Journal of the Japan Society of Powder and Powder Metallurgy
Online ISSN : 1880-9014
Print ISSN : 0532-8799
ISSN-L : 0532-8799
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Volume 61, Issue 1
January
Displaying 1-10 of 10 articles from this issue
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Special Issue: Functionall Oxide Materials
Summarization
Memorial Lecture of JSPM Award
  • Study on Fabrication of Novel Monolithic and Hybrid Materials by Combined Use of Newly Synthesized Ceramics Powders and Various Kinds of Sintering Methods
    Ken HIROTA
    2014 Volume 61 Issue 1 Pages 3-10
    Published: January 15, 2014
    Released on J-STAGE: March 23, 2014
    DOIhttps://doi.org/10.2497/jjspm.61.3
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    Bronze-type TiO2(B) single-crystal fibers with several microns in length and 300～400 nm in diameter, were synthesized from anatase TiO2 by the supercritical fluid hydrothermal treatment at c.a. 375～425 ˚C under 23～37 MPa in 10 mol • L−1 NaOH aq. followed by ion-exchange of Na to H in dilute HCl aq. and post-heating at 400 ˚C for 5 h in air. Thus prepared TiO2(B) fibers were characterized by XRD analysis, SEM/TEM observations, ED analysis, DTA/TG and BET surface area measurements. Electrical conductivity of the fibers was also evaluated using “Nano-probe” measurement system. Compared to the conventional TiO2(B) fibers prepared from the normal hydrothermal treatment at c.a.185 ˚C for 8 h, the present TiO2(B) showed higher thermal stability; TiO2(B) phase was stable even after heating at 800 ˚C for 1 h in air. And they show an extreme high electrical conductivities of 1.2 ～1.3 S • m−1; they were higher 1011 and 1.5 times than those of anatase TiO2 and conventional TiO2(B), respectively
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Review
  • High Refractive Index Glasses Prepared by Containerless Processing
    Atsunobu MASUNO
    2014 Volume 61 Issue 1 Pages 11-17
    Published: January 15, 2014
    Released on J-STAGE: March 23, 2014
    DOIhttps://doi.org/10.2497/jjspm.61.11
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    TiO2 – based and Nb2O5 – based glasses without any network former oxides were prepared by containerless processing. The glasses exhibit excellent optical properties such as high refractive index with low wavelength dispersion, and transparency in visible light. It was indicated that the high refractive index is caused by unusual dense state of highly ionic constituent elements. Structural analyses revealed that the dense packed structure is realized because oxygen coordination numbers of cations are rather larger than those of conventional oxide glasses and the cation-oxygen polyhedra are connected to each other not only by corner-sharing but also edge – or face sharing. These results raise the possibility that novel higher refractive index with lower wavelength dispersion glasses, which contain highly ionic heavy elements at the lower left in the periodic table, may be synthesized.
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Paper
  • Synthesis and Thermoelectric Properties of Carrier-Doped CuFeS2 Sintered Samples
    Naohito TUJII, Takao MORI
    2014 Volume 61 Issue 1 Pages 18-27
    Published: January 15, 2014
    Released on J-STAGE: March 23, 2014
    DOIhttps://doi.org/10.2497/jjspm.61.18
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    Carrier-doped CuFeS2 samples have been synthesized by a solid-state reaction (SSR) and the spark-plasma sintering (SPS) methods, and the relation between the synthesis conditions and the thermoelectric properties is shown. Samples prepared by SSR have a density less than 80 %, while SPS samples show a high density close to 100 %. This results in the great improvement to reduce the electrical resistivity (ρ) in the SPS samples. ρ is further reduced by the subsequent annealing. Seebeck coefficient S shows large negative values for all the samples. S of Fe – and Zn – doped CuFeS2 samples are almost independent to the sample preparation methods. As a result, power factor S2/ρ of the SPS and annealed samples have almost doubled from that of the SSR samples, reaching 1 mW/K2m at 400 K.
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  • Evaluation of Defect Structure in Piezoelectric Multilayer using Raman Spectroscopy
    Takeshi TAI, Hiromi SHIMA, Ken NISHIDA, Takashi YAMAMOTO
    2014 Volume 61 Issue 1 Pages 28-34
    Published: January 15, 2014
    Released on J-STAGE: March 23, 2014
    DOIhttps://doi.org/10.2497/jjspm.61.28
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    Degradation effects in piezoelectric multilayer ceramic (PZT – PML) have been investigated by optical microscopy and Raman spectroscopy. Optical microscopy with dark field revealed that black color points were existed in PZT – PML after conducted by HALT – test. These black color points existed intensively in PZT layer near the negative electrode of PZT – PML. Moreover, we have investigated these black color points by Raman spectroscopy. The Raman spectra of the black color points show some difference compared with Raman spectra at normal colored area. The black color points shows the increase of relative intensity ratio E(2TO)/E+B1 mode and simultaneously the decrease of relative intensity ratio A1(3TO)/E+B1 mode. These changes of peak intensity have discussed with structural change.
