Journal of the Ceramic Society of Japan
Online ISSN : 1348-6535
Print ISSN : 1882-0743
ISSN-L : 1348-6535
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Displaying 1-21 of 21 articles from this issue
  • Natsuki Hosoya, Hirotaka Fujimori
    Article ID: 24031
    Published: 2024
    Advance online publication: May 25, 2024
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    Supplementary material

    Wollastonite is a natural ore of calcium silicate (β-CaSiO3), which is used as a ceramic raw material. In this study, we prepared porous wollastonite ceramics by using American and Mexican wollastonite powders which contain different amounts of Mg as a trace component. We investigated sintering behavior and physical property of these porous ceramics. As a result, it was revealed that when wollastonite contains at least 0.5 mol % of Mg, phase transition temperature from β-CaSiO3 to α-CaSiO3 increased by about 50 °C. Additionally, temperature-dependent phase transition becomes more gradual. This would be due to a phenomenon of “phase transformation” that solid solution of Mg stabilizes β-CaSiO3 during firing. Moreover, such transformation also affects bulk density, porosity and pore structure of porous wollastonite ceramics.

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  • Zhi-Qing Wan, You-Jun Lu, Yan-Min Wang, Yun-Fang Meng, Hun-Fang Shen, ...
    Article ID: 24028
    Published: 2024
    Advance online publication: June 14, 2024
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  • Naoki Kondo, Ryutaro Usukawa, Akihiro Shimamura, Mikinori Hotta
    Article ID: 24058
    Published: 2024
    Advance online publication: June 14, 2024
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  • Yuki Nakashima
    Article ID: 24040
    Published: 2024
    Advance online publication: June 13, 2024
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  • Jiawei Fu, Shigeomi Takai, Takeshi Yabutsuka, Takeshi Yao
    Article ID: 24051
    Published: 2024
    Advance online publication: June 13, 2024
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  • Shingo Hara, Ayumi Kato, Kazunori Takeuchi
    Article ID: 24030
    Published: 2024
    Advance online publication: June 12, 2024
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  • Shunsuke Kayukawa, Yutaro Katsuyama, Tomoharu Tokunaga, Takahisa Yamam ...
    Article ID: 24036
    Published: 2024
    Advance online publication: May 22, 2024
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    Flash events can cause rapid mass diffusion through instantaneous power spikes that occur in electric fields and at temperatures above certain thresholds. Recent research suggests that such mass diffusion caused by the flash event may include athermal effects in addition to Joule heating due to the power spikes. However, this perspective has not been applied to surface diffusion, one of the mass diffusion pathways. This study examines the athermal effect on surface diffusion during the flash event by analyzing the surface morphology variation of material uplift formed after the flash-/thermal-healing of Vickers-indentation-induced microcracks. The results show that the formation of surface facet structures, one of the material uplift surface morphologies, varies depending on the direction of the direct current (DC) electric field. The direction dependence of the facet structure formed on the material up-lifted surface due to the DC electric field is a result of the electric field drift effect. The athermal effects associated with flash events can be considered to exist also in mass diffusion involving surface diffusion.

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  • Taro Ueda, Satoshi Ono, Takayuki Suzuki, Yasuhiro Shimizu, Takeo Hyodo
    Article ID: 24011
    Published: 2024
    Advance online publication: May 15, 2024
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    CeO2-added Au films were drop-coated on a YSZ film fabricated on an alumina substrate embedded a Pt heater on the back side as sensing electrodes (SEs), and their toluene sensing properties were examined in dry air at elevated temperatures (400–600 °C). The suitable addition of polyvinyl alcohol in the precursor solution for drop-coating improved the roughness of the obtained film. The sensor using a 8 wt% CeO2-added Au SE showed relatively larger toluene responses at higher temperatures (450–600 °C), and the toluene response of the sensor at 500 °C was the largest (ca. 167 mV to 50 ppm toluene) among all sensors in the whole temperature range. The toluene-sensing mechanism of the sensors was discussed on the basis of the mixed potential theory. In addition, we explained that the mixed potential appeared at the interface between SE and gas [SE(Au/CeO2)/gas] in the SE layer as well as the interface on the YSZ (SE/YSZ/gas) in this study.

