Enhanced Spontaneous Polarization by V4+ Substitution in a Lead-Free Perovskite CaMnTi2O6

Masayuki Fukuda; Takumi Nishikubo; Zhao Pan; Yuki Sakai; Mao-Hua Zhang; Shogo Kawaguchi; Hongwu Yu; Yoichi Okimoto; Shin-Ya Koshihara; Mitsuru Itoh; Jürgen Rödel; Masaki Azuma

doi:10.1021/acs.inorgchem.0c01697

Enhanced Spontaneous Polarization by V⁴⁺ Substitution in a Lead-Free Perovskite CaMnTi₂O₆

Inorg Chem. 2020 Aug 17;59(16):11749-11756. doi: 10.1021/acs.inorgchem.0c01697. Epub 2020 Aug 6.

Authors

Masayuki Fukuda¹, Takumi Nishikubo¹, Zhao Pan¹, Yuki Sakai^{1

2}, Mao-Hua Zhang³, Shogo Kawaguchi⁴, Hongwu Yu⁵, Yoichi Okimoto⁵, Shin-Ya Koshihara⁵, Mitsuru Itoh¹, Jürgen Rödel^{3

6}, Masaki Azuma^{1

2}

Affiliations

¹ Laboratory for Materials and Structures, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
² Kanagawa Institute of Industrial Science and Technology, 705-1 Shimoimaizumi, Ebina, Kanagawa 243-0435, Japan.
³ Department of Materials and Earth Sciences, Nonmetallic Inorganic Materials, Technical University of Darmstadt, Darmstadt, Germany.
⁴ Diffraction and Scattering Division, Japan Synchrotron Radiation Research Institute (JASRI), SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan.
⁵ Department of Chemistry, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan.
⁶ Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, Kanagawa 226-8503, Japan.

PMID: 32799500
DOI: 10.1021/acs.inorgchem.0c01697

Abstract

Spontaneous polarization (P_s) of novel order-disorder type lead-free ferroelectric CaMnTi₂O₆ was successfully enhanced by partial V⁴⁺ substitution for Ti⁴⁺. A synchrotron X-ray diffraction study revealed that the polar displacement of octahedrally coordinated (Ti, V) in CaMn(Ti_1-xV_x)₂O₆ (0 ≤ x ≤ 0.4) increases with V⁴⁺ substitution having Jahn-Teller activity owing to the d¹ electronic configuration. Our magnetic study suggested the presence of antisite disorder between Ca²⁺ and square planar coordinated Mn²⁺ associated with Mn-V intermetallic charge transfer for x ≥ 0.4, resulting in decreases in spontaneous polarization and the ferroelectric-paraelectric transition temperature. This is the first report on the enhanced polarization owing to the Jahn-Teller distortion of V⁴⁺ without stereochemical Pb²⁺ or Bi³⁺.