Laboratory for Materials and Structures, IIR,Tokyo Institute of Technology Professor Masaki Azuma, PhD Student Masayuki Fukuda and Department of Materials and Earth Sciences, Nonmetallic Inorganic Materials, Technical University of Darmstadt, Professor Jürgen Rödel
“Enhanced Spontaneous Polarization by V4+ Substitution in a Lead-Free Perovskite CaMnTi2O6”
ACS Publications doi.org/10.1021/acs.inorgchem.0c01697

<Abstract>
Spontaneous polarization (P_s) of novel order–disorder type lead-free ferroelectric CaMnTi₂O₆was 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 d¹electronic configuration. Our magnetic study suggested the presence of antisite disorder between Ca²⁺and square planar coordinated Mn²⁺associated with Mn–V intermetallic charge transfer forx≥ 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⁺.