LiNdP4O12的晶体结构

对于盐熔法合成的LiNdP₄O₁₂单晶进行了X射线衍射分析,该晶体属于单斜晶系,空间群为C2/c,z=4,晶胞参数为:α=16.486?,b=7.073?,c=9.775?,β=126.23°,全矩阵最小二乘法修正给出1251个独立反射的R=0.054,R_ω=0.050,经吸收和次级消光校正后,R=0.048,R_ω=0.043,基本的结构单位是(PO₃)_n的螺旋带,它们由共角 关键词：     

LiErP4O12的晶体结构

对于盐熔法合成的LiErP₄O₁₂单晶进行了X射线衍射分析。该晶体属于单斜晶系,空间群为C2/c,z=4,晶胞参数为:a=16.229?,b=7.009?,c=9.524?,β=125.92°。包括把二次消光作为晶体结构参数的全矩阵最小二乘法修正给出1282个独立反射的R=0.058。基本的结构单位为(PO₃)_n的螺旋带,它们由共角的四面体构成。十二面体ErO₈不共有任何O原子,从这意义来说是相互分立的。 关键词：     

Synthesis and properties of Au-Fe3O4 and Ag-Fe3O4 heterodimeric nanoparticles

Monodisperse Au-Fe 3 O 4 heterodimeric nanoparticles (NPs) were prepared by injecting precursors into a hot reaction solution.The size of Au and Fe 3 O 4 particles can be controlled by changing the injection temperature.UV-Vis spectra show that the surface plasma resonance band of Au-Fe 3 O 4 heterodimeric NPs was evidently red-shifted compared with the resonance band of Au NPs of similar size.The as-prepared heterodimeric Au-Fe 3 O 4 NPs exhibited superparamagnetic properties at room temperature.The Ag-Fe 3 O 4 heterodimeric NPs were also prepared by this synthetic method simply using AgNO 3 as precursor instead of HAuCl 4.It is indicated that the reported method can be readily extended to the synthesis of other noble metal conjugated heterodimeric NPs.     

CoFe2O4和MnFe2O4纳米复合介质的制备及其磁性研究

采用热分解法制备了分散程度高且平均晶粒尺寸为20 nm的CoFe₂O₄和MnFe₂O₄复合介质.低温磁化曲线测量显示,制备的复合介质具有软-硬磁交换弹性耦合效应,且合成温度以及软磁和硬磁相的成分比例对磁交换弹性耦合的强度有很大的影响.变温磁测量显示,温度为20K时,复合纳米介质的表面自旋冻结效应导致饱和磁化强度显著增加.Henkel测量显示,对分散的CoFe₂O₄和MnFe₂O₄复合介质,磁偶极相互作用占主导作用.     

LaxBi2-xTi4O11的合成及相变研究

合成了Ｌａ_xＢｉ_2-xＴｉ₄Ｏ₁₁系列样品，并完成了它们的喇曼光谱和ｘ射线衍射测量；结果表明，该体系在Ｘ＝１．２经历了一次相变，且相变与最低频声子模随Ｘ的变化有关。Ｌａ_0.2Ｂｉ_1.8·Ｔｉ₄Ｏ₁₁的相变温度为２００℃。初步获得Ｌａ₂Ｔｉ₄Ｏ₁₁的结构为正交结构。 关键词：     

Mn3O4包覆对LiNi0.5Mn1.5O4正极材料界面电化学性能的提高

本文采用化学湿磨法,首次将金属氧化物Mn₃O₄包覆于LiNi_0.5Mn_1.5O₄颗粒表面,使得电极材料的电子电导率从1.53×10^-7 S/cm 提高到3.15×10^-5 S/cm. 电化学测试结果表明Mn₃O₄包覆大大提高LiNi_0.5Mn_1.5O₄正极材料的倍率性能和高温循环稳定性. 最佳包覆样品为2.6wt% Mn₃O₄包覆的LiNi_0.5Mn_1.5O₄,在10 C倍率下具有108 mAh/g的高放电容并且在55 °C下100次循环后仍有78%的容量保持率,远大于未包覆样品67%的容量保持率.     

