著者

Kotaro FUJII Masatomo YASHIMA

出版者

The Ceramic Society of Japan

雑誌

Journal of the Ceramic Society of Japan (ISSN:18820743)

巻号頁・発行日

vol.126, no.10, pp.852-859, 2018-10-01 (Released:2018-10-01)

参考文献数

64

被引用文献数

13 33

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This article provides the first critical review on the discovery and development of BaNdInO4. Exploring a new structure family of ionic conductors is an important task to develop ceramic ionic conductors. Since some A2BO4 compositions exhibit high oxide-ion conductivities, we investigated ABCO4 compositions to explore new oxide-ion conductors with A/B/C cation-ordered structures. Here A, B and C are cations [ionic radii: r(A) ≥ r(B) ≥ r(C)]. In 2014, we discovered a new material BaNdInO4 which belongs to a new structure family of perovskite-related structures. This BaNdInO4-type structure (monoclinic, P21/c) consists of alternative stacking of the A rare earth oxide unit and perovskite unit with a− b− c− tilt system. We also discovered new materials BaRInO4 (R = Sm, Y, Ho, Er, Yb) having the BaNdInO4-type structure, and report their lattice parameters and anisotropic chemical expansion. Electrical conductivity of BaNdInO4 was higher than those of BaRInO4 (R = Sm, Y, Er). Oxide-ion conduction was dominant for BaNdInO4 in the P(O2) region from 3.8 × 10−22 to 5.5 × 10−9 atm at 858°C. Oxide-ion conductivities of Ba1.1Nd0.9InO3.95, BaSr0.1Nd0.9InO3.95 and BaCa0.2Nd0.8InO3.9 were higher than that of BaNdInO4. Structure analyses of Ba1.1Nd0.9InO3.95 and BaSr0.1Nd0.9InO3.95 indicated that the excess Ba and doped Sr cations were partially substituted for Nd cation and that there existed oxygen vacancies, leading to the increase of the carrier concentration and higher oxide-ion conductivity. Following the discovery of BaNdInO4, BaRScO4 (R = Nd, Eu, Y, Yb) and SrYbInO4 were reported as new ABCO4 materials. BaYScO4 and BaYbScO4 have the BaNdInO4-type structure. BaNdScO4 and BaEuScO4 crystallize into the space group Cmcm, which has a higher symmetry than P21/c for BaNdInO4. SrYbInO4 is the first example of pure oxide-ion conductors with CaFe2O4-type structure. Further investigations of ABCO4 compositions and BaNdInO4 related materials will lead to development of materials science and solid state ionics.

著者

Masanobu NAKAYAMA

出版者

The Ceramic Society of Japan

雑誌

Journal of the Ceramic Society of Japan (ISSN:18820743)

巻号頁・発行日

vol.129, no.6, pp.286-291, 2021-06-01 (Released:2021-06-01)

参考文献数

28

被引用文献数

7

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In this review, we introduce our work in the field of materials informatics for the prediction of ionic conduction properties in inorganic crystalline solids. Rational material development based on information-derived prediction of the ionic conductivity for the materials listed in the crystal structure database is attractive to reduce processing time and labor costs. For this purpose, the development of general descriptors and a sufficient volume of ionic conductivity datasets are required. As an example, herein we describe machine learning regression and Bayes optimization schemes and their results by using histogram descriptors and a bond valence-based force field approach.

著者

Hiroki TANAKA Kiyoshi UCHIYAMA Takao SHIMIZU Hiroshi FUNAKUBO

出版者

The Ceramic Society of Japan

雑誌

Journal of the Ceramic Society of Japan (ISSN:18820743)

巻号頁・発行日

vol.128, no.8, pp.436-440, 2020-08-01 (Released:2020-08-01)

参考文献数

24

被引用文献数

1 4

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A SrZrO3 thin film with yttrium (Y) concentration of 20 at % (SZYO) was successfully deposited by the pulsed laser deposition (PLD) technique. The laser power of PLD affected Y-concentration significantly even though it used the same PLD target. On contrary, the laser reputation frequency and the deposition temperature did not significantly affect the composition. The SZYO film deposited at the optimized conditions was well crystallized and showed no secondary phase and showed (111) and (110) orientations when they were deposited on (111)Pt/SiOx/Si and on (111)Pd/(111)Pt/SiOx/Si substrates, respectively. This SZYO film is expected to use as an electrode of our proposed novel solid oxide fuel cells.

