Faculty Profiles - TANIGUCHI Hiroki

Papers - TANIGUCHI Hiroki

Division display 1 - 20 of about 323 ／ All the affair displays >>

Unconventional Polarization Response in Titanite-Type Oxides due to Hashed Antiferroelectric Domains Reviewed

Hiroki Taniguchi, Takumi Watanabe, Taro Kuwano, Akitoshi Nakano, Yukio Sato, Manabu Hagiwara, Hiroko Yokota, Kazuhiko Deguchi

ACS nano Vol. 18 ( 22 ) page： 14523 - 14531 2024.5

Effects of Bi3+ incorporation and charge compensation on the dielectric properties of CaTiSiO5 antiferroelectric ceramics Reviewed

Kosuke Watanabe, Taro Kuwano, Hiroki Taniguchi, Shinobu Fujihara, Manabu Hagiwara

Journal of the European Ceramic Society Vol. 46 ( 4 ) page： 117984 - 117984 2026.4

Atomic-scale insights into the high dielectric permittivity of bismuth silicate glass Invited Reviewed International coauthorship

J.R. Stellhorn, A. Masuno, Y. Onodera, S. Kohara, K. Yoshida, Y. Yanaba, H. Inoue, T. Ohkubo, and H. Taniguchi

Physical Review B Vol. 133 page： 014201 2026.1

Catalytic In Situ Acetalization Strategy for High-Yield Synthesis of C4- and C2-Carbohydrate Derivatives from Glucose Reviewed International coauthorship

Osuga R., Bhat N.S., Shi Q., Shibayama N., Yabushita M., Suganuma S., Taniguchi H., Tada M., Kato H., Zhang L., Filot I., Hensen E.J.M., Nakajima K.

ACS Catalysis Vol. 16 ( 2 ) page： 1675 - 1683 2026.1

Language：English Publishing type：Research paper (scientific journal) Publisher：ACS Catalysis

The development of heterogeneous catalytic upgrading processes for glucose, the most abundant carbohydrate in plant biomass, is crucial for advancing the production of renewable chemicals. Among the promising strategies, retro-aldolization enables direct and selective cleavage of C–C bonds, offering a route to valuable C<inf>4</inf> and C<inf>2</inf> carbohydrates: erythrose (ERT) and glycolaldehyde (GA). These compounds serve as key precursors to a range of high-value chemicals. However, their susceptibility to degradation by humin formation hinders practical implementation. Here, we present a catalytic strategy involving Nb<inf>2</inf>O<inf>5</inf> and H-MOR zeolite for converting glucose in ethanol to ERT and GA through selective retro-aldolization (Nb<inf>2</inf>O<inf>5</inf>), followed by in situ acetalization to form the corresponding stable acetals of ERT and GA (H-MOR). Lewis acidic Nb5+ in NbO<inf>4</inf> tetrahedra in the Nb<inf>2</inf>O<inf>5</inf> surface catalyzes retro-aldolization of glucose, while Bro̷nsted acid sites in the H-MOR pores provide a shape-selective reaction environment for the acetalization of ERT and GA with ethanol. The exclusion of glucose from the one-dimensional micropores of H-MOR is critical to the high efficiency achieved. This method for glucose conversion in heterogeneous catalysis, based on protection principles common in synthetic organic chemistry, can impact the use of glucose as a feedstock for making renewable C4 and C2 chemicals.

DOI： 10.1021/acscatal.5c08041

Scopus

Electric-Field-Induced Increase in Permittivity in Uniaxial Antiferroelectric K3Nb3B2O12Polycrystalline Ceramics Reviewed

Uohashi T., Hirose Y., Maruyama K., Takeuchi H., Taniguchi H.

Inorganic Chemistry Vol. 64 ( 49 ) page： 23861 - 23867 2025.12

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Inorganic Chemistry

Potassium niobate borate K<inf>3</inf>Nb<inf>3</inf>B<inf>2</inf>O<inf>12</inf> exhibits uniaxial antiferroelectricity, where polarization flipping occurs along only one crystallographic direction, while a linear dielectric response is observed in perpendicular directions. The present study investigates the temperature dependence of dielectric permittivity and electric-field-induced polarization of K<inf>3</inf>Nb<inf>3</inf>B<inf>2</inf>O<inf>12</inf> polycrystalline ceramics to clarify its potential for high-voltage applications. The results demonstrated a high relative permittivity of approximately 130 at room temperature and its enhancement under an applied electric field. Notably, the onset electric field for permittivity boosting was found to be markedly smaller than that observed in typical uniaxial antiferroelectrics. This study paves the way for the development of next-generation capacitors for power electronics with uniaxial antiferroelectricity.

