添加Cu2S对Bi-Pb-Sr-Ca-Cu-O体系超导性的影响

本文对Cu_2S添加的Bi-Pb-Sr-Ca-Cu-O体系进行了低温电阻、X射线衍射和XPS研究．实验结果表明，加入少量的Cu_2S能够降低高T_c相的形成温度，改善超导性能，加入Cu_2S引起了Cu 2p_(3/2)谱的主峰向低结合能方向移动，并减少其卫星峰的面积．这表明Cu_2S的加入减少了Cu~(2+)的量，即导致空穴载流子浓度的减小．     

Synthesis, structure, and conductivity of molecular conductor (PyEt)[Ni(dmit)_2]_2

A new electrical conductive crystal PyEt[Ni(dmit)2]2 (dmit=4,5-dimercapto-1,3-dithiole-2-thione) has been synthesized and its X-ray structure has been determined to be in monoclinic system, C2/c space group. In PyEt[Ni(dmit)2]2 crystal, the conducting component [Ni(dmit)2]0.5- is face-to-face packed forming molecular column along the c-direction, and these molecular columns are then side-by-side extended along the a-direction forming a kind of two-dimensional conducting sheet on (010). The measured conductivity at room temperature along a certain direction on (010) plane is 10 S .cm-1. From 282 to 269 K, the crystal shows metallic behavior but changes to semiconductor below 269 K. Based on the measured crystal structure and calculated band structure, this conductor-semiconductor phase transformation can be primarily interpreted: The metallic conductivity is corresponding to the uniform molecular column and the atomic-lattice-chain structure of Ni chain, while the semi-conductive behavior to staggered mo     

分子导体(PyEt)[Ni(dmit)2]2的合成、结构与导电性

合成了一种新的导电分子晶体PyEt[Ni(dmit)₂]₂ (dmit=4,5-dimercapto-1,3-dithiole-2-thione). X射线衍射测定表明, 该晶体属于单斜晶系, C2/c空间群. PyEt[Ni(dmit)₂]₂晶体中, 导电组元[Ni(dmit)₂]^0.5−沿c方向面对面平行堆积成分子柱, 各分子柱沿a方向肩并肩并行伸展构成(010)面的二维导电层. 测得二维导电层上某方向的室温电导率为10 S∙cm^−1. 从282~269 K, 该晶体表现出金属导电性, 269 K以下则为半导体. 用实测的晶体结构和计算的能带结构对这种导体→半导体的相变予以解释: 金属导电性对应于均匀的分子柱和直线点列型Ni原子链; 而半导体导电性则对应于交错的分子柱和锯齿型Ni原子链.     

分子导体θ-(ET)(C7H7SO3)·3H2O的合成、结构和导电性

用恒电流电化学结晶的方法合成了一种新的基于电子给体BEDT-TTF(双亚乙基二硫四硫富瓦烯) 的电荷转移盐θ-(ET)(C7H7SO3)·3H2O (ET为BEDT-TTF的简写,C7H7SO-3=对甲苯磺酸根).用四圆X衍射的方法测定了θ-(ET)(C7H7SO3)·3H2O的结构.晶体属于三斜晶系,P-1空间群;a=0.8682(1) nm, b= 1.2027(1) nm, c=2.5890(3) nm, α=87.025(6)°, β=89.117(8)°, γ=69.071(7)°, V=2.5216(5) nm3, R=0.0580.晶体中ET自由基沿a轴方向堆积成柱,相邻两个分子柱中的ET分子平面的夹角为49.30°.在b轴方向存在着分子柱侧向间的S…S近距作用.ET阳离子层与对甲苯磺酸根阴离子层沿c轴方向上交替排列.位于阳离子层与阴离子层之间的许多H2O形成了有利于晶体导电性的二维氢键网络.θ-(ET)(C7H7SO3)·3H2O在(001)晶面上某方向上的室温导电率为0.011 S·cm-1,所测变温电导曲线表明,该晶体在120～278 K温度区间内表现为半导体导电行为,导电激活能Ea=0.316 eV.从278～286 K表现为金属导电性.在276 K附近存在金属-半导体相变.     

分子导体(PyH)[Ni(dmit)_2]_2的合成、结构与导电性

合成了一种新的导电分子晶体(PyH)[Ni(dmit)_2]_2 (Py = pyridine, dmit = (C_3S_5)~(2-) = 4,5-dimercapto-1,3-dithiole-2-thione)，用元素分析、红 外光谱对其进行了表征，并用四圆X射线衍射方法确定了结构，该晶体属于三斜晶 系，P-1空间群；晶胞参数为: a = 0.59227(4) nm，b = 0.82279(6) nm, c = 1. 67535(9) nm, α = 90.233(5)°, β = 92.107(5)°, γ = 104.654(6)°; V = 0.78925(9) nm~3, Z = 1. (PyH)[Ni(dmit)_2]_2晶体中，导电组元[Ni(dmit)_2] ~(-0.5) 沿b轴方向形成具有二聚体结构的柱状堆积，在(001)面形成以肩并肩分子 间的S…S强相互作用为特征的二维导电层，这种二维导电层上的室温电导率为0. 13 Ω~(-1)·cm~(-1)，在c轴方向，(PyH)~+与[Ni(dmit)_2]~(-0.5)之间除库仑作 用外，还存在N-H…S，C-H…S氢键相互作用。单晶(001)面上变温电阻的测定结果 表明，在90 K到室温的温度范围内，(PyH)[Ni(dmit)_2]_2具有半导体导电行为， 导电激活能为0.15 eV。     

高T~cYBa~2Cu~3O~7-xF~y超导体表面和体相的化学态的XPS研究

以NH~4F作为F^-源,制备了一系列不同含F量的高T~cYBa~2Cu~3O~7-xF~y超导体,在名义F含量小于1.5mol范围内,基T~c值均比与之对照的不含F样品高2～6K.用XPS研究了这类含F材料表面和体相的化学态及其变化,根据同种化合物中不同元素间的结合能差和其它辅助实验结果,标识了每个元素不同化学态的光电子峰,并对各个峰的可能来源及其对应原子在结构中的位置和作用进行了讨论.结果揭示,表现和体相的体学态存在着较大差异.     

Anodic synthesis and XPS analysis of La_(1-x)Na_xCu_2O_4

The single phase La1-x NaxCu2O4 crystals were synthesized by an electrochemical method from molten KOH/NaOH/KNO3 at 280-300℃ while La2-yNayCuO4 were prepared by precipitation from the same molten salt. The resulting crystals were characterized by using SEM, XRD, EDX and XPS. XPS analysis revealed that the La3d satellite structures of La1-xNaxCu2O4 were quite different from those of La2-yNayCuO4. These differences have been attributed to the changes in crystal structures, bond lengths and covalent character of the metal-ligand bonds.     

BaKPbO和BaKPbBiO的熔盐阳极电结晶

钙钛石（ＡＢＯ３）型复杂氧化物由于Ａ位、Ｂ位在适当范围内掺杂其他离子而成为性能宽广的功能材料．例如ＢａＰｂＯ３及其取代物ＢａＰｂＢｉＯ是甲烷偶联反应的催化剂［１］,ＢａＰｂＢｉＯ［２］和ＢａＫＢｉＯ［３］还具有超导性．另一方面,这些复杂氧化物的功能又?..