DSpace Repository

Influence of Cation Size on the Structural Features of Ln1/2A1/2MnO3 Perovskites at Room Temperature

Show simple item record

dc.contributor.author Woodward, P M
dc.contributor.author Vogt, T
dc.contributor.author Cox, D E
dc.contributor.author Arulraj, A
dc.contributor.author Rao, C N R
dc.contributor.author Karen, P
dc.contributor.author Cheetham, A K
dc.date.accessioned 2012-11-06T11:15:59Z
dc.date.available 2012-11-06T11:15:59Z
dc.date.issued 1998-11
dc.identifier 0897-4756 en_US
dc.identifier.citation Chemistry Of Materials 10(11), 3652-3665 (1998) en_US
dc.identifier.uri https://libjncir.jncasr.ac.in/xmlui/10572/926
dc.description Restricted Access en_US
dc.description.abstract Polycrystalline samples of Ln(1/2)Sr(1/2)MnO(3) (Ln = La, Pr, La0.33Nd0.67, Nd, Nd0.5Sm0.5, Sm, and Gd) and Ln(1/2)Ca(1/2)MnO(3) (Ln = La, Pr, La0.5Nd0.5, Nd, Sm, and Y0.5Sm0.5) have been prepared, and structure determinations have been carried out at room temperature using high-resolution synchrotron X-ray powder diffraction data. The octahedral tilting distortion increases as the average ionic radius of the Ln/A cations, [rA], decreases. The two crystallographically distinct Mn-O-Mn bonds [Mn-O(eq)-Mn and Mn-O(ax)-Mn] are almost identical for Ln(0.5)Ca(0.5)MnO(3) compounds, with the exception of La0.5Ca0.5MnO3. The La0.5Ca0.5MnO3 compound and the entire Ln(0.5)Sr(0.5)MnO(3) series adopt structures where the Mn-O(eq)-Mn bond angle is consistently and significantly larger (2-6 degrees) than the Mn-O(ax)-Mn bond angle. All of the Ln(0.5)Ca(0.5)MnO(3) compounds have Pnma symmetry, whereas across the Ln(0.5)Sr(0.5)MnO(3) series with increasing (rA), an evolution from Pnma (tilt system a(-)b(+)a(-)) over Imma (tilt system a(-)b(0)a(-)) to I4/mcm (tilt system a(0)a(0)c(-)) symmetry is observed. It appears that the latter two tilt systems are stabilized with respect to the rhombohedral (R (3) over bar c) a(-)a(-)a(-) tilt system, by short-range layered ordering of A-site cations. Changes in the octahedral tilt system at room temperature are linked to changes in the low-temperature magnetic structure. In particular, the simultaneous onset of charge ordering and CE-type antiferromagnetism in the Ln(0.5)Sr(0.5)MnO(3) series appears to be closely associated with the Imma structure. The average Mn-O bond distance is relatively constant across the entire series, but individual Mn-O bond distances show the presence of a cooperative Jahn-Teller effect (orbital ordering) at room temperature in Sm0.5Ca0.5MnO3 and Sm0.25Y0.25Ca0.5MnO3. en_US
dc.description.uri http://dx.doi.org/10.1021/cm980397u en_US
dc.language.iso en en_US
dc.publisher American Chemical Society en_US
dc.rights © 1998 American Chemical Society en_US
dc.subject Metal-Insulator-Transition en_US
dc.subject Rare-Earth Manganates en_US
dc.subject A-Site Cations en_US
dc.subject Giant Magnetoresistance en_US
dc.subject Neutron-Diffraction en_US
dc.subject Crystal-Structure en_US
dc.subject Colossal Magnetoresistance en_US
dc.subject Manganese Perovskites en_US
dc.subject Phase-Transitions en_US
dc.subject Magnetic-Field en_US
dc.title Influence of Cation Size on the Structural Features of Ln1/2A1/2MnO3 Perovskites at Room Temperature en_US
dc.type Article en_US


Files in this item

This item appears in the following Collection(s)

Show simple item record

Search DSpace


Advanced Search

Browse

My Account