Journal of the Ceramic Society of Japan
vol. 133, no.9, 2025
Feature: Hyper-Ordered Structure Science
◆Preface◆
https://doi.org/10.2109/jcersj2.133.P9-1P9-1
◆Full paper◆
Transformation from a network to a close-packed structure in the structural models of CaO–SiO2 binary glasses
https://doi.org/10.2109/jcersj2.25072
Atsunobu Masuno, Motoki Shiga and Hiroyuki Inoue
481
Structural models of CaO–SiO2 binary glasses across the entire composition range, including compositions beyond the glass-forming region, were generated using molecular dynamics simulations. The packing density increased with CaO content, reproducing the experimental values within the known glass-forming region. Local structure analysis around Si atoms revealed a systematic transition in Qn species, indicating progressive network depolymerization with increasing CaO content. The reduced atomic arrangement method was employed to determine and visualize glass structures with different compositions. At a CaO content exceeding 60 mol %, where the corner-sharing SiO4 network was completely depolymerized, oxide ions formed a nearly close-packed arrangement. This unique atomic arrangement was corroborated by the oxygen–oxygen partial pair distribution function. The formation of the nearly close-packed oxide ion arrangement in CaO-rich compositions was attributed to the transformation from a network structure owing to strong depolymerization. The highly ordered atomic arrangement found in oxide glasses can be considered a type of hyperordered structure within disordered materials—an alternative to the conventional random network structure in oxide glasses.
◆Review◆
Hyperordered structures in silica polymorphs
https://doi.org/10.2109/jcersj2.25038
Shinji Kohara
488
We have been exploring with the quest hyperordered structures in terms of order within disorder in silica (SiO2) polymorphs. In this article, we review and discuss our recent findings on this topic comprehensively in comparison with those of previous studies. We chose several SiO4 tetrahedral corner-sharing crystalline silica and siliceous zeolites of various density. Furthermore, we attempted to control the intermediate-range ordering of glass by tuning of the density of silica glass under high pressures and temperatures. We extracted the density-driven modification of the topology of tetrahedral silica polymorphs in a wide density range. Our state-of-the-art analyses revealed two descriptors for hyperordered structures in silica polymorphs. The first descriptor of hyperordered structures in silica glass can be expressed by the position and height of diffraction peaks observed in X-ray and neutron diffraction data. This descriptor is not new, but we can systematically understand the density-driven behaviour of diffraction peaks in silica glass. The second descriptor of hyperordered structures in a series of silica polymorphs can be expressed in terms of topological characteristics: ring size distribution, cavity distribution, ring shape, and tetrahedral order. We found an unusually large cavity volume in β-cristobalite which was attributable to the formation of highly symmetrical –Si–O– sixfold rings, and highly symmetrical eightfold and twelvefold rings in coesite even though most of the small rings were significantly buckled, which was due to coesite having the highest density of coesite among the series of silica polymorphs. Moreover, we found a topological similarity between glass and siliceous zeolite (MFI), in which fivefold and sevenfold rings are observed. It is concluded that both diffraction measurement and topological analysis provide us crucial information on hyperordered structures in silica polymorphs.
◆Full papers◆
Oxygen-defective Gd2O3−x films with visible-light absorption produced by precisely controlling oxidation of Gd metal foil
https://doi.org/10.2109/jcersj2.25047
Mitsuhiro Matsuda, Yuzuru Aramaki, Kenji Shida and Motohide Matsuda
497
Introducing oxygen deficiencies into metallic oxides dramatically improves their functional properties, such as their catalytic activity, ion conductivity, visible-light response, ferroelectric behavior, and ferromagnetism. We successfully produced oxygen-defective Gd2O3−x films by an oxidation process using Gd metal foil as the starting material and investigated the films’ optical properties and microstructures. A black oxygen-defective Gd2O3−x film nearly 1 µm thick was formed on the surface of Gd metal foil annealed at 773 K for 600 s in air. The Gd2O3−x film consisted of a cubic-Gd2O3 structure with an equiaxed grain size of a few hundred nanometers. The diffuse reflectance of the Gd2O3−x film was less than 30 %, indicating the absorption of both visible and near-infrared light. We also produced several-micrometer-thick oxygen-defective Gd2O3−x films on the surface of a Gd metal foil by a two-step heat treatment involving annealing at 773 K for 600 s in air and subsequent heating at 1073 K for 3.6 ks under an O2 partial pressure of 1.01 × 10−5 Pa. The Gd2O3−x film exhibited less than 20 % reflectance in the visible region. Transmission electron microscopy and high-angle annular dark-field scanning transmission electron microscopy observations revealed that the Gd2O3−x film was composed of a periodic structure with a spacing of several nanometers, which originated from the presence and absence of oxygen deficiencies in the cubic-Gd2O3 structure; that is, it was composed of a “hyper-ordered structure.”
