Stability of Ruddlesden–Popper-structured oxides in humid conditions

Lehtimäki, Matti; Yamauchi, H.; Karppinen, Maarit

doi:10.1016/j.jssc.2013.05.012

Cited by 19 publications

(24 citation statements)

References 60 publications

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“…Indeed, for some Ruddlesden-Popper (RP) phases such as Sr 3 FeMnO 7Àd , increasing the amount of oxygen vacancies by annealing in a N 2 atmosphere at 500 C was shown to have a positive impact on the hydration reaction, possibly due to kinetics. 27 In the analysis of the data collected above room temperature in an argon atmosphere, isotropic ADPs were rened for all the atoms and for all the oxygen atoms they were constrained to be the same. Isothermal datasets collected for 30 minutes at 300 and 400 C show insignicant variations in the oxygen content along with the retention of the orthorhombic space group.…”

Section: Structural Analysis As a Function Of Temperature In An Argonmentioning

confidence: 99%

Stability of NdBaCo_2−xMn_xO_5+δ (x = 0, 0.5) layered perovskites under humid conditions investigated by high-temperature in situ neutron powder diffraction

et al. 2015

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The double perovskites NdBaCo2−xMnxO5+δ (x = 0 and 0.5) were investigated using in situ high temperature neutron powder diffraction in dry argon and wet atmospheres (40% D2O/argon and 40% D2O/air) in order to assess their stability as cathodes in proton conducting fuel cells. The x = 0 oxide loses oxygen on heating in dry argon at T > 400 °C and exhibits an oxygen vacancy order–disorder transition as evidenced by the orthorhombic Pmmm to tetragonal P4/mmm transition. Refinement of site occupancy factors suggests that the oxygen vacancies mainly form in the Nd layers and to a lesser extent at the equatorial positions of the transition metal polyhedra; at 800 °C, δ ∼ 0. When the gas was changed to wet argon at 800 °C and the sample cooled to 260 °C, no structural modification or change in the oxygen content was detected and no impurity phases formed, highlighting the excellent stability of the sample in wet atmospheres. On switching the gas to wet air at 260 °C, thermal analysis and neutron powder diffraction data together reveal that the sample intercalates mainly oxygen rather than proton defects within a two-phase process involving two orthorhombic phases, reflecting the symmetry of the reduced and oxidised materials. On heating, the sample transforms at T ≥ 600 °C to a single tetragonal phase whose symmetry is retained up to 800 °C and on subsequent cooling. The x = 0.5 material prepared in argon adopted a tetragonal P4/mmm structure at RT with δ ∼ 0. Its symmetry remains tetragonal on heating/cooling in wet argon. On changing the gas to wet air at 260 °C, it takes up oxygen via a two-phase process involving two tetragonal phases. Since fast oxidation is the main process that fills the oxygen vacancies of these double perovskites in wet air, a large oxygen deficiency seems to be not the only requirement for effective proton incorporation in this family of materials with basic characteristics

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Section: Structural Analysis As a Function Of Temperature In An Argonmentioning

confidence: 99%

Stability of NdBaCo_2−xMn_xO_5+δ (x = 0, 0.5) layered perovskites under humid conditions investigated by high-temperature in situ neutron powder diffraction

et al. 2015

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“…3). Hydrated systems that exhibit the configuration of adjacent perovskite blocks with alkaline or alkaline-earth metals in the rock salt block have been reviewed by Lehtimäki et al [14].…”

Section: Resultsmentioning

confidence: 99%

“…This structure produces a staggered arrangement in which two contiguous perovskite blocks are shifted by (a+b)/2 in the crystal cell. During intercalation of water into the RP structure, the water molecules form new layers inside the rock-salt type block [14], and a structural change from the I4/mmm to the P4/mmm (No. 123) SG occurs [15].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of K2Ln2/3Ta2O7·nH2O (Ln= La, Pr, Nd), Layered Tantalates Photocatalysts for Water Splitting.

et al. 2017

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<p>Three compounds of the K2Ln2/3Ta2O7 (Ln = La, Nd, Pr) cation-deficient Ruddlesden-Popper series were prepared by the Pechini (polymeric complex) method. The crystal structures of the hydrated form of these compounds were determined by Rietveld analysis of the X-ray powder diffraction data and High Resolution Transmission Electron Microscopy (HRTEM). The samples were also analyzed to determine specific area (BET), degree of hydration (TGA), and photocatalytic activity for hydrogen evolution from water and aqueous methanol solution.</p>