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  • Shuya Sato, Masashi Miyakawa, Takashi Taniguchi, Yohei Onodera, Koji O ...
    Article ID: 24013
    Published: 2024
    Advance online publication: May 14, 2024
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    Synthesizing densified glasses with structure ordering is an important issue for the development of new optical fibers with high refractive index and low dispersion. Herein, we report on our attempt to synthesize densified silica (SiO2) glasses by hot compression at a pressure of 7.7 GPa and temperatures above 1200 °C. We succeeded for the first time in recovering densified SiO2 glasses compressed at 7.7 GPa and 1300 °C. Samples compressed above 1300 °C were crystallized into coesite by heterogeneous nucleation. The height of the first sharp diffraction peak in high-energy X-ray and neutron diffraction data of densified SiO2 glasses increased with increasing temperature, indicating the evolution of intermediate-range ordering. Furthermore, the density increase of hot-compressed SiO2 glasses was estimated by analyzing reduced pair distribution functions. We found that the SiO2 glass compressed at 7.7 GPa and 1300 °C is by far the most densified and structurally ordered (hyperorderd) glass in the world.

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  • Kazuki Murai
    Article ID: 24032
    Published: 2024
    Advance online publication: May 17, 2024
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    Supplementary material

    Biomineralization is a biochemical process forming biominerals under mild conditions. Although many studies have explored nucleation to crystal growth mechanisms of bioinorganic matter, no universal principle has been established. Herein, four topics related to biomineralization are described: (1) molecular, structural, and functional designs of peptide-based templates for mineralization; (2) structural control mechanisms for inorganic matters; (3) functional modification of organic–inorganic hybrid materials; (4) functional hydrogel fabrication by applying the structural control mechanism inspired by mineralization. The described studies provide significant breakthroughs for improving the functions of organic–inorganic hybrid materials utilizing mineralization-inspired environmentally friendly processes and for the fabrication of functional organic polymer-based materials by mineralization-inspired structural control techniques.

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  • Kenta Iyoki
    Article ID: 24042
    Published: 2024
    Advance online publication: May 22, 2024
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    The ability to freely control the performance of ceramics through post-synthetic treatment would be a seed of innovation for various applications. Zeolites, a class of porous ceramics, have regular pores of molecular size and are used as catalysts, adsorbents, and ion exchangers. The control of zeolite composition and pore characteristics by post-synthetic treatments such as steaming has been known, but is still under development, including for target zeolites, more simple methods, achievement of uncharted properties, and so on. In this review, the concept of ‘pore-filler stabilization’ has been developed and utilized to achieve high performance in zeolites, which was previously thought to be impossible.

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  • Rintaro Ashihara, Masami Kawahara, Hiroyuki Okazaki, Shunya Yamamoto, ...
    Article ID: 24021
    Published: 2024
    Advance online publication: May 03, 2024
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    We investigated the relationship between the self-orientation and process conditions of self-oriented LaNiO3 (LNO) thin films fabricated by a chemical solution deposition method. The LNO thin films were deposited on Pt-coated Si, SiO2/Si, glass, c-plane sapphire, and stainless-steel substrates, which have crystal structures different from that of LNO. Increasing the heating rate during the transition from 200 °C (pre-heating) to 380 °C (pyrolysis) enhanced the self-orientation of the resulting LNO thin films. The LNO thin films deposited on the various substrate materials exhibited (h00) self-oriented growth because Pb(Zr0.52Ti0.48)O3 (PZT) thin films deposited on the self-oriented LNO thin films clearly adopted the (h00) preferential orientation. As a unique behavior of PZT/LNO bilayer structures, the PZT upper layer has stronger (h00) oriented growth than that of the underlying self-oriented LNO layer.

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  • Zannatul Mumtarin Moushumy, Haruka Oyama, Hiroshi Yoshida, Masato Mach ...
    Article ID: 24022
    Published: 2024
    Advance online publication: May 02, 2024
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    The development of precious metal-free three-way catalysts presents numerous complex challenges, among which thermal aging is a significant hurdle. The effects of different thermal aging conditions, including varying heating and cooling rates, were studied using a Cu oxide catalyst supported on γ-Al2O3, prepared via a conventional wet impregnation method. Intriguing results emerged after subjecting the Cu/Al2O3 catalyst to rapid heating and cooling during thermal aging at 900 °C under 10 %H2O/air. Notably, the integration of Cu2+ into γ-Al2O3 resulted in the preservation of a metastable low-crystalline solid with a notably higher surface area of 88 m2 g−1. This solid-state transformation facilitated the preferential generation of Cu+ species at tetrahedral Al sites during the CO and C3H6 oxidation process within the stoichiometric three-way catalytic reaction (NO–CO–C3H6–O2). Consequently, a higher quantity of active sites for NO reduction was obtained, achieving a remarkable >70 % NO conversion at 600 °C. Conversely, subjecting the catalyst to slow heating and cooling (at a rate of 5 °C min−1) during thermal aging at 900 °C resulted in a distinct outcome. This condition produced a thermodynamically favorable phase transition from the metastable phase to highly crystalline CuAl2O4 and α-Al2O3, leading to a drastic reduction in surface area (9 m2 g−1) and consequently, a notable decrease in NO reduction activity (<20 % NO conversion even at 600 °C). Furthermore, regardless of the heating rate employed during thermal aging, it was observed that a slow cooling rate of 5 °C min−1 rendered the catalyst susceptible to phase transitions, resulting in lower surface areas and less active catalytic products.

