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Express Letter
published : vol. 129, no. 10, October 2021
Yusuke DAIKO, Junki KATO, Sawao HONDA and Yuji IWAMOTO
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A few GPa-order high-pressure impedance measurement was performed by utilizing an indentation method, which is often used to evaluate mechanical characteristics, and the alternating current (AC) impedance method simultaneously. We succeeded in estimating the activation volume (Δ V = 3.2 cm3/mol) for O2− ion conduction of YSZ with a single sweep of load at 0.25 N/s up to 25 N. Such a quick and easy method for determining Δ V is completely new that has not been proposed so far.
The 75th CerSJ Awards for Advancements in Ceramic Science and Technology; Paper
Special Article
published : vol. 129, no. 9, September 2021
Kengo OKA
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Studies on mixed anion compounds require determination of its anion order. The characteristics of mixed anion compounds vary depending on presence of anion order. Here, we found that application of the steric effect arose from 6s2 lone pair electrons of Pb2+ induces O/F anion order in oxyfluorides. Functional properties such as a high dielectric constant and visible light photocatalysis were found in the Pb-containing oxyfluorides. These properties are strongly correlated with the O/F anion order. On the other hand, when O/F anion order is absent, mixing anion just act as electron doping on cations. Electron doping induced by mixing O2− and F led a colossal negative thermal expansion in PbVO3−xFx oxyfluoride. Material design based on O/F anion order is promising for the development of applications of ceramics materials.
Full Paper
published : vol. 129, no. 9, September 2021
Bin FENG, Akihito KUMAMOTO, Koji MATSUI, Masatoshi TANEMURA, Masato YOSHIYA, Hidehiro YOSHIDA and Yuichi IKUHARA
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Atomic structure of the surfaces in commercial 3 mol % yttria-doped tetragonal zirconia (TZP) nano-particulate powders were studied by atomic resolution scanning transmission electron microscopy (STEM), and the surface segregation of Y were investigated by STEM energy-dispersive X-ray spectroscopy (EDS) at atomic scale. STEM-EDS observations revealed that the Y cations tend to segregate on the top surface layer, forming a monolayer segregation structure. Static lattice calculations revealed that the surface segregation of Y is energetically favorable. These results indicate that Y surface segregation occurs in the TZP powders, which might partially account for the grain boundary segregation in the sintered body of TZP ceramics.
Full Paper
published : vol. 129, no. 9, September 2021
Xuehai ZHOU, Ke ZHOU, Tianchi ZHANG, Lining FAN, Hongbo ZHANG and Hui ZHENG
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The regulation of magnetic and dielectric properties for hexagonal barium ferrites by ion doping is highly desirable in magnetic recording and microwave absorption. Herein, aluminum (Al)-substituted barium hexaferrite with the general formula of BaFe12−xAlxO19 (x: 0, 0.6, 1,2, 1.8) was obtained. The influences of the Al3+ doping concentration on the crystal structure, microstructure, static magnetic, complex dielectric and permeability properties of hexagonal barium ferrites were studied. The morphologies and crystal structure characterizations confirm the Al3+ ion has effective doping in the hexagonal barium ferrites and substituted for Fe3+ in positions of 2b site. The lattice parameters and grain size of the hexagonal barium ferrites were dependent on the doping concentration. The magnetic characterization displays the saturation magnetization decrease while the coercivity increase with the doping concentration. The high-value about 8249 Oe of coercivity can be obtained at x = 1.8. The dielectric properties measurement further indicates that Al doping could improve both real and imaginary parts of permittivity. The highest value of the real part of permittivity was obtained at x = 1.2. Lastly, the complex permeability spectrum displayed the doping of Al ions not only regulate the complex permeability but also influence the domain wall resonance frequency, which is significant for controlling the application frequency.
Full Paper
published : vol. 129, no. 9, September 2021
Honghua LI, Gang HE, Nan LU and Jiangtao LI
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Zr1−xTixC (x = 0, 0.2, 0.4, 0.6, 0.8, 1) solid solution ceramics were fabricated by flash spark plasma sintering (FSPS). The phase composition, microstructure, and mechanical property of the flash sintered ceramics were investigated. The results showed that the composition of Zr1−xTixC solid solution plays a key role on the densification of the ceramics. A high relative density (98.6 %) and hardness (>20 GPa) was achieved in a solid solution composition of Zr0.4Ti0.6C. The unique in-situ high temperature, fast cooling rate, and mold-free sintering in the FSPS sintering process leads to the formation of gradient microstructure in Zr1−xTixC solid solution, where the corresponding density and hardness show gradient distribution characteristics.