BaO-Li2O-B2O3三元系中BaB2O4-Li2B2O4和BaB2O4-Li2O截面相平衡关系的研究

本文用X射线和差热分析方法对BaO-Li₂O-B₂O₃三元系中的两个截面:BaB₂O₄-Li₂B₂O₄和BaB₂O₄-Li₂O作了研究。在BaB₂O₄-Li₂B₂O₄赝二元系中发现了一个新的化合物4BaB₂O₄·Li₂B₂O₄。化合物在930±3℃由包晶反应形成,并与Li₂B₂O₄形成共晶反应。共晶温度为797±3℃,共晶点组分为79mol％Li₂B₂O₄。在BaB₂O₄-Li₂O截面中也存在化合物4BaB₂O₄·Li₂B₂O₄,其包晶反应温度从930±3℃随Li₂O含量增加下降到908±3℃。在组分60mol％Li₂O处形成另一个新的化合物2BaB₂O₄·3Li₂O。该化合物在630±3℃也是由包晶反应形成,并与Li₂O和Li₂CO₃分别形成共晶反应,共晶温度分别为400±3℃和612±3℃。在BaB₂O₄-Li₂B₂O₄和BaB₂O₄-Li₂O体系中都没有观察到固溶体。用计算机程序分别对化合物4BaB₂O₄·Li₂B₂O₄和2BaB₂O₄·3Li₂O的X射线粉末衍射图案进行了指标化,其结果:4BaB₂O₄·Li₂B₂O₄的空间群为Pmma,a=13.033?,b=14.630?,c=4.247?,每个单胞包含两个化合式单位;2BaB₂O₄·3Li₂O的空间群为Pmmm,a=4.814?,b=9.897?,c=11.523?,每个单胞也含有两个化合式单位。 关键词：     

BaB2O4-K2O和BaB2O4-K2B2O4赝二元系相图的研究

用X射线衍射和差热分析方法研究了BaB₂O₄-K₂O和BaB₂O₄-K₂B₂O₄赝二元系的相平衡关系。BaB₂O₄-K₂B₂O₄属共晶体系,共晶温度为850±3℃,共晶点成分为45mol％K₂O。在Ba 关键词：     

超细Fe3O4的氧化过程

根据穆斯堡尔谱分析,Fe₃O₄转变为γ-Fe₂O₃是γ-Fe₂O₃成核生长过程。根据氧化过程磁矩的变化确定Fe₃O₄浓度随时间的变化,-(dc)/(dt)=mc³仅在氧化初始阶段适合。     

含铋层状结构铁电体PbBi4Ti4O15和SrBi4Ti4O15的X射线衍射数据的测定

用衍射仪和Guinier聚焦相机收集了含秘层状结构铁电体PbBi₄Ti₄O₁₅SrBi₄Ti₄O₁₅的X射线粉末衍射图谱(Cu K_a),给出了d值大1.13?的88和76条衍射线的衍射数据和指标。它们都属正交晶系,空间群Bb2₁m(C_2v¹²),点阵常数和X射线理论密度为PbBi₄Ti₄O₁₅α=5.431?,b=5.459?,c=41.36?; z=4;D_x=7.986g/cm³.SrBi₄Ti₄O₁₅:α=5.428?,b=5.438?,c=40.94?;Z=4;D_x=7.447g/cm³.     

Magnetic field dependence of piezoelectric resonance frequency in CoFe2O4–BaTiO3 composites

The particulate and the multilayer CoFe₂O₄(CFO)–BaTiO₃(BT) composites were prepared by the conventional solid state reaction method and the tape casting method, respectively. Both the prepared composites were simultaneously ferroelectric and ferromagnetic at room temperature. For the multilayer composite sample, a piezoelectric resonance frequency remarkably depended on the applied DC magnetic field, while no remarkable magnetic field dependence was observed for the particulate composite samples. An uniform magnetostriction of the CFO phase in the multilayer composite contributes to piezoelectric effect of the BT phases, resulting in the modulation of the piezoelectric resonance frequency.     

Exchange bias behavior of monodisperse Fe3O4/γ-Fe2O3 core/shell nanoparticles

We have carried out systematic studies on well-characterized monodisperse Fe₃O₄/γ-Fe₂O₃ core/shell nanoparticles of 2-30 nm having a very narrow size distribution and possessing a uniquely mono-layer of surface γ-Fe₂O₃. This unique core-shell structure, probably having a disordered magnetic surface state, leads us to three key observations of unusual magnetic properties: i) a very large magnetic exchange anisotropy reaching over 7 × 10⁶ erg/cm³ for the smaller particles, ii) exchange bias behavior in the magnetization data of the core/shell Fe₃O₄/γ-Fe₂O₃ nanoparticles, and iii) the temperature dependence of the coercive field following an unusual exponential behavior.     

