Structural transformation and oxidation of Sr2MnO3.5+x determined by in-situ neutron powder diffraction

Munnings, Christopher; Sayers, Ruth; Stuart, Paul A.; Skinner, Stephen J.

doi:10.1016/j.solidstatesciences.2011.10.015

Cited by 8 publications

(4 citation statements)

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“…The I 4/ mmm Sr 2 MnO 4.00 → P 2 1 / c Sr 2 MnO 3.55(1) phase transition is associated to a molar volume expansion of 2.44% (Tables and ). These Sr 2 MnO 3.69(2) → I 4/ mmm Sr 2 MnO 4.00 and Sr 2 MnO 3.55(1) Sr 2 MnO 4.00 are reversible according to Kriegel et al and Munnings et al, respectively . Munnings et al found by in situ NPD in air that oxidation of Sr 2 MnO 3.5+ x proceeds at ∼275 °C with a change from monoclinic to tetragonal symmetry .…”

Section: Discussionmentioning

confidence: 95%

“…These Sr 2 MnO 3.69(2) → I4/mmm Sr 2 MnO 4.00 and Sr 2 MnO 3.55(1) Sr 2 MnO 4.00 are reversible according to Kriegel et al 21 and Munnings et al, respectively. 39 Munnings et al found by in situ NPD in air that oxidation of Sr 2 MnO 3.5+x proceeds at ∼275 °C with a change from monoclinic to tetragonal symmetry. 39 Our moderate reduction conditions and neutron diffraction data indicate narrow structural relations between the I4/mmm and P2 1 /c phases consistent with simple relations between the lattice constants a m = 1/2 (−a t − b t + c t ), b m = 2 (−a t + b t ), c m = 2 (a t + b t ).…”

Section: Discussionmentioning

confidence: 99%

“…39 Munnings et al found by in situ NPD in air that oxidation of Sr 2 MnO 3.5+x proceeds at ∼275 °C with a change from monoclinic to tetragonal symmetry. 39 Our moderate reduction conditions and neutron diffraction data indicate narrow structural relations between the I4/mmm and P2 1 /c phases consistent with simple relations between the lattice constants a m = 1/2 (−a t − b t + c t ), b m = 2 (−a t + b t ), c m = 2 (a t + b t ). Gillie et al 19 reported that the reduction is topotactic.…”

Section: Discussionmentioning

confidence: 99%

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Reduction of Sr₂MnO₄ Investigated by High Temperature in Situ Neutron Powder Diffraction under Hydrogen Flow

et al. 2013

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This experiment emphasizes the first example of two-phase sequential Rietveld refinements throughout a solid/gas chemical reaction monitored by Neutron Powder Diffraction (NPD) at high temperature. The reduction of the n = 1 Ruddlesden-Popper (RP) oxide Sr(2)MnO(4) heated under a flow of 5% H(2)-He has been investigated throughout two heating/cooling cycles involving isothermal heating at 500 and 550 °C. Oxygen loss proceeds above T ∼ 470 °C and increases with temperature and time. When the oxygen deintercalated from the "MnO(2)" equatorial layers of the structure results in the Sr(2)MnO(3.69(2)) composition, the RP phase undergoes a first order I4/mmm → P2(1)/c, tetragonal to monoclinic phase transition as observed from time-resolved in situ NPD. The phase transition proceeds at 500 °C but is incomplete; the weight ratio of the P2(1)/c phase reaches ∼41% after 130 min of isothermal heating. The fraction of the monoclinic phase increases with increasing temperature and the phase transition is complete after 80 min of isothermal heating at 550 °C. The composition of the reduced material refined to Sr(2)MnO(3.55(1)) and does not vary on extended heating at 550 °C and subsequent cooling to room temperature (RT). The symmetry of Sr(2)MnO(3.55(1)) is monoclinic at 550 °C and therefore consistent with the RT structure determined previously for the Sr(2)MnO(3.64) composition obtained from ex situ reduction. Consequently, the stresses due to phase changes on heating/cooling in reducing atmosphere may be minimized. The rate constants for the reduction of Sr(2)MnO(4.00) determined from the evolution of weight ratio of the tetragonal and monoclinic phase in the time-resolved isothermal NPD data collected on the isotherms at 500 and 550 °C are k(500) = 0.110 × 10(-2) and k(550) = 0.516 × 10(-2) min(-1) giving an activation energy of ∼163 kJ mol(-1) for the oxygen deintercalation reaction.