Full Paper
published : vol. 129, no. 9, September 2021
Hideyuki HIRAZAWA, Reika MATSUMOTO, Masanori SAKAMOTO, Uyanga ENKHNARAN, Deleg SANGAA, Tatiana Yu. KISELEVA, Jun YANO, Hiroshi FUKUOKA and Hiromichi AONO
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Fine Y3Fe5O12 (YIG) powder with self-heat generation ability in an AC magnetic field was prepared by a modified co-precipitation method and calcined at 600–1100 °C. Using this method, a single phase of the YIG ferrite structure was obtained at a low calcination temperature. The heat generation ability of the modified synthesis sample with a particle diameter of ∼120 nm in a AC magnetic field was significantly improved. The correlation between heat generation ability and hysteresis loss was not confirmed for this sample, which suggests that the heat generation of YIG ferrite powder might have been caused by another factor that differs from the magnetic loss.
Full Paper
published : vol. 129, no. 9, September 2021
Takayuki NONOYAMA, Lei WANG, Ryuji KIYAMA, Naohiro KASHIMURA, Kazunori YASUDA, Shinya TANAKA, Takayuki KUROKAWA and Jian Ping GONG
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Double network (DN) hydrogels, possessing biocompatibility, low sliding friction, high strength and toughness, are promising as artificial cartilages for next-generation joint disease treatment. For such application, a fast and robust fixation of DN hydrogel to bone tissue in vivo is indispensable. However, bonding the DN hydrogel that contains ∼90 wt % of water to bone is a grand challenge since glues do not work on hydrated surfaces. Recently, we reported that a DN hydrogel of its subsurface hybridized with low crystalline hydroxyapatite (HAp) can achieve robust fixation to bone after 4 weeks implantation in rabbit knees, owing to the HAp-induced osteogenesis penetration into the hydrogel matrix. For clinical application, achieving a quick fixation at the early stage of implantation remains as a next subject. In this study, instead of HAp, we hybridized calcium monohydrogen phosphate (monetite), which is a HAp precursor calcium phosphate salt, in the subsurface of the DN hydrogel and we observed an increase in the pushout resistance of the DN hydrogel to bone after 1 week implantation, prior to the HAp-induced osteogenesis penetration. In physiological environment, the monetite hybridized in the subsurface of the DN gel spontaneously dissolved to calcium and phosphate ions and then re-crystallized to more stable HAp. We consider that the HAp formed in the boundary between the gel and the bone forms physical interlocking that significantly enhances the frictional resistance against the pushout force. The fast temporally pre-fixation to the bone by monetite surface hybridization makes one step closer to the clinical application of the DN gels as artificial cartilages.
Technical Report
published : vol. 129, no. 9, September 2021
Hiromichi TAKEBE, Mayuna OKAMOTO and Kentaro MORI
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Gold ruby glasses were fabricated by melt quenching and subsequent isothermal treatment using solar panel glass cullet with B2O3 and Au. In this study, the effect of B2O3 addition on the melt viscosity was evaluated. Moreover, the B2O3 concentration and melting conditions were optimized to prepare homogeneous glass samples at laboratory scale. As a raw material of gold, Au2O3 powder with 0.014 mass % was added into aqua regia via a known dissolution process. The Sb2O3 constituent (∼0.2 mol %) contained in the glass cullet probably played the role of a reducing agent for gold. Homogeneous red glasses were obtained through isothermal treatments at 600–620 °C for ten days.
Technical Report
published : vol. 129, no. 9, September 2021
Rayko SIMURA, Hisanori YAMANE, Terutoshi SAKAKURA and Kazumasa SUGIYAMA
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A single crystal X-ray diffraction (XRD) measurement system composed of white X-rays from an in-house X-ray generator, a four-circle diffractometer, and a compact energy dispersive detector was constructed to acquire XRD data including the effect of anomalous scattering of X-rays with selective energy. The obtained data are available for crystal structure analysis to determine the atomic positions of a specific element by the δ-synthesis method. A single crystal of Sr3Y(BO3)3 containing neighboring elements of Sr and Y, which could not be distinguished by conventional XRD analysis, was tested to demonstrate the performance of the present system.