著者

Michele Back Jian Xu Jumpei Ueda Setsuhisa Tanabe

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.131, no.4, pp.57-61, 2023-04-01 (Released:2023-04-01)

参考文献数

26

被引用文献数

3

---

Nd3+-doped Y3Al2Ga3O12 garnet ceramic pellet was prepared by solid state reaction and used as prototype to investigate the potential of Nd3+-activated garnet phosphors as Boltzmann thermometers for cryogenic and high temperature ranges. Despite the conventional use of the near-infrared emitting Nd3+-activated phosphors for biological applications, their real use is hindered by a low sensitivity in the physiological temperature range. Instead, the photoluminescence analysis in the 100–800 K range demonstrated interesting performances in both the cryogenic and high temperature ranges. Indeed, by taking advantage of the Stark levels of 4F3/2 (Z-levels) and the ratio between the emission from the 4F5/2 and the 4F3/2 excited states is possible to build two reliable Boltzmann thermometers in the same material working in the cryogenic temperature range (100–220 K) and at high temperatures (300–800 K), respectively.

著者

Hiroki ITO Akira MIURA Yosuke GOTO Yoshikazu MIZUGUCHI Chikako MORIYOSHI Yoshihiro KUROIWA Nataly Carolina ROSERO-NAVARRO Kiyoharu TADANAGA

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.5, pp.249-253, 2021-05-01 (Released:2021-05-01)

参考文献数

38

被引用文献数

1

---

The magnetic and electronic properties of CeOInS2 and their influence on phase transition were analyzed in this study. High-temperature XRD measurements of CeOInS2 revealed that orthorhombic CeOInS2 transformed into tetragonal CeOInS2 at a high temperature of 636 K. The transport properties of CeOInS2 showed semiconducting behavior, with a larger temperature dependence of electronic resistivity in the tetragonal phase compared to that in the orthorhombic phase. Unlike structurally similar Ce(O,F)BiS2 superconductors that show long-range magnetic ordering, CeOInS2 neither exhibited superconductive transition nor long-range magnetic ordering at temperatures between 2 and 300 K.

著者

Takuma Noda Hanseul Kim Kenta Watanabe Kota Suzuki Naoki Matsui Ryoji Kanno Masaaki Hirayama

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.131, no.10, pp.651-658, 2023-10-01 (Released:2023-10-01)

参考文献数

27

---

The reaction distribution in the composite cathode of an all-solid-state battery (ASSB) was directly tracked by in situ scanning electron microscopy (SEM) combined with energy dispersive X-ray spectroscopy (EDX). Contact between an electrode active material and a solid electrolyte is important for improving the properties of ASSBs as a promising next-generation battery. An in situ analysis is significant for establishing strategies to obtain sufficient contact areas between the active material and solid electrolyte particles. SEM-EDX has the advantages of in-situ measurement in spatial/time resolution, non-destruction, and versatility. We investigated the sensitivity of EDX to the Na signal and distinguishable distance to ensure sufficient spatial/time resolution. The acceleration voltage of 5 kV for the electron beam provided the highest sensitivity to the Na signal among all acceleration voltages. The distinguishable distance decreased with increasing magnification owing to the decrease in pixel size. Cross-sectional SEM-EDX images of the TiS2–Na3PS4/Na3PS4/Na–Sn cell were collected during charge/discharge. The time variation of Na signal intensity confirms the deintercalation of Na+ in the TiS2–Na3PS4 cathode layer. Moreover, intercalation on the solid electrolyte side proceeded faster than that on the current collector side. This was because the rate-determining step was ionic conductivity rather than electronic conductivity based on the difference between ionic and electronic conductivities. Ex situ observations detected only a uniform distribution in the composite after Na+ diffusion had relaxed. Operando SEM-EDX is a new tool to directly explore the intermediate conditions of electrode materials under ASSB operation.