DOI： 10.1021/acs.inorgchem.5c03298

Scopus

Thermally stable dielectric and structural properties of titanite-type SrZrGeO5 Reviewed

Taro Kuwano, Hiroko Yokota, Manabu Hagiwara, Toshiya Uohashi, Akitoshi Nakano, Kazuhiko Deguchi, Hiroki Taniguchi

Ceramics International Vol. 51 ( 30 ) page： 64979 - 64984 2025.12

Coexisting Displacive and Order-Disorder Lattice Instabilities in the Antiferroelectric Titanite CaTiSiO5 Reviewed

Akitoshi Nakano, Toshiya Uohashi, Ayako Taguchi, Hiroki Moriwake, Hiroki Taniguchi

INORGANIC CHEMISTRY Vol. 64 ( 40 ) page： 20103 - 20110 2025.10

Focused Thermal Energy at Atomic Microwave Antenna Sites for Eco-catalysis Reviewed Open Access

Toshiaki Ina, Kazuhiro Takanabe, Hiroki Yamada, Akira Nakayama, Hiroki Taniguchi, Toru Wakihara, Tatsushi Yoshioka, Koki Muraoka, Fuminao Kishimoto, Ryo Ishibashi

Science Advances Vol. 11 ( 41 ) 2025.10

Improving the dielectric temperature stability of Bi2SiO5-based ceramics through the spontaneous formation of paraelectric-ferroelectric nanocomposite structures Reviewed Open Access

Yasumoto Y., Kuwano T., Taniguchi H., Fujihara S., Hagiwara M.

Dalton Transactions Cambridge England 2003 Vol. 54 ( 37 ) page： 13869 - 13878 2025.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Dalton Transactions Cambridge England 2003

The substitution of a portion (∼3%) of Bi3+ in ferroelectric Bi2SiO5 ceramics with La3+ induces a paraelectric phase and stabilizes the dielectric permittivity by eliminating the ferroelectric-paraelectric phase transition. However, the non-negligible negative temperature dependence of the permittivity remains an issue for practical applications in capacitors, resonators, and antennas. Herein, we show that the additional substitution of Si4+ with Ge4+ in paraelectric (Bi0.97La0.03)2SiO5 can substantially improve its dielectric temperature stability. Ceramic samples with compositions of (Bi0.97La0.03)2Si1-xGexO5 with x up to 0.3 were prepared via a sol-gel process and subsequent low-temperature sintering below 720 °C. The incorporation of Ge stabilized the ferroelectric phase with an elevated Curie temperature, leading to the spontaneous formation of a paraelectric-ferroelectric nanocomposite structure. The fraction of the ferroelectric phase increased from 0% at x = 0 to 53% at x = 0.3. Because of the negative and positive temperature dependence of the paraelectric and ferroelectric phases, respectively, the sample with x = 0.2 exhibited a dielectric permittivity over 50 with a small temperature coefficient of -70 ± 50 ppm °C-1 in a temperature range from -55 to 125 °C. The ceramics also showed a paraelectric-like linear polarization response under electric fields up to 280 kV cm-1.

DOI： 10.1039/d5dt01380a

Open Access

Scopus

Phase variety of titanite-type solid solutions (Ca, Pb)TiGeO5: paraelectric and antiferroelectric states in monoclinic and triclinic lattices Reviewed

Zerui Li, Taro Kuwano, Hiroko Yokota, Shintaro Yasui, Manabu Hagiwara, Toshiya Uohashi, Akitoshi Nakano, Hiroki Taniguchi

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 64 ( 8 ) 2025.8

Sub-unit-cell-segmented ferroelectricity in brownmillerite oxides by phonon decoupling Reviewed International coauthorship

Jang J., Jin Y., Nam Y.S., Park H.S., Kim J., Kang K.T., So Y., Choi J., Choi Y., Shim J., Sriboriboon P., Lee D.K., Go K.J., Kim G.Y., Hong S., Lee J.H., Lee D., Han M.G., Son J., Kim Y., Taniguchi H., Kang S., Lee J.S., Tian H., Yang C.H., Zhu Y., Cheong S.W., Choi W.S., Lee J., Choi S.Y.

