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Title: Effect of pressure on octahedral distortions in RCrO3 (R=Lu, Tb, Gd, Eu, Sm): the role of R-ion size and its implications
Authors: Bhadram, Venkata Srinu
Swain, Diptikanta
Dhanya, R.
Polentarutti, Maurizio
Sundaresan, A.
Narayana, Chandrabhas
Keywords: Materials Science
Raman Spectroscopy
High Pressure
X-Ray Diffraction
Issue Date: 2014
Publisher: IoP Publishing Ltd
Citation: Bhadram, VS; Swain, D; Dhanya, R; Polentarutti, M; Sundaresan, A; Narayana, C, Effect of pressure on octahedral distortions in RCrO3 (R=Lu, Tb, Gd, Eu, Sm): the role of R-ion size and its implications. Materials Research Express 2014, 1 (2), 26111
Materials Research Express
Abstract: The effect of rare-earth ion size on the octahedral distortions in rare-earth chromites (RCrO3, R = Lu, Tb, Gd, Eu, Sm) crystallizing in the orthorhombic structure has been studied using Raman scattering and synchrotron powder x-ray diffraction up to 20 GPa. From our studies on RCrO3 we found that the octahedral tilts (distortions) increase with pressure. This is contrary to the earlier report which suggests that in LaCrO3, the distortions decrease with pressure leading to a more ordered phase at high pressure. Here, we observe that the rate of increase in distortion decreases with the increase in R-ion radii. This occurs due to the reduction in the compression of RO12 polyhedra with a corresponding increase in the compression of the CrO6 octahedra with increasing R-ion radii. From the Raman studies, we predict a critical R-ion radii, above which we expect the distortions in RCrO3 to reduce with increasing pressure leading to what is observed in the case of LaCrO3. These Raman results are consistent with our pressure dependent structural studies on RCrO3 (R = Gd, Eu, Sm). Also, our results suggest that the pressure dependence of Neel temperature, T-N(Cr), (where the Cr3+ spin orders) in RCrO3 is mostly affected by the compressions of Cr-O bonds rather than the alteration of octahedral tilts.
Description: Restricted Access
ISSN: 2053-1591
Appears in Collections:Research Articles (Chandrabhas N.)

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