流体静压力下快离子导体Rb4Cu16I7Cl13离子电导的研究

在流体静压力为0.5—11.6kbar,温度-80—80℃范围内,测量了Rb₄Cu₁₆I₇Cl₁₃多晶粉末“松散”样品和“致密”样品的离子电导。“松散”样品电导与压力的关系表明,在4.0—5.0kbar附近,电导存在极大值;“致密”样品电导随压力单调下降。在一定压力下,“致密”样品电导率随温度变化的趋势与常压结果相同,压力对Rb₄Cu₁₆I₇Cl_关键词：     

d(x2-y2)+idxy混合波正常金属/绝缘层/超导体结中的隧道谱

考虑界面粗糙散射,在Blonder-Tinkham-Klapwijk(BTK)理论框架下,通过求解Bogoliubov-de-Gennes(BdG)方程,分别计算T=0K和有限温度下,d_(x²-y²)+id_xy混合波正常金属绝缘层超导体结中的准粒子输运系数和隧道谱.研究表明:隧道谱中的电导峰的劈裂程度强烈地依赖于d_xy波分量的强度、超导体的晶轴方位和界面粗糙强度,而温度的升高能压低电导峰. 关键词： NIS结 (x²-y²)+id_xy混合波超导体')" href="#">d_(x²-y²)+id_xy混合波超导体 隧道谱     

非晶态Cu12.5Ni10Zr41Ti14Be22.5合金相分离的动力学标度

利用实时小角中子散射实验研究了非晶态Cu_12.5Ni₁₀Zr₄₁Ti₁₄Be_22.5合金相分离的动力学标度性质．通过对相分离过程中实时小角中子散射谱进行详细的标度分析，揭示出散射函数S（q，t）（q为散射波矢，t为时间）在相分离的早期即达到动力学标度态，从而证明动力学标度假设也适用于描述深过冷液态的相分离过程 关键词：     

非晶态B2O3-0.7Li2O-0.7LiCl电导率频谱的研究

本文对非晶态快离子导体的B₂O₃-0.7Li₂O-0.7LiCl的电导率与外电场频率的关系进行了研究。结果表明:在较宽的频率范围内,样品的体电导约等于总电导;电导率频谱在中频段有一平台,在高频段上升,而且温度越高,开始上升的频率也越高。这一结果使电导率的测定有可能简化,即可以采用交流电桥法或在某一合适频率下采用交流伏安法直接测量样品的总电导或总导纳的模值作为体电导的值,从而求得电导率。本文考虑到非晶态结构的长程无序对离子迁移的影响,从局域极 关键词：     

Sm0.9Sr0.1AlO3-δ钙钛矿氧化物的固相反应合成和电学性能

用固相反应法制备了Sm_0.9Sr_0.1AlO_3-δ钙钛矿氧化物陶瓷.通过XRD,SEM和交流复阻抗谱以及氧浓差电池方法研究了样品的物相结构、微观形貌、电学性能及输运机理.结果表明,在1650℃烧结时,可以制备出单相的具有四方钙钛矿结构的氧化物Sm_0.9Sr_0.1AlO_3-δ;1650℃烧结16 h时的Sm_0.9Sr_0.1AlO_3-δ样品具有最高的相对密度和电导率,其值分别为96.7%和1.3×10^-2S/cm(900℃),比未掺杂的SmAlO₃的电导率大4个数量级左右,高温区电导活化能(T>670℃)小于低温区电导活化能(T<670℃);Sm_0.9Sr_0.1AlO_3-δ在空气气氛中是一个氧离子和电子空穴的混合导体,氧离子迁移数在0.7左右,并随温度升高逐渐增加,氧离子电导活化能(0.95eV)大于空穴电导活化能(0.84eV),900℃时氧离子电导率为9.65×10^-3S/cm. 关键词： 3')" href="#">SmAlO₃ 氧离子导电性 混合导体 活化能     

