Energy Functional Materials Engineering Laboratory

Our paper entitled “Theoretical Analysis of Nanogenerators with Aligned Nanorods for Piezoelectric Energy Harvesting” has been published in Sens. Mater. We theoretically analyzed nanogenerators with aligned piezoelectric nanorods. It was shown that for the same piezoelectric materials, using a rod-shaped unit will increase the piezoelectric constant d₃₃ by 33% compared with using a film, owing to less substrate clamping. In addition, for the case of applying normal force, the aligned nanorod array can generate an output power one or more orders of magnitude higher than films within the same volume. This sort of nanogenerator will play an important role in the integration with miniaturized sensors in the off-resonant mode.

Citation: Sens. Mater. 31, 3669-3679 (2019).

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Our paper entitled “Large Impact of Strain on the Electro-optic Effect in (Ba, Sr)TiO₃ Thin Films: Experiment and Theoretical Comparison” has been published in Appl. Phys. Lett. We experimentally clarified that the EO properties of compressively strained BST thin films are enhanced toward the phase transition temperature modified by the strain. Although the measured EO coefficient r_c was less than that theoretically predicted, the experimentally observed strain effect on the EO properties is in good qualitative agreement.

This paper was was selected as a featured article.

Citation: Appl. Phys. Lett. 115, 092901 (2019).

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Jundong SONG won Best Student Paper Award of 2019 ISAF-ICE-FEM-IWPM-PFM Joint Conference – f2cπ2 held in Lausanne, Switzerland for his poster “Study on Output Power of Nanogenerators with Tetragonal Pb(Zr,Ti)O₃ Nanorods for Piezoelectric Energy Harvesting”.

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Our paper entitled “Theoretical Estimation of the Linear Electro-optic Effect in Compressively Strained c-domain (Ba, Sr)TiO₃ Thin Films using a Phenomenological Thermodynamic Model” has been published in J. Ceram. Soc. Jpn. To estimate the EO coefficients, we considered not only the intrinsic EO effect but also the elasto-optic effect by converse piezoelectric response. We found that the EOresponse is mostly determined by the difference in temperature from the ferroelectric-to-paraelectric phase transition boundary modified by the strain.

Citation: J. Ceram. Soc. Jpn. 127, 348-352 (2019).

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Kazuki OKAMOTO won the Best Student Paper Award of Journal of the Ceramic Society of Japan for his paper on self-assembled growth of PZT nanorods.

Citation: J. Ceram. Soc. Jpn. 126, 276-280 (2018).

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Shinya KONDO won the presentation award of The 38th Electronics Division Meeting of the Ceramic Society of Japan held in Kawasaki, Japan for his presentation on the electro-optic effect in c-domain (Ba, Sr)TiO₃ thin films.

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Our paper entitled “Significant Effect of Mg-pressure-controlled Annealing: Non-stoichiometry and Thermoelectric Properties of Mg_2-δSi_1-xSb_x” has been published in Phys. Chem. Chem. Phys. Non-stoichiometry of Mg_2−δSi_1−xSb_xcontrolled via Mg-pressure-controlled annealing has significant influence on the carrier concentration and other thermoelectric properties.

Citation: Phys. Chem. Chem. Phys. 20, 25939-25950 (2018).

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Shinya KONDO won Poster Award of The 10th China-Japan Symposium on Ferroelectric Materials and Their Applications (JCFMA10) held in Inuyama, Japan for his poster “Temperature and Strain Dependences of Electro-optic Effect in c-domain (Ba, Sr)TiO₃ Thin Films Fabricated by Pulsed Laser Deposition”.

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Our paper entitled “Strong Impact of SrTiO₃/TiO₂ Buffer Layer on Epitaxial Growth and Dielectric Response of Ba_0.7Sr_0.3TiO₃ Thin Films on MgO” has been published in Jpn. J. Appl. Phys. 270-nm-thick (001)-epitaxial BST films were deposited by pulsed laser deposition on STO/TiO₂-buffered MgO with a SrRuO₃ bottom electrode. It was found that the insertion of SrTiO₃/TiO₂ buffer layer enabled a two-dimensional growth of BST film, which resulted in the out-of-plane dielectric constant exceeding 1000.

Citation: Jpn. J. Appl. Phys. 57, 0902B1 (2018).

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On Jun. 1, Dr. Cosmin Sandu (Swiss Federal Institute of Technology, Lausanne – EPFL) and Dr. Petr Yudin (Siberian Branch of Russian Academy of Sciences / Academy of Science of the Czech Republic) visited us and lectured on AlScN thin film growth and pyroelectric energy harvesting.

Lecturer	Seminar title
Dr. Cosmin Sandu (Swiss Federal Institute of Technology – Lausanne (EPFL))	Growth and Complexion Formation for Ab-normal Oriented Grains in AlScN Thin Films Deposited by Sputtering
Dr. Petr Yudin (Siberian Branch of Russian Academy of Sciences / Academy of Science of the Czech Republic)	Pyroelectric Energy Harvesting from a Fluid Source

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