Nature Materials Vol. 24 ( 8 ) page： 1228 - 1235 2025.8

Language：English Publishing type：Research paper (scientific journal) Publisher：Nature Materials

The ultimate scaling limit in ferroelectric switching has been attracting broad attention in the fields of materials science and nanoelectronics. Despite immense efforts to scale down ferroelectric features, however, only few materials have been shown to exhibit ferroelectricity at the unit-cell level. Here we report a controllable unit-cell-scale domain in brownmillerite oxides consisting of alternating octahedral/tetrahedral layers. By combining atomic-scale imaging and in situ transmission electron microscopy, we directly probed sub-unit-cell-segmented ferroelectricity and investigated their switching characteristics. First-principles calculations confirm that the phonon modes related to oxygen octahedra are decoupled from those of the oxygen tetrahedra in brownmillerite oxides, and such localized oxygen tetrahedral phonons stabilize the sub-unit-cell-segmented ferroelectric domain. The unit-cell-wide ferroelectricity observed in our study could provide opportunities to design high-density memory devices using phonon decoupling.

DOI： 10.1038/s41563-025-02233-7

Scopus

Titanite-type solid solutions (Ca,Pb)TiGeO5: a competition between triclinic and antiferroelectric distortions Reviewed Open Access

Zerui Li, Taro Kuwano, Akitoshi Nakano, Manabu Hagiwara, Shintaro Yasui, Hiroki Taniguchi, Hiroko Yokota

Journal of the Ceramic Society of Japan Vol. 133 ( 7 ) page： 275 - 280 2025.7

Cu Doping Effects on Magnetic Properties of Ba3ZnRu2O9 Reviewed

Kimura A., Yasui Y., Nakano A., Taniguchi H., Terasaki I.

Journal of the Physical Society of Japan Vol. 94 ( 3 ) 2025.3

Designing Dielectric Properties by Local Structure Engineering Invited Reviewed

TANIGUCHI Hiroki

Nihon Kessho Gakkaishi Vol. 67 ( 1 ) page： 30 - 37 2025.2

Authorship：Corresponding author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Crystallographic Society of Japan

Here we demonstrate antiferroelectricity and antiferroelectric domain engineering to enhance permittivity in titanite-type oxides. Despite the conventional understanding that antiferroelectric domains, unlike ferroelectric ones, do not provide an additional polarization response due to their non-polar nature, it has been discovered that condensed domain walls（anti-phase boundaries）in titanite-type CaTi（Si1–xGex）O5 cooperatively form polar clusters, markedly enhancing the dielectric permittivity of the system. This finding introduces a new concept of domain engineering in dielectric materials to boost permittivity.

DOI： 10.5940/jcrsj.67.30

CiNii Research

Biosensor Application of CMOS Inverter and Ring Oscillator with Organic Field-Effect Transistors Reviewed

Utsumi M., Fujiwara A., Goto H., Okamoto H., Takeyasu N., Saitoh Y., Suga M., Takahashi Y., Imanaka H., Taniguchi H., Yasui S., Eguchi R., Kubozono Y.

ACS Applied Electronic Materials Vol. 7 ( 4 ) page： 1483 - 1492 2025.2

Language：English Publishing type：Research paper (scientific journal) Publisher：ACS Applied Electronic Materials