(BiFeO3)25/(La0.7Sr0.3MnO3)25 多层膜的光学和电学性质

采用射频磁控溅射方法在(001)SrTiO₃衬底上制备(001)取向的(BiFeO₃)₂₅/(La_0.7Sr_0.3MnO₃)₂₅多层膜.光学测试结果表明,1.3-2.1 eV范围内,相对于衬底而言多层膜光吸收增强; BiFeO₃的带隙为2.7 eV. 另外,结合绝缘介质导电模型分析了所测得的电流-电压数据,在所测试的温度及电压下,所制备的(BiFeO₃)₂₅/(La_0.7Sr_0.3MnO₃)₂₅多层膜的导电机理由空间电荷限制电导主导. 关键词： 多层膜 吸光度 空间电荷限制电导     

Li4SiO4-Li3VO4赝二元系和Li4GeO4-Li4SiO4-Li3VO4赝三元系中新的锂离子导体

本文在室温到300℃的温度范围内研究了Li₄SiO₄-Li₃VO₄和Li₄GeO₄-Li₄SiO₄-Li₃VO₄体系中的离子导电性,发现γ_II相固溶体Li_3+xV_1-xSi_xO₄是好的锂离子导体。所研究的成分中Li_3.3V_0.7Si_0.3O₄的离子电导率最高,室温下为1×10^-5Ω^-1·cm^-1,在42—192℃的电导激活能为0.36eV,电子电导率可以忽略,因而这是迄今所发现的最好的锂离子导体之一。粗略确定了Li₄GeO₄-Li₄SiO₄-Li₃VO₄三元系中电导率高的范围,发现在Li_3.5V_0.5Ge_0.5O₄中Si部分取代Ge可以使电导率进一步提高,Li_3.5V_0.5Ge_0.4Si_0.1O₄的室温电导率可达1.3×10^-5Ω^-1·cm^-1,电导激活能为0.40eV。 关键词：     

BaSn1-xSbxO3-δ和Ba1-yLaySnO3-δ的导电机制

测量了ＢａＳｎ_1-xＳｂ_xＯ_3-δ和Ｂａ_1-yＬａ_yＳｎＯ_3-δ样品的低温电阻率和磁化率．实验结果表明，在较低温度区域，两类样品的导电机制均是传导电子的范围可变跳跃。而在较高温度区域，ＢａＳｎ_1-xＳｂ_xＯ_3-δ样品的电导主要是电子从定域态到扩展态的跃迁所贡献，Ｂａ_1-yＬａ_yＳｎＯ_3-δ样品的电导则可能来源于电子的最近邻跳跃。 关键词：     

C20F20分子电子输运性质的第一性原理研究

利用第一性原理密度泛函理论和非平衡格林函数方法研究了C₂₀F₂₀分子的电子输运性质. 计算得到了C₂₀F₂₀分子的平衡电导为0385 G₀ 其I-V曲线表现出较好的线性特性. 在有限偏压范围内具有较稳定的电导值, 可以用于制备稳恒电阻分子器件. 关键词： 20F₂₀分子')" href="#">C₂₀F₂₀分子 电子输运 分子器件     

YBa2Cu3O6+δ/BaTiO3系复合功能陶瓷特性研究

报道了超导陶瓷ＹＢａ₂Ｃｕ₃Ｏ_6+δ与铁电陶瓷ＢａＴｉＯ₃进行复合的结果。研究了该复合功能陶瓷的物相、（超）导电性和低温电阻温度特性。结果表明，采用合理的合成工艺，可得到呈现混和分布的两相复合功能陶瓷材料；该复合材料的电导特征符合三维渗流导电行为，发现在较高ＹＢａ₂Ｃｕ₃Ｏ_6+δ含量时，样品呈超导电性，并对此作了初步讨论。 关键词：     

Y1Ba2Cu3O7的维度特性分析

本文中利用变换生成函数的技术计算了在Y₁Ba₂Cu₃O₇晶格上无规行走的逃逸几率,得到了弱耦合极限下的渐近表达式,推算了Y₁Ba₂Cu₃O₇的维度与Cu-O层间的耦合参量的关系,并得到从低维到三维的渡越(crossover)。理论计算表明,Y₁Ba₂Cu₃O₇是一个十分接近三维的体系。 关键词：     

