Origin of ferroelectricity in cubic phase of Hf substituted BaTiO3

Aanchal Sati; Preeti Pokhriyal; Anil Kumar; Shahid Anwar; Archna Sagdeo; N P Lalla; P R Sagdeo

doi:10.1088/1361-648X/abf0bf

Origin of ferroelectricity in cubic phase of Hf substituted BaTiO₃

J Phys Condens Matter. 2021 Apr 20;33(16). doi: 10.1088/1361-648X/abf0bf.

Authors

Aanchal Sati¹, Preeti Pokhriyal^{2

3}, Anil Kumar¹, Shahid Anwar⁴, Archna Sagdeo^{2

3}, N P Lalla⁵, P R Sagdeo¹

Affiliations

¹ Material Research Laboratory, Discipline of Physics, Indian Institute of Technology Indore, Indore-453552, India.
² Synchrotron Utilization Section, Raja Ramanna Center for Advanced Technology, Indore 452013, India.
³ Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India.
⁴ CSIR-Institute of Minerals and Materials Technology, Bhubaneswar-751-013, India.
⁵ UGC-DAE Consortium for scientific research, University campus, Khandwa road, Indore-452001, India.

PMID: 33752190
DOI: 10.1088/1361-648X/abf0bf

Abstract

The origin of ferroelectricity in the cubic phase of BaTi_1-xHf_xO₃has been investigated. The presence of well-defined ferroelectric polarization versus electric field (PE) hysteresis loop in the samples with global cubic symmetry suggests the presence of 'local polar regions', induced possibly due to the huge difference in the electronegativity and also difference in the ionic radii of Hf⁺⁴and Ti⁺⁴ions, which may lead to local structural disorder. The presence of polar regions is also supported through the appearance of A₁(TO) polar mode in Raman spectra which in principle should be absent in the samples with cubic symmetry. The results are discussed in terms of disorder-induced local dipoles due to the electronegativity difference between Hf and Ti ions.

Keywords: barium titanate; electron phonon; polar Raman mode; structural disorder.