发光性能的改善和发光机理的探索3个方面介绍了稀土掺杂玻璃和薄膜材料的研究进展。结合已经取得的结果和积累的经验,探讨了提高发光效率的方法,指出纳米结构设计的共掺材料体系可以获得有效的宽带发光。最后展望了本领域的发展前景。     

可用于光存储的氧化物、次氧化物薄膜材料的研究及发展

介绍了可用于可录、可擦除、全息光存储及超分辨掩膜层的氧化物、次氧化物薄膜材料的种类、制备方法、光存储特性和存储机制。这类薄膜材料由于具有种类多、应用范围广、制备方法多样、写入灵敏度高和记录稳定性好等优点 ,正受到各国研究者越来越多的关注。分析总结了这类材料的研究现状、存在的主要问题和未来发展方向     

利用光镊技术演示光的自旋角动量

阐述了光与物体相互作用时自旋角动量的传递与扭力矩原理.基于光镊光致旋转原理,利用能够悬浮单个粒子的光镊技术并采用具有双折射特性的CaCO3晶体粒子,设计了微粒在不同偏振光场中的旋转运动实验内容,研究光与双折射晶体粒子相互作用产生的光致旋转效应,观察和测量由自旋角动量引起粒子的扭转力矩的大小、方向以及旋转速度等力学效应.     

有机铬富勒烯衍生物的激发态与光限幅特性

应用倍频ｎｓ／ｐｓＮｄ：ＹＡＧ脉冲激光系统,在波长为５３２ｎｍ,脉冲宽度为２１ｐｓ的条件下,研究了新型有机铬富勒烯衍生物的激发态吸收与光限幅特性,其光限幅特性优于富勒烯甲苯溶液;并应用单重态激发态吸收理论对实验结果进行了分析,实验结果与理论结果基本一致。     

固体材料中原子相干效应的研究进展

原子相干效应是光与物质相互作用的结果,它导致了一系列重要的物理现象。目前原子相干的实验研究工作主要在原子气体中开展,而与之相比固体材料中的相关实验研究具有更实际的应用前景。本文系统介绍了近年来固体材料中原子相干效应的研究进展,主要涉及电磁感应光透明、光速减慢与相干存储、存储光信息的可控制擦除、基于光存储的全光路由、双光脉冲的速度减慢和可逆存储和基于原子相干的增强四波混频等基本内容,最后还讨论了其在相关领域的应用。     

固体材料中原子相干效应的研究进展

原子相干效应是光与物质相互作用的结果,它导致了一系列重要的物理现象。目前原子相干的实验研究工作主要在原子气体中开展,而与之相比固体材料中的相关实验研究具有更实际的应用前景。本文系统介绍了近年来固体材料中原子相干效应的研究进展,主要涉及电磁感应光透明、光速减慢与相干存储、存储光信息的可控制擦除、基于光存储的全光路由、双光脉冲的速度减慢和可逆存储和基于原子相干的增强四波混频等基本内容,最后还讨论了其在相关领域的应用。     

氧化物高温超导体的能隙和比热跃变

应用自由载流子与负 U 中心相互作用机制模型,我们讨论了氧化物高温超导体的能隙和比热跃变.所得结果与实验基本一致.     

基于法拉第磁光效应的电流方向测量研究

为解决法拉第磁光效应测量电流方向问题,利用法拉第效应原理搭建了测量电流方向的实验系统,研究不同方向电流作用下的磁致旋光特性,测量了不同方向的电流与光传播方向、光旋转角度之间的关系,实验结果表明:迎着光观测,出射线偏振光的旋光方向表现为右旋时,相应的电流方向沿光传播方向;当出射线偏振光的旋光方向表现为左旋时,相应的电流方向与光传播方向相反。实验结果与理论相符,对指导设计同时可以测量电流大小和方向的光学电流互感器等法拉第磁光器件具有重要的应用价值。     

掺杂稀土锰氧化物的巨磁电阻效应

介绍了掺杂稀土锰氧化物的巨磁电阻效应研究概况和最新进展，在综合目前实验和理论研究结果的基础上，对在掺杂稀土锰氧化物材料中引起巨磁电阻效应的物理机制进行了探讨，对这一材料的应用前景和需要做的工作进行了讨论。     

Semiconducting large bandgap oxides as potential thermoelectric materials for high-temperature power generation?

