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Temperature dependent X‐ray diffraction and Raman spectroscopy studies of polycrystalline YCrO 3 ceramics across the T C ~ 460 K
Author(s) -
Mall Ashish Kumar,
Paul Barnita,
Garg Ashish,
Gupta Rajeev
Publication year - 2020
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.5807
Subject(s) - ferroelectricity , orthorhombic crystal system , raman spectroscopy , crystallography , octahedron , neutron diffraction , materials science , condensed matter physics , phase transition , diffraction , rietveld refinement , dielectric , chemistry , crystal structure , physics , optics , optoelectronics
In this paper, we report the X‐ray diffraction studies over the temperature range of 300–900 K and subsequent Rietveld refinement of the diffraction patterns shows that there is no evidence of any structural phase transition in YCrO 3 (YCO) across the paraelectric to ferroelectric phase transitions ( T C ~ 460 K), and the material retains the orthorhombic structure with Pnma space group. However, a detailed analysis reveals local distortions in the CrO 6 octahedra. To probe the local structural distortion, we have carried out temperature‐dependent, unpolarized Raman measurements, from 300 to 600 K. YCrO 3 shows a strong anomalous deviation in both phonon wavenumbers and line widths around T C . YCrO 3 is reported to possess as an incipient ferroelectric material to show that there are two competing phenomenon—onset of ferroelectricity due to rotation of CrO 6 octahedra and displacement of Y atom leading to suppression of ferroelectricity. This competition reveals that although the octahedral rotations favor a lower symmetry state, the Y atom displacement opposes it leaving YCO to exhibit only an incipient ferroelectric state. These results while being in agreement with the earlier theoretical predictions can also help suggest a pathway to a more stable ferroelectric state in these oxides by using a larger cationic substitution at the Y site.