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Author |
Parsons, T.G.; d' Hondt, H.; Hadermann, J.; Hayward, M.A. |
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Title |
Synthesis and structural characterization of La1-xAxMnO2.5 (A = Ba, Sr, Ca) phases: mapping the variants of the brownmillerite structure |
Type |
A1 Journal article |
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Year |
2009 |
Publication |
Chemistry of materials |
Abbreviated Journal |
Chem Mater |
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Volume |
21 |
Issue |
22 |
Pages |
5527-5538 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
Analysis of the structural parameters of phases that adopt brownmillerite-type structures suggests the distribution of the different complex ordering schemes adopted within this structure type can be rationalized by considering both the size of the separation between the tetrahedral layers and the tetrahedral chain distortion angle. A systematic study using structural data obtained from La1−xAxMnO2,5 (A = Ba, Sr, Ca,) phases, prepared by the topotactic reduction of the analogous La1−xAxMnO3 perovskite phases, was performed to investigate this relationship. By manipulating the A-cation composition, both the tetrahedral layer separation and tetrahedral chain distortion angle in the La1−xAxMnO2,5 phases were controlled and from the data obtained a ¡°structure map¡± of the different brownmillerite variants was plotted as a function of these structural parameters. This map has been extended to include a wide range of reported brownmillerite phases showing the structural ideas presented are widely applicable. The complete structural characterization of La1−xAxMnO2,5 0.1 ¡Ü x ¡Ü 0.33, A = Ba; 0.15 ¡Ü x ¡Ü 0.5 A = Sr, and 0.22 ¡Ü x ¡Ü 0.5 A = Ca is described and includes compositions which exhibit complex intralayer ordered structures and Mn2+/Mn3+ charge ordering. |
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Place of Publication |
Washington, D.C. |
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Wos |
000271756400021 |
Publication Date |
2009-10-29 |
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ISSN |
0897-4756;1520-5002; |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
9.466 |
Times cited |
60 |
Open Access |
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Notes |
Iap Vi |
Approved |
Most recent IF: 9.466; 2009 IF: 5.368 |
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Call Number |
UA @ lucian @ c:irua:79935 |
Serial |
3435 |
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Author |
Parsons, T.G.; Hadermann, J.; Halasyamani, P.S.; Hayward, M.A. |
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Title |
Preparation of the noncentrosymmetric ferrimagnetic phase La0.9Ba0.1Mn0.96O2.43 by topochemical reduction |
Type |
A1 Journal article |
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Year |
2020 |
Publication |
Journal Of Solid State Chemistry |
Abbreviated Journal |
J Solid State Chem |
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Volume |
287 |
Issue |
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Pages |
121356-121357 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
Topochemical reduction of La0.9Ba0.1MnO3 with NaH at 225 degrees C yields the brownmillerite phase La0.9Ba0.1MnO2.5. However, reduction with CaH2 at 435 degrees C results in the formation of La0.9Ba0.1Mn0.96O2.43 via the deintercalation of both oxide anions and manganese cations from the parent perovskite phase. Electron and neutron diffraction data reveal La0.9Ba0.1Mn0.96O2.43 adopts a complex noncentrosymmetric structure, described in space group I23, confirmed by SHG measurements. Low-temperature neutron diffraction data reveal La0.9Ba0.1Mn0.96O2.43 adopts an ordered magnetic structure in which all the nearest neighbor interactions are antiferromagnetic. However, the presence of ordered manganese cation-vacancies results in a net ferrimagnetic structure with net saturated moment of 0.157(2) mu B per manganese center. |
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Wos |
000533632700029 |
Publication Date |
2020-04-05 |
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ISSN |
0022-4596 |
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Additional Links |
UA library record; WoS full record |
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Impact Factor |
3.3 |
Times cited |
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Open Access |
Not_Open_Access |
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Notes |
; We thank the EPSRC for funding this work and E. Suard for assisting with the collection of the neutron powder diffraction data. PSH thanks the Welch Foundation (Grant E-1457) for support. ; |
Approved |
Most recent IF: 3.3; 2020 IF: 2.299 |
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Call Number |
UA @ admin @ c:irua:169450 |
Serial |
6583 |
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Permanent link to this record |