All issues
Volume 32 (2005)
- Issue 5 Pages 218-
- Issue 4 Pages 162-
- Issue 3 Pages 110-
- Issue 2 Pages 70-
- Issue 1 Pages 2-
Volume 32, Issue 5
Displaying 1-6 of 6 articles from this issue
- |<
- <
- 1
- >
- >|
-
Tetsuya Hasegawa, Sohei Okazaki2005 Volume 32 Issue 5 Pages 218-225
Published: November 30, 2005
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSScanning tunneling microscopes (STM) that can operate under UHV at low temperatures have been developed. STM observations of Bi-based oxide superconductors have shown that Pb atoms occupying Bi sites and Sr-site defects could be imaged selectively by appropriately setting bias voltage. Furthermore, scanning tunneling spectroscopic measurements have successfully visualized electronic phase separation into superconducting and non-superconducting domains. A variable temperature SPM instrument with sub-micron scale resolution and wide scanning range up to 15mm has also been constructed. The instrument enables us to measure local magnetic and electric properties by using a miniature SQUID sensor and cylindrical resonator tube, respectively, as scanning probes. The former was applied to direct observation of vortices trapped in La1-xSrxCuO4. The latter was utilized to investigate conductivity of a Mn-based oxide, Nd1-xSrxMnO3, as functions of chemical composition x and temperature, in a systematic manner.View full abstractDownload PDF (4114K) -
Natsuko Sakai2005 Volume 32 Issue 5 Pages 226-231
Published: November 30, 2005
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSThe data of heat capacity, thermal conductivity, and thermal expansion behavior for materials in solid oxide fuel cells (SOFCs) are reviewed. Most of the SOFC materials are complex metal oxides and their thermal conductivities are generally low, that causes a large temperature distribution during the operation. Since the SOFC consists of metal oxides and composites, a good thermal expansion matching is the most important point in order to fabricate durable cells and stacks. The electrolytes and interconnects are exposed in a large gradient of oxygen partial pressure at a high temperature, and isothermal expansion is observed for rare earth substituted ceria and alkaline earth substituted lanthanum chromites. Although the isothermal expansion in lanthanum chromites can be alleviated by substituting the transition metals, it can not in rare earth substituted ceria.View full abstractDownload PDF (836K) -
Ove Andersson, Hiroshi Suga2005 Volume 32 Issue 5 Pages 232-240
Published: November 30, 2005
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSAlmost all the numerous forms of ice including 13 crystalline phases, several distinct amorphous states as well as clathrate hydrates have been characterized in terms of their thermal conductivity κ. A few deviations from both the typically strongly decreasing κ(T)(κ∼T-1) associated with crystals and the weakly increasing κ(T) associated with glassy states are observed. In particular, the crystalline clathrate hydrates show glass-like κ, whereas low-density amorphous (LDA) ice shows crystal-like κ(κ∼T-0.6). The latter is unique for an amorphous state and indicates that LDA ice exhibits a surprisingly high degree of structural order that allows for high-frequency phonon propagation. It also implies that LDA ice is not the glassy counterpart of ambient liquid water that shows typical amorphous-like behavior. Moreover, the crystalline ices Ih and Ic and LDA ice exhibit abnormal negative pressure coefficients of κ. Both ices Ih and Ic demonstrate pressure-induced amorphization to high-density amorphous (HDA) ice, a state to which also LDA ice transforms on pressurization. The negative pressure coefficient is a signature of phonon softening which leads to a disordering transition upon pressurization.View full abstractDownload PDF (1591K) -
Haruhiko Yao, Kenji Ema2005 Volume 32 Issue 5 Pages 241-248
Published: November 30, 2005
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSPhase transitions and critical phenomena have been central subjects in condensed-matter physics, where calorimetric investigations play a significant role. In this review, we focus on the study of critical heat anomaly in liquid crystalline phase transitions. Liquid crystals exhibit amazingly wide variety of phases, and therefore provide attractive examples for studying the phase transitons and critical phenomena. First, some of the basic liquid crystalline phases are described, and then elementary ideas of critical phenomena and universality are briefly reviewed. Developments in high-precision calorimetric techniques have greatly contributed to the investigations of critical phenomena in liquid crystal systems. In this review, analyses of critical heat anomalies have been described in detail: necessity of including critical constant term, correction terms, and also data-range shrinking, etc. Finally, examples of recent investigations are shown. The critical heat anomaly observed in antiferroelectric liquid crystals exhibits crossover from 3D XY to tricritical behavior. The results on the de Vries Sm-A-Sm-C phase transition are also displayed.View full abstractDownload PDF (1640K) -
II. Gelling SystemsFumihiko Tanaka, Yukinori Okada2005 Volume 32 Issue 5 Pages 249-255
Published: November 30, 2005
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSTheory of associating polymer solutions introduced in Part I is applied to thermoreversible gelation induced by pairwise cross-links of polymers. Phase diagrams showing coexisting phase separation and gelation are derived. The theory is then extended to gelation with multiple cross-links to study aqueous solutions of associating polymers whose network junctions are formed by micelles of hydrophobic groups. The effect of hydration leading to phase diagrams with LCST coexisting with low-temperature gelation is studied and compared with the recent experiments.View full abstractDownload PDF (1646K) -
2005 Volume 32 Issue 5 Pages 256-257
Published: November 30, 2005
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSDownload PDF (329K)
- |<
- <
- 1
- >
- >|