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Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Reduction of Sr₂MnO₄ Investigated by High Temperature in Situ Neutron Powder Diffraction under Hydrogen Flow

et al. 2013

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“…Neutrons offer distinct advantages over X-ray diffraction for structural studies. [20][21][22] Here, the synthesis of Sr 2 Fe 1.5 Mo 0.5 O 6Àd and its complete structural characterization by high temperature powder neutron diffraction under oxidizing and reducing conditions is presented.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the high-temperature redox chemistry of Sr₂Fe_1.5Mo_0.5O_6−δvia in situ neutron diffraction

et al. 2014

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ChemInform Abstract: Structural Transformation and Oxidation of Sr₂MnO_3.5+x Determined by in situ Neutron Powder Diffraction.

et al. 2012

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Structural Transformation and Oxidation of Sr 2 MnO 3.5+x Determined by in situ Neutron Powder Diffraction. -The title compound with 0 ≤ x ≤ 0.5 crystallizes in the monoclinic space group P21/c at room temperature. On heating in air Sr2MnO3.5+x undergoes rapid oxidation at about 275°C accompanied by a phase transformation to the tetragonal space group I4/mmm. In the oxygen deficient phase (x > 0) the Mn coordination in square pyramidal. Oxidation of Sr 2 MnO 3.5+x results in the filling of partially occupied O4 positions and an increase in symmetry, with the Mn coordination adopting solely a distorted octahedral environment. -(MUNNINGS, C. N.; SAYERS, R.; STUART, P. A.; SKINNER*, S. J.; Solid State Sci. 14 (2012) 1, 48-53, http://dx.

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Structural transformation and oxidation of Sr2MnO3.5+x determined by in-situ neutron powder diffraction

Cited by 8 publications

References 23 publications

Reduction of Sr₂MnO₄ Investigated by High Temperature in Situ Neutron Powder Diffraction under Hydrogen Flow

Reduction of Sr₂MnO₄ Investigated by High Temperature in Situ Neutron Powder Diffraction under Hydrogen Flow

Investigation of the high-temperature redox chemistry of Sr₂Fe_1.5Mo_0.5O_6−δvia in situ neutron diffraction

ChemInform Abstract: Structural Transformation and Oxidation of Sr₂MnO_3.5+x Determined by in situ Neutron Powder Diffraction.

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Structural transformation and oxidation of Sr2MnO3.5+x determined by in-situ neutron powder diffraction

Cited by 8 publications

References 23 publications

Reduction of Sr2MnO4 Investigated by High Temperature in Situ Neutron Powder Diffraction under Hydrogen Flow

Reduction of Sr2MnO4 Investigated by High Temperature in Situ Neutron Powder Diffraction under Hydrogen Flow

Investigation of the high-temperature redox chemistry of Sr2Fe1.5Mo0.5O6−δvia in situ neutron diffraction

ChemInform Abstract: Structural Transformation and Oxidation of Sr2MnO3.5+x Determined by in situ Neutron Powder Diffraction.

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Reduction of Sr₂MnO₄ Investigated by High Temperature in Situ Neutron Powder Diffraction under Hydrogen Flow

Reduction of Sr₂MnO₄ Investigated by High Temperature in Situ Neutron Powder Diffraction under Hydrogen Flow

Investigation of the high-temperature redox chemistry of Sr₂Fe_1.5Mo_0.5O_6−δvia in situ neutron diffraction

ChemInform Abstract: Structural Transformation and Oxidation of Sr₂MnO_3.5+x Determined by in situ Neutron Powder Diffraction.