Semiconducting large bandgap oxides are considered as interesting candidates for high-temperature thermoelectric power generation (700–1,200 °C) due to their stability, lack of toxicity and low cost, but so far they have not reached sufficient performance for extended application. In this review, we summarize recent progress on thermoelectric oxides, analyze concepts for tuning semiconductor thermoelectric properties with view of their applicability to oxides and determine key drivers and limitations for electrical and thermal transport properties in oxides based on our own experimental work and literature results. For our experimental assessment, we have selected representative multicomponent oxides that range from materials with highly symmetric crystal structure (SrTiO₃ perovskite) over oxides with large densities of planar crystallographic defects (Ti _n O_2n?1 Magnéli phases with a single type of shear plane, NbO _x block structures with intersecting shear planes and WO_3?x with more defective block and channel structures) to layered superstructures (Ca₃Co₄O₉ and double perovskites) and also include a wide range of their composites with a variety of second phases. Crystallographic or microstructural features of these oxides are in 0.3–2 nm size range, so that oxide phonons can efficiently interact with them. We explore in our experiments the effects of doping, grain size, crystallographic defects, superstructures, second phases, texturing and (to a limited extend) processing on electric conductivity, Seebeck coefficient, thermal conductivity and figure of merit. Jonker and lattice-versus-electrical conductivity plots are used to compare specific materials and material families and extract levers for future improvement of oxide thermoelectrics. We show in our work that oxygen vacancy doping (reduction) is a more powerful driver for improving the power factor for SrTiO₃, TiO₂ and NbO _x than heterovalent doping. Based on our Seebeck-conductivity plots, we derived a set of highest achievable power factors. We met these best values in our own experiments for our titanium oxide- and niobium oxide-based materials. For strontium titanate-based materials, the estimated highest power factor was not reached; further material improvement is possible and can be reached for materials with higher carrier densities. Our results show that periodic crystallographic defects and superstructures are most efficient in reducing the lattice thermal conductivity in oxides, followed by hetero- and homovalent doping. Due to the small phonon mean free path in oxides, grain boundary scattering in nanoceramics or materials with nanodispersions is much less efficient. We investigated the impact of texturing in Ca₃Co₄O₉ ceramics on thermoelectric performance; we did not find any improvement in the overall in-plane performance of a textured ceramic compared to the corresponding random ceramic.     

高自旋极化氧化物材料的颗粒边界磁电阻效应

颗粒边界磁电阻是高自旋极化氧化物颗粒体系中由于颗粒边界的存在而导致显著的磁电阻效应。本文将这种磁电阻效应定义为颗粒边界磁电阻效应。这里所说的颗粒边界,包括各种自然和人工晶界、粉末颗粒表面、复合材料中的颗粒界面等多种情况;所涉及的材料包括高自旋极化氧化物多晶、压缩粉末和各种复合材料等。对颗粒边界磁电阻效应的研究,不仅有助于人们进一步理解高自旋极化氧化物磁输运性质的基本机制,并为寻求具有高磁电阻效应的新型自旋电子学器件提供理论基础。本文综述了高自旋极化氧化物颗粒边界磁电阻研究的主要背景和发展现状,介绍了该领域中主要的实验发现和理论模型,展望了未来的发展。     

新颖化学链燃烧与空气湿化燃气轮机循环

本文基于工程热力学和化学环境学的有机结合,注重能源与环境的领域交叉,揭示化学链 燃烧新机理,旨在取代传统的造成能源品位利用最差并且引起环境生态污染（产生ＳＯｘ、ＮＯｘ、 ＣＯ２等）的燃烧过程,开拓出第三代能源环境动力系统,寻找同时解决能源与环境两个重大问题的 科学途径。     

Oxides,Oxides, and More Oxides: High-κ Oxides,Ferroelectrics, Ferromagnetics,and Multiferroics

We review and critique the recent developments on multifunctional oxide materials, which are gaining a good deal of interest. Recongnizing that this is a vast area, the focus of this treatment is mainly on high-κ dielectric, ferroelectric, magnetic, and multiferroic materials. Also, we consider ferrimagnetic oxides in the context of the new, rapidly developing field of negative-index metamaterials. This review is motivated by the recent resurgence of interest in complex oxides owing to their coupling of electrical, magnetic, thermal, mechanical, and optical properties, which make them suitable for a wide variety of applications, including heat, motion, electric, and magnetic sensors; tunable and compact microwave passive components; surface acoustic wave devices; nonlinear optics; and nonvolatile memory, and pave the way for designing multifunctional devices and unique applications in spintronics and negative refraction-index media. For most of the materials treated here, structural and physical properties, preparation methods accompanied by particulars of synthesis of thin films, devices based on them, and some projections into their future applications are discussed.     

