Technischen UniversitätDarmstadt

I visited the laboratory of Professor Jürgen Rödel (Tokyo Tech WRHI Specially Appointed Professor) Technischen UniversitätDarmstadt for “Evaluation of Dielectric Properties of Ferroelectric Oxide CaMn(Ti_1-xV_x)₂O₆” by WRHI support. Prof. Dr. Jürgen Rödel is a pioneer in the field of ferroelectric material research, and has focused on the mechanical properties of materials, such as ferroelasticity, a property in which the polarization direction of a material changes depending on applied stress.

The purpose of this visit was to evaluate the dielectric properties and ferroelasticity of CaMn(Ti_1-xV_x)₂O₆, which is a new material synthesized by our group. This material is a solid solution obtained by substituting V⁴⁺ for CaMnTi₂O₆. It is known that V⁴⁺ can produce giant spontaneous polarization in some lead-based materials such as PbVO₃. A new ferroelectric transition mechanism is proposed for CaMnTi₂O₆. From the results of the crystal structure analysis to date, it has been confirmed that spontaneous polarization increases with increasing x values of CaMn(Ti_1-xV_x)₂O₆ when x ≤ 0.4. It has been expected that the evaluation of ferroelasticity, which can evaluate spontaneous polarization of a material mechanically rather than electrically, could be used to evaluate CaMn(Ti_1-xV_x)₂O₆, which indicates leakage current. Further, the ferroelectric phase transition temperature of this material was evaluated through the measurement of the dielectric constant temperature dependency.

Unfortunately, the ferroelasticity evaluation could not be performed successfully due to the problem of the sample strength, but the temperature dependence of the dielectric constant was successfully measured, and the dependence of the ferroelectric phase transition temperature on x values was clarified. Regarding the content of this study, we are submitting a co-authored paper as soon as possible with additional measurements.