Photoelectron holography characterization of protonated brownmillerite SrCoO2.5 epitaxial films
https://doi.org/10.2109/jcersj2.25062
Daisuke Kan, Yusuke Hashimoto, Thanh Ngoc Pham, Lingling Xie, Yosuke Isoda, Tomohiro Matsushita, Yoshitada Morikawa and Yuichi Shimakawa
503
We characterized protonated SrCoO2.5 epitaxial films by the photoelectron holography technique. We found that photoelectron holography patterns change due to cation displacements induced by electrochemical protonation. By simulating holography patterns based on structural models of the protonated SrCoO2.5 using machine-learning enhanced global optimization and comparing them with the experimentally observed patterns, we evaluated hydrogen concentration and cation displacements in protonated SrCoO2.5 films. Our results show that photoelectron holography is useful in characterizing protonation-induced changes in metal transition oxides.
Superconductivity in graphene induced by atomic intercalation
https://doi.org/10.2109/jcersj2.25075
Ryota Akiyama, Shunsuke Sato, Yudai Miyai, Yusuke Hashimoto, Jehong Jung, Rei Hobara, Yogendra Kumar, Amit Kumar, Shota Shimizu, Ryotaro Minakawa, Yuta Yamamoto, Hiroto Tomita, Takashi Tadamura, Takuya Moriki, Yuya Yamada, Shin-ichiro Ideta, Kenya Shimada, Tomohiro Matsushita and Shuji Hasegawa
508
We report the emergence of superconductivity (SC) in graphene via atomic intercalation with calcium (Ca) and ytterbium (Yb), each producing distinct electronic environments. In the case of Ca-intercalation, SC arises below 5 K due to electron doping that lowers an interlayer band (ILB) to the Fermi level (EF), enabling hybridization with graphene’s π* bands around the K point in the Brillouin zone, which was confirmed by angle-resolved photoemission spectroscopy (ARPES). This results in a high density of states at EF conducive to Cooper pairing. Systematic tuning of carrier density reveals a dome-shaped dependence of the SC transition temperature on the carrier density, suggesting involvement of van Hove singularity (vHs) around the M point with appropriate doping. In contrast, Yb intercalation leads to SC at 0.85 K, accompanied by a markedly different band structure. ARPES shows that Yb 4f levels lie near EF and clearly hybridize with graphene’s π and π* bands, while no distinct ILB is observed around EF. X-ray photoelectron spectroscopy (XPS) and photoelectron diffraction reveal that divalent Yb ions reside between the graphene layers, acting as the primary contributor to SC. If the anisotropic nature of Yb 4f orbitals is introduced into the graphene band relevant to SC, it enables us to realize potentially unconventional pairing mechanisms in the two-dimensional limit. Our comparative study highlights how the characteristics of the intercalant—its valence, orbital character, and stacking structures—profoundly influence the superconducting state. The Ca system follows a more conventional band-filling picture except for possible electron correlation at vHs, while the Yb system exhibits hybridized bands and enhanced correlations. These results suggest that introducing heavy elements such as Yb into graphene, a light electron system, to induce hybrid orbitals can transform it into a heavy-electron system, thereby enabling the extraction of a wealth of physical phenomena.
Effect of Zn doping on p-type conduction of γ-CuI studied by X-ray fluorescence holography and positron annihilation spectroscopy
https://doi.org/10.2109/jcersj2.25054
Mamoru Kitaura, Koji Kimura, Halubai Sekhar, Koichi Hayashi, Koji Michishio, Manabu Ishizaki, Takahiro Hayasaka, Atsushi Kinomura and Shinta Watanabe
515
γ-CuI is a p-type semiconductor with high mobility and chemical stability; it has potential applications as a hole-transport layer in organic solar cells and light-emitting diodes. To clarify the mechanism by which Zn doping controls the p-type conduction in γ-CuI, the types of defects formed in Zn-doped γ-CuI were comprehensively investigated through X-ray fluorescence holography (XFH), positron annihilation lifetime spectroscopy (PALS), coincidence Doppler broadening spectroscopy (CDBS), and density functional theory (DFT) calculations. The XFH demonstrated the presence of Zn atoms at the Cu sites (ZnCu). Furthermore, PALS and DFT calculations revealed the presence of isolated Cu vacancies (VCu). The CDBS suggested the formation of ZnCu–VCu defect pairs due to Zn doping. These findings supported that Zn doping suppresses p-type conduction via the formation of ZnCu–VCu defect pairs, as predicted by previous DFT studies. The combination of XFH, PALS and CDBS experiments and DFT calculations is effective for identifying the defect types in semiconductors.
