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291 results on '"Tu, Chi-Shun"'

19. Ultrahigh energy storage in multilayer BiFeO3–BaTiO3–NaTaO3 relaxor ferroelectric ceramics.

Author

Montecillo, Rhys, Chien, R. R., Chen, Cheng-Sao, Wu, Po-Hsien, Tu, Chi-Shun, and Feng, Kuei-Chih

Abstract

The rising challenge of high-density electric energy storage has accelerated the research of electric energy-storage capacitors due to their high power density and voltage resistance, excellent temperature stability, and environmental friendliness. However, lead-free ferroelectric capacitors generally have a low discharge energy density. This study used a multilayer ceramic capacitor (MLCC) design with active ceramic layers of relaxor ferroelectric NaTaO3-modified BiFeO3–BaTiO3 co-sintered with 90Ag/10Pd interlayer electrodes. Superb recoverable energy densities of Wrec ∼2.8 J cm−3 with an energy efficiency of η ∼73% at 400 kV cm−1 and Wrec ∼4.5 J cm−3 with an energy efficiency of η ∼77% at 450 kV cm−1 were attained, respectively, in 9-active-ceramic-layer and 24-active-ceramic-layer MLCCs. Excellent thermal stability and fatigue resistance of energy storage capability were achieved up to 180 °C and exceeding 1 × 104 cycles. The ultrahigh energy-storage properties can be linked to the synergistic effects of multiple local lattice distortions, nanoscale structures, and interfacial E fields at grain boundaries. This report demonstrates an efficient scheme to utilize ternary BiFeO3–BaTiO3-based ceramics via the MLCC technology for ultrahigh-energy-density electrostatic energy storage. [ABSTRACT FROM AUTHOR]

Published
2024
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28. Achieving high microscale photoconductivity in Gd-modified bismuth ferrite via modulating ferroelectric polarization.

Author

Mana-ay, Haidee, Chen, Cheng-Sao, Chien, R. R., Tu, Chi-Shun, and Chen, Pin-Yi

Abstract

This work demonstrates the critical role of ferroelectric polarization in determining the two-dimensional photoconduction properties of 7 mol% Gd-modified bismuth ferrite (BiFeO3, BFO) ceramics under 405 nm-wavelength illumination. A significant enhancement in photocurrent upon external electric field poling is correlated with adjustment in the internal electric field induced by ferroelectric polarization, which boosts the charge mobility via tilting the energy-band structure. The enhanced photoconduction is linked to the domain reorientation and increased domain walls. The evolution plays a critical role in the electric field-enhanced photocurrent since domain walls serve as conductive transport networks for charge flow. Furthermore, a sequential increase in photocurrent with increasing illumination intensity can be attributed to an increased number of photo-generated charge carriers. This study uncovers the vital effects of ferroelectric polarization on the photoelectric properties of BFO-based materials, thus providing essential insight for optoelectronic applications. [ABSTRACT FROM AUTHOR]

Published
2024
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29. Composite bone graft of CaO–MgO–SiO2 glass–ceramics and CaSO4 ceramics for boosting bone formation rate.

Author

Hung, Guan-Yi, Wang, Chi-Yun, Hsiao, Hui-Yi, Tu, Chi-Shun, Mana-ay, Haidee, Chen, Ching-Ting, Lai, Po-Liang, Feng, Kuei-Chih, and Chen, Pin-Yi

Abstract

This study develops a composite bone graft of CaO–MgO–SiO2 glass–ceramic and CaSO4 [abbreviated as (CMS)3−x(CS)x] via the sponge replication technique with weight fractions of x = 0, 1, 1.5, 2, and 3. The (CMS)1.5(CS)1.5 composite displays a superior degradability and, a suitable compressive strength of ∼3 MPa, and excellent cell proliferation and differentiation. The in vivo rat femur test in the hybrid-pore (CMS)1.5(CS)1.5 composite granules achieves a higher rate of bone formation, which is ∼2.7 times better than that of the commercial HAP/β-TCP at 12 weeks. Improved expressions of osteocyte and mature osteocyte marker genes, namely (Spp1, Dmp1, and Fgf23), were observed in the (CMS)1.5(CS)1.5 group, indicating a faster differentiation into mature bone tissue. The ions release of (CMS)1.5(CS)1.5 through the ERK1/2 signaling pathway promotes osteogenic differentiation. The high bone generation rate can be attributed to faster active ions release and modified surface topography. This work highlights an excellent bone graft candidate for clinical applications in orthopedic surgery. [ABSTRACT FROM AUTHOR]

Published
2024
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40. Configuration-entropy effects on BiFeO3–BaTiO3 relaxor ferroelectric ceramics for high-density energy storage.

Author

Montecillo, Rhys, Chen, Cheng-Sao, Feng, Kuei-Chih, Chien, R. R., Chen, Pin-Yi, and Tu, Chi-Shun

Abstract

High energy-storage capability and electric breakdown strength are critical elements in next-generation pulse-power dielectric capacitors. In this report, perovskite (Bi0.7Ba0.3)1−xNax(Fe0.7Ti0.3)1−xTaxO3 relaxor ferroelectric ceramics (x = 0–0.3) were tailored in terms of configuration entropy from a medium entropy of 1.21R to a high entropy of 2.07R to improve energy storage. The integration of paraelectric NaTaO3 into BiFeO3–BaTiO3 results in breaking of the long-range order and formation of multiple lattice distortions toward relaxor ferroelectric characteristics. Excellent recoverable energy densities of 9.6 J cm−3 and 10.3 J cm−3 with efficiencies of 77% and 68% at 350 kV cm−1 and 550 kV cm−1 (at 10 Hz) were achieved for x = 0.15 and 0.20, respectively. Wide operating frequency (1–100 Hz) and temperature (25 °C–150 °C) stabilities were confirmed at 300 kV cm−1. Grain boundaries and nanoclusters play critical roles as electric barriers to suppress charge mobility and increase electric breakdown strength. This study presents a promising scheme to utilize high-configuration entropy BiFeO3–BaTiO3-based ceramics for high energy-density electrostatic capacitors. [ABSTRACT FROM AUTHOR]

Published
2024
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