著者

Mizuki Watanabe Honoka Takahashi Kazuyoshi Uematsu Mineo Sato Takaki Masaki Dae-Ho Yoon Kenji Toda

出版者

The Ceramic Society of Japan

雑誌

Journal of the Ceramic Society of Japan (ISSN:18820743)

巻号頁・発行日

vol.130, no.7, pp.458-463, 2022-07-01 (Released:2022-07-01)

参考文献数

49

被引用文献数

2

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All-inorganic halides exhibit excellent optical as well as luminescence properties. Among them, non-toxic copper-doped halide Cs2ZnCl4 with high stability is a promising material. However, the conventional method for preparing these materials, using the hot injection technique, is unsuitable for mass production. Therefore, herein, we suggest a simple and low-temperature (below 100 °C) method without using special equipment, regents, and treatments. Cu-doped Cs2ZnCl4 was successfully synthesized using the water-assisted solid-state reaction (WASSR) method, and the oxidation state of Cu in the samples was estimated through the iodometric titration technique. The optical and luminescence properties were investigated using the absorption and photoluminescence excitation/emission spectra. Significantly, Cu-doped Cs2ZnCl4 exhibited unique green emission centered at ∼520 nm under ultraviolet irradiation. Moreover, the oxidation of Cu in the Cs2ZnCl4 lattice was suppressed owing to the low-temperature conditions in the WASSR.

著者

Katsuyuki Matsunaga Masato Yoshiya Naoya Shibata Hiromichi Ohta Teruyasu Mizoguchi

出版者

The Ceramic Society of Japan

雑誌

Journal of the Ceramic Society of Japan (ISSN:18820743)

巻号頁・発行日

pp.22080, (Released:2022-07-09)

参考文献数

255

被引用文献数

32

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Point defects, dislocations, grain boundaries and interfaces are always involved in ceramic microstructures and play important roles for physical and chemical properties of ceramics. Currently, proper control of these crystal defects is inevitable to tailor ceramic materials with superior properties. This article reviews recent research projects on distinct properties and phenomena in ceramics due to crystal defects. In particular, we would like to emphasize importance of central core regions of crystal defects, namely, “crystal defect cores”. They have specific electronic and atomic structures that are different from those in bulk. Recent advances of nanoscale characterizations and theoretical calculations make it possible to acquire a variety of quantitative data on electronic structures enclosed at the crystal-defect cores, which gives clear understanding of various ceramic properties at the electronic and atomic levels.

著者

Kota Hasegawa Takao Shimizu Naoki Ohashi

出版者

The Ceramic Society of Japan

雑誌

Journal of the Ceramic Society of Japan (ISSN:18820743)

巻号頁・発行日

vol.130, no.7, pp.452-457, 2022-07-01 (Released:2022-07-01)

参考文献数

42

被引用文献数

2

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The density functional theory (DFT) was employed to understand the ferroelectric behaviors of wurtzite (WZ)-type aluminum nitride (AlN). To explain the decrease in the coercive field (Ec) due to lattice deformation, the total energy and enthalpy of the strained WZ phase were compared to those of the non-polar (NP) phase, which acted as a transition state during polarity switching. The shrinkage of the c-axis length and elongation of the a-axis length were favorable for reducing Ec. In addition, the calculated residual stress in the transient NP phase was as high as 30 GPa, suggesting that such a high residual stress may be related to the polarity switching behavior under a very high electric field.