著者

Hiroki Matsuo

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.131, no.8, pp.429-436, 2023-08-01 (Released:2023-08-01)

参考文献数

115

---

Ferroelectric materials exhibit a unique photovoltaic (PV) response that conventional pn junctions of semiconductors do not show. Above bandgap photovoltages, light-polarization-dependent photocurrents, photocurrent generation by terahertz light, etc. in ferroelectric PV effect are attractive features for novel optoelectronic devices. Recent studies on the ferroelectric PV effects have revealed that ferroelastic domain walls (DWs) are an active center for the generation of photocarriers. In this review paper, firstly, the history and status of studies on the DW-PV effect are briefly surveyed. Then, an analysis method that we have developed to experimentally quantify the magnitude of the PV response in the DW regions is introduced for BiFeO3-based ferroelectric epitaxial thin films. Moreover, materials design strategies for further enhancement of the photoresponse based on the engineering of impurity levels, domain structures, and their combinations are presented.

出版者

The Ceramic Society of Japan

雑誌

大日本窯業協會雑誌 (ISSN:03669998)

巻号頁・発行日

vol.35, no.409, pp.Plate1-Plate1, 1927

著者

中平 敦 武田 真一 塩見 治久 大西 宏司

出版者

The Ceramic Society of Japan

雑誌

Journal of the Ceramic Society of Japan (日本セラミックス協会学術論文誌) (ISSN:09145400)

巻号頁・発行日

vol.107, no.1247, pp.662-667, 1999-07-01 (Released:2010-08-06)

参考文献数

29

---

Effect of alcohol solvent in mixing process on the microstructure and sintering behavior of ceramic-based composites was investigated in detail. The mixture of fine ceramic powders was prepared through the conventional ball-milling method with various alcohol media. The particle distributions of fine ceramic powders were strongly dependent on the kind of alcohol employed during ball-milling. Ceramic-based composites were fabricated by hot-pressing the mixture of fine ceramic powders. Their microstructures and some mechanical properties of the ceramic-based composites were evaluated. It was found that the viscosity of alcohol, surface tension and contact angle greatly affect the sinterability and some of the mechanical properties of ceramic-based composites.

著者

佐多 敏之

出版者

The Ceramic Society of Japan

雑誌

Journal of the Ceramic Society of Japan (日本セラミックス協会学術論文誌) (ISSN:09145400)

巻号頁・発行日

vol.107, no.1242, pp.166-173, 1999-02-01 (Released:2010-08-06)

参考文献数

39

被引用文献数

4 3

---

NaCl powder specimens composed of equally sized (approximately 1.8μm), cubic single crystals were prepared by additions of acetone to saturated NaCl solution at -21°C under various preparation conditions. Grain growth during storage of the powder specimens was found to be greatly influenced by moisture in the ambient atmosphere. Storage of the specimens in a furnace at 400°C prevented grain growth. Compacts of the powder specimens produced by cold pressing (CP) and cold isostatic pressing (CIP) were sintered, or the powders were directly hot-pressed (HP). Relative densities (RD) of the resulting sintered bodies depended on the compaction or sintering conditions. From these sintered bodies, appropriate equations relating bending strength with porosity and grain size were obtained. The high-temperature bending strength increased up to 300°C and then decreased at higher temperatures. Deflections observed in the bending tests incerased with sintering temperature, that is, with the increase in grain size. Observed tensile strength values (5-10MPa) were smaller than observed bending strength values (8-20MPa). Measured values of the Weibull coefficient and fracture toughness were m=5.34 and K1C=1.05MPa·m1/2, respectively. Single crystal specimens obtained from melts by the Czochralski method were also subjected to bending tests. These specimens showed large deflections above 200°C, and strain-hardening phenomena were also observed. Tension tests for single crystal whiskers prepared by condensation of vaporized NaCl in a flowing air conducted along the [100] direction, and showed that the strength incresed with the whisker cross sectional area up to a maximum value and then decreased. The highest stregth value was obtained in vacuum with lower values being obtained in dry air and moist air because of the effects of oxygen and moisture, respectively.