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  • Tetsuo Uchikoshi
    Article ID: 24023
    Published: 2024
    Advance online publication: May 01, 2024
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    The electrophoresis of particles by applying an electric field to a colloidal suspension allows the simultaneous manipulation and shaping of particles. A film forming process utilizing the electrophoretic phenomenon of charged particles in a liquid is called “electrophoretic deposition (EPD)” and is used for powder coating. The main difference between the EPD process and other colloidal processes is the coexistence of electrode reactions, i.e., electrochemical reactions that occur at the interface between the electrode and the electrolyte solution. The applied electric field in the EPD method plays an important role not only in the electrophoresis of charged particles but also in controlling the coagulation mechanism and film quality. This paper introduces the principle of the EPD process considering the electrode reaction and an example of the functional film formation process.

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  • Su-Hyun Baek, Toshihiro Isobe, Miki Inada
    Article ID: 24033
    Published: 2024
    Advance online publication: May 02, 2024
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    Silica (SiO2) porous glass materials is expected as a support in environmental fields due to transparency, high surface reactivity and so on. In this study, silica porous glass with high strength was fabricated by addition of potassium carbonate (K2CO3) as sintering aid and mullite as reinforcing materials. At first, a sintering condition was investigated using silica disk-type samples. A brittle amorphous silica disk with low density was obtained by firing at 1200 °C. At 1400 °C, crystallization was occurred and cristobalite formed. A small amount (∼1 wt %) of K2CO3 was effective to densification of amorphous silica, whereas more than 1 wt % K2CO3 addition accelerated the crystallization of silica. This was due to the formation of liquid phase. In addition, a highly dispersed mullite to SiO2 matrix was effective to enhance the mechanical property. The porous structure was successfully fabricated by template method using polyurethane.

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  • Ryuta Miyoshi, Akira Saitoh, Naoki Kanno, Seiki Ohara, Satoshi Yoshida ...
    Article ID: 24035
    Published: 2024
    Advance online publication: May 10, 2024
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    We have explored ultra-high refractive index over 2.05 in multi-component borate glasses with large optical bandgap (∼3.7 eV) and high Young’s modulus (∼130 GPa). The niobate-based borate glasses commonly contain highly electronic polarized oxides like Nb2O5 and TiO2, chosen from transition metal oxides. Although these glasses have a large amount of Nb2O5, TiO2, and La2O3, they are vitrified by melting at 1300 °C. The obtained borate glasses with internal transmissions of 99 % per 10 mm-thick estimated from the optical absorption coefficient for the visible light might be used for “Augmented Reality glass” devices.

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  • Koichiro Fukuda, Ryoji Watanabe, Hiroshi Nakamori, Daisuke Urushihara, ...
    Article ID: 24027
    Published: 2024
    Advance online publication: April 26, 2024
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    Supplementary material

    The c-axis-aligned polycrystalline lanthanum silicate oxyapatite (LSO) was prepared by the reactive diffusion between random grain oriented La2SiO5 polycrystal and [SiO + 1/2O2] gases at 1873 K for 10 h. Based on the grain sizes, aspect ratios, elongation directions, and c-axis orientations for the constituent LSO crystals, the polycrystalline microtexture was classified into three regions denoted by I, II, and III. Region I was located on the innermost side of the pellet sample, region III was situated on the surface, and region II was positioned between the regions I and III. The region I with the layer thickness of approximately 140 µm was composed of relatively large crystal grains with their elongation directions along the c-axes. The individual crystal grains were aligned almost along their c-axes, with their a-axis directions being randomly oriented around the grain alignment direction. Although this region exhibited the highest orientation compared to the other two regions, there were also significantly lower orientation grains present, accounting for approximately 6.1 % of the total. If the formation of these grains that reduce the degree of orientation can be prevented, a higher degree of orientation can be achieved for the region I. On the other hand, there were much smaller crystal grains in the regions II and III. The LSO polycrystal with the region II showed the lowest orientation degree among those of the three regions. The region III consisted of grains with a relatively high degree of c-axis orientation and elongated along the c-axis. The differences in microtexture between the three regions would be attributed to the distinct growth behaviors of the constituent LSO crystal grains.