著者

Takeshi HIGUCHI Haruna OIZUMI Tatsuya SASAKI Tadahiro AITA

出版者

The Ceramic Society of Japan

雑誌

Journal of the Ceramic Society of Japan (ISSN:18820743)

巻号頁・発行日

vol.117, no.1368, pp.873-877, 2009 (Released:2009-08-01)

参考文献数

25

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A silica-polymer composite with oriented macropores was fabricated from tetraethoxysilane (TEOS) incorporated with poly(ethylene glycol) (PEG) via a sol-gel method. The solution mixture containing PEG and TEOS after hydrolysis was subjected to shear stress so that the macroporous structure generated by spinodal decomposition during the process of polycondensation to a silica-PEG-rich phase and a solvent-rich phase was elongated and oriented toward the shear flow direction. It was found that shear flow is effective for macropore elongation after the solution mixture becomes turbid. The optimum PEG content for macropore elongation was also revealed. The elongation ratio of the macropores was dependent to a certain extent on the shear rate.

著者

Kengo OKA Wataru NISHIKI Miho TAKASU Naoki NOMA Mitsunobu IWASAKI

出版者

The Ceramic Society of Japan

雑誌

Journal of the Ceramic Society of Japan (ISSN:18820743)

巻号頁・発行日

vol.130, no.1, pp.35-38, 2022-01-01 (Released:2022-01-01)

参考文献数

28

被引用文献数

1

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The crystallographic parameters of fluoro-apatite A5(VO4)3F (A = Pb, Sr, and Ba) were refined by the Rietveld method. The refined parameters indicate that the F− anions in Pb5(VO4)3F occupy sites different from those in Sr5(VO4)3F and Ba5(VO4)3F. The F− anions in Pb5(VO4)3F are located around center of the Pb6 octahedra, while those for Sr5(VO4)3F and Ba5(VO4)3F are located around the center of Sr3 or Ba3 triangle. Our structural analysis suggested that this difference is attributed to the over-bonding state of F− anion in Pb5(VO4)3F. The electron density distribution for F− anions suggests the potential ionic conductivity along the c axis in Pb5(VO4)3F.

著者

Yasushi SATO Chihiro KUMASHIRO Kokoro OKIMOTO Koji TOMITA Masato KAKIHANA

出版者

The Ceramic Society of Japan

雑誌

Journal of the Ceramic Society of Japan (ISSN:18820743)

巻号頁・発行日

vol.130, no.1, pp.49-54, 2022-01-01 (Released:2022-01-01)

参考文献数

37

被引用文献数

2

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Eu2+-activated Ca3MgSi2O8 (Ca3MgSi2O8:Eu2+) phosphors were successfully synthesized by an amorphous metal complex method using propylene glycol-modified silane (PGMS) and heat-treatment under a reduced atmosphere at 1400 °C. The photoluminescence (PL) of Ca3MgSi2O8:Eu2+ was studied as a function of total Eu concentration. Furthermore, Ca3MgSi2O8 with Eu2+ concentrations at 1.0–30 % for Ca exhibited a blue-green emission peaking at approximately 480 nm. In contrast, with increasing Eu2+ concentration up to 50 % for Ca, the emission peak of Ca3MgSi2O8:Eu2+ phosphors exhibited a redshift to 521 nm with green emissions. The redshift of emissions in Ca3MgSi2O8:Eu2+ phosphors could be attributed to the strong electrostatic interactions related to the Eu2+ ions occupying the peculiar Ca sites.

著者

Naoyoshi NUNOTANI Marina TAIRA Nobuhito IMANAKA

出版者

The Ceramic Society of Japan

雑誌

Journal of the Ceramic Society of Japan (ISSN:18820743)

巻号頁・発行日

vol.130, no.1, pp.44-48, 2022-01-01 (Released:2022-01-01)

参考文献数

27

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Green-emitting phosphors of Rb3La1−xTbxSi2O7 with a K3NdSi2O7-type structure were synthesized via a solid-state reaction technique. Their crystal structures and photoluminescence properties were investigated. Crystal structural analyses of Rb3LaSi2O7 and Rb3TbSi2O7 were carried out for the first time and revealed that the rare-earth sites (La or Tb) were separated by the RbO6 and SiO4 units. According to photoluminescence spectroscopy of Rb3La1−xTbxSi2O7 monitored at 249 and 481 nm, the highest emission intensity was obtained for the Rb3TbSi2O7 phosphor under the 481-nm excitation, which indicates that the satisfactory separation of the Tb3+ ions suppressed the concentration quenching. The intensity of Rb3TbSi2O7 was 32 % in comparison to that of the commercial green-emitting (La0.52Ce0.31Tb0.17)PO4 phosphor.