Measurements of fractal dimensionality in 0.1Cs2O-0.9TeO2 glass-forming tellurite system by Raman spectroscopy

Low-frequency Raman spectroscopy was utilized in order to estimate the fractal dimensionality for tellurite 0.1Cs₂O-0.9TeO₂ binary glass-forming system in a temperature range, which includes the glassy and supercooled liquid state. A variation in fractal dimensionality was observed and calculated directly from the Raman spectroscopic data. This variation can be interpreted as an indication of structural alterations caused by temperature variation and correlated with existing structural models concerning tellurite network. Low-frequency Raman spectroscopy has proved to be a valuable tool for studying the fractal dimensionality and structural transformation in amorphous phases. The estimation of the localization degree of lattice vibration in disordered materials is important and discussed in the context of current phenomenological status of the field.     

Electrical conduction and critical magnetic field for superconductivity of a Nb3Se4 single crystal

With respect to the quasi-one dimensionality of single crystals of Nb₃Se₄, the electrical resistivity from 1.3 to 320 K and the critical magnetic field for superconductivity are measured. The resistivity along the Nb-chain direction is represented as a sum of a temperature independent and an intrinsic temperature dependent term. The temperature dependence of the intrinsic resistivity subjects to T³ form between 10 and 80 K above which it tends to a T linear form. The critical magnetic field is proportional to the temperature difference from the transition temperature. Its dependence is well fitted by the elliptical fluxoid model of Ginzburg-Landau theory. The ratio of the parallel and the perpendicular to the c-axis is 5.7.     

Y0.9Eu0.1Ba2Cu3O7-δ中的磁通蠕动研究

在较宽的温度（４．２－８０Ｋ）和磁场（０－８Ｔ）范围内测量了ＹＢａ₂Ｃｕ₃Ｏ_7-δ和Ｙ_0.9Ｅｕ_0.1Ｂａ₂·Ｃｕ₃Ｏ_7-δ样品的磁滞回线和磁弛豫，研究了其Ｍ（ｔ），Ｊ_c（Ｔ）和Ｕ_eff（Ｊ）关系，并与现有的一些理论模型所预言的结果进行了比较。结果表明：（１）与ＹＢａ₂Ｃｕ₃Ｏ_7-δ相比，Ｙ_0.9Ｅｕ_0.1·Ｂａ₂Ｃｕ₃Ｏ_7-δ样品的有效钉扎势和无磁通蠕动时的临界电流密度有明显提高，表明Ｅｕ的部分替代引入了新的、具有更大的钉扎势的钉扎中心；（２）与其它模型相比，集体钉扎——蠕动理论对我们的实验结果作了更好的描述，因而本文为这一理论提供了新的实验证据。 关键词：     

Two-dimensional critical behaviour in antiferrodistortive Al ur6(CIO4)3 and Ga ur6(ClO4)3

Critical behaviour with dimensionality d = 2 has been observed for the 300 K antiferrodistortive phase transition in Al ur₆(ClO₄)₃ and Ga ur₆(ClO₄)₃ by means of the temperature dependence of the ESR parameter D. The systems exhibited d = 2 behaviour in the static critical behaviour for T<T_c?40 K for T>T_c + 40 K. From the ESR data including line width measurements the local order parameter relaxation rate ω₁ has been obtained for various temperatures above T_c, with a lowest value of ω₁ = 150 MHz at T_c + 15 K     

Spectroscopic properties of Er/Ce-codoped La3Ga5SiO14

The Er-single-doped and Er/Ce-codoped La₃Ga₅SiO₁₄ polycrystalline powders are synthesized by the solid-phase synthesis method. The room-temperature luminescence spectra of the samples are investigated. The Near-infrared-region spectroscopic properties of Er³⁺ ions in the La₃Ga₅SiO₁₄ systems are analysed with Judd-Ofelt theory and rate equations. The effective deactivating effect of Ce³⁺ ions on Er³⁺ ions is confirmed.     