著者

Hiroyuki SHIMADA Toshiaki YAMAGUCHI Hirofumi SUMI Yuki YAMAGUCHI Katsuhiro NOMURA

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.4, pp.257-261, 2017-04-01 (Released:2017-04-03)

参考文献数

28

被引用文献数

9 10

---

Perovskite-type mixed protonic and oxide ionic conductors for electrolyte material of solid oxide fuel cells were investigated, focusing on BaZr0.1Ce0.7Y0.1Yb0.1O3−δ (BZCYYb) due to its high ionic conductivity and chemical stability. BZCYYb and NiO-added BZCYYb were evaluated using electrolyte-supported cell (ESC) and anode-supported cell (ASC) samples. 2 wt.% NiO was solid solute into the BZCYYb, resulting in improvement in the sinterability and thermal-expansion behavior. The addition of NiO, however, lead to the deterioration of cell performance. Compared with the ESC, power density of the ASC was much higher due to thin electrolyte, whereas its open-circuit voltage (OCV) was lower. This is due to Ni diffusion from the NiO–BZCYYb anode into the BZCYYb electrolyte during high-temperature co-sintering process at 1350°C. From the results of OCV measurements, 0–2 wt.% NiO was considered to be dissolved in the BZCYYb electrolyte of the ASC, suggesting that controlling Ni diffusion during co-sintering process is essential to achieve higher-performance ASCs using BZCYYb.

著者

Tomohiro ISHIYAMA Haruo KISHIMOTO Katherine DEVELOS-BAGARINAO Katsuhiko YAMAJI Toshiaki YAMAGUCHI Yoshinobu FUJISHIRO

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.4, pp.247-251, 2017-04-01 (Released:2017-04-03)

参考文献数

23

被引用文献数

9 10

---

The perovskite-type proton conductor with the composition of BaZr0.1Ce0.7Y0.1Yb0.1O3−δ (BZCYYb) has been reported to exhibit the highest proton conductivity among proton conductors. However, cerate-based perovskite materials such as BZCYYb are also known to react with carbon dioxide which causes phase decomposition through the formation of barium carbonate. This is a significant issue because chemical stability is an important property to enable these materials to be utilized for fuel cell applications. In this study, the chemical stability of BZCYYb was investigated in CO2 or CO2 + H2 atmosphere, with or without nickel addition as sintering aid. Some nickel addition is assumed to occur from nickel diffusion in anode-support-type fuel cells. The enhancement of reactivity with carbon dioxide species by adding nickel into BZCYYb was attributed to barium enrichment at grain boundary regions and the formation of an impurity phase of Ba(Y(1−x)Ybx)2NiO5. Moreover, different decomposition reactions depending on the atmosphere have been inferred. In a pure CO2 atmosphere, barium carbonate formation occurred without appearance of the CeO2-based phase, in other words, without decomposition of the perovskite phase. On the other hand, in hydrogen-containing CO2 atmosphere, both the barium carbonate and CeO2-based phase were observed.

著者

Takuya Kataoka Yuhi Yasuhira Eiji Fujii Tomohiko Yoshioka Satoshi Hayakawa

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.131, no.9, pp.569-574, 2023-09-01 (Released:2023-09-01)

参考文献数

29

---

In this study, the impact of chitosan (CS) on Mg2+ incorporation into hydroxyapatite (HAp) was investigated. Initial Mg/(Ca+Mg) ratios of 0–0.15 resulted in Mg-incorporated HAp containing CS (CMgHAp), while a ratio of 0.2 yielded amorphous calcium phosphate containing CS. Mg/(Ca+Mg) and (Ca+Mg)/P molar ratios of the obtained CMgHAp particles were lower than those of Mg-incorporated HAp particles without CS, suggesting that Mg incorporation into HAp was suppressed by CS. Initial Mg/(Ca+Mg) ratio of 0.025 led to CMgHAp particles with lower specific surface area than HAp particles containing CS, while ratios of 0.05–0.15 led to particles with higher specific surface area. Transmission electron microscopy showed aggregated particles of CMgHAp, since the observed particle sizes were larger than the crystallite sizes of CMgHAp calculated using X-ray diffraction patterns. Analyses of Fourier transform infrared spectroscopy confirms the interaction of CS with the phosphate group in Mg-incorporated HAp. Calcination of the CMgHAp particles decreased the particle size and increased the specific surface area due to decomposition of CS, indicating that CS aggregated Mg-incorporated HAp particles.