Mo掺杂SrBi4Ti4O15陶瓷的铁电介电性能

用传统的固相烧结工艺，制备了钼掺杂铁电陶瓷样品SrBi₄Ti₄O₁₅(SBTi)铁电陶瓷SrBi_4-2x/3Ti_4-xMo_xO₁₅(x=0.00，0.003，0.012，0.03，0.06，0.09).X射线衍射的结果表明，样品均为单一的层状钙钛矿结构相，Mo掺杂未改变SBTi的晶体结构.通过扫描电子显微镜观测发现，样品晶粒为片状，随掺杂量的增加，晶粒逐 关键词： 4Ti₄O₁₅')" href="#">SrBi₄Ti₄O₁₅ Mo掺杂 剩余极化 居里温度     

SrBi4Ti4O15的化学键性质和铁电性研究

通过原子环境计算方法分析了正交相SrBi₄Ti₄O₁₅晶体内的键络结构、各原子的空间配位数及局域团簇结构. 在此基础上, 结合晶体分解理论将SrBi₄Ti₄O₁₅晶体分解为多个二元赝晶体, 根据化学键介电理论计算得到各赝晶体所对应化学键的有效价电子密度、离子性等化学键性质. 通过键偶极矩建立了铁电体自发极化强度与化学键性质之间的关系, 求得正交相SrBi₄Ti₄O₁₅沿a轴方向的自发极化强度为28.03 μC/cm², 与实验结果和其他理论计算值符合较好.     

Li2SO4—Li2B2O4,Li2SO4—(NH4)2SO4赝二元系相图及离子导电性研究

本文用差热分析和X射线衍射方法对Li₂SO₄-Li₂B₂O₄和Li₂SO₄-[NH₄]₂SO₄两个赝二元系相图进行了研究。Li₂SO₄-Li₂B₂O₄是共晶体系,共晶温度为720℃ 关键词：     

Chemical expansion of La0.8Sr0.2Fe0.7Ga0.3O3-δ

This paper deals with the chemical expansion measurements and modelling of La_0.8Sr_0.2Fe_0.7Ga_0.3O_3-δ. The expansion behavior has been evaluated using a dilatometer and X-ray diffraction over a wide range of temperatures (RT to 1373 K) and oxygen partial pressures (10^− 21 to 1 atm). The material stoichiometry evolution with temperature and oxygen partial pressure has been measured using thermogravimetry analysis at different oxygen partial pressure, from 10^− 21 to 0.5 atm and from RT to 1473 K. Considering a typical defect model for lanthanum ferrite oxides, chemical expansion depends linearly on the Fe⁴⁺ concentration rather than on the oxygen vacancy concentration. A model of chemical expansion as a function of pO₂ and temperature is then proposed. It helps to understand and anticipate the chemical expansion behavior exhibited by this material when used as Ionic Transport Membrane (ITM).     

Inhomogeneous spin state in the organic conductor κ-(BEDT-TTF)4Hg2.78Cl8

The static and dynamical local spin susceptibility of the nonstoichiometric organic conductor, κ-(BEDT-TTF)₄Hg_2.78Cl₈, is studied by ¹³C NMR spectroscopy from room temperature down to 1.7 K. We observe a gradual growth of inhomogeneity in the spin state as a spectral broadening down to the lowest temperature, which is sustained even under 0.4 GPa but suppressed under 0.8 GPa. The emergence of the inhomogeneity is discussed in the light of the doped triangular-lattice Mott insulator.     

The magnetoelectric effect in layered composites Ni0.4Zn0.6Fe2O4—Pb0.95Sr0.05Zr0.53Ti0.47O3

The magnetoelectric effect in two- and three-layered composites based on nickel-zinc ferrite and lead zirconate-titanate was investigated. The value of the magnetoelectric response in layered composites depends largely on the frequency of the alternating magnetic field, the volume ratio of the electric phase forming the composite, and the mechanical interaction between magnetostriction and piezoelectric layers.     

Growth and Characterization of a New Superconductor GaBa2Ca3Cu4O11+δ

We successfully grow a new superconductor GaBa₂Ca₃Cu₄O_11+δ(Ga-1234) with a transition temperature of 113 K, using the Walker-type high-pressure synthesis apparatus. X-ray diffraction measurements on the powderized samples show a mixture of the Ga-1234 phase and the Ca_0.85CuO₂ phase, and the former is dominant. Under the scanning electron microscope, plate-like crystals of the Ga-based 1234 phase with shiny surfaces can be seen.The...     

La掺杂SrBi4Ti4O15铁电材料性能研究

按x=0.00，0.10，0.25，0.50，0.75和1.00，采用固相烧结工艺，制备了不同La掺杂量的SrBi_4-xLa_xTi₄O₁₅的陶瓷样品. 用x射线衍射对其微结构进行了分析，并测量了铁电、介电性能.结果发现，La掺杂未改变SrBi₄Ti ₄O₁₅的晶体结构.随掺杂量的增加，样品的矫顽场(E_c)下降，剩余极化(2P_{关键词： 4-x}La_xTi₄O₁₅')" href="#">SrBi_4-xLa_xTi₄O₁₅ La掺杂 铁电性能 相变温度 弛豫铁电