Influence of synthesis conditions on the valence state of tin in zinc phosphate glass prepared by melt-quenching
https://doi.org/10.2109/jcersj2.25068
Hirokazu Masai, Ko Mibu, Tomoko Onoue, Hiroumi Maegawa, Koji Kimura and Koichi Hayashi
521
Metastable species play a crucial role in glass functionalization. It has been reported that tin(II) is easily oxidized in air and that tailoring tin’s valence state is essential for designing tin-doped glasses. In this study, we examined the valence state of tin in zinc phosphate glass using 119Sn Mössbauer spectroscopy and Sn L2-edge X-ray absorption near-edge structure. The synthesis of glasses using ZnO, SnO, and ZnP2O6 revealed the conversion of tin from the divalent to tetravalent state, even in an Ar atmosphere. However, the oxidation process can be mitigated by incorporating reducing agents, such as ammonium phosphate or carbon. The oxidation kinetics were affected by several factors, including the SnO concentration, melting duration, and the quenching process from glass melt. The effect of tin’s valence state on the glass’s physical properties was further explored through elastic properties.
In situ reductive transformation of indium oxides on zeolites towards efficient microwave heating
https://doi.org/10.2109/jcersj2.25082
Fuminao Kishimoto, Ryo Ishibashi and Kazuhiro Takanabe
528
The interaction of incident microwaves with heterogeneous catalysts presents unique opportunities for selective and energy-efficient heating in catalytic and materials processes. Recently, microscopic selective heating phenomena have emerged as a promising strategy to revolutionize microwave-assisted systems by enabling targeted energy absorption and improved control over local reaction environments. However, since the interaction between catalysts and microwaves is highly dependent on the temperature, catalysts that induce such localized heating at elevated temperatures do not necessarily absorb microwave energy efficiently at room temperature. Typically, catalysts that do not absorb microwaves well at room temperature require the addition of microwave susceptors such as SiC to initiate heating. However, under high-temperature reaction conditions, these susceptors can interfere with the efficient delivery of microwave energy directly to the catalyst. In this work, to propose a new material heating method that leverages structural transformations during microwave irradiation, the structural transformation of indium oxide (In2O3) deposited MFI-type zeolites under H2 condition was investigated. At lower temperature (<200 °C), In2O3 played a role of moderate microwave absorber. Once the sample reached 200 °C, In2O3 was reduced to form In+ cations, which migrate into zeolite pores via reductive solid-state ion exchange. This results in a sharp increase in heating efficiency, reaching 500 °C with only 40 W of microwave power. In contrast, thermally pretreated samples showed minimal heating under the same conditions. These findings reveal that In+ cations act as atomic-scale microwave hotspots at elevated temperatures, potentially applicable to thermally-effective catalysis. This discovery provides a new strategy for the design of practical catalysts tailored for microwave heating, enabling more efficient and selective catalytic processes without relying on external susceptors.
Regular Issue
◆Full papers◆
Temperature variation of the magnetic properties of mechanochemically synthesized (Fe2O3)1−x(Al2O3)x solid solutions through the Mössbauer spectroscopy
https://doi.org/10.2109/jcersj2.25053
Dong Luo, Hayato Nakaishi, Takeshi Yabutsuka, Shinji Kitao, Makoto Seto and Shigeomi Takai
535
Mössbauer spectroscopy experiments were carried out on corundum-type structured (Fe2O3)1−x(Al2O3)x solid solutions (x = 0–0.67) synthesized by the mechanical alloying method to clarify the contribution of temperature and aluminum concentration to the magnetic properties. The Mössbauer spectra at room temperature gradually change from a sextet (weak ferromagnetism) to a doublet (paramagnetism) with increasing aluminum contents. As the temperature decreases down to 10 K, the sextet component develops for lower aluminum substitution, while the doublet profile changes to sextet for higher aluminum region. The absolute values of quadrupole splitting for the weak ferromagnetic component slightly increase with the aluminum substitution, primarily due to the reduction of the symmetry of the crystal field. The isomer shift δ decreases with the aluminum concentration due to the shrinkage of the lattice, and it also decreases with increasing temperature for the enhanced lattice vibration. Additionally, the hyperfine magnetic field Bhf weakens with the aluminum substitution presumably due to a diminished interaction between the nuclear magnetic moments, which can be observed in the lower temperatures.
Direct observation of pulse poling effect on reversible 90° domain wall motion in tetragonal Pb(Zr,Ti)O3 thin films
https://doi.org/10.2109/jcersj2.25024
Yoshitaka Ehara, Ayumi Wada, Hitoshi Morioka, Takeshi Kobayashi, Shintaro Yasui and Hiroshi Funakubo
542
We investigated the effects of the pulse poling process on macroscopic ferroelastic domain structures in (100)/(001)-oriented Pb(Zr0.44Ti0.56)O3 films. The poling process consisted of an applied electric field square waveform for poling cycles (100–107 cycles) combined with triangular waveforms for polarization–electric field and strain–electric field measurements. The remanent polarization (Pr) and the inverse piezoelectric coefficient (d33,f) were enhanced at 103 poling cycles but decreased with further increases in poling cycles. After 103 poling cycles, the 90° domain switching behavior was directly observed via in situ X-ray diffraction (XRD). The results showed a 4 % change in the volume fraction of the c-domain (VC) during the application of an electric field of +150 kV/cm. The 90° domain structure was altered by the poling process, contributing to increased electric field-induced strain. However, in situ XRD results after 107 poling cycles indicated only slight changes in VC under an applied electric field, with degraded Pr and d33,f. The degradation of d33,f values by pulse poling is partly due to the reduced contribution of ferroelastic 90° domain switching.
Effect of Al addition on the yellowness of V-doped t-ZrO2: A first-principles study
https://doi.org/10.2109/jcersj2.25057
Hiroki Kojima, Ryo Kaminaga, Junko Ishii, Kenji Obata, Masao Arai, Hisahiro Einaga and Shigenori Matsushima
548
First-principles calculations were performed to clarify the reason for the increase in yellowness upon the addition of Al to V-doped tetragonal ZrO2 (t-ZrO2). First-principles energy band calculations were performed using V-doped and (V, Al)-doped t-ZrO2 supercells with theoretically optimized structures. When t-ZrO2 was doped with V, the band gap exhibited a strongly localized energy level originating from the V 3d states. The V-doped t-ZrO2 supercell co-doped with Al modified the number and energy positions of the V 3d levels within the ZrO2 band gap. In the calculated dielectric function of the V-doped ZrO2 supercell, broad absorption from the O 2p VB states to the V 3d gap states was observed in the visible region, in addition to the d-d transition in V4+. When Al was co-doped in the V-doped t-ZrO2, no increase in the optical absorption in the visible-light region was observed. In contrast, the (V, Al)-doped t-ZrO2 supercells with oxygen vacancies exhibited stronger absorption in the visible light region than the V-doped t-ZrO2 supercell.
Preparation and structural characterization of nanoporous silica/magnesium(II)-whitlockite composite particles
https://doi.org/10.2109/jcersj2.25059
Takuya Kataoka, Daiki Hirota, Eiji Fujii, Tomohiko Yoshioka and Satoshi Hayakawa
555
The preparation of particles composed of nanoporous silica (NS) and Mg2+-whitlockite (Mg-WH) would provide valuable insights for designing particles for biomedical applications. In this study, NS and Mg-WH composite particles were successfully synthesized. The addition of chitosan during synthesis possibly promoted the crystallization of calcium phosphate phases in the composite particles. Pore size distribution analysis of the particles showed a maximum at 3.2 nm. Investigating the adsorption of methylene blue onto the particles in a phosphate buffer (pH 7.4) showed that the saturated adsorption amount of methylene blue on the particles was significantly higher than that on commercial hydroxyapatite. The composite particles provided important results for potential applications as drug carriers for bone regeneration and repair.
Atmospheric pressure hydrothermal synthesis and characterization of hollandite-type α-Mn1−xTixO2 for rechargeable magnesium battery cathodes
https://doi.org/10.2109/jcersj2.25049
Masanao Ishijima, Yu Sakano, Kentaro Okada, Tamao Ishida, Kiyoshi Kanamura, Toshihiko Mandai and Koichi Kajihara
562
Hollandite-type α-MnO2 and its solid solutions with TiO2 for the cathode active materials of rechargeable magnesium batteries were synthesized with a hydrothermal method under atmospheric pressure through the oxidation of Mn2+ ions with ammonium persulfate [(NH4)2S2O8] within 2 h. The solubility limit of Ti in α-Mn1−xTixO2 was x ≃ 0.2, and average particle size decreased with an increase in x. Despite the high surface area, α-Mn1−xTixO2 exhibited lower catalytic activity for oxidative electrolyte decomposition and better discharge capacity retention than α-MnO2. Capacity retention was the highest and the increment of charge overpotential during cycles was the smallest at x = 0.2.
Hetero-coating of spherical graphite with sulfide solid electrolytes via the SEED process for all-solid-state lithium batteries
https://doi.org/10.2109/jcersj2.25056
Reiko Matsuda, Masayo Takahashi, Kazuhiro Hikima, Hiroyuki Muto and Atsunori Matsuda
569
Spherical graphite (SG) particles coated with an Li7P2S8I solid electrolyte (SE) were synthesized using a liquid-phase process to fabricate high-performance anode composites for all solid-state batteries. Initially, an Li2S layer was deposited onto SG, which subsequently combined with an Li2S–P2S5–LiI ethyl propionate solution, forming a uniform Li7P2S8I precursor layer. This process utilized the Li2S layer as a scaffold to promote homogeneous growth of the Li7P2S8I SE. The resulting SE layers established excellent interfacial contact with SG, enhancing ionic transport efficiency. The obtained anode composite (87 wt % SG and 13 wt % Li7P2S8I) demonstrated favorable charge–discharge performance despite low SE wt %. The microstructure and electrochemical properties of the SE layers were investigated using scanning electron microscopy and electrochemical impedance spectroscopy. To further enhance Li-ion conductivity in the anode layer, ultrathin Li7P2S8I coatings on SG particles were combined with argyrodite-type SE, which is well known for its high ionic conductivity. A composite of 97 wt % SG, 3 wt % Li7P2S8I, and argyrodite-type SE (SG:total SE = 70:30) exhibited excellent cycle performance in a half-cell, maintaining a capacity of 251 mAh g−1 after 100 cycles with a 95 % capacity retention rate.
◆Technical report◆
Oxide ionic conduction anisotropy of apatite-type RE9.33Si6O26 (RE = La–Ho) ceramics
https://doi.org/10.2109/jcersj2.25051
Susumu Nakayama
577
Rare earth-silicate RE9.33Si6O26 ceramics [RE = La(Nd), Pr, Nd, Sm, Gd, Dy, Ho, Y, Er, and Yb] with an apatite-type c-axis-oriented crystal structure were prepared under a magnetic field using a neodymium magnet. RE = La(Nd)–Ho had an apatite structure, whereas RE = Y, Er, and Yb did not show an apatite structure. The lattice constants a and c and cell volume decreased monotonically with decreasing ionic radius of RE3+ in La(Nd)–Ho. The intragranular conductivity parallel to the c-axis direction (σ∥) of c-axis oriented RE9.33Si6O26 [RE = La(Nd), Pr, Nd, Sm, Gd, Dy, and Ho] is more than twice as large as the intragranular conductivity perpendicular to the c-axis direction (σ⊥). Both σ∥ and σ⊥ decreased monotonically as the ionic radius of RE3+ decreased from La(Nd) to Gd. However, in the case of Dy and Ho, the intragranular conductivity increased more than that of Gd. Furthermore, the difference between σ∥ and σ⊥ tends to decrease with decreasing ionic radius of RE3+.
◆Note◆
Preparation of silica/polyethyleneimine inorganic–organic hybrid oil/water separation membranes via sol–gel method
https://doi.org/10.2109/jcersj2.25070
Koji Kuraoka and Takuma Tanaka
584
Silica/polyethyleneimine (PEI) inorganic–organic hybrid oil/water separation membranes were prepared by sol–gel method using tetramethoxysilane (TMOS), 3-glycidoxypropyltrimethoxysilane (GPTMOS) and PEI, and cross-linking reaction between glycidoxy functional group of 3-glycidoxypropyltrimethoxysilane (GPTMOS) and amino functional group of PEI. The effects of TMOS content on the water flux and oil/water separation efficiency of the membranes were also investigated. Oil/water separation efficiency of PEI60TM10 (60 wt % PEI to GPTMOS, 1.0 molar ratio TMOS to GPTMOS) was high (96 %) and water flux was also high (680 L·m−2·h−1). The hybrid oil/water separation membranes exhibit higher oil/water separation efficiency and higher water flux.
◆Announcement◆
Call for a Guest Editor for the Feature
https://doi.org/10.2109/jcersj2.133.A9-1A9-1
© Copyright by The Ceramic Society of Japan