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  • Gota Asano, Tetsuo Umegaki, Yoshiyuki Kojima
    Article ID: 24009
    Published: 2024
    Advance online publication: April 24, 2024
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    Zinc silicate (ZS), which occurs naturally as willemite, is primarily used as a ceramic pigment and finds wide applications as a fluorescent material and in nonlinear voltage resistor devices. In recent years, ZS has been studied as a coating material for the electrode surfaces of air batteries and as a negative electrode material for Li-ion batteries. In this study, we investigated its suitability as an anode material in aqueous Zn secondary batteries. Conventional ZnO dissolves and precipitates as zincate ions in alkaline electrolytes, leading to dendritic growth and passivation. By utilizing ZS as the anode material, we observed significant improvements in cycle characteristics. Furthermore, substituting a portion of the ZS with P resulted in increased battery capacity and confirmed the reversible dissolution–precipitation reactions of Zn ions during charging and discharging.

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  • Hidenobu Murata, Atsushi Nakahira
    Article ID: 24014
    Published: 2024
    Advance online publication: April 12, 2024
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    Supplementary material

    This study investigates the reaction of a Zn2+ aqueous solution on the surface of hydroxyapatite (HAp) containing different crystallinities using X-ray absorption near edge structure (XANES). Low- and high-crystallinity HAp were prepared using the aqueous solution precipitation method, followed by calcination. Zn-K XANES revealed that Zn2+ is incorporated into both high- and low-crystallinity HAp via a dissolution–reprecipitation process. In addition, ZnO is formed on the surface of high-crystallinity HAp, which indicates that the surface of high-crystallinity HAp directly immobilizes Zn2+. This is the second example of the direct immobilization of cations after Mg2+. Our findings provide a better understanding of the behavior of HAp in aqueous solutions and lead to the development of environmental purification materials.

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  • Koichiro Fukuda, Fumiya Nakajima, Daisuke Urushihara, Toru Asaka, Tohr ...
    Article ID: 24026
    Published: 2024
    Advance online publication: April 24, 2024
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    Supplementary material

    To investigate the anisotropy of Ca2+ conduction, the b-axis-aligned CaAl4O7 (space group C2/c) polycrystal was prepared by colloidal processing under high magnetic field of 12 T followed by sintering at 1773 K for 2 h. The textured polycrystal was characterized by X-ray diffractometry and impedance spectroscopy with respect to the grain alignment direction, which was parallel to the applied magnetic field. The texture fraction of {0k0}, expressed as the Lotgering factor f0k0, was 0.63. The 〈101〉 directions of individual crystal grains were randomly distributed around the grain-alignment direction of the polycrystal. The conductivities perpendicular (σ) and parallel (σ) to the grain alignment direction were compared with the conductivity (σrandom) of random grain oriented polycrystal between 773 and 1073 K. The σ, ranging from 3.09 × 10−7 to 1.80 × 10−5 S cm−1, showed the highest value at each temperature, followed by σrandom and σ in that order. The results have confirmed for the first time the anisotropy of Ca2+ conduction and strongly supported the preferential conduction in the 〈101〉 direction predicted in the literature by the bond valence method.

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  • Biao Zhang, Yichen Wu, Zhiwei Jin, Hongjun Ning, Fen Wang, Hongjie Luo ...
    Article ID: 24010
    Published: 2024
    Advance online publication: April 13, 2024
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    Supplementary material

    By adjusting the addition amount of Ca3(PO4)2 and boron frit, the amorphous photonic crystal structural color glazes with different colors were prepared without introducing colorants with the average heating rate of 4.1 °C/min and the firing temperature of 1300 °C. Furthermore, the effects of firing temperature and heating rate on the structural colors were studied. The results indicated that the contents of Ca3(PO4)2 and boron frit were 2 and 4 %, 2 and 10 %, 3 and 8 % (mass fraction), respectively, the amorphous photonic crystal structural color glazes with purple, blue, and light cyan colors were prepared. When the firing temperature decreased from 1300 to 1250 °C, the presence of residual quartz and the uneven distribution of phase separation structures increased the brightness of structural colors and decreased the color saturation. In addition, after decreasing the average heating rate from 4.1 to 2.8 °C/min, the diopside was formed in the glazes. It absorbed iron at high temperatures and transformed into green diopside. Under the coupling effect of the chemical color generated by diopside and the structural color generated by phase separation structures, a cyan color with high color saturation appeared in the glaze.

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