著者

Naoki Tarutani Miki Asanome Kenji Okada Masahide Takahashi Takuo Minato Masahiro Sadakane Kiyofumi Katagiri Kei Inumaru

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.131, no.10, pp.830-836, 2023-10-01 (Released:2023-10-01)

参考文献数

44

---

Additive manufacturing by vat-photopolymerization is important technique to prepare designed objects because of its features of availability, low cost, low energy consumption, and high-speed printing. One of the major challenges of this technique is how to expand the chemical composition towards metals and ceramics in addition to organic compounds. In this paper, we report synthesis of highly concentrated nanocolloids of nickel hydroxide acrylate and use them for vat-photopolymerization. Epoxide-mediated basification induced formation of dispersed nickel hydroxide acrylate monolayer/bilayer nanoparticles (diameter of 2.31 nm). The concentration of nanocolloid was prepared as 2.5 mol L−1 (Ni basis), which corresponds to 43 wt % and 30 vol %. The concentrated nanocolloids enabled to produce objects through vat-photopolymerization by using commercially available 3D printers. Addition of small quantity of organic cross-linker efficiently interconnect nanoparticles to form bulky objects. Owing to the organic moiety of nickel hydroxide salt nanoparticles, metal/carbon composites formed by heat-treatment without any reduction gas supply. Further heat-treatment led metal oxide bulky object with macroporous structure.

著者

Yuichi Shimakawa

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.131, no.10, pp.771-776, 2023-10-01 (Released:2023-10-01)

参考文献数

51

---

Oxides containing unusually high-valence transition-metal ions often exhibit charge transitions to relieve the electronic instabilities. A-site-ordered quadruple perovskites LnCu3Fe4O12 with the unusually high-valence Fe3.75+, which are synthesized under high-pressure conditions, show intermetallic-charge-transfer transitions. In this review article, novel thermo-related functional properties induced by the charge transitions in LnCu3Fe4O12 are highlighted. A large negative-thermal-expansion behavior was observed at the intermetallic-charge-transfer transition temperature. The negative-thermal-expansion property is primarily caused by the size effect of constituent ions by the charge changes. The property is useful for developing materials to compensate the normal positive thermal expansion. Significant latent heat was also found to be provided by the intermetallic-charge-transfer transition in LnCu3Fe4O12. The large latent heat is considered to be related with unusual first-order magnetic entropy change induced by the charge transition. The large entropy change can be utilized for thermal control through a caloric effect, which can make effective energy systems for thermal energy storage and refrigeration.

著者

Daisuke Mori Miho Sato Sou Taminato Nobuyuki Imanishi Kota Suzuki Masaaki Hirayama

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.131, no.10, pp.690-695, 2023-10-01 (Released:2023-10-01)

参考文献数

36

被引用文献数

1

---

Li ionic conductors that are stable to lithium metal with high ionic conductivity are required as solid electrolytes for all-solid-state lithium metal batteries with high energy density. Lithium dendrite growth leading to short-circuit is one of the major issues to solve for developing practical batteries using lithium metal electrodes. We have introduced Li3PO4 (LPO) and Li3BO3 (LBO) as a grain boundary phase in the garnet-type lithium ionic conductor, Li6.25Ga0.25La3Zr2O12 (LGLZ), by co-sintering. The lattice parameters, sinterability, elemental distribution, particle morphology, and electrochemical properties have been investigated. The sinterability has decreased with the introduction of LPO and LBO, while no significant change in the ionic conductivity is observed. The LGLZ with LPO was unstable to Li metal and did not exhibit the improvement of Li plating/stripping. Meanwhile, the LBO introduction into the grain boundary as a functional core increased the critical current density of the short circuit. Li dendrite growth could be suppressed by modifying the grain boundaries of the sintered body.