出版者

The Ceramic Society of Japan

雑誌

Journal of the Ceramic Society of Japan (ISSN:18820743)

巻号頁・発行日

vol.129, no.9, pp.H9-1, 2021-09-01 (Released:2021-09-01)

著者

Shungo TAKANO Kiyoto SHIN-MURA Eiki NIWA Takuya HASHIMOTO Kazuya SASAKI

出版者

The Ceramic Society of Japan

雑誌

Journal of the Ceramic Society of Japan (ISSN:18820743)

巻号頁・発行日

vol.126, no.6, pp.482-487, 2018-06-01 (Released:2018-06-01)

参考文献数

32

被引用文献数

1 6

---

Sr2MgMoO6−δ (SMM) is one of promising anode materials for direct internal reforming solid oxide fuel cells as its excellent performance has been demonstrated. However, it is necessary to be chemically compatible with the electrolyte material to realize the original performance. In this study, we investigate chemical compatibility between SMM and typical electrolyte materials (8% mol Y2O3–92% mol ZrO2; YSZ, 10% mol Sc2O3–1% mol CeO2–89% mol ZrO2; ScSZ, La0.9Sr0.1Ga0.8Mg0.2O3−δ; LSGM) and anode interlayer materials (Gd0.1Ce0.9O2−δ; GDC, Ce0.8La0.2O2−δ; LDC) under conditions for preparing SMM electrode and operation. SMM formed a reaction layer with all of the typical electrolyte materials studied. LDC was the only material for the interlayer that maintains chemical compatibility with SMM, though it forms the reaction layer with YSZ and ScSZ. From these results, this study clarifies that LSGM and LDC should be used as electrolyte and interlayer, respectively, when SMM is used as the anode.

著者

Son Thanh NGUYEN Tsuyoshi TAKAHASHI Ayahisa OKAWA Hisayuki SUEMATSU Koichi NIIHARA Tadachika NAKAYAMA

出版者

The Ceramic Society of Japan

雑誌

Journal of the Ceramic Society of Japan (ISSN:18820743)

巻号頁・発行日

vol.129, no.4, pp.209-216, 2021-04-01 (Released:2021-04-01)

参考文献数

33

被引用文献数

12

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In the emerging era of aircraft industry, silicon carbide (SiC) is regarded as an appropriate material for gas turbine engine blades. In order to protect this ceramic component against the oxidation and volatilization in hot steam environments, environmental barrier coating should be utilized. The composite of SiC/Yb2Si2O7–Yb2SiO5 with self-healing ability is a candidate for the top layer of this coating. In this study, the crack-healing behavior of SiC/Yb2Si2O7–Yb2SiO5 nanocomposites is investigated by pre-cracking followed by annealing in oxidizing environments. Comparing to previous studies, the healing time and healing temperature can be reduced to 15 min and 800 °C by increasing the volume fraction of SiC to 20 %. In addition, nanocomposites with both self-healing ability and superior strength were created in this research by combining two types of SiC filler (whiskers and nanoparticulates). The self-healing mechanism in these composites is the SiC oxidation and silicate transformation associated with their volume expansion, which is evidenced by X-ray diffraction and scanning electron microscope. According to the results, the best volume ratio between whisker and nanoparticulate is determined as 1/3.