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“…A Ruddlesden–Popper phase formed in Sr 2 Fe 1+ x Mo 1− x O 6 is Sr 3 Fe 5/4 Mo 3/4 O 6.9 , which also decomposes in the ambient (even in the glovebox) over a period of months . The instability of SFMO Ruddlesden–Popper phases in humid conditions originates from the intercalation of two water molecules per formula unit forming a new OH − /H 3 O + layer between two rocksalt layers . SrO decomposes into Sr(OH) 2 when reacting with CO 2 to form a carbonate.…”

Section: Phase Stability and Point Defects In Sr2femoo6−δmentioning

confidence: 99%

“…[50] The instability of SFMO Ruddlesden-Popper phases in humid conditions originates from the intercalation of two water molecules per formula unit forming a new OH À /H 3 O þ layer between two rocksalt layers. [51] SrO decomposes into Sr(OH) 2 when reacting with CO 2 to form a carbonate.…”

Section: Strontium Nonstoichiometrymentioning

confidence: 99%

Challenges in Sr₂FeMoO_6−δ Thin Film Deposition

Suchaneck

Каланда

Artsiukh

et al. 2019

Physica Status Solidi (b)

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This work reviews some fundamental issues that are relevant for the fabrication of stable‐phase strontium ferromolybdate thin films. The main challenges for strontium ferromolybdate thin film deposition arise from the sensitivity of the material's magnetic properties to point defect formation: i) Antisite defect formation and oxygen nonstoichiometry should be avoided by precise composition control during film manufacturing; ii) a highly ordered state of the correct phase and B‐site cation valence will be obtained only in a very narrow window of growth conditions; iii) to avoid additional antisite disorder with decreasing synthesis temperature, the effective temperature at the film surface should be increased by an energy flux to the growing film surface. Since thin film deposition is nonequilibrium in nature, the review starts with the consideration of equilibrium phase stability. Cation and oxygen stoichiometries are analyzed with regard to their effect on key magnetic properties. Film strain formed due to thermal and lattice mismatch is of great concern since it influences the choice of the substrate. Finally, thin film deposition techniques are valued for their benefits in strontium ferromolybdate thin film technology.

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Stability of Ruddlesden–Popper-structured oxides in humid conditions

Cited by 19 publications

References 60 publications

Stability of NdBaCo_2−xMn_xO_5+δ (x = 0, 0.5) layered perovskites under humid conditions investigated by high-temperature in situ neutron powder diffraction

Stability of NdBaCo_2−xMn_xO_5+δ (x = 0, 0.5) layered perovskites under humid conditions investigated by high-temperature in situ neutron powder diffraction

Synthesis and Characterization of K2Ln2/3Ta2O7·nH2O (Ln= La, Pr, Nd), Layered Tantalates Photocatalysts for Water Splitting.

Challenges in Sr₂FeMoO_6−δ Thin Film Deposition

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Stability of Ruddlesden–Popper-structured oxides in humid conditions

Cited by 19 publications

References 60 publications

Stability of NdBaCo2−xMnxO5+δ (x = 0, 0.5) layered perovskites under humid conditions investigated by high-temperature in situ neutron powder diffraction

Stability of NdBaCo2−xMnxO5+δ (x = 0, 0.5) layered perovskites under humid conditions investigated by high-temperature in situ neutron powder diffraction

Synthesis and Characterization of K2Ln2/3Ta2O7·nH2O (Ln= La, Pr, Nd), Layered Tantalates Photocatalysts for Water Splitting.

Challenges in Sr2FeMoO6−δ Thin Film Deposition

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About

Stability of NdBaCo_2−xMn_xO_5+δ (x = 0, 0.5) layered perovskites under humid conditions investigated by high-temperature in situ neutron powder diffraction

Stability of NdBaCo_2−xMn_xO_5+δ (x = 0, 0.5) layered perovskites under humid conditions investigated by high-temperature in situ neutron powder diffraction

Challenges in Sr₂FeMoO_6−δ Thin Film Deposition