Temperature dependent X‐ray diffraction and Raman spectroscopy studies of polycrystalline YCrO₃ ceramics across the T_C ~ 460 K

Abstract

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 YCrO3 (YCO) across the paraelectric to ferroelectric phase transitions (TC ~ 460 K), and the material retains the orthorhombic structure with Pnma space group. However, a detailed analysis reveals local distortions in the CrO6 octahedra. To probe the local structural distortion, we have carried out temperature‐dependent, unpolarized Raman measurements, from 300 to 600 K. YCrO3 shows a strong anomalous deviation in both phonon wavenumbers and line widths around TC. YCrO3 is reported to possess as an incipient ferroelectric material to show that there are two competing phenomenon—onset of ferroelectricity due to rotation of CrO6 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.

Octahedral tilting dominated phase transition in compressed double perovskite Ba2SmBiO6

“…For the Pnma structure, t < 1 indicates that the stress can be relieved bond length changes of Ba-O, Sm-O, and Bi-O or octahedral BiO 6 tilting. The orthorhombic distortion factor can be estimated by D ,35 where a, b, and c are the refined lattice parameters at different pressures. The distortion factor D as a function of pressure is shown in Fig.2(d).…”

Enhanced Charge Transport by Regulating the Electronic Structure in 2D Tin-Based Perovskite Solar Cells

“…Relatively speaking, its lattice distortion is lighter and more regular. In order to quantify this distortion value, we introduce the distortion factor as follows where a , b , and c are the corresponding lattice parameters.…”

Crystallization of Amorphous Silicon via Excimer Laser Annealing and Evaluation of Its Passivation Properties

“…The thickness of a-Si:H layer was confirmed from nanoview ellipsometry. Raman spectroscopy for ellipsometry (VASE, JA Woollam, 240 < λ < 1700 nm) was used to measure the crystallinity and passivation by measuring carrier lifetime (τ eff ) and implied open circuit voltage (i-V OC ) using the WCT Sintrom-120 QSSPC measuring system [20][21][22]. The experimental results indicated significant progress in crystallization when using ELA compared to that achieved using conventional thermal treatment methods.…”