尖晶石型LiMn2O4晶体中单斜相的鉴定

在缺氧或含A1的尖晶石型LiMn2O4晶体中经常观察到成孪晶关系的单斜晶系的晶体(见附图)。图e为沿立方的[111]方向的选区电子衍射花样(EDP)。显见除了过原点的[440]^ 方向的衍射斑点之外，左右的倒易点列的每一衍射斑都沿着[440]^ 方向分裂成两个斑点，且距中线的垂直距离越大的     

双层锰酸盐La2-2x（Ca，Sr）1＋2xMn2O7系统中的电荷有序化研究

本文系统地分析了双层锰酸盐La2-2xCa1 2xMn2O7(0．5≤x≤1．0)与La2-2xSr1 2xMn2O7(0．45≤x≤0．60)的结构及物理性质。低温下，在0．6≤x≤0．75的样品中La2-2xCa1 2xMn2O7系统显示出电荷轨道有序化。温度低于160K时，在x=0．6的材料中观察到了因电荷有序态和铁磁态互相竞争而导致的微观     

压电家族新成员Li2B4O7晶体

四硼酸锂晶体是近年来发展起来的一种新型压电材料，在声表面波器件等方面有着广阔的应用前景。本文介绍了该晶体的性能、生长及其在器件上的应用，简要讨论了目前国内外的研究进展，展望了ＬＢＯ晶体与器件的前景。     

铌酸锂晶体铁电畴电极化反转结构的ESEM观察

用高压电场实现铁电晶体电畴的极化反转，制备极化方向周期性反转的非线性晶体人工微结构是实现准相位匹配的有效方法。扫描电镜常用于观察刻蚀处理后的铁电畴和畴反转光栅的结构，而环境扫描电镜ESEM可对绝缘样品进行直接观察，因而是本研究的更为有效手段。     

用RHEED方法实时观测GaSb晶体表面的溶化

晶体不存在过热溶化。人们普遍认为，这是因为在熔点之下晶体的某些表面已发生表面熔化。熔化层的厚度随温度升高而增加，从几个原子层到百个原子层，达到熔点时晶体则完全熔化。已观察到Pb、Au、Cu、Ag及H2O等晶体一些晶面的表面熔化现象。表面熔化已成为人们关注的一个重要     

几种α相Si3N4纳米结构的TEM表征

作为一种陶瓷材料，氮化硅(Si3N4)具有许多优良的性质，如高强度、高硬度和高红外吸收率，耐磨性、耐高温性和耐腐蚀性等。一维尺度的纳米结构是未来纳米器件的基本组成单元。     

SiO2-Al2O3-PbF2-ZnF2-ErF3玻璃陶瓷的显微结构

氟氧化物玻璃陶瓷综合了传统激光晶体和激光玻璃的优点，是近年来激光材料研究的新热点。我们制备了掺杂Er离子的SiO2-Al2O3-PbF2-ZnF2玻璃陶瓷材料，并对其显微结构进行了初步研究。     

Mg或Cd掺杂尖晶石型LiMn2O4的晶格畸变

采用室温固相法,用Mg或Cd掺杂制备了LiMn2O4前驱体,经分步煅烧获得晶型良好的尖晶石型LiM0.2Mn1.8O4(M=Mg,Cd)。结果表明,不同元素掺杂会导致LiMn2O4产生不同程度的晶格畸变。Mg掺杂引起晶格收缩,并导致Mn(Ⅳ)—O和Mn(Ⅲ)—O键能强度增加,对应的红外吸收峰波数增加17.59和2.16cm–1而发生蓝移;Cd掺杂引起晶格膨胀及Mn(Ⅳ)—O和Mn(Ⅲ)—O键能强度降低,对应的红外吸收峰波数均减少2.13cm–1而发生红移。     

SrIn0．1Ti0．9O3／SrNb0．2Ti0．8O3双层膜的微结构研究

具有钙钛矿结构的金属氧化物多层膜比单层膜具有更良好的电学或光学性能，实际应用价值更大。另外，虽然p-n结在半导体技术中已经得到了广泛地应用，但是对钙钛矿结构的金属氧化物p-n结的研究工作才刚刚起步。因此，对掺杂不同元素而形成的以SrTiO3为母体的p-n结进行研究不     

尖晶石型LiMn_(2-x)Ga_xO_4的合成及电化学性能研究

为了提高锂离子电池尖晶石锰酸锂正极材料的循环性能和倍率性能,采用柠檬酸辅助溶胶-凝胶法制备了LiMn2–xGaxO4(x=0,0.02,0.05,0.07)正极材料。研究了Ga掺杂对所制材料性能的影响。结果表明:制得的LiMn2–xGaxO4具有单一的尖晶石结构。当Ga3+掺杂量为x=0.05时,LiMn2–xGaxO4首次放电比容量为117.1 mAh/g,经过95次循环后,放电容量保持率高达97.9%;在高倍率4C条件下,首次放电比容量为100.9 mAh/g,30次循环后放电比容量为102.4 mAh/g,具有优异的倍率性能。     

Atomically Interlocked Chemistry Activated by Interstitial Sites in LiMn2O4 Cathode

