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木文研究了Al2O3对B2O3-0.7Li2O-0.7LiCl非晶态的形成和电学性能的影响,我们发现:加入适量的Al2O3后,无需借助液氮骤冷技术,直接将熔体倾倒在室温下的紫铜板上就很容易形成大块非晶锂离子导体B2O3-0.7Li2O-0.7LiCl-xAl2O3。Al2O3的加入使B2O3-0.7Li2O-0.7LiCl的电导率有所降低,但在高温下不太明显,电导激活能略微升高,实验发现:Al2O3含量x=0.03是较合适的剂量,较容易形成大块非晶态,对电导率的影响也不大。
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本文报道了非晶态离子导体Li2B2O4的7Li核磁共振研究。测量了7Li核磁共振谱与温度的关系。实验中发现,Li2B2O4的晶态、非晶态和部分晶化样品的7Li核磁共振谱有很大的不同,且在部分晶化样品的7Li核磁共振谱上有附加的小峰,它与LiCl(Al2O3)的7Li核磁共振谱上附加的小峰相类似。我们也对非晶态离子导体B2O3-0.7Li2O-0.7LiCl进行了7Li核磁共振研究,其结果与上面的类似。研究结果表明,它们都起因于非晶母体与微晶的界面效应。
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本文改进实验方法,在0.0001—1.23GPa流体静高压下测量了整片非晶锂离子导体B2O3-0.7Li2O-0.7LiCl-xAl2O3(x=0.05;0.15)及其粉末压片的离子电导率及激活体积。发现粉末压片电导率峰值是由非晶微粒间的接触电导及非晶微粒体电导两者叠加;对整片非晶电导率的压力效应用离子迁移通道的物理图象给出初步的微观解释。此外,还观测到氧化铝组分减少使电导率的压力转变点明显降低;测量出不同温度热处理以及300℃等温热处理4—20h后离子电导率-压力曲线的变化规律,仍可归因于非晶态相分离及两种非晶相的先后晶化。
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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
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G. Albinet J.M. Debierre P. Knauth C. Lambert L. Raymond 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,22(4):421-427
We describe a two-dimensional (2D) and a three-dimensional (3D) percolation model for ionic conductor-insulator composites
such as copper(I) bromide-titanium dioxide (CuBr-TiO2) or lithium iodide-alumina (LiI-Al2O3). These composites present an enhanced conductivity closely related to the insulator concentration. This effect is explained
by the formation of highly conducting space charge regions near the phase boundaries which are represented by good conductor
bonds. Our numerical model takes into account grain size and correlation effects. The dimension has a leading role for the
conduction properties. In the 2D case, the good conductor bonds do not percolate, whatever the insulator concentration, and
the maximum conductivity of the composite samples is of the same order as that of the ionic conductor grains. The behavior
of the system is very different in the 3D case where, for a large domain of composition, the good conductors percolate through
the regions between the conductor grains. For the CuBr-TiO2 composites the conductivity versus composition curve is bell-shaped. Conversely, in the LiI-Al2O3 system, a linear relation between the conductivity and the insulator volume fraction is obtained in the experiments. Our
model gives a plausible interpretation of the conductivity in both systems.
Received 10 April 2001 相似文献
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Oxide eutectic composites prepared by a directional solidification are noticeable for their good mechanical properties and
high temperature stability in oxidizing environments. In this paper we study the influence of stabilizers (Y, Sc) on the phase
composition, microstructure and electrical properties of Al2O3 - ZrO2 eutectic composites. At a hypereutectic composition of the melt, we have prepared the composites with tetragonal ZrO2, which possesses conductivities comparable to those of the composites containing cubic ZrO2. An addition of Sc2O3 improves the ionic conductivity of the Al2O3 - (Y2O3)ZrO2 eutectic composite at high temperatures. Both the microstructure and ionic conductivity do not change along the composite
(grown at a constant growth rate).
Paper presented at the 8th EuroConference on Ionics, Carvoeiro, Algarve, Portugal, Sept. 16–22, 2001. 相似文献
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《Solid State Ionics》2006,177(26-32):2597-2599
Vitrification and transport properties measurements for (AgBr)x(As2Se3)1−x glasses have been carried out in order to investigate the ion conduction phenomena of these systems. Glass samples were successfully obtained in a composition range of 0 ≤ x ≤ 0.65. The addition of AgBr leads these systems to an exponential increase of electrical conductivity. The ionic component of the electrical conductivity is dominant in highly AgBr-doped glasses. The vitrification brings the fast ion conduction to the present glass systems. 相似文献
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本文研究了Agl(Cr2O3)混合离子导体的红外吸收光谱、近紫外、可见反射光谱,透射电子显微镜的显微形貌及成份分析,发现混合离子导体的微观结构与纯Agl,Cr2O3不同。由透射电子显微镜的显微形貌得出不同于他人的介质模型。提出电介质引起的变形极化,导致了微观精细结构改变的观点。并对其物性改变的机理给予了讨论。
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Dillip K. Pradhan B. K. Samantaray R. N. P. Choudhary Awalendra K. Thakur 《Ionics》2005,11(1-2):95-102
A plasticized composite polymer electrolyte (PCPE) based on Poly (ethylene oxide) + NaI with Na2SiO3 as the ceramics filler and Poly (ethylene glycol) as the plasticizer has been prepared by solution cast technique. Effect
of plasticization on microstrucutre and electrical properties of the materials has been investigated. The changes in the structural
and microstructural properties of the material have been investigated by XRD and SEM studies. The electrical conductivity
estimated using a. c. impedance spectroscopy was found to be dependent on plasticizer concentration. An enhancement in the
ionic conductivity value by three times has been recorded on addition of plasticizer when compared with that of unplasticized
composite polymer electrolyte. The temperature dependence of conductivity of the polymer films is found to obey the Arrhenius
behavior below and above the melting temperature of PEO. The electrical transport has been found to be a thermally activated
process with ions being the predominant charge carrier. 相似文献
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The electrical properties and proton conduction of Gd0.1Ce0.9O1.95 (10GCO) were investigated via impedance spectroscopy in different atmospheres and various gas concentration cells. In oxygen
atmosphere, GCO is nearly a pure oxygen ionic conductor, while in hydrogen GCO behaves as a mixed conductor of oxygen ions,
electrons and protons. Depending on the temperature, the total conductivity is usually enhanced by one to two orders of magnitude
in hydrogen than in air/oxygen due to mixed conduction.
