Reducibility of La2Mo2O9 based ceramics versus porosity

Goel, Meenal; Djurado, Elisabeth; Georges, Samuel

doi:10.1016/j.ssi.2011.10.001

Cited by 10 publications

(11 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As other authors have observed, the partial reduction of Mo in La 2 Mo 2 O 9−δ leads to an increase of electrical conductivity. 20,25,26 This behaviour would be expected for LM896 compound. Arrhenius plots of measured conductivity values for both LM (in air) and LM896 (in Ar-H 2 -H 2 O) are shown in Fig.…”

Section: Electrical Characterization Of La 2 Mo 2 O 896supporting

confidence: 59%

See 1 more Smart Citation

Thermodynamic stability, structural and electrical characterization of mixed ionic and electronic conductor La2Mo2O8.96

et al. 2012

View full text Add to dashboard Cite

Thermogravimetric analysis (TGA) technique in controlled oxygen partial pressure (pO(2)) atmospheres has been used to obtain equilibrium oxygen content data as a function of pO(2) on the La(2)Mo(2)O(9-δ) system resulting from the partial reduction of fast oxide-ion conductor La(2)Mo(2)O(9) (LM). Thermodynamic conditions for stabilization of crystalline La(7)Mo(7)O(30) and amorphous La(2)Mo(2)O(7-y) at 718 °C have been determined and discussed. At 608 °C, the compound reported for the first time La(2)Mo(2)O(8.96) (LM896) has been found. The crystalline form and transition temperature in LM896 have been identified by X-ray diffraction at room temperature (XRD) and at controlled temperature. Conductivity curves obtained by electrochemical impedance spectroscopy (EIS) as a function of temperature for both LM and LM896 have been compared. The results indicate that LM896 is a mixed ionic and electronic conductor (MIEC).

show abstract

Section: Electrical Characterization Of La 2 Mo 2 O 896supporting

confidence: 59%

“…Recently, Goel et al analysed the increase of electrical conductivity on La 2 Mo 2−y W y O 9 under Ar-(10%)H 2 . 26 They found that the electrical conductivity of these partial reduced samples varies depending on both the porosity of initial ceramics and the W content.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic stability, structural and electrical characterization of mixed ionic and electronic conductor La2Mo2O8.96

et al. 2012

View full text Add to dashboard Cite

show abstract

“…23 These successes have led to further investigation of the utility of these materials in SOFCs as both the electrolyte 24-26 and the anode. [27][28][29] Investigation into the precise mechanisms of conduction in La2Mo2O9, on the other hand, has been relatively sparse. Initially it was assumed that the partially occupied O2 and O3 sites were the cause of conductivity, with the O1 sites remaining static.…”

Section: Introductionmentioning

confidence: 99%

Direct Observation of Oxide Ion Dynamics in La₂Mo₂O₉ on the Nanosecond Timescale

et al. 2017

View full text Add to dashboard Cite

Quasielastic neutron scattering (QENS), underpinned by ab-initio molecular dynamics (AIMD) simulations, has been used to directly observe oxide ion dynamics in solid electrolyte La 2 Mo 2 O 9 on the nanosecond timescale, the longest timescale probed in oxide ion conductors by neutron scattering to date. QENS gives the activation energy of 0.61(5) eV for this process, while AIMD simulations reveal that the exchange processes, which ultimately lead to long-range oxide ion diffusion in La 2 Mo 2 O 9 , rely on the flexibility of the coordination environment around Mo 6+ , with oxide ions jumps occurring between vacant sites both within and between Mo coordination spheres. Simulations also differentiate between the crystallographic sites which participate in the oxide ion exchange processes, offering the first atomic-level understanding of the oxide ion dynamics in La 2 Mo 2 O 9 , which is consistent with the macroscopic experimental observations on this material.

show abstract

“…Goel et al obtained similar conductivity increases at reducing W doped LAMOX samples in dry Ar-(10%)H 2 at 650 °C for 24 h, with a gas flow rate of 6 L h −1 . 30 For highly dense samples, the oxygen stoichiometries measured after annealing were 7.93, 8.62 and 8.9 for y = 0, 0.5 and 1.0, respectively. We think that these authors could have reduced transitorily La 2 Mo 2−y W y O 9 to La 2 Mo 2−y W y O 8.96+0.02y but the reduction continued to yield a more severe weight loss and perhaps a partial amorphization of samples.…”

Section: Dalton Transactions Papermentioning

confidence: 95%

Thermodynamic stability of La₂Mo_2−yW_yO₉, La₂Mo_2−yW_yO_8.96+0.02yand La₇Mo_7(2−y)/2W_7y/2O₃₀(y = 0, 0.5 and 1.0)

et al. 2014

View full text Add to dashboard Cite

The role of W content on the limit oxygen partial pressure (pO2) for stability of fast oxygen-ion conductors La2Mo2-yWyO9 with y = 0, 0.5 and 1.0 has been studied by means of thermogravimetric analysis (TGA) under controlled atmospheres. At 718 °C, below the pO2 stability limit of La2Mo2-yWyO9, the perovskite related compounds La7Mo7(2-y)/2W7y/2O30 were stabilized even for y = 1.0. At 608 °C, the first stage of reduction of β-La2Mo2-yWyO9 leads to the formation of the crystallized oxygen deficient La2Mo2-yWyO8.6+0.02y phase. X-ray powder diffraction shows that the stabilization of the high temperature β-form through tungsten substitution observed in fully oxidized La2Mo2-yWyO9 samples is preserved upon slight reduction. The n-type conductivity arising from the mixed valence state of molybdenum becomes less and less predominant as the W content increases. Further reduction causes amorphization. At both temperatures, W substitution does not enhance the thermodynamic stability of the La2Mo2-yWyO9 ion conductor under a reducing atmosphere but only slows down the kinetics of reduction.

show abstract

Reducibility of La2Mo2O9 based ceramics versus porosity

Cited by 10 publications

References 28 publications

Thermodynamic stability, structural and electrical characterization of mixed ionic and electronic conductor La2Mo2O8.96

Thermodynamic stability, structural and electrical characterization of mixed ionic and electronic conductor La2Mo2O8.96

Direct Observation of Oxide Ion Dynamics in La₂Mo₂O₉ on the Nanosecond Timescale

Thermodynamic stability of La₂Mo_2−yW_yO₉, La₂Mo_2−yW_yO_8.96+0.02yand La₇Mo_7(2−y)/2W_7y/2O₃₀(y = 0, 0.5 and 1.0)

Contact Info

Product

Resources

About

Reducibility of La2Mo2O9 based ceramics versus porosity

Cited by 10 publications

References 28 publications

Thermodynamic stability, structural and electrical characterization of mixed ionic and electronic conductor La2Mo2O8.96

Thermodynamic stability, structural and electrical characterization of mixed ionic and electronic conductor La2Mo2O8.96

Direct Observation of Oxide Ion Dynamics in La2Mo2O9 on the Nanosecond Timescale

Thermodynamic stability of La2Mo2−yWyO9, La2Mo2−yWyO8.96+0.02yand La7Mo7(2−y)/2W7y/2O30(y = 0, 0.5 and 1.0)

Contact Info

Product

Resources

About

Direct Observation of Oxide Ion Dynamics in La₂Mo₂O₉ on the Nanosecond Timescale

Thermodynamic stability of La₂Mo_2−yW_yO₉, La₂Mo_2−yW_yO_8.96+0.02yand La₇Mo_7(2−y)/2W_7y/2O₃₀(y = 0, 0.5 and 1.0)