Aberration-corrected scanning transmission electron microscopy for complex transition metal oxides

Lattice,charge,orbital,and spin are the four fundamental degrees of freedom in condensed matter,of which the interactive coupling derives tremendous novel physical phenomena,such as high-temperature superconductivity(high-T_c SC) and colossal magnetoresistance(CMR) in strongly correlated electronic system.Direct experimental observation of these freedoms is essential to understanding the structure-property relationship and the physics behind it,and also indispensable for designing new materials and devices.Scanning transmission electron microscopy(STEM) integrating multiple techniques of structure imaging and spectrum analysis,is a comprehensive platform for providing structural,chemical and electronic information of materials with a high spatial resolution.Benefiting from the development of aberration correctors,STEM has taken a big breakthrough towards sub-angstrom resolution in last decade and always steps forward to improve the capability of material characterization;many improvements have been achieved in recent years,thereby giving an indepth insight into material research.Here,we present a brief review of the recent advances of STEM by some representative examples of perovskite transition metal oxides;atomic-scale mapping of ferroelectric polarization,octahedral distortions and rotations,valence state,coordination and spin ordering are presented.We expect that this brief introduction about the current capability of STEM could facilitate the understanding of the relationship between functional properties and these fundamental degrees of freedom in complex oxides.     

Monte Carlo study of half-magnetization plateau and magnetic phase diagram in pyrochlore antiferromagnetic Heisenberg model

The antiferromagnetic Heisenberg model on a pyrochlore lattice under external magnetic field is studied by classical Monte Carlo simulation. The model includes bilinear and biquadratic interactions; the latter effectively describes the coupling to lattice distortions. The magnetization process shows a half-magnetization plateau at low temperatures, accompanied with strong suppression of the magnetic susceptibility. Temperature dependence of the plateau behavior is clarified. Finite-temperature phase diagram under the magnetic field is determined. The results are compared with recent experimental results in chromium spinel oxides.     

Recent progress of computational investigation on anode materials in Li ion batteries

Computations have been widely used to explore new Li ion battery materials because of its remarkable advantages. In this review, we summarize the recent progress on computational investigation on anode materials in Li ion batteries. By introducing the computational studies on Li storage capability in carbon nanotubes, graphene, alloys and oxides, we reveal that computations have successfully addressed many fundamental problems and are powerful tools to understand and design new anode materials for Li ion batteries.     

Mechanisms and origin of multiferroicity

Motivated by the potential applications of their intrinsic cross-coupling properties, the interest in multiferroic materials has constantly increased recently, leading to significant experimental and theoretical advances. From the theoretical point of view, recent progresses have allowed one to identify different mechanisms responsible for the appearance of ferroelectric polarization coexisting—and coupled—with magnetic properties. This chapter aims at reviewing the fundamental mechanisms devised so far, mainly in transition-metal oxides, which lie at the origin of multiferroicity.     

Effect of the Spin Fluctuations on the Carrier Thermal Conductivity in High-Tc Oxides

A theory of the carrier thermal conductivity for electron antiferromagnetic spin fluctuation scattering has been developed and on this basis the experimental results of high-T_c oxides have been interpreted. Our theoretical analysis fits the experimental results excellently and suggests that the antiferromagnetic spin fluctuations affect the carrier thermal conductivity in high-T_c oxides.     

The interaction of water with solid surfaces: Fundamental aspects

The purpose of this review is to compare and discuss recent experimental and theoretical results in the field of H₂O-solid interactions. We emphasize studies of low (submonolayer) coverages of water on well-characterized, single-crystal surfaces of metals, semiconductors and oxides. We discuss the factors which influence dissociative versus associative adsorption pathways. When H₂O adsorbs molecularly, it tends to form three-dimensional hydrogen-bonded clusters, even at fractional monolayer coverages, because the strength of the attractive interaction between two molecules is comparable to that of the substrate-H₂O bond. The template effect of the substrate is important in determining both the local orientation and long-range order of H₂O molecules in these clusters. The influence of surface additive atoms (e.g., O, Br, Na, K) and also surface imperfections (e.g. steps and defects) on the surface structure and chemistry of H₂O is examined in detail. Some results on single-crystal substrates are compared with earlier measurements of H₂O adsorption on high-area materials.