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  • Suppression of Temperature Hysteresis of Negative Thermal Expansion Induced by Charge Transfer in BiNi1−xFexO3
    Koichiro NABETANI, Kengo OKA, Masaki AZUMA
    2014 Volume 61 Issue 1 Pages 35-38
    Published: January 15, 2014
    Released on J-STAGE: March 23, 2014
    DOIhttps://doi.org/10.2497/jjspm.61.35
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    BiNiO3 is a perovskite compound with a triclinic crystal structure and an unusual oxidation state of Bi3+0.5Bi5+0.5Ni2+O3 at ambient condition. Partial substitution of La3+ for Bi destabilizes the charge disproportionation of Bi into Bi3+ and Bi5+ and orthorhombic (Bi, La)3+Ni3+O3 state appears at high temperature. Because of the shrinkage of the Ni – O bond length, the high-temperature phase has smaller volume. The coexistence of both phases changing their fractions in Bi0.95La0.05NiO3 leads to a negative thermal expansion (NTE) with a dilatometric thermal expansion coefficient of − 82 × 10−6 /K, three times as large as the existing compound. This phenomenon is generally observed in Bi1−xLnx NiO3 (Ln: lanthanide ions). NTE is also expected for BiNi1−xMxO3 (M: trivalent ions) because Ni substitution with other trivalent ion stabilizes Bi3+(Ni, M)3+O3 state. The presence of 50 K hysteresis between the heating and cooling cycles of Bi1−xLnx NiO3 owing to the first order nature of the transition might be a problem for the practical application. From an analogy to relaxer ferroelectrics, suppression of the temperature hysteresis is also expected for BiNi1−xMxO3. BiNi1−xFexO3 samples showed NTE with reduced hysteresis compared with Ln substituted samples. This result strongly suggests that the phase transition is approaching to the second-order like.
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  • Preparation of Epoxy Resin/BiNiO3 Composites with Reduced Thermal Expansion
    Yuya MURAMATSU, Koichiro NABETANI, Kengo OKA, Masaki AZUMA
    2014 Volume 61 Issue 1 Pages 39-43
    Published: January 15, 2014
    Released on J-STAGE: March 23, 2014
    DOIhttps://doi.org/10.2497/jjspm.61.39
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    Thermal expansion causes problems in semiconductor industry and optical communications where precise positioning is required. There are a few materials that show negative thermal expansion (NTE). It was recently found that perovskite Bi1−xLaxNiO3 and BiNi1−xFexO3 show giant NTE around room temperature. In this study, the effect of these NTE materials as filler on the thermal expansion of epoxy resin was investigated. Bi0.95La0.05NiO3 and BiNi0.85Fe0.15O3 powders were prepared by high-pressure synthesis at 6 GPa and 1000 ˚C and were dispersed as filler in a liquid epoxy resin followed by curing for 1 hour at 150 ˚C to form composites. Structural transition of the filler materials as an origin of NTE was confirmed by XRD measurement. The thermal expansion was evaluated by thermal mechanical analyzer (TMA) and strain gauge measurements. The structural phase transitions of the fillers from the triclinic low-temperature to orthorhombic high-temperature phases were confirmed by the temperature variation of XRD patterns. The dilatometric curve showed plateaus owing to the NTE of fillers. It should be noted that, the linear thermal expansion coefficient of 21 vol% BiNi0.85Fe0.15O3/epoxy resin composite was negative (～− 14 ppm/K) between 300 and 310 K.
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  • Crystal Structure and Electrical Properties of (1 −x)BiFeO3–xBiCoO3 Thin Films Prepared by Pulsed Laser Deposition
    Ko ONUMA, Hajime HOJO, Yuichi IKUHARA, Masaki AZUMA
    2014 Volume 61 Issue 1 Pages 44-49
    Published: January 15, 2014
    Released on J-STAGE: March 23, 2014
    DOIhttps://doi.org/10.2497/jjspm.61.44
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    BiFeO3 (BFO) has attracted much attention because of its room-temperature multiferroic properties with a ferroelectric Curie temperature of TC～830 ˚C and an antiferromagnetic Néel temperature of TN～370 ˚C. Concerning the electrical properties, although its spontaneous polarization is as large as ～100 µC/cm2, the piezoelectric constant (d33～60 pm/V) is far smaller than those of lead containing piezoceramics, such as Pb(Zr,Ti)O3 (PZT). An improved piezoelectric response is expected in the solid solution of rhombohedral BFO and tetragonal BiCoO3, (1− x)BiFeO3 – xBiCoO3 (BFCO), owing to the presence of morphotropic phase boundary (MPB)1) similar to PZT. In this study,epitaxial thin films of BFCO with x = 0 − 0.1 were prepared on SrRuO3(SRO)(001)/SrTiO3(STO)(001) substrates by pulsed laser deposition, and their crystal structure and electrical properties were investigated. We successfully obtained single phase of epitaxial BFCO thin films with well-saturated polarization-electric field hysteresis loops at room temperature. Sharp BFCO/SRO and SRO/STO interfaces without intermixing and a good quality of BFCO were found by transmission electron microscopy. The effective d33 estimated from the slope of the displacement-electric curve of the BFO film was ～60 pm/V, which is comparable to that reported by other investigators. The d33 value of the BFCO thin film increased with increasing Co content and reached ～100 pm/V at x = 0.1.
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