著者

Kota Suzuki Jinan Cui Jiang Peilu Hanseul Kim Yumi Yamaguchi Satoshi Hori Masaaki Hirayama Ryoji Kanno

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.131, no.10, pp.717-722, 2023-10-01 (Released:2023-10-01)

参考文献数

20

---

In this study, high-sulfur-containing carbon replica (sulfur-rich S-CR) composites were prepared using a melt-diffusion method. Melt diffusion under vacuum enabled the introduction of four times the weight ratio of sulfur into the mesopores of a carbon replica (CR). The obtained sulfur-rich S-CR exhibited an initial discharge capacity of 700 mAh gsulfur−1, indicating the low utilization of sulfur in the composite. The classification of the particle sizes of the solid electrolyte and CR contributed to the improvement in electrochemical performance. An initial discharge capacity of over 1,200 mAh g−1 was confirmed for the S-CR composite using the smaller solid electrolyte and CR prepared via a dry classification process. An analysis of the effect of the additives indicated that the rational design of electronic and ionic conduction pathways is required for higher cycle performance when using sulfur-rich S-CRs.

著者

Takumi Yabuzaki Miho Sato Hanseul Kim Kenta Watanabe Naoki Matsui Kota Suzuki Satoshi Hori Kazuhiro Hikima Satoshi Obokata Hiroyuki Muto Atsunori Matsuda Ryoji Kanno Masaaki Hirayama

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.131, no.10, pp.675-684, 2023-10-01 (Released:2023-10-01)

参考文献数

36

被引用文献数

1

---

Sulfide-type solid electrolytes for all-solid-state lithium-ion batteries are required to have high ionic conductivity, high (electro) chemical stability, and suitable mechanical properties. Compositing different materials is widely performed in developing multifunctional materials. However, only a few studies have investigated sulfide electrolytes due to the concern of lowering ionic conductivity. In this study, composite electrolytes comprising Li10GeP2S12 (LGPS)-type electrolytes and nanosized Al2O3 are fabricated by a solid-state reaction. Al2O3 particles are mainly located in the voids between LGPS particles, whereas very limited oxygen content is substituted for sulfur in the LGPS structure. LGPS–Al2O3 composites exhibit ionic conductivities of ∼5 mS cm−1 without significant changes by compositing Al2O3. LGPS–Al2O3 composites are softer and have higher atmospheric stability than uncomposed LGPS. All solid-state cells that use air-exposed LGPS–Al2O3 as a separator layer exhibit an improved cycle retention compared with that using air-exposed LGPS. These results demonstrate that electrolyte compositing is an effective means of improving other properties while maintaining high lithium ionic conductivity.

著者

Takeshi HAGIWARA Katsuhiro NOMURA Hiroyuki KAGEYAMA

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.2, pp.65-70, 2017-02-01 (Released:2017-02-01)

参考文献数

20

被引用文献数

10 15

---

We synthesized Eu2Zr2O7 and La2Zr2O7 using high purity ZrO2 of extremely low Hf content. The crystal structures of Eu2Zr2O7 and La2Zr2O7 were refined by the Rietveld analysis of the powder X-ray diffraction data (indexed as a cubic pyrochlore-type structure, space group: No.227, Fd3m) measured from 1173 to 298 K in a dry condition and from 1173 to 323 K in a wet condition. The crystal structure of La2Zr2O7 is near to an ideal pyrochlore-type structure, whereas that of Eu2Zr2O7 is a distorted pyrochlore-type structure. The thermal expansion coefficients of Eu2Zr2O7 were larger than those of La2Zr2O7. The value of the equivalent isotropic atomic displacement parameters (Beq) calculated from the anisotropic atomic displacement parameter for the Zr in Eu2Zr2O7 at 298 K was around 1.4 Å2, and the increase of this value in Eu2Zr2O7 with increasing temperature was smaller than that in La2Zr2O7.

著者

Takeshi HAGIWARA Hiroshi YAMAMURA Katsuhiro NOMURA Manabu IGAWA

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.121, no.1410, pp.205-210, 2013-02-01 (Released:2013-02-01)