By examining ionic transport properties of oxygen ions and protons using gas concentration cells we have discovered that the
ionic transport properties depend largely on the gas atmospheres and change from one type to the other. Proton conduction
generally exists in GCOs, and becomes significant in hydrogen atmospheres, which normally results in a contribution between
5 to 10 % of the total conductivity for 10 GCO. A maximum value of 17 % of the contribution by protons has been observed.
The reduction of Ce4+ to Ce3+ of the sample in reduced atmospheres causes the formation of additional oxygen vacancies and electrons, associated also with
the creation of protons. All these charge carriers are responsible for the electrical and transport properties of the investigated
GCO materials.
Paper presented at the 5th Euroconference on Solid State Ionics, Benalmádena, Spain, Sept. 13–20, 1998. 相似文献
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Glassy LiPO3/crystalline Al2O3 and glassy LiPO3/crystalline ZrO2 (0–12.5 vol.% of oxide fillers) composite solid electrolytes have been prepared by glass matrix softening. Their thermal and transport properties have been investigated by differential scanning calorimetry (DSC) and impedance spectroscopy methods. The addition of ZrO2 leads to a decrease in the crystallization temperature of LiPO3 glass. It was found that the conductivity behavior depends on the nature of the dispersed addition. In the case of the Al2O3 addition, the increase in the electrical conductivity is observed. The ionic conductivity of the LiPO3/10% Al2O3 composite reaches 5.8 × 10?8 S/cm at room temperature. In contrast, the conductivity in the LiPO3/ZrO2 composite system decreases. 相似文献
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H. E. Roman 《Phase Transitions》2013,86(2):435-461
Dispersed ionic conductors are random mixtures of a solid salt, e.g. AgI, LiI, with fine particles of an insulating second phase, like Al2O3 or SiO2. These composites can show a dramatic increase in ionic conductivity compared to the pure homogeneous system. Generally, this observation is attributed to an increased conductivity along the internal interface between the conducting salt and the insulating material. In this work a three-component random resistor network (RRN) model for dispersed ionic conductors is reviewed. In the model, the ionic conductor is represented by normally conducting bonds, the insulating material by non-conducting bonds and the interface between the two phases by highly conducting bonds. A special feature of the model is the existence of two critical concentrations of the insulating phase, p′c and p″c , for interface percolation and bulk conduction, respectively, where critical transport properties corresponding to conductor/superconductor and conductor/insulator networks are predicted. The model describes satisfactorily the dependence on composition of the conductivity and activation energy of dispersed ionic conductors. Furthermore, the observed effect on the conductivity of the size of dispersed particles can be described qualitatively well by a generalized version of the RRN model, which in addition predicts a sensitive dependence of the critical thresholds on particle size. Non-universality features in the critical exponents for the conductivity are also discussed within a continuum percolation analog of the model. 相似文献
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R.H. ChenS.C. Shern 《Journal of Physics and Chemistry of Solids》2002,63(11):2069-2077
Optical observation under the polarizing microscope and DSC measurements on K3H(SeO4)2 single crystal have been carried out in the temperature range 25-200 °C. It reveals a high-temperature structural phase transition at around 110 °C. The crystal system transformed from monoclinic to trigonal. Electrical impedance measurements of K3H(SeO4)2 were performed as a function of both temperature and frequency. The electrical conduction and dielectric relaxation have been studied. The temperature dependence of electrical conductivity indicates that the sample crystal became a fast ionic conductor in the high-temperature phase. The frequency dependence of conductivity follows the Jonscher's universal dynamic law with the relation σ(ω)=σ(0)+Aωn, where ω is the frequency of the AC field, and n is the exponent. The obtained n values decrease from 1.2 to 0.1 from the room temperature phase to fast ionic phase. The high ionic conductivity in the high-temperature phase is explained by the dynamical disordering of protons between the neighboring SeO4 groups, which provide more vacant sites in the crystal. 相似文献
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The electrical, structural, and photoelectrochemical properties of the polymer electrolyte PEO:NaI/I2 doped with an ionic liquid 1-ethyl 3-methylimidazolium dicyanamide (EMImDCN) have been reported. Incorporation of the ionic
liquid (IL) increases the membrane homogeneity, decreased surface roughness, and enhances the short current (J
sc). Additionally, the doping of IL provides more charge carriers which enhances overall ionic conductivity (σ). The optimized
σ was found at 40 wt.% IL composition. The fabricated DSSC using this new solid electrolyte showed 1.43% efficiency at 100 mW
cm−2. 相似文献