著者

Tohru SUGAHARA Michitaka OHTAKI Takeshi SOUMA

出版者

The Ceramic Society of Japan

雑誌

Journal of the Ceramic Society of Japan (ISSN:18820743)

巻号頁・発行日

vol.116, no.1360, pp.1278-1282, 2008 (Released:2008-12-01)

参考文献数

35

被引用文献数

31 46

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Doping effects for the A-site in double-perovskite type oxide Sr2-xMxFeMoO6 (M = Ba, La) are investigated on the thermoelectric properties of the oxides. The Seebeck coefficient, S, shows that all the samples of both Ba- and La-doped Sr2FeMoO6 systems are n-type over the measured temperature range. In particular, the power factor, S2σ, of the Sr2FeMoO6 system largely increased with increasing Ba doping level up to x = 0.3. As a consequence, S2σ of Sr1.7Ba0.3FeMoO6 reached ca. 0.8 × 10-4 W/mK2, the largest value of all the samples in this study. The thermal conductivity, κ, shows a general trend in which the value decreases from ca. 1 W/mK at room temperature to ca. 0.7 W/mK at 1100 K. The dimensionless figure of merit, ZT, of the Ba-doped samples increased with increasing Ba doping level. Moreover, the ZT value drastically increased above 700 K due to the S2σ value increasing above 700 K and the κ value decreasing monotonically. As a result, the ZT value of Sr1.7Ba0.3FeMoO6 reached 0.31 at 1100 K.

著者

Kazuya SASAKI Kiyoto SHIN-MURA

出版者

The Ceramic Society of Japan

雑誌

Journal of the Ceramic Society of Japan (ISSN:18820743)

巻号頁・発行日

vol.125, no.6, pp.487-493, 2017-06-01 (Released:2017-06-01)

参考文献数

62

被引用文献数

3 5

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A high purity powder of Sr2MgMoO6−δ (SMM) was synthesized by a solid-state reaction under atmosphere-controlled conditions. The powder was sintered at a relatively low temperature (1200°C) to prepare compacts with high grain boundary density. SMM is a promising anode material for solid oxide fuel cells and hence, the samples were characterized under conditions relevant to this application. The electrical conductivity values of SMM under various oxygen partial pressures (pO2 = 10−15–104.3 Pa) over the temperature range of 300–850°C were measured by AC impedance spectroscopy. The grain boundary resistivity and bulk resistivity exhibited different oxygen-partial-pressure-dependent behavior. Electron conduction is proposed as the primary mechanism for electrical conductivity in the bulk of the sintered body of SMM under both low and high oxygen partial pressures. Electron conduction and oxygen ion conduction were found to be the primary mechanisms for electrical conductivity at the grain boundary of SMM under low and high oxygen partial pressures, respectively.

著者

Zenji YATABE Koshi NISHIYAMA Takaaki TSUDA Yusui NAKAMURA

出版者

The Ceramic Society of Japan

雑誌

Journal of the Ceramic Society of Japan (ISSN:18820743)

巻号頁・発行日

vol.127, no.8, pp.590-593, 2019-08-01 (Released:2019-08-01)

参考文献数

22

被引用文献数

1 2

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Excellent quality amorphous aluminum oxide (AlOx) thin films have been obtained by atmospheric pressure solution-processed mist chemical vapor deposition (mist-CVD) technique at 400°C using water-free solvent. X-ray fluorescence investigations verified the formation of AlOx film by the mist-CVD. X-ray diffraction, X-ray photoelectron spectroscopy, ellipsometry and X-ray reflectivity analyses revealed that the synthesized amorphous AlOx films have bandgap of 6.5 eV, refractive index of 1.64 and mass density of 2.78 g/cm3. These values are comparable to those reported for high-quality amorphous Al2O3 thin films deposited by atomic layer deposition method.

著者

Hiroshi NISHIYAMA Alexander MARTIN Keiichi HATANO Sumiaki KISHIMOTO Nobuhiro SASAKI Kyle G. WEBBER Ken-ichi KAKIMOTO

出版者

The Ceramic Society of Japan

雑誌

Journal of the Ceramic Society of Japan (ISSN:18820743)

巻号頁・発行日

vol.129, no.3, pp.127-134, 2021-03-01 (Released:2021-03-01)

参考文献数

38

被引用文献数

6

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While lead-free (Li,Na,K)NbO3 piezoceramics have a high Curie temperature (TC > 400 °C) and an excellent piezoelectric constant (d33 > 200 pC/N), the process window regarding the sintering temperature and dwelling time is narrow. Inappropriate sintering conditions can induce the volatilization of A-site alkali ions, leading to a deterioration in dielectric and piezoelectric properties. However, the effect of alkali volatilization on the ferroelastic properties is still uncertain. In this study, (Li,Na,K)NbO3 piezoceramics were deliberately exposed to the sintering temperature for varying times to compare the susceptibility of the effect of alkali volatilization on the ferroelastic properties and compared to changes in the ferroelectric and ferroelastic and dielectric properties.