Organic field-effect transistors (FETs) were fabricated for use in a biosensor that detects urea hydrolysis under urease. Here, a 60 nm thick 2,6-diphenylanthracene (DPA) thin film was used to prepare a p-channel FET that effectively detected this enzymatic reaction. The absolute drain current, |ID|, of the transfer curve rapidly increased at any gate voltage, VG, when a droplet of 0.1 M phosphate buffer solution (pH = 6.7 at 25 °C) containing 25 mM urea and 49 nM urease was placed on a different gate electrode (i.e., sensor electrode) than the VG electrode. Thus, urea hydrolysis directly affected the value of VG, enhancing |ID|. The usage of high-k gate dielectric ZrO2 in the FET device caused the absolute value of VG, |VG|, to decrease by ≈1.0 V in the transfer curve. The value of |ID| at any absolute drain voltage |VD| and |VG| was plotted as a function of time and urea concentration [S], showing a rapid increase and reaching saturation within ≈1.0 min or up to [S] = 250 mM. Furthermore, we prepared the complementary metal oxide semiconductor (CMOS) inverter with thin films of DPA as a p-channel and N,N′-di-n-octyl-3,4,9,10-perylenetetracarboxylic diimide (PTCDI-C8) as an n-channel to detect urea hydrolysis. The logic threshold voltage VTIC in the CMOS inverter increased by placing a droplet containing urea and urease on a different gate electrode than that delivering the input voltage Vin. Finally, a ring oscillator consisting of five CMOS inverters was fabricated to detect the variation in oscillation frequency throughout the reaction, revealing an unambiguous decrease in the frequency. The successful detection of urea hydrolysis is the first step toward the realization of a practical biosensor incorporating a CMOS inverter and ring oscillator.

DOI： 10.1021/acsaelm.4c02031

Scopus

Theoretical and data-driven approaches to semiconductors and dielectrics: from prediction to experiment Reviewed

Fumiyasu Oba, Takayuki Nagai, Ryoji Katsube, Yasuhide Mochizuki, Masatake Tsuji, Guillaume Deffrennes, Kota Hanzawa, Akitoshi Nakano, Akira Takahashi, Kei Terayama, Ryo Tamura, Hidenori Hiramatsu, Yoshitaro Nose, Hiroki Taniguchi

Science and Technology of Advanced Materials Vol. 25 ( 1 ) page： 2423600 2024.12

High dielectric breakdown strength of antipolar CaTiGeO5 ceramics sintered at optimized temperature Reviewed

Vol. 50 ( 18 ) page： 34197 - 34204 2024.9

Effect of Al–Nb codoping on dielectric properties and breakdown strength of rutile TiO2 ceramics Reviewed

Mitsuha Kawasaki, Taro Kuwano, Hiroki Taniguchi, Shinobu Fujihara, Manabu Hagiwara

Journal of the Ceramic Society of Japan Vol. 132 ( 7 ) page： 304 - 311 2024.7

Effect of Al–Nb codoping on dielectric properties and breakdown strength of rutile TiO2 ceramics Reviewed

Mitsuha Kawasaki, Taro Kuwano, Hiroki Taniguchi, Shinobu Fujihara, Manabu Hagiwara

Journal of the Ceramic Society of Japan Vol. 132 ( 7 ) page： 304 - 311 2024.7

Language：English Publishing type：Research paper (scientific journal) Publisher：Ceramic Society of Japan

Acceptor–donor codoping is gaining attention as a novel method for enhancing the intrinsic dielectric permittivity of TiO2 ceramics. Aiming at the application of TiO2 in high-voltage multilayer ceramic capacitors, this study investigated the dielectric properties and breakdown strength of TiO2 ceramics doped with equimolar amounts of Al3+ and Nb5+ ions at a total doping concentration of up to 10.0 mol %. The dielectric permittivity was not increased by the codoping, but gradually decreased with increasing the codoping concentration. Meanwhile, a small amount of Al–Nb codoping (up to 2.0 mol %) suppressed dielectric loss at both room and elevated temperatures. The dielectric breakdown field was also significantly improved at up to 5.0 mol % codoping concentrations. The effects of Al–Nb codoping on the dielectric properties and breakdown strength are discussed in terms of microstructure, defect concentration, and mobility of charged oxygen vacancies.

DOI： 10.2109/jcersj2.23212

Scopus

CiNii Research

Ferroelectric polycrystalline Bi2SiO5 thin films on Pt-covered Si substrates prepared by pulsed laser deposition combined with post-annealing Reviewed Open Access

Haruto Takahashi, Shingo Maruyama, Hiroshi Naganuma, Hiroki Taniguchi, Ryota Takahashi, Shintaro Yasui, Kenichi Kaminaga, Yuji Matsumoto

Journal of Alloys and Compounds Vol. 988 ( 15 ) page： 174195 2024.6

　 PREV - NEXT 　

<TANIGUCHI Hiroki>

Papers - TANIGUCHI Hiroki