Tm3+/Ho3+共掺镓铋酸盐玻璃1.47μm发光特性和能量传递的研究

报道了Tm³⁺/Ho³⁺共掺的镓铋酸盐玻璃14Ga₂O₃-25Bi₂O₃-20GeO₂-31PbO-10PbF₂玻璃1.47μm(S波段)发光和能量传递特征，应用Judd-Ofelt理论计算了玻璃的强度参数Ω_t(t=2，4，6)，自发辐射概率A、荧光分支比β，荧光辐射寿命τ等各项光谱参数以及有效荧光线宽Δλ_eff和峰值发射截面σ^peak_e.通过测量荧光光谱和荧光寿命研究了Ho³⁺离子掺杂浓度对Tm³⁺离子1.47μm波段发光性能的影响，分析了Tm³⁺和Ho³⁺之间的能量传递过程.结果表明一定浓度内Ho³⁺的共掺迅速降低了Tm³⁺：³F₄能级的粒子数，而对³H₄能级粒子数影响不大，从而降低了³F₄和³H₄能级间布居数反转的难度，极大地提高了1.47μm发光效率.研究表明镓铋酸盐玻璃是适用于S波段光纤放大器的一种潜在基质材料，而掺杂一定浓度的Ho³⁺离子有利于提高Tm³⁺离子在1.47μm波段的发光效率. 关键词： 重金属氧化物玻璃 光谱性质 3+/Ho³⁺离子')" href="#">Tm³⁺/Ho³⁺离子 能量传递     

Magnetic behavior of the II-V-diluted magnetic semiconductor Cd1−xMnxSb

Polycrystalline samples of the II-V-diluted magnetic semiconductor Cd_1−xMn_xSb (x=0.05-0.20) were synthesized. Standard high temperature ceramic methods under an inert atmosphere were utilized for sample fabrication. Structural characterization was done using X-ray diffractometry (XRD), which indicated that a simple substitution of Mn for Cd is probably not occurring. Hysteresis, ac susceptibility, dc magnetization, and spontaneous magnetization measurements were performed for Cd_0.90Mn_0.10Sb. The hysteresis data indicated the presence of a ferromagnetic component. Ferromagnetism in the Cd_0.90Mn_0.10Sb system is likely due to two sources: Mn spins in small Mn-rich regions and a small amount of MnSb in a minority phase. Analysis of the spontaneous magnetization as a function of temperature for Cd_0.90Mn_0.10Sb yielded the value 0.172 for the critical exponent β. In MnSb, β was found to have the value 0.379, which is close to the theoretical value for 3D-Heisenberg systems. Thus, in Cd_0.90Mn_0.10Sb, the ferromagnetism is not of the 3D-Heisenberg type; rather, it is closer to 2D Ising behavior, indicating reduced effective dimensionality.     

A light neutral intermediate vector boson without large e+e−→ μ+μ− asymmetries

An effective SU(2)×U(1)×U(1)' electroweak theory is shown to permit the occurence of a pair of neutral intermediate vector bosons with masses 40 GeV?m_light?70 GeV, m^W.S._Z⁰<m_heavy?100 GeV. Neutrino neutral current interactions are shown to be the same as in the standard electroweak model, and e⁺e^?→μ⁺μ^? forward-backward asymmetries are within experimental bounds for m_light?40 GeV.     

Sound velocity in La0.5Ca0.5MnO3

In this Letter the microscopic theory of the relative change in velocity of sound with temperature of La_0.5Ca_0.5MnO₃ is reported. The phonon Green function is calculated using the Green function technique of Zubarev in the limit of zero wave vector and low temperature. The lattice model electronic Hamiltonian in the presence of the phonon interaction with hybridization between the conduction electrons and the l-electrons is used. The relative change in velocity of sound at various temperatures is studied for different model parameters namely the position of the l-level, the effective phonon coupling strength and hybridization strength. The phonon anomalies observed experimentally at different temperatures are explained theoretically. An abrupt change in velocity at Neel temperature (TN) is observed clearly. It is observed that different parameters influence the velocity of sound.