参考文献数

29

被引用文献数

20 22

---

Crystal structures of the Ln2Zr2O7 (Ln = Nd and La) were refined by the Rietveld analysis of powder neutron diffraction (ND) data at room temperature. La2Zr2O7 had a pyrochlore (P)-type structure of almost completely ordered for oxygen vacancy. On the other hand, Nd2Zr2O7 had the P-type structure for the oxygen vacancy distributed between the O2 (8b) and O3 (48f) sites. The Rietveld refinement results of powder X-ray diffraction (XRD) data of Ln2Zr2O7 (Ln = Eu, Nd and La) indicated that the Ln3+ and Zr4+ ions exist in ordered states in 16c and 16d sites, respectively. The refined lattice parameters (a), occupancies (g) for oxygen sites (O1, O2 and O3) and x-positional parameters for O3 (48f) site of La2Zr2O7 and Nd2Zr2O7 by using powder XRD data were in almost agreement with those by using powder ND data. The refined ND and XRD data of Ln2Zr2O7 (Ln = Eu, Nd and La) system revealed that the O3 (48f) site occupancy (g48f) decreases with increasing O2 (8b) site occupancy, while O1 (8a) site occupancy keeping 1.0. The change in oxide-ion conductivity (σ) in Ln2Zr2O7 (Ln = Eu, Nd and La) system can be related to a change in the product of site occupancy (g48f) and the oxygen vacancy rate (1-g48f) in the O3 (48f) site, g48f(1-g48f).

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

鮫島 宗一郎 河南 学 平田 好洋

出版者

The Ceramic Society of Japan

雑誌

Journal of the Ceramic Society of Japan (日本セラミックス協会学術論文誌) (ISSN:09145400)

巻号頁・発行日

vol.110, no.1283, pp.597-600, 2002-07-01 (Released:2010-08-06)

参考文献数

20

被引用文献数

38 51

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The thermal expansion of CeO2 and rare-earth-doped ceria (Ce0.8R0.2O1.9, R: Yb, Y, Gd, Sm, Nd and La) was measured in the temperature range from 298 to 1473 K. The coefficients of thermal expansion (CTE) were determined by differentiating the thermal expansion expressed by a polynominal equation of temperature with respect to temperature. The CTE (α1) for Ce0.8R0.2O1.9 was in the range from 10×10-6 to 14×10-6K-1 and increased nonlinearly with increasing temperature. This result was explained by the asymmetric curve of potential energy based on the lattice energy theory. The kinds of dopant gave small effect on the α1 of rare-earth-doped ceria. On the other hand, the average CTE for CeO2 and rare-earth-doped ceria (12.0-12.5×10-6K-1), determined from a linear approximation of thermal expansion with respect to temperature at 298-1273 K, was lower than the α1 and close to the previously reported values.

著者

水野 正雄 山田 豊章

出版者

The Ceramic Society of Japan

雑誌

Journal of the Ceramic Society of Japan (日本セラミックス協会学術論文誌) (ISSN:09145400)

巻号頁・発行日

vol.97, no.1131, pp.1334-1338, 1989-11-01 (Released:2010-08-06)

参考文献数

11

被引用文献数

1 3

---

In the phase diagram study on the system Ga2O3-Sm2O3, the liquidus and eutectic temperatures were measured from the cooling curves of specimens by the specular reflection method with a heliostat type solar furnace. Quenched specimens from the melt were examined by X-ray diffractometry and chemical analysis. In the system, four compounds were found; garnet-type 3Sm2O3⋅5Ga2O3, perovskite-type SmGaO3, monoclinic 2Sm2O3⋅Ga2O3 and orthorhombic 3Sm2O3⋅Ga2O3. These compounds, showed no phase transition during repeated heating and cooling cycles. The compound 3Sm2O3⋅Ga2O3 was found to melt incongruently at 1755±20°C. The lattice parameter were determined to be a0=12.431Å for 3Sm2O3⋅5Ga2O3, a0=7.658Å, b0=10.856Å, c0=11.560Å, β=109.240 for 2Sm2O3⋅Ga2O3 and a0=11.400Å, b0=5.515Å, c0=9.070Å for 3Sm2O3⋅Ga2O3. The solidification points of 3Sm2O3⋅5Ga2O3 and 2Sm2O3⋅Ga2O3 were determined as 1680±20°C, and 1708±20°C, respectively. The phase diagram shows three eutectic points at 1555°C, 1640°C, and 1690°C with 22.5, 55, and 70mol% Sm2O3 composition, respectively. A high temperature phase diagram for Ga2O3-Sm2O3 system was proposed.