The extensive applications of spinel LiMn₂O₄ (LMO) are severely plagued by grievous capacity degradation and structural collapse, mainly ascribed to deleterious Jahn−Teller distortion and subsequent dissolution of Mn²⁺. Herein, highly stable LMO with atomic interlocking effect is rationally designed via engineering Al into the unoccupied 16c sites. The local coordination environment of the surficial MnO₆ octahedron is reconstructed by robust Al−O band coherency, giving strengthened lattice oxygen skeleton and constraining heterophase evolution with the suppression of Jahn−Teller distortion, validated by theoretical calculations coupled with synchrotron X-ray absorption spectrum. Concomitantly, with the occupation of Al in interstitial site, the migration of Mn is effectively restrained, directly observed by scanning transmission electron microscopy, leading to the inhibition of inactivation as well as dissolution loss of Mn. Resultantly, splendid long cycling stability of Al-LMO after 1000 loops with only 0.019% capacity fading per cycle is presented. Given this, this elaborate study can provide an ingenious avenue for regulating the structure/interface chemistry architecture in electrode materials.     

中间相碳微球改性的正极材料LiMn2O4性能研究

采用柠檬酸络合法制备中间相碳微球(Mesocarbon microbeads,以下用C表示)改性的LiMn2O4。通过X射线衍射、循环伏安、电化学阻抗、充放电测试对模拟电池性能进行了测试。结果表明:C的加入有助于Li+在正负极之间嵌入和脱嵌,其中w(C)为3%时效果最好,首次放电容量达128.82mAh/g,经过30次循环后的比容量为119.58mAh/g,说明C加入增大了比容量,稳定了其循环性能。     

尖晶石结构LiTi2O4薄膜光学性质研究

用激光脉冲沉积(PLD)方法,以MgAl_2O_4(001)为衬底制备了过渡金属氧化物LiTi_2O_4薄膜.采用X射线衍射(XRD)对所制备材料进行结构测试,结果表明,材料具有立方尖晶石单相结构,结晶性能良好.应用拉曼光谱和光谱椭偏仪(SE)分别研究了材料在常温下的拉曼活性声子特性和可见-近红外波段的折射率和消光系数.应用第一性原理计算了LiTi_2O_4材料的能带结构和态密度,结果表明理论计算结果和实验测试结果具有很好的一致性,能带计算结果能够很好的解释薄膜的光学常数.     

尖晶石相ZnCr_2O_4陶瓷生成条件

用 XRD法研究配料粒度、烧结温度及陈化处理诸因素对生成尖晶石相 Zn Cr2 O4数量的影响 ,结果表明 ,在 80 0～ 110 0℃间 ,原料的陈化处理可促进尖晶石相 Zn Cr2 O4的生成。     

超声波化学法合成纳米铁酸镁粉末

用超声波化学法合成了纳米尖晶石型铁酸镁(MgFe_2O_4)粉末,并用 X 射线衍射(XRD)、电子透射电镜(TEM)、红外光谱对产品的纯度、结晶度,粒径以及内部形态及结构进行了分析表征。结果表明:当镁和铁以 1:2 的摩尔比配合、超声频率为 20.81 kHz、超声辐射 50 min 时,可得到纯度较高、结晶度好、粒径分布窄的尖晶石型铁酸镁纳米颗粒。     

Phase transition of Cu2O to CuO nanocrystals by selective laser heating

In this paper, we reported the preparation of CuO nanocrystals by microwave irradiation method. With the aid of suitable surfactants, CuO nanoparticles of uniform size and shape were successfully prepared. The as-prepared nano-products were characterized by different techniques such as Xray diffraction (XRD), Raman scattering, scanning electron microscopy (SEM), which all confirmed the good quality of the product. However, Raman spectra showed some peaks, which were attributed to impurity phases such as Cu₂O or Cu(OH)₂. Post annealing the samples by laser is a good method to convert these phases into pure CuO. Phase transition was observed in situ by Raman spectroscopy. After laser treatment process, Raman spectra of the samples showed that the nano-product is single phase and the crystal quality of CuO nanocrystal was improved clearly.     

Synthesis, Structure, and Electrochemistry of Sm-Modified LiMn2O4 Cathode Materials for Lithium-Ion Batteries

Spinel lithium manganese oxide and a series of Sm/LiMn₂O₄ spinels with different Sm additive contents (x = 0.02%, 0.05%) were prepared for the first time via a coprecipitation method for rechargeable lithium-ion batteries. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive analysis of x-rays (EDAX), infrared (IR), and electron spin resonance spectral studies as well as various electrochemical measurements were used to examine the structural and electrochemical characteristics of LiMn_2?x Sm _x O₄ (x = 0.00%, 0.02%, 0.05%). XRD and SEM studies confirmed the nano materials size for all prepared spinels. From cyclic voltammetry studies, in terms of peak splitting, electrochemical active surface area, and intensity of the peaks, the LiMn_1.98Sm_0.02O₄ sample possesses better electrochemical performance compared with the LiMn_1.95Sm_0.05O₄ sample. Hence, limited addition of a rare-earth dopant is preferable to obtain better efficiency. Direct-current (DC) electrical conductivity measurements indicated that these samples are semiconducting and their activation energies decrease with increasing rare-earth Sm³⁺ content.