Structural stability and ion conductivity of the Dy and W substituted La2Mo2O9

Jin, Tsu-Yung; Rao, M. V. Madhava; Cheng, Chia-Liang; Tsai, Dah–Shyang; Hung, Ming-Hao

doi:10.1016/j.ssi.2007.01.031

Cited by 53 publications

(38 citation statements)

References 36 publications

(57 reference statements)

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“…1 shows that due to the partial substitution of Nd in La 2 Mo 1.7 W 0.3 O 9−δ , activation energy decreases but it is still higher than the activation energy of Table 2) . Similar observations have been obtained in the case of Dy and W substituted compounds by other workers [23].…”

Section: Impedance and Electrical Conductivity Analysissupporting

confidence: 91%

“…As reported by Yang et al [12] ionic conductivity of La 2 Mo 2 O 9 increased at intermediate temperatures for the substitutes La 2-x A x Mo 1.7 W 0.3 O 9-δ (A=Sm, Bi) for x=0.3. Jin et al [23] reported Dy and W substituted La 2 Mo 2 O 9, in which 10 mol% of Dy suppressed phase transition and the temperature dependence of conductivity had been correlated to Vogel-TammanFulcher (VTF) form above 450°C. In this typical substitute, La 1.8 Dy 0.2 Mo 2−x W x O 9−δ , high temperature conductivity decreased with increasing W concentration.…”

Section: Introductionmentioning

confidence: 99%

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Conductivity and electrical modulus studies of La2−x Nd x Mo1.7W0.3O9−δ oxygen ion conductor

Borah

Paik

Hashmi

et al. 2012

Ionics

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La 2−x Nd x Mo 1.7 W 0.3 O 9−δ (x 00 − 0.5) and, for comparison, La 2 Mo 2 O 9 compounds have been synthesized following solid state reaction technique. Temperaturedependent electrical conductivity of La 2−x Nd x Mo 1.7 W 0.3 O 9−δ reveals suppression of the phase transition as compared to parent La 2 Mo 2 O 9 compound. Partial substitution of Nd at the La site of La 2 Mo 1.7 W 0.3 O 9−δ increases the conductivity of La 2 Mo 1.7 W 0.3 O 9−δ in the entire temperature regime. In the intermediate temperature region (405°C≤T≤ 570°C), the overall conductivity of La 2−x Nd x Mo 1.7 W 0.3 O 9−δ (0.1≤x≤0.5) is higher than that of the parent compound, and the conductivity of the compound with x00.1 is almost same with the La 2 Mo 2 O 9 in the high temperature region (T≥640°C). Arrhenius to Vogel-Tamman-Fulcher (VTF) transition is observed in all doped specimens above 460°C. Ion relaxation mechanism has been discussed in the framework of electrical modulus analysis in the temperature range RT-530°C and is found to be non-Debye type of conductivity relaxation with the distribution of transition rates for hopping ions in the range of 0.60-0.70.

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Section: Impedance and Electrical Conductivity Analysissupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Conductivity and electrical modulus studies of La2−x Nd x Mo1.7W0.3O9−δ oxygen ion conductor

Borah

Paik

Hashmi

et al. 2012

Ionics

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“…The total conductivity of La 2 CuO 4 þ d , which exhibits a small oxygen excess in air, has a pseudometallic character and is considerably lower than that of lanthanum nickelate (see Figure 9.11); moderate acceptor-type doping enhances the p-type electronic transport, whereas decreasing the Ln 3 þ size has an opposite effect. The oxygen diffusion and surface exchange in all cuprates are rather slow, and tend to decrease when the Ln 3 þ radius decreases [36,204,[220][221][222][223][224][225]. In the case of La 2Àx Sr x CuO 4AEd , the ion diffusivity becomes slightly higher on modest Sr doping (x < 0.1) and drops with further additions.…”

Section: Perovskite-related Mixed Conductors: a Short Overviewmentioning

confidence: 94%

“…Further information on these applications is available elsewhere [1-4, 11, 159, 217-219]. 9.9 La 2 Mo 2 O 9 -Based Electrolytes Another group of oxygen ionic conductors (the so-called LAMOX series) is based on the high-temperature polymorph of lanthanum molybdate, b-La 2 Mo 2 O 9 , having a cubic lattice which is isostructural with b-SnWO 4 [13,16,65,81,[220][221][222][223][224][225]. The fast anion migration in b-La 2 Mo 2 O 9 was explained by the lone-pair substitution concept [81,220,221] by which lone electron pairs of cations could stabilize oxygen vacancies.…”

Section: Perovskite-related Mixed Conductors: a Short Overviewmentioning

confidence: 99%

“…Figures 9.5-9.7 and 9.13 compare the transport properties of La 2 Mo 2 O 9 -based materials and other solid electrolytes. The disadvantages of LAMOX include a relatively high electronic contribution to the total conductivity under ambient conditions, degradation in moderately reducing atmospheres, high TECs, and reactivity with electrode materials [65,222,[225][226][227][228]. These problems are less prominent if compared to the Bi 2 O 3 -based compositions, but the ionic conductivity of LAMOX is also lower.…”

Section: Perovskite-related Mixed Conductors: a Short Overviewmentioning

confidence: 99%

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Oxygen Ion‐Conducting Materials

Хартон

Marques

Kilner

et al. 2009

Solid State Electrochemistry I

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Oxygen ionic and mixed ionic-electronic conductors find important applications in solid-state electrochemical devices, including sensors, solid oxide fuel cells, hightemperature electrolyzers, and oxygen separation membranes. This chapter presents a brief overview of oxide phases with high diffusivity of O 2À anions, providing an introduction to this fascinating topic. Particular emphasis is centered on the comparative analysis of ionic and electronic conductivity variations in the major groups of solid oxide electrolytes and mixed conductors, such as perovskite-and fluorite-related compounds, apatite-type silicates, and derivatives of g-Bi 4 V 2 O 11 and b-La 2 Mo 2 O 9 . The defect chemistry mechanisms relevant to the oxygen ion migration processes are briefly discussed. IntroductionTechnologies based on the use of high-temperature electrochemical cells with oxygen anion-or mixed-conducting ceramics provide important advantages with respect to the conventional industrial processes [1][2][3][4][5][6][7][8]. In particular, solid oxide fuel cells (SOFCs) are considered as alternative electric power generation systems due to high energy-conversion efficiency, fuel flexibility, and environmental safety [1][2][3]. Dense ceramic membranes with mixed oxygen-ionic and electronic conductivity have an infinite theoretical separation factor with respect to oxygen, and can be used for gas separation and the partial oxidation of light hydrocarbons [4,5,7,8] (these and other applications are reviewed in Chapters 12 and 13). For all types of electrochemical cells, the key properties which determine the use of a material are the partial ionic and electronic conductivities. As an example, solid electrolytes for SOFCs, oxygen pumps and electrochemical sensors should exhibit a maximum oxygen ionic conductivity, while the electronic transport should be minimal. In contrast, for SOFC electrodes Solid State Electrochemistry I: Fundamentals, Materials and their Applications. Edited by Vladislav V. Kharton

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Fuel Cell Fundamentals

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Structural stability and ion conductivity of the Dy and W substituted La2Mo2O9

Cited by 53 publications

References 36 publications

Conductivity and electrical modulus studies of La2−x Nd x Mo1.7W0.3O9−δ oxygen ion conductor

Conductivity and electrical modulus studies of La2−x Nd x Mo1.7W0.3O9−δ oxygen ion conductor

Oxygen Ion‐Conducting Materials

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