Role of phonon mode in the enhancement of ferroelectric polarization in a perovskite-based eco-friendly functional material

Digvijay Nath Dubey; Gurvinderjit Singh; Akhilesh Kumar Singh; Saurabh Tripathi

doi:10.1209/0295-5075/ac985d

All issues

Volume 140 / No 2 (October 2022)

EPL, 140 2 (2022) 26003

Abstract

Issue		EPL Volume 140, Number 2, October 2022


Article Number		26003
Number of page(s)		7
Section		Condensed matter and materials physics
DOI		https://doi.org/10.1209/0295-5075/ac985d
Published online		27 October 2022

EPL, 140 (2022) 26003

Role of $\Gamma_{4}^{-}$ phonon mode in the enhancement of ferroelectric polarization in a perovskite-based eco-friendly functional material

Digvijay Nath Dubey¹, Gurvinderjit Singh², Akhilesh Kumar Singh³ and Saurabh Tripathi¹^(a)

¹ Department of Physics, Indian Institute of Technology (BHU) - Varanasi, 221005, India
² Laser and Functional Materials Division, Raja Ramanna Centre for Advanced Technology - Indore, 452013, India
³ School of Materials Science and Technology, Indian Institute of Technology (BHU) - Varanasi, 221005, India

^(a) E-mail: stripathi.phy@itbhu.ac.in (corresponding author)

Received: 23 May 2022
Accepted: 7 October 2022

Abstract

We report here the role of component freezing of three-dimensional polar ( $\Gamma_{4}^{-}$ ) phonon mode corresponding to the center of cubic Brillouin zone in tuning the structure-property correlations of a scientifically enriched and technologically important barium-titanate–based eco-friendly functional material (Ba_0.92Ca_0.08)(Zr_0.05Ti_0.95−xSn_x)O₃; BCZTSnx $(0\leq x\leq 0.10)$ synthesized via solid-state reaction method. The combined X-ray diffraction, Raman spectroscopic analysis, and temperature-dependent dielectric studies have revealed the presence of several crystallographic phase transitions with coexisting phases, viz., $P4mm \rightarrow (P4mm+Amm2+R3m) \rightarrow (Amm2+R3m) \rightarrow R3m \rightarrow (Pm\overline{3}m+R3m)$ , as a function of Sn(x) content. These crystallographic phases, viz., P4mm, Amm2, and R3m results due to freezing of the component(s) of $\Gamma_{4}^{-}$ phonon mode (belonging to $Pm\overline{3}m$ space group), with the respective order parameter directions (0,0,a), (a,a,0), and (a,a,a) leading to ferroelectric polarization along $\langle{}001\rangle$ , $\langle{}110\rangle$ and $\langle{}111\rangle$ directions, respectively. The ceramic composition corresponding to $x = 0.025$ exhibits a significant reduction in the coercive field (E_c) and an enhancement in ferroelectric polarization (P_r) in comparison to $x = 0$ , inferred from PE loop measurements. The enhancement in ferroelectric polarization at has been attributed to the inter-ferroelectric three-phase $(P4mm+Amm2+R3m)$ coexistence around this composition and significantly enhanced amplitudes of ferroelectric phonon modes corresponding to orthorhombic and rhombohedral phases, calculated using the symmetry mode analysis technique. The existence of a high ferroelectric polarization and low coercive field may lead to $x = 0.025$ composition as an eco-friendly candidate for ferroelectric memory devices.

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