著者

Yusuke ASAKURA Takuya HASEGAWA Shu YIN

出版者

The Ceramic Society of Japan

雑誌

Journal of the Ceramic Society of Japan (ISSN:18820743)

巻号頁・発行日

vol.128, no.12, pp.1061-1065, 2020-12-01 (Released:2020-12-01)

参考文献数

29

被引用文献数

5

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Attention has recently been paid to oxyfluorides, one of the mixed anion materials, because they possess unique properties for many kinds of application fields. Because the general synthesis processes for oxyfluorides are based on troublesome methods, novel safe and facile processes are required. In this study, MoO3 was solvothermally reacted with KF, RbF, and CsF at 200 °C to form potassium, rubidium, and cesium molybdenum oxyfluorides. The reaction of MoO3 with KF and RbF led to the formation of K3MoO3F3 and Rb3MoO3F3 with a known structure, respectively, while the reaction of MoO3 with CsF induced an unknown phase which should be Cs3MoO3F3 with the similar structure to those of K3MoO3F3 and Rb3MoO3F3. A3MoO3F3 (A = K, Rb, and Cs) has not been synthesized under liquid phase until now, and this research clarified this kind of the solvothermal reaction can lead to the formation of unique oxyfluorides at low temperature. In addition, Cs3MoO3F3 was converted into Cs3Mo2O6F3 by treatment with methanol, suggesting the instability of Cs3MoO3F3. This kind of conversion reaction from one oxyfluoride to the other oxyfluoride has not been reported, and the development of such chemical conversion may lead to the formation of new oxyfluorides.

著者

Satoshi YOSHIDA

出版者

The Ceramic Society of Japan

雑誌

Journal of the Ceramic Society of Japan (ISSN:18820743)

巻号頁・発行日

vol.128, no.7, pp.340-348, 2020-07-01 (Released:2020-07-01)

参考文献数

60

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The indentation test using a sharp diamond indenter, such as a Vickers indenter, has been long employed for comparing mechanical properties among various glass compositions, because of its simple procedure and easy operation. However, mechanisms of permanent deformation and crack nucleation in glass are far from simple. This has made it difficult to understand what controls the threshold load for cracking in a certain glass during indentation. In this review, the author’s works on indentation-induced deformation and cracking in glass are introduced, and relevant issues on the indentation technique are discussed. Especially, it is pointed out that permanent densification of glass under the indenter is a key phenomenon which controls the following cracking event. Further, it is also shown that the micro-photoelastic observation system, by which the indentation-induced stress field can be visualized, and the indentation microscope, which enables one to measure the contact area between glass and the indenter, are powerful tools to stimulate new and fresh ideas for improving mechanical properties of glass.

著者

Yuji NAKABAYASHI Satoru YAMADA Satoshi ITOH Takeshi KAWAE

出版者

The Ceramic Society of Japan

雑誌

Journal of the Ceramic Society of Japan (ISSN:18820743)

巻号頁・発行日

vol.126, no.11, pp.925-930, 2018-11-01 (Released:2018-11-01)

参考文献数

32

被引用文献数

10

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Single-crystal thin films of gallium oxide (Ga2O3), an ultra-wide bandgap semiconductor, were fabricated on c-plane sapphire by mist chemical vapor deposition (mist CVD). The grown α-Ga2O3 thin films had low surface roughness, and we characterized their initial crystal growth phase by using atomic force microscopy and X-ray diffraction. By varying the precursor concentration, we changed the surface roughness and crystallinity of the thin films. The lattice constants of the α-Ga2O3 thin films almost matched those of the single crystal in the initial growth phase. We also found that these thin films grew hetero-epitaxially. Finally, mist